I was unable to find a how long canned soda takes to get cold in the refrigerator but I have provided you a link to an experiment on to figure out what is the fastest way to cool a soda.
Canning is a method of preserving food in which the food contents are processed and sealed in an airtight container. Canning provides a typical shelf life ranging from one to five years, although under specific circumstances a freeze-dried canned product, such as canned, dried lentils, can last as long as 30 years in an edible state.
In 1795 the French military offered a cash prize of 12,000 francs for a new method to preserve food. Nicolas Appert suggested canning and the process was first proven in 1806 in test with the French navy and the prize awarded in 1809 or 1810. The packaging prevents microorganisms from entering and proliferating inside.
To prevent the food from being spoiled before and during containment, a number of methods are used: pasteurisation, boiling (and other applications of high temperature over a period of time), refrigeration, freezing, drying, vacuum treatment, antimicrobial agents that are natural to the recipe of the foods being preserved, a sufficient dose of ionizing radiation, submersion in a strong saline solution, acid, base, osmotically extreme (for example very sugary) or other microbially-challenging environments.
Other than sterilization, no method is perfectly dependable as a preservative. For example, the microorganism Clostridium botulinum (which causes botulism), can only be eliminated at temperatures above the boiling point.
From a public safety point of view, foods with low acidity (a pH more than 4.6) need sterilization under high temperature (116-130 °C). To achieve temperatures above the boiling point requires the use of a pressure canner. Foods that must be pressure canned include most vegetables, meat, seafood, poultry, and dairy products. The only foods that may be safely canned in an ordinary boiling water bath are highly acidic ones with a pH below 4.6, such as fruits, pickled vegetables, or other foods to which acidic additives have been added.
During the first years of the Napoleonic Wars, the French government offered a hefty cash award of 12,000 francs to any inventor who could devise a cheap and effective method of preserving large amounts of food. The larger armies of the period required increased and regular supplies of quality food. Limited food availability was among the factors limiting military campaigns to the summer and autumn months. In 1809, Nicolas Appert, a French confectioner and brewer, observed that food cooked inside a jar did not spoil unless the seals leaked, and developed a method of sealing food in glass jars. The reason for lack of spoilage was unknown at the time, since it would be another 50 years before Louis Pasteur demonstrated the role of microbes in food spoilage. However, glass containers presented challenges for transportation.
Glass jars were largely replaced in commercial canneries with cylindrical tin or wrought-iron canisters (later shortened to "cans") following the work of Peter Durand (1810). Cans are cheaper and quicker to make, and much less fragile than glass jars. Glass jars have remained popular for some high-value products and in home canning. Can openers were not invented for another thirty years — at first, soldiers had to cut the cans open with bayonets or smash them open with rocks. The French Army began experimenting with issuing canned foods to its soldiers, but the slow process of canning foods and the even slower development and transport stages prevented the army from shipping large amounts across the French Empire, and the war ended before the process was perfected. Unfortunately for Appert, the factory which he had built with his prize money was razed in 1814 by Allied soldiers invading France.
Following the end of the Napoleonic Wars, the canning process was gradually employed in other European countries and in the US.
Based on Appert's methods of food preservation, the tin can process was allegedly developed by Frenchman Philippe de Girard, who came to London and used British merchant Peter Durand as an agent to patent his own idea in 1810. Durand did not pursue food canning himself, selling his patent in 1811 to Bryan Donkin and John Hall, who were in business as Donkin Hall and Gamble, of Bermondsey. Bryan Donkin developed the process of packaging food in sealed airtight cans, made of tinned wrought iron. Initially, the canning process was slow and labour-intensive, as each large can had to be hand-made, and took up to six hours to cook, making canned food too expensive for ordinary people. The main market for the food at this stage was the British Army and Royal Navy. By 1817 Donkin recorded that he had sold £3000 worth of canned meat in six months. In 1824 Sir William Edward Parry took canned beef and pea soup with him on his voyage to the Arctic in HMS Fury, during his search for a northwestern passage to India. In 1829, Admiral Sir James Ross also took canned food to the Arctic, as did Sir John Franklin in 1845. Some of his stores were found by the search expedition led by Captain (later Admiral Sir) Leopold McLintock in 1857. One of these cans was opened in 1939, and was edible and nutritious, though it was not analysed for contamination by the lead solder used in its manufacture.
Throughout the mid-19th century, canned food became a status symbol amongst middle-class households in Europe, becoming something of a frivolous novelty. Early methods of manufacture employed poisonous lead solder for sealing the cans, which may have worsened the disastrous outcome of the 1845 Franklin expedition to chart and navigate the Northwest Passage.][
Increasing mechanisation of the canning process, coupled with a huge increase in urban populations across Europe, resulted in a rising demand for canned food. A number of inventions and improvements followed, and by the 1860s smaller machine-made steel cans were possible, and the time to cook food in sealed cans had been reduced from around six hours to thirty minutes.
Canned food also began to spread beyond Europe — Robert Ayars established the first American canning factory in New York City in 1812, using improved tin-plated wrought-iron cans for preserving oysters, meats, fruits and vegetables. Demand for canned food greatly increased during wars. Large-scale wars in the nineteenth century, such as the Crimean War, American Civil War, and Franco-Prussian War introduced increasing numbers of working-class men to canned food, and allowed canning companies to expand their businesses to meet military demands for non-perishable food, allowing companies to manufacture in bulk and sell to wider civilian markets after wars ended. Urban populations in Victorian Britain demanded ever-increasing quantities of cheap, varied, quality food that they could keep at home without having to go shopping daily. In response, companies such as Underwood, Nestlé, Heinz, and others provided quality canned food for sale to working class city-dwellers. In particular, Crosse and Blackwell took over the concern of Donkin Hall and Gamble. The late 19th century saw the range of canned food available to urban populations greatly increase, as canners competed with each other using novel foodstuffs, highly decorated printed labels, and lower prices.
Demand for canned food skyrocketed during World War I, as military commanders sought vast quantities of cheap, high-calorie food to feed their millions of soldiers, which could be transported safely, survive trench conditions, and not spoil in transport. Throughout the war, soldiers generally subsisted on low-quality canned foodstuffs, such as the British "Bully Beef" (cheap corned beef), pork and beans and Maconochies Irish Stew, but by 1916 widespread boredom with cheap canned food amongst soldiers resulted in militaries purchasing better-quality food to improve morale, and the complete meals in a can began to appear. In 1917 the French Army began issuing canned French cuisine, such as coq au vin, while the Italian Army experimented with canned ravioli and spaghetti bolognese. Shortages of canned food in the British Army in 1917 led to the government issuing cigarettes and amphetamines to soldiers to suppress their appetites. After the war, companies that had supplied military canned food improved the quality of their goods for civilian sale.
Today, tin-coated steel is the material most commonly used. Laminate vacuum pouches are also used for canning, such as used in MREs and Capri Sun drinks.
Invented in 1888 by Max Ams, modern double seams provide an airtight seal to the tin can. This airtight nature is crucial to keeping micro-organisms out of the can and keeping its contents sealed inside. Thus, double seamed cans are also known as Sanitary Cans. Developed in 1900 in Europe, this sort of can was made of the traditional cylindrical body made with tin plate. The two ends (lids) were attached using what is now called a double seam. A can thus sealed is impervious to contamination by creating two tight continuous folds between the can’s cylindrical body and the lids. This eliminated the need for solder and allowed improvements in manufacturing speed, reducing cost.
Double seaming uses rollers to shape the can, lid and the final double seam. To make a sanitary can and lid suitable for double seaming, manufacture begins with a sheet of coated tin plate. To create the can body, rectangles are cut and curled around a die, and welded together creating a cylinder with a side seam.
Rollers are then used to flare out one or both ends of the cylinder to create a quarter circle flange around the circumference. Precision is required to ensure that the welded sides are perfectly aligned, as any misalignment will cause inconsistent flange shape, compromising its integrity.
A circle is then cut from the sheet using a die cutter. The circle is shaped in a stamping press to create a downward countersink to fit snugly into the can body. The result can be compared to an upside down and very flat top hat. The outer edge is then curled down and around about 140 degrees using rollers to create the end curl.
The result is a steel tube with a flanged edge, and a countersunk steel disc with a curled edge. A rubber compound is put inside the curl.
The body and end are brought together in a seamer and held in place by the base plate and chuck, respectively. The base plate provides a sure footing for the can body during the seaming operation and the chuck fits snugly into the end (lid). The result is the countersink of the end sits inside the top of the can body just below the flange. The end curl protrudes slightly beyond the flange.
Once brought together in the seamer, the seaming head presses a first operation roller against the end curl. The end curl is pressed against the flange curling it in toward the body and under the flange. The flange is also bent downward, and the end and body are now loosely joined together. The first operation roller is then retracted. At this point five thicknesses of steel exist in the seam. From the outside in they are:
The seaming head then engages the second operation roller against the partly formed seam. The second operation presses all five steel components together tightly to form the final seal. The five layers in the final seam are then called; a) End, b) Body Hook, c) Cover Hook, d) Body, e) Countersink. All sanitary cans require a filling medium within the seam because otherwise the metal-to-metal contact will not maintain a hermetic seal. In most cases, a rubberized compound is placed inside the end curl radius, forming the critical seal between the end and the body.
Probably the most important innovation since the introduction of double seams is the welded side seam. Prior to the welded side seam, the can body was folded and/or soldered together, leaving a relatively thick side seam. The thick side seam required that the side seam end juncture at the end curl to have more metal to curl around before closing in behind the Body Hook or flange, with a greater opportunity for error.
Many different parts during the seaming process are critical in ensuring that a can is airtight and vacuum sealed. The dangers of a can that is not hermetically sealed are contamination by foreign objects (bacteria or fungicide sprays), or that the can could leak or spoil.
One important part is the seamer setup. This process is usually performed by an experienced technician. Amongst the parts that need setup are seamer rolls and chucks which have to be set in their exact position (using a feeler gauge or a clearance gauge). The lifter pressure and position, roll and chuck designs, tooling wear, and bearing wear all contribute to a good double seam.
Incorrect setups can be non-intuitive. For example, due to the springback effect, a seam can appear loose, when in reality it was closed too tight and has opened up like a spring. For this reason, experienced operators and good seamer setup are critical to ensure that double seams are properly closed.
Quality control usually involves taking full cans from the line - one per seamer head, at least once or twice per shift, and performing a teardown operation (wrinkle/tightness), mechanical tests (external thickness, seamer length/height and countersink) as well as cutting the seam open with a twin blade saw and measuring with a double seam inspection system. The combination of these measurements will determine the seam's quality.
Use of a Statistical Process Control (SPC) software in conjunction with a manual double-seam monitor, computerized double seam scanner, or even a fully automatic double seam inspection system makes the laborious process of double seam inspection faster and much more accurate. Statistically tracking the performance of each head or seaming station of the can seamer allows for better prediction of can seamer issues, and may be used to plan maintenance when convenient, rather than to simply react after bad or unsafe cans have been produced.
Canning is a way of processing food to extend its shelf life. The idea is to make food available and edible long after the processing time. A 1997 study found that canned fruits and vegetables are as rich with dietary fiber and vitamins as the same corresponding fresh or frozen foods, and in some cases the canned products are richer than their fresh or frozen counterparts. The heating process during canning appears to make dietary fiber more soluble, and therefore more readily fermented in the colon into gases and physiologically active byproducts. Canned tomatoes have a higher available lycopene content. Consequently, canned meat and vegetables are often among the list of food items that are stocked during emergencies. In 2013, the Can Manufacturers Institute launched the Cans Get You Cooking Campaign with the support of Crown Holdings, Inc., Ball Corporation, and Silgan Containers. The goal of the campaign is to get consumers to use more canned goods in their daily meals.
To improve food safety for those who eat canned food, governments have enacted laws requiring alphanumeric codes being put on food cans during manufacture indicating information relevant to health, such as the date of canning, etc.
In canning toxicology, migration is the movement of substances from the can itself into the contents. Potential toxic substances that can migrate are lead, causing lead poisoning, or bisphenol A, a potential endocrine disruptor that is an ingredient in the epoxy commonly used to coat the inner surface of cans.
Canned food can be a major source of dietary salt (sodium chloride). Too much salt increases the risk of health problems, including high blood pressure. Therefore, health authorities have recommended limitations of dietary sodium. Many canned products are available in low-salt and no-salt alternatives.
Foodborne botulism results from contaminated foodstuffs in which C. botulinum spores have been allowed to germinate and produce botulism toxin, and this typically occurs in canned non-acidic food substances. C. botulinum prefers low oxygen environments, and can therefore grow in canned foods. Botulism is a rare but serious paralytic illness, leading to paralysis that typically starts with the muscles of the face and then spreads towards the limbs. In severe forms, it leads to paralysis of the breathing muscles and causes respiratory failure. In view of this life-threatening complication, all suspected cases of botulism are treated as medical emergencies, and public health officials are usually involved to prevent further cases from the same source.
Canned goods and canning supplies sell particularly well in times of recession due to the tendency of financially stressed individuals to engage in cocooning, a term used by retail analysts to describe the phenomenon in which people actively avoid straying from their houses.
In February 2009, the United States, while in a recession, saw an 11.5% rise in sales of canning-related items.
A soda fountain is a device that dispenses carbonated soft drinks, called fountain drinks. They can be found in restaurants, concession stands and other locations such as convenience stores. The device combines flavored syrup or syrup concentrate and carbon dioxide with chilled and purified water to make soft drinks, either manually, or in a vending machine which is essentially an automated soda fountain that is operated using a soda gun. Today, the syrup often is pumped from a special container called a bag-in-box (BIB).
A soda fountain is also referred to as a postmix machine in some markets. Any brand of soft drink that is available as postmix syrup may be dispensed by a fountain.
By extension, the term also may refer to a small eating establishment, common in the late 19th and early 20th centuries, often within a pharmacy or other business, where a soda jerk served soda beverages, ice cream, and sometimes light meals. The soda jerk's fountain generally dispensed only unflavored carbonated water, to which syrup was added by hand.
The soda fountain was an attempt to replicate mineral waters that bubbled up from the Earth. Many civilizations believed that drinking and/or bathing in these mineral waters cured diseases, and large industries often sprang up around hot springs, such as Bath in England or the many onsen of Japan. Early scientists tried to create effervescent waters with curative powers, including Robert Boyle, Friedrich Hoffmann, Jean Baptiste van Helmont, William Brownrigg, Antoine Laurent Lavoisier, and David Macbride. In the early 1770s, Swedish chemist Torbern Bergman and English scientist Joseph Priestley invented equipment for saturating water with carbon dioxide. In 1774 John Mervin Nooth demonstrated an apparatus that improved upon Priestley's design. In 1807 Henry Thompson received the first British patent for a method of impregnating water with carbon dioxide. This was commonly called soda water, although it contained no soda.
The soda fountain began in Europe, but achieved its greatest success in the U.S. Benjamin Silliman, a Yale chemistry professor, was among the first to introduce soda water to America. In 1806 Silliman purchased a Nooth apparatus and began selling mineral waters in New Haven, Connecticut. Sales were brisk, so he built a bigger apparatus, opened a pump room, and took in three partners. This partnership opened soda fountains in New York City and Baltimore, Maryland. At roughly the same time, other businessmen opened fountains in NYC and Philadelphia. Although Silliman's business eventually failed, he played an important role in popularizing soda water.
In 1832, John Matthews of NYC and John Lippincott of Philadelphia began manufacturing soda fountains. Both added innovations that improved soda-fountain equipment, and the industry expanded as retail outlets installed newer, better fountains. Other pioneering manufacturers were Alvin Puffer, Andrew Morse, Gustavus Dows, and James Tufts. In 1891 the four largest manufacturers—Tufts, Puffer, Lippincott, and Matthews—formed the American Soda Fountain Company, which was a trust designed to monopolize the industry. The four manufacturers continued to produce and market fountains under their company names. The trust controlled prices and forced some smaller manufacturers out of business.
Before mechanical refrigeration, soda fountains used ice to cool drinks and ice cream. Ice harvesters cut ice from frozen lakes and ponds in the winter and stored the blocks for use in the summer. In the early 20th century, new companies entered the soda fountain business, marketing "iceless" fountains that used brine.
The L.A. Becker Company, the Liquid Carbonic Company, and the Bishop & Babcock Company dominated the iceless fountain business. In 1888 Jacob Baur of Terre Haute, Indiana founded the Liquid Carbonics Manufacturing Company in Chicago, becoming the Midwest's first manufacturer of liquefied carbon dioxide. In 1903 Liquid Carbonic began market-testing its prototype iceless fountain in a Chicago confectionary. Louis A. Becker was a salesman who started his own manufacturing business in 1898, making the 20th-Century Sanitary Soda Fountain. In 1904 Becker's company produced its first iceless fountain. In 1908 William H. Wallace obtained a patent for an iceless fountain and installed his prototype in an Indianapolis drugstore. He sold his patent to Marietta Manufacturing Company, which was absorbed by Bishop & Babcock of Cleveland.
Liquid Carbonic spawned another leading soda fountain manufacturer, the Bastian-Blessing Company. Two Liquid Carbonic employees, Charles Bastian and Lewis Blessing, started their company in 1908. The newer manufacturers competed with the American Soda Fountain Company and took a large share of the market. The trust was broken up, and its member companies struggled to stay in business. During WWI, some manufacturers marketed "50% fountains," which used a combination of ice and mechanical refrigeration. In the early 1920s, many retail outlets purchased soda fountains using ammonia refrigeration.
In their heyday, soda fountains flourished in pharmacies, ice cream parlors, candy stores, dime stores, department stores, milk bars and train stations. They served an important function as a public space where neighbors could socialize and exchange community news. In the early 20th century, many fountains expanded their menus and became lunch counters, serving light meals as well as ice cream sodas, egg creams, sundaes, and such. Soda fountains reached their height in the 1940s and 1950s.
In 1950, Walgreens, one of the largest chains of American drug stores introduced full self-service drug stores that began the decline of the soda fountain, as did the coming of the Car Culture and the rise of suburbia. Drive-in restaurants and roadside ice cream outlets, such as Dairy Queen, competed for customers. North American retail stores switched to self-service soda vending machines selling pre-packaged soft drinks in cans, and the labor-intensive soda fountain didn't fit into the new sales scheme. Today only a sprinkling of vintage soda fountains survive.
In the Eastern Bloc countries, self-service soda fountains, located in shopping centers, farmers markets, or simply on the sidewalk in busy areas, became popular by the mid-20th century. In the USSR, a glass of carbonated water would sell for 1 kopeck, while for 3 kopecks one could buy a glass of fruit-flavored soda. Most of these vending machines have disappeared since 1990; a few remain, usually provided with an operator.
Refrigeration is a process in which work is done to move heat from one location to another. The work of heat transport is traditionally driven by mechanical work, but can also be driven by heat, magnetism, electricity, laser, or other means. Refrigeration has many applications, including, but not limited to: household refrigerators, industrial freezers, cryogenics, and air conditioning. Heat pumps may use the heat output of the refrigeration process, and also may be designed to be reversible, but are otherwise similar to refrigeration units.
The use of ice to refrigerate and thus preserve food goes back to prehistoric times. Through the ages, the seasonal harvesting of snow and ice was a regular practice of most of the ancient cultures: Chinese, Greeks, Romans, Persians. Ice and snow were stored in caves or dugouts lined with straw or other insulating materials. The Persians stored ice in a pit called a yakhchal. Rationing of the ice allowed the preservation of foods over the warm periods. This practice worked well through the centuries, with icehouses remaining in use into the 20th century.
In the 16th century, the discovery of chemical refrigeration was one of the first steps toward artificial means of refrigeration. Sodium nitrate or potassium nitrate, when added to water, lowered the water temperature and created a sort of refrigeration bath for cooling substances. In Italy, such a solution was used to chill wine and cakes.
During the first half of the 19th century, ice harvesting became big business in America. New Englander Frederic Tudor, who became known as the "Ice King", worked on developing better insulation products to ship ice long distances, especially to the tropics.
The first known method of artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in Scotland in 1756. Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled, absorbing heat from the surrounding air. The experiment even created a small amount of ice, but had no practical application at that time.
In 1758, Benjamin Franklin and John Hadley, professor of chemistry at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed evaporation of highly volatile liquids, such as alcohol and ether, could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to "quicken" the evaporation; they lowered the temperature of the thermometer bulb down to , while the ambient temperature was . Franklin noted that soon after they passed the freezing point of water (32 °F), a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about a quarter inch thick when they stopped the experiment upon reaching . Franklin concluded, "From this experiment, one may see the possibility of freezing a man to death on a warm summer's day".
In 1805, American inventor Oliver Evans designed, but never built, a refrigeration system based on the vapor-compression refrigeration cycle rather than chemical solutions or volatile liquids such as ethyl ether.
In 1820, the British scientist Michael Faraday liquefied ammonia and other gases by using high pressures and low temperatures.
An American living in Great Britain, Jacob Perkins, obtained the first patent for a vapor-compression refrigeration system in 1834. Perkins built a prototype system that worked although it did not succeed commercially.
In 1842, an American physician, John Gorrie, designed the first system to refrigerate water to produce ice. He also conceived the idea of using his refrigeration system to cool the air for comfort in homes and hospitals (i.e., air conditioning). It was also thought at the time that cooling the rooms would prevent the spread of disease (particularly malaria) by preventing the formation of "bad air". His system used a steam engine to compress air, then partly cooled the hot compressed air with water before allowing it to expand while doing part of the work needed to drive the air compressor. That isentropic expansion cooled the air to a temperature low enough to freeze water and produce ice, or to flow "through a pipe for effecting refrigeration otherwise" as stated in his patent granted by the U.S. Patent Office in 1851. Gorrie built a working prototype, but his system was a commercial failure.
Alexander Twining began experimenting with vapor-compression refrigeration in 1848, and obtained patents in 1850 and 1853. He is credited with having initiated commercial refrigeration in the United States by 1856.
Meanwhile in Australia, James Harrison began operation of a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong, Victoria. His first commercial ice-making machine followed in 1854, and his patent for an ether liquid-vapour compression refrigeration system was granted in 1855. Harrison introduced commercial vapour-compression refrigeration to breweries and meat packing houses, and by 1861, a dozen of his systems were in operation.
Australian, Argentine, and American concerns experimented with refrigerated shipping in the mid-1870s; the first commercial success came when William Soltau Davidson fitted a compression refrigeration unit to the New Zealand vessel Dunedin in 1882, leading to a meat and dairy boom in Australasia and South America. J & E Hall of Dartford, England outfitted the 'SS Selembria' with a vapor compression system to bring 30,000 carcasses of mutton from the Falkland Islands in 1886.
Carl Paul Gottfried Linde, ennobled in 1897 as Ritter von Linde, was a German engineer who developed refrigeration and gas separation technologies. Linde started in the design of locomotive engines, and then cut his teeth in refrigeration developing large refrigerated tanks for the production of lager in the 1870s. In 1890, he became a lecturer at the Technische Hochschule in Munich. A few years later, he became a full professor and set up a laboratory where he worked on developing new refrigeration cycles. In 1892, an order from the Guinness Brewery in Dublin for a carbon dioxide liquefaction plant drove Linde's research into the area of low temperature refrigeration, and in 1894 he started work on a process for the liquefaction of air. In 1895, Linde first achieved success, and filed for patent protection of his process (not approved in the United States until 1903). In 1901, Linde began work on a technique to obtain pure oxygen and nitrogen based on the fractional distillation of liquefied air. By 1910, coworkers (including Linde's son Friedrich) had developed the Linde double-column process, variants of which are still in common use today.
The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as "aqua ammonia") was developed by Ferdinand Carré of France in 1859 and patented in 1860. The Servel company built gas powered, absorption refrigerators in Evansville IN from 1927 through 1956. In the United States at that time the consumer public still used ice boxes with ice brought in from commercial suppliers, many of whom were still harvesting ice and storing it in icehouses.
Thaddeus Lowe, an American balloonist from the Civil War, had experimented over the years with the properties of gases. One of his mainstay enterprises was the high-volume production of hydrogen gas. He also held several patents on ice-making machines. His "Compression Ice Machine" would revolutionize the cold-storage industry. In 1869, other investors and he purchased an old steamship onto which they loaded one of Lowe's refrigeration units and began shipping fresh fruit from New York to the Gulf Coast area, and fresh meat from Galveston, Texas back to New York. Because of Lowe's lack of knowledge about shipping, the business was a costly failure, and it was difficult for the public to get used to the idea of being able to consume meat that had been so long out of the packing house.
Domestic mechanical refrigerators became available in the United States around 1911.
By the 1870s, breweries had become the largest users of commercial refrigeration units, though some still relied on harvested ice. Though the ice-harvesting industry had grown immensely by the turn of the 20th century, pollution and sewage had begun to creep into natural ice, making it a problem in the metropolitan suburbs. Eventually, breweries began to complain of tainted ice. This raised the demand for more modern and consumer-ready refrigeration and ice-making machines.
Refrigerated railroad cars were introduced in the US in the 1840s for short-run transport of dairy products. In 1867, J.B. Sutherland of Detroit, Michigan, patented the refrigerator car designed with ice tanks at either end of the car and ventilator flaps near the floor which would create a gravity draft of cold air through the car. That same year in San Antonio, Texas, a French immigrant named Andrew Muhl built an ice-making machine to help service the expanding beef industry before moving it to Waco in 1871. In 1873, the patent for this machine was contracted by the Columbus Iron Works, a company acquired by the W. C. Bradley Co., which went on to produce the world's first commercial ice-makers.
Carl von Linde, an engineering professor at the Technological University Munich in Germany, patented an improved method of liquefying gases in 1876. His new process made possible using gases such as ammonia, sulfur dioxide (SO2) and methyl chloride (CH3Cl) as refrigerants and they were widely used for that purpose until the late 1920s.
By 1900, the meat packing houses of Chicago had adopted ammonia-cycle commercial refrigeration. By 1914, almost every location used artificial refrigeration. The big meat packers, Armour, Swift, and Wilson, had purchased the most expensive units which they installed on train cars and in branch houses and storage facilities in the more remote distribution areas.
By the middle of the 20th century, refrigeration units were designed for installation on trucks or lorries. Refrigerated vehicles are used to transport perishable goods, such as frozen foods, fruit and vegetables, and temperature-sensitive chemicals. Most modern refrigerators keep the temperature between -40 and 20 °C, and have a maximum payload of around 24,000 kg gross weight (in Europe).
With the invention of synthetic refrigerants based mostly on a chlorofluorocarbon (CFC) chemical, safer refrigerators were possible for home and consumer use. Freon is a trademark of the Dupont Corporation and refers to these CFCs, and later hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HFC), refrigerants developed in the late 1920s. These refrigerants were considered at the time to be less harmful than the commonly-used refrigerants of the time, including methyl formate, ammonia, methyl chloride, and sulfur dioxide. The intent was to provide refrigeration equipment for home use without danger. These CFC refrigerants answered that need. In the 1970s, though, the compounds were found to be reacting with atmospheric ozone, an important protection against solar ultraviolet radiation, and their use as a refrigerant worldwide was curtailed in the Montreal Protocol of 1987.
Probably the most widely used current applications of refrigeration are for air conditioning of private homes and public buildings, and refrigerating foodstuffs in homes, restaurants and large storage warehouses. The use of refrigerators in kitchens for storing fruits and vegetables has allowed adding fresh salads to the modern diet year round, and storing fish and meats safely for long periods.
In commerce and manufacturing, there are many uses for refrigeration. Refrigeration is used to liquify gases - oxygen, nitrogen, propane and methane, for example. In compressed air purification, it is used to condense water vapor from compressed air to reduce its moisture content. In oil refineries, chemical plants, and petrochemical plants, refrigeration is used to maintain certain processes at their needed low temperatures (for example, in alkylation of butenes and butane to produce a high octane gasoline component). Metal workers use refrigeration to temper steel and cutlery. In transporting temperature-sensitive foodstuffs and other materials by trucks, trains, airplanes and seagoing vessels, refrigeration is a necessity.
Dairy products are constantly in need of refrigeration, and it was only discovered in the past few decades that eggs needed to be refrigerated during shipment rather than waiting to be refrigerated after arrival at the grocery store. Meats, poultry and fish all must be kept in climate-controlled environments before being sold. Refrigeration also helps keep fruits and vegetables edible longer.
One of the most influential uses of refrigeration was in the development of the sushi/sashimi industry in Japan. Before the discovery of refrigeration, many sushi connoisseurs were at risk of contracting diseases. The dangers of unrefrigerated sashimi were not brought to light for decades due to the lack of research and healthcare distribution across rural Japan. Around mid-century, the Zojirushi corporation, based in Kyoto, made breakthroughs in refrigerator designs, making refrigerators cheaper and more accessible for restaurant proprietors and the general public.
Methods of refrigeration can be classified as non-cyclic, cyclic, thermoelectric and magnetic.
In non-cyclic refrigeration, cooling is accomplished by melting ice or by subliming dry ice (frozen carbon dioxide). These methods are used for small-scale refrigeration such as in laboratories and workshops, or in portable coolers.
Ice owes its effectiveness as a cooling agent to its melting point of 0 °C (32 °F) at sea level. To melt, ice must absorb 333.55 kJ/kg (about 144 Btu/lb) of heat. Foodstuffs maintained near this temperature have an increased storage life.
Solid carbon dioxide has no liquid phase at normal atmospheric pressure, and sublimes directly from the solid to vapor phase at a temperature of -78.5 °C (-109.3 °F), and is effective for maintaining products at low temperatures during sublimation. Systems such as this where the refrigerant evaporates and is vented to the atmosphere are known as "total loss refrigeration".
This consists of a refrigeration cycle, where heat is removed from a low-temperature space or source and rejected to a high-temperature sink with the help of external work, and its inverse, the thermodynamic power cycle. In the power cycle, heat is supplied from a high-temperature source to the engine, part of the heat being used to produce work and the rest being rejected to a low-temperature sink. This satisfies the second law of thermodynamics.
A refrigeration cycle describes the changes that take place in the refrigerant as it alternately absorbs and rejects heat as it circulates through a refrigerator. It is also applied to HVACR work, when describing the "process" of refrigerant flow through an HVACR unit, whether it is a packaged or split system.
Heat naturally flows from hot to cold. Work is applied to cool a living space or storage volume by pumping heat from a lower temperature heat source into a higher temperature heat sink. Insulation is used to reduce the work and energy needed to achieve and maintain a lower temperature in the cooled space. The operating principle of the refrigeration cycle was described mathematically by Sadi Carnot in 1824 as a heat engine.
The most common types of refrigeration systems use the reverse-Rankine vapor-compression refrigeration cycle, although absorption heat pumps are used in a minority of applications.
Cyclic refrigeration can be classified as:
Vapor cycle refrigeration can further be classified as:
The vapor-compression cycle is used in most household refrigerators as well as in many large commercial and industrial refrigeration systems. Figure 1 provides a schematic diagram of the components of a typical vapor-compression refrigeration system.
The thermodynamics of the cycle can be analyzed on a diagram as shown in Figure 2. In this cycle, a circulating refrigerant such as Freon enters the compressor as a vapor. From point 1 to point 2, the vapor is compressed at constant entropy and exits the compressor as a vapor at a higher temperature, but still below the vapor pressure at that temperature. From point 2 to point 3 and on to point 4, the vapor travels through the condenser which cools the vapor until it starts condensing, and then condenses the vapor into a liquid by removing additional heat at constant pressure and temperature. Between points 4 and 5, the liquid refrigerant goes through the expansion valve (also called a throttle valve) where its pressure abruptly decreases, causing flash evaporation and auto-refrigeration of, typically, less than half of the liquid.
That results in a mixture of liquid and vapor at a lower temperature and pressure as shown at point 5. The cold liquid-vapor mixture then travels through the evaporator coil or tubes and is completely vaporized by cooling the warm air (from the space being refrigerated) being blown by a fan across the evaporator coil or tubes. The resulting refrigerant vapor returns to the compressor inlet at point 1 to complete the thermodynamic cycle.
The above discussion is based on the ideal vapor-compression refrigeration cycle, and does not take into account real-world effects like frictional pressure drop in the system, slight thermodynamic irreversibility during the compression of the refrigerant vapor, or non-ideal gas behavior (if any).
More information about the design and performance of vapor-compression refrigeration systems is available in the classic Perry's Chemical Engineers' Handbook.
In the early years of the twentieth century, the vapor absorption cycle using water-ammonia systems was popular and widely used. After the development of the vapor compression cycle, the vapor absorption cycle lost much of its importance because of its low coefficient of performance (about one fifth of that of the vapor compression cycle). Today, the vapor absorption cycle is used mainly where fuel for heating is available but electricity is not, such as in recreational vehicles that carry LP gas. It is also used in industrial environments where plentiful waste heat overcomes its inefficiency.
The absorption cycle is similar to the compression cycle, except for the method of raising the pressure of the refrigerant vapor. In the absorption system, the compressor is replaced by an absorber which dissolves the refrigerant in a suitable liquid, a liquid pump which raises the pressure and a generator which, on heat addition, drives off the refrigerant vapor from the high-pressure liquid. Some work is needed by the liquid pump but, for a given quantity of refrigerant, it is much smaller than needed by the compressor in the vapor compression cycle. In an absorption refrigerator, a suitable combination of refrigerant and absorbent is used. The most common combinations are ammonia (refrigerant) with water (absorbent), and water (refrigerant) with lithium bromide (absorbent).
When the working fluid is a gas that is compressed and expanded but doesn't change phase, the refrigeration cycle is called a gas cycle. Air is most often this working fluid. As there is no condensation and evaporation intended in a gas cycle, components corresponding to the condenser and evaporator in a vapor compression cycle are the hot and cold gas-to-gas heat exchangers in gas cycles.
The gas cycle is less efficient than the vapor compression cycle because the gas cycle works on the reverse Brayton cycle instead of the reverse Rankine cycle. As such the working fluid does not receive and reject heat at constant temperature. In the gas cycle, the refrigeration effect is equal to the product of the specific heat of the gas and the rise in temperature of the gas in the low temperature side. Therefore, for the same cooling load, a gas refrigeration cycle needs a large mass flow rate and is bulky.
Because of their lower efficiency and larger bulk, air cycle coolers are not often used nowadays in terrestrial cooling devices. However, the air cycle machine is very common on gas turbine-powered jet aircraft as cooling and ventilation units, because compressed air is readily available from the engines' compressor sections. Such units also serve the purpose of pressurizing the aircraft.
Thermoelectric cooling uses the Peltier effect to create a heat flux between the junction of two different types of materials. This effect is commonly used in camping and portable coolers and for cooling electronic components and small instruments.
Magnetic refrigeration, or adiabatic demagnetization, is a cooling technology based on the magnetocaloric effect, an intrinsic property of magnetic solids. The refrigerant is often a paramagnetic salt, such as cerium magnesium nitrate. The active magnetic dipoles in this case are those of the electron shells of the paramagnetic atoms.
A strong magnetic field is applied to the refrigerant, forcing its various magnetic dipoles to align and putting these degrees of freedom of the refrigerant into a state of lowered entropy. A heat sink then absorbs the heat released by the refrigerant due to its loss of entropy. Thermal contact with the heat sink is then broken so that the system is insulated, and the magnetic field is switched off. This increases the heat capacity of the refrigerant, thus decreasing its temperature below the temperature of the heat sink.
Because few materials exhibit the needed properties at room temperature, applications have so far been limited to cryogenics and research.
Other methods of refrigeration include the air cycle machine used in aircraft; the vortex tube used for spot cooling, when compressed air is available; and thermoacoustic refrigeration using sound waves in a pressurized gas to drive heat transfer and heat exchange; steam jet cooling popular in the early 1930s for air conditioning large buildings; thermoelastic cooling using a smart metal alloy stretching and relaxing. Many Stirling cycle heat engines can be run backwards to act as a refrigerator, and therefore these engines have a niche use in cryogenics. In addition there are other types of cryocoolers such as Gifford-McMahon coolers, Joule-Thomson coolers, pulse-tube refrigerators and, for temperatures between 2 mK and 500 mK, dilution refrigerators.
The measured capacity of refrigeration is always dimensioned in units of power. Domestic and commercial refrigerators may be rated in kJ/s, or Btu/h of cooling. For commercial and industrial refrigeration systems, most of the world uses the kilowatt (kW) as the basic unit of refrigeration. Typically, commercial and industrial refrigeration systems in North America are rated in tons of refrigeration (TR). Historically, one TR was defined as the energy removal rate that will freeze one short ton of water at 0 °C (32 °F) in one day. This was very important because many early refrigeration systems were in ice houses. The simple unit allowed owners of these early refrigeration systems to measure a day's output of ice against energy consumption, and to compare their plant to one down the street. While ice houses make up a much smaller part of the refrigeration industry than they once did, the unit TR has remained in North America. The unit's value as historically defined was approximately 11,958 Btu/hr (3.505 kW), and has now been conventionally redefined as exactly 12,000 Btu/hr (3.517 kW).
A refrigeration system's coefficient of performance (CoP) is very important in determining a system's overall efficiency. It is defined as refrigeration capacity in kW divided by the energy input in kW. While CoP is a very simple measure of performance, it is typically not used for industrial refrigeration in North America. Owners and manufacturers of these systems typically use performance factor (PF). A system's PF is defined as a system's energy input in horsepower divided by its refrigeration capacity in TR. Both CoP and PF can be applied to either the entire system or to system components. For example, an individual compressor can be rated by comparing the energy needed to run the compressor versus the expected refrigeration capacity based on inlet volume flow rate. It is important to note that both CoP and PF for a refrigeration system are only defined at specific operating conditions, including temperatures and thermal loads. Moving away from the specified operating conditions can dramatically change a system's performance.
A beverage can is a metal container designed to hold a fixed portion of liquid such as a carbonated soft drinks, alcoholic beverages, fruit juices, teas, tisanes, energy drinks, etc. Beverage cans are made of aluminium (75% of worldwide production) or tin-plated steel (25% worldwide production). Worldwide production for all beverage cans is approximately 475 billion cans per year worldwide, 52 billion per year in Europe.
Beginning in the 1930s, after an established history of success with storing food, metal cans were used to store beverages. The first beer was available in cans beginning in 1935. Not long after that, sodas, with their higher acidity and somewhat higher pressures, were available in cans. The key development for storing beverages in cans was the interior liner, typically plastic or sometimes a waxy substance, that helped to keep the beverage's flavor from being ruined by a chemical reaction with the metal. Another major factor for the timing was the end of Prohibition in the US at the end of 1933.
Canned beverages were factory-sealed and required a special opener tool in order to consume the contents. Cans were typically formed as cylinders, having a flat top and bottom. These would become known as "punch top" cans, they required an opener, typically a wedge shaped metal cutter known as a church key that latched onto the top rim for leverage where lifting it by hand would cut a triangular opening at the top edge of the can. A small second hole was usually punched at the opposite side of the top in order to let air in, allowing the beverage to flow freely.
In the mid-1930s, some cans were developed with caps so that they could be opened and poured more like a bottle. These were called "cone tops", as their tops had a conical taper up to the smaller diameter of the cap. Cone top cans were sealed by the same crimped caps that were put on bottles, and could be opened with the same bottle-opener tool. There were three types of conetops: high profile, low profile, and j-spout. The low profile and j-spout were the earliest, dating from about 1935. The "crowntainer" was a different type of can that was drawn steel with a bottom cap. These were developed by Crown Cork & Seal (now known as Crown Holdings, Inc.), a leading beverage packaging and beverage can producer. Various breweries used crowntainers and conetops until the late 1950s, but many breweries kept producing the simple cylinder-cans.
The popularity of canned beverages was slow to catch on, as the metallic taste was difficult to overcome with the interior liner not perfected, especially with more acidic sodas. But one significant advantage that cans had over bottles is that they were discarded after use, unlike the deposit typically paid for bottles and not reimbursed until after consumers returned the empties back to the store. For the distributors, flat-top cans were more compact for transportation and storage, with cans also weighing less than bottles. By the time the US entered World War II, cans had gained only about ten percent of the beverage container market. And this was brought drastically down during the war to accommodate strategic needs for metal.
In 1959, Ermal Fraze devised a can-opening method that would come to dominate the canned beverage market. His invention was the "pull-tab". This eliminated the need for a separate opener tool by attaching an aluminium pull-ring lever with a rivet to a pre-scored wedge-shaped tab section of the can top. It was like having an opener tool built into every can. The ring was riveted to the center of the top, which created a wedge opening long enough so that one hole served to both let the beverage flow out while air flowed in. Into the 1970s, the pull-tab was widely popular, however its popularity came with a significant problem as people would frequently discard the pull-tabs on the ground as litter. One technique that avoided littering was to drop the pull-tab into the drink. The littering problem was also addressed by the invention of the "push-tab".
Used primarily on Coors Beer cans in the mid-70s, the push-tab was a raised circular scored area used in place of the pull-tab. It needed no ring to pull up. Instead, the raised aluminium blister was pushed down into the can, with a small unscored piece that kept the tab connected after being pushed inside. Push-tabs never gained wide popularity because while they had solved the litter problem of the pull-tab, they created a safety hazard where the person's finger upon pushing the tab into the can was immediately exposed to the sharp edges of the opening. (An unusual feature of the push-tab Coors Beer cans was that they had a second smaller push-tab at the top as an airflow vent—a convenience that was lost with the switch from can opener to pull-tab.)
The safety and litter problems were both eventually solved later in the 1970s with the invention of the non-removing "pop-tab". The pull-ring was replaced with a stiff aluminium lever, and the removable tab was replaced with a pre-scored round tab that functioned similarly to the push-tab, however the raised blister was no longer needed as the riveted lever would now do the job of pushing the tab open and into the interior of the can.
In 2008, an aluminium version of the crowntainer design was adopted for packaging Coca-Cola's Caribou Coffee beverage. In 2004, Anheuser-Busch adopted an all-aluminium bottle for use with Budweiser and Bud Light beers.
Various standard capacities are used throughout the world.
In Australia the standard can size is 375 ml. But for Energy Drinks, most commonly 500 ml
In New Zealand the standard can size is 355 ml.
In China the most common size is 330 ml.
Can dimensions may be cited in metric or imperial units. Imperial dimensions for canmaking are written as inches+sixteenths of an inch (e.g. "202" = 2 inches + 2 sixteenths). The US standard can is 4.83 inches high, 2.13 inches in diameter at the lid, and 2.60 inches in diameter at the widest point of the body.
In most of Europe standard cans are 330 ml. In some European countries there is a second standard can size, 500 ml, often used for beer, cider and energy drinks.
In the UK 440 ml is commonly used for lager.
In Hong Kong most cans are either 355 mL or 350 mL.
In India standard cans are 330 ml.
In Japan the most common sizes are 350 ml and 500 ml. Larger and smaller cans are also sold.
In Korea 250 ml cans are the most common for soft drinks. However, when accompanying take out food (such as pizza or chicken), a short 245 ml can is standard. Recently, some 355 ml cans which are similar to North American cans are increasingly available, but limited mostly to Coca-Cola and Dr Pepper. Finally, beer cans also come in 500 ml forms.
In both Malaysia and Singapore, the most commonly found cans are 300 ml. Larger 330 ml/350 ml cans are limited to imported drinks where it would usually cost a lot more than local ones.
In North America, the standard can size is 12 US fl oz or 355 ml.
In Canada, the standard size was previously 10 Imperial fluid ounces (284 ml), later redefined and labeled as 280 ml in around 1980. This size was commonly used with steel beverage cans in the 1970s and early 1980s. However, the US standard 355 ml can size was standardized in the 1980s and 1990s, upon the conversion from steel to aluminium.
South African standard cans are 330 ml and the promotional size is 440 ml. A smaller 200 ml can is used for "mixers" such as tonic or soda water. It has a smaller diameter than the other cans.
Most metal beverage cans manufactured in the United States are made of aluminium, whereas in some parts of Europe and Asia approximately 55 percent are made of steel and 45 percent are aluminium alloy. Steel cans often have a top made of aluminium. The aluminium used in United States and Canada are alloys containing 92.5% to 97% aluminium, <5.5% magnesium, <1.6% manganese, <0.15% chromium and some trace amounts of iron, silicon and copper according to MSDS from aluminium producer Alcoa.
An empty aluminium can weighs approximately half an ounce (15 g). There are roughly 30 empty aluminium cans to a pound or 70 to a kilogram.
In many parts of the world a deposit can be recovered by turning in empty plastic, glass, and aluminium containers. Scrap metal dealers often purchase aluminium cans in bulk, even when deposits are not offered. Aluminium is one of the most cost-effective materials to recycle. When recycled without other metals being mixed in, the can–lid combination is perfect for producing new stock for the main part of the can—the loss of magnesium during melting is made up for by the high magnesium content of the lid. Also, reducing ores such as bauxite into aluminium requires large amounts of electricity, making recycling cheaper than producing new metal.
Aluminium cans are coated internally to protect the aluminium from oxidizing. Despite this coating, trace amounts of aluminium can be degraded into the liquid, the amount depending on factors such as storage temperature and liquid composition. Chemical compounds used in the internal coating of the can include types of epoxy resin.
Cans are filled before the top is crimped on. The key engineering issue is that can walls are about 80 micrometers thick,][ so empty cans are light, weak, and can easily be damaged. The filling and sealing operations need to be extremely fast and precise. The filling head centers the can using gas pressure, purges the air, and lets the beverage flow down the sides of the can. The lid is placed on the can, and then crimped in two operations. A seaming head engages the lid from above while a seaming roller to the side curls the edge of the lid around the edge of the can body. The head and roller spin the can in a complete circle to seal all the way around. Then a pressure roller with a different profile drives the two edges together under pressure to make a gas-tight seal. Filled cans usually have pressurized gas inside, which makes them stiff enough for easy handling.
Modern cans are generally produced through a mechanical cold forming process that starts with punching a flat blank from very stiff cold-rolled sheet. This sheet is typically alloy 3104-H19 or 3004-H19, which is aluminium with about 1% manganese and 1% magnesium to give it strength and formability. The flat blank is first formed into a cup about three inches in diameter. This cup is then pushed through a different forming process called "ironing" which forms the can. The bottom of the can is also shaped at this time. The malleable metal deforms into the shape of an open-top can. With the sophisticated technology of the dies and the forming machines, the side of the can is significantly thinner than either the top and bottom areas, where stiffness is required. A single can-making production line can turn out up to 2400 cans per minute.][
Plain lids (known as shells) are stamped from a coil of aluminium, typically alloy 5182-H48, and transferred to another press that converts them to easy-open ends. This press is known as a conversion press which forms an integral rivet button in the lid and scores the opening, while concurrently forming the tabs in another die from a separate strip of aluminium. The tab is pushed over the button, which is then flattened to form the rivet that attaches the tab to the lid.][
Finally, the top rim of the can is trimmed and pressed inward or "necked" to form a taper conical where the can will later be filled and the lid (usually made of an aluminium alloy with magnesium) attached.][
Aluminium cans are coated internally to protect the aluminium from oxidizing. Despite this coating, trace amounts of aluminium can be degraded into the liquid, the amount depending on factors such as storage temperature and liquid composition. Chemical compounds used in the internal coating of the can include types of epoxy resin.
A small opening
A type of opening that can be closed
Early metal beverage cans had no tabs; they were opened by a can-piercer or churchkey, a device resembling a bottle opener with a sharp point. The can was opened by punching two triangular holes in the lid—a large one for drinking, and a second (smaller) one to admit air.
As early as 1922, inventors were applying for patents on cans with tab tops, but the technology of the time made these inventions impractical. Later advancements saw the ends of the can made out of aluminium instead of steel.
Cans are usually in sealed paperboard cartons, corrugated fiberboard boxes, or trays covered with plastic film. The entire distribution system and packaging need to be controlled to ensure freshness.
Mikola Kondakow of Thunder Bay, Ontario, Canada, invented the pull tab version for bottles in 1956 (Canadian patent 476789). Then, in 1962, Ermal Cleon Fraze of Dayton, Ohio, invented the similar integral rivet and pull-tab version (also known as ring pull in British English), which had a ring attached at the rivet for pulling, and which would come off completely to be discarded. He received US Patent No. 3,349,949 for his pull-top can design in 1963 and licensed his invention to Alcoa and Pittsburgh Brewing Company, the latter of which first introduced the design on Iron City Beer cans. The first soft drinks to be sold in all-aluminium cans were R.C. Cola and Diet-Rite Cola, both made by the Royal Crown Cola company, in 1964.
The early pull-tabs detached easily. The New England Journal of Medicine reported a case of one person ingesting a pull-tab that had broken off and dropped into the can.][ The design of the pull-tabs was addressed by Daniel F. Cudzik of Reynolds Metals, who in 1975 developed stay-tabs.
Full-top pull-tabs were also used in some oil cans and are currently used in some soup, pet food, tennis ball, nuts and other cans.
The stay-on-tab was designed by Daniel F. Cudzik for a Reynolds Metals Co. aluminium can. This design reduced injuries and reduced roadside litter caused by removable tabs. The mechanism uses a separate tab attached to the upper surface as a lever to depress a scored part of the lid, which folds underneath the top of the can and out of the way of the resulting opening.
Beverages like Pepsi began using this new type of tab in the United States by 1977. Such "retained ring-pull" cans supplanted pull-off tabs in the United Kingdom in 1989 for soft drinks and 1990 for alcohol.
One of the more recent modifications to can design was Mountain Dew's introduction of the "wide mouth" can in the late 1990s. The American Can Company, now a part of Rexam, and Coors Brewing Company have owned wide mouth design patent (number D385,192) since 1997. Other companies have similar designs for the wide mouth. Ball Corporation's from 2008 has a vent tube to allow direct airflow into the can reducing the amount of gulps during the pour.
A large or "wide mouth" can opening, common since the late 1990s.
The SuperEnd® from Crown Holdings launched in 2000 was designed to use 10% less metal in production than standard beverage ends.
One unsuccessful variation was the press button can, which featured two pre-cut buttons—one small and one large—in the top of the can,c sealed with a plastic membrane. These buttons were held closed by the outward pressure of the carbonated beverage. The consumer would open the can by depressing both buttons, which would result in two holes. The small hole would act as a vent to relieve internal pressure so the larger button could then be pressed down to create the hole used for drinking the beverage. Consumers could also easily cut themselves on the edges of the holes or get their fingers stuck.
Press button cans were used by Pepsi in Canada from the 1970s to 1980s and Coors in the 1970s. They have since been replaced with pull tabs.
A recent innovation to the beverage can is the full aperture end, where the entire lid is removed turning the aluminum can into a cup. Crown Holdings first designed the 360 End™ for use by SABMiller at the 2010 FIFA World Cup in South Africa. It has been used by Anheuser-Busch InBev in China and Brazil and most recently by Sly Fox Brewing Company in the United States.
Beer can collecting was a minor fad in the late 1970s and 1990s. However, the hobby waned rapidly in popularity. The Beer Can Collectors of America (BCCA), founded in 1970, was an organization supporting the hobby, but has now renamed itself Brewery Collectibles Club of America to be more modern.
As of late 2009, membership in the Brewery Collectibles Club of America was 3,570, down from a peak of 11,954 in 1978. Just 19 of the members were under the age of 30, and the members' average age had increased to 59.
A refrigerant is a substance used in a heat cycle usually including, for enhanced efficiency, a reversible phase transition from a liquid to a gas. Traditionally, fluorocarbons, especially chlorofluorocarbons, were used as refrigerants, but they are being phased out because of their ozone depletion effects. Other common refrigerants used in various applications are ammonia, sulfur dioxide, and non-halogenated hydrocarbons such as propane. Many refrigerants are important ozone depleting and global warming inducing compounds that are the focus of worldwide regulatory scrutiny.
The ideal refrigerant has favorable thermodynamic properties, is noncorrosive to mechanical components, and is safe (including nontoxic, nonflammable, and environmentally benign). The desired thermodynamic properties are a boiling point somewhat below the target temperature, a high heat of vaporization, a moderate density in liquid form, a relatively high density in gaseous form, and a high critical temperature. Since boiling point and gas density are affected by pressure, refrigerants may be made more suitable for a particular application by choice of operating pressures. The inert nature of many Halons, Chlorofluorocarbons (CFC) and Hydrochlorofluorocarbons (HCFC), with the benefits of them being nonflammable and nontoxic, made them good choices as refrigerants, but their stability in the atmosphere and their corresponding global warming potential and ozone depletion potential raised concerns about their usage. In order from the highest to the lowest potential of ozone depletion are Bromochlorofluorocarbon, CFC then HCFC.
Though HFC and PFC are non-ozone depleting, many have global warming potentials that are thousands of times greater than CO2. Other refrigerants such as propane and ammonia are not inert, and are flammable or toxic if released. New refrigerants have been developed that are safe to humans and to the environment, but their application has been held up by regulatory hurdles.
Early mechanical refrigeration systems employed sulfur dioxide, methyl chloride and ammonia. Being toxic, sulfur dioxide and methyl chloride rapidly disappeared from the market with the introduction of CFCs.
Occasionally, one may encounter older machines with methyl formate, chloromethane, or dichloromethane (called carrene in the trade).
Until concerns about depletion of the ozone layer arose in the 1980s, the most widely used refrigerants were the halomethane chlorofluorocarbons.][
Following legislative regulations on ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), substances used as substitute refrigerants such as perfluorocarbons (FCs) and hydrofluorocarbons (HFCs) have also come under criticism. They are currently subject to prohibition discussions on account of their harmful effect on the climate. In 1997, FCs and HFCs were included in the Kyoto Protocol to the Framework Convention on Climate Change. In 2006, the EU adopted a Regulation on fluorinated greenhouse gases, which makes stipulations regarding the use of FCs and HFCs with the intention of reducing their emissions. The provisions do not affect climate-neutral refrigerants.
Ammonia (R717) has been used in industrial refrigeration plants for more than 130 years and is thought to be environment-friendly, economical, and energy-efficient. Carbon dioxide (R744) has a similarly long tradition in refrigeration technology.
Refrigerants such as ammonia, carbon dioxide and non-halogenated hydrocarbons preserve the ozone layer and have no (ammonia) or only a low (carbon dioxide, hydrocarbons) global warming potential. They are used in air-conditioning systems for buildings, in sport and leisure facilities, in the chemical/pharmaceutical industry, in the automotive industry and above all in the food industry (production, storage, retailing). New applications are opening up for non-halogenated refrigerants; for example, in vehicle air-conditioning.
Emissions from automotive air-conditioning are a growing concern because of their impact on climate change. From 2011 on, the European Union will phase out refrigerants with a global warming potential (GWP) of more than 150 in automotive air conditioning (GWP = 100 year warming potential of one kilogram of a gas relative to one kilogram of CO2). This will ban potent greenhouse gases such as the refrigerant HFC-134a—which has a GWP of 1410—to promote safe and energy-efficient refrigerants. One of the most promising alternatives is CO2 (R-744). Carbon dioxide is non-flammable, non-ozone depleting, has a global warming potential of 1, but is toxic and potentially lethal in concentrations above 5% by volume. R-744 can be used as a working fluid in climate control systems for cars, residential air conditioning, hot water pumps, commercial refrigeration, and vending machines. R12 is compatible with mineral oil, while R134a is compatible with synthetic oil that contains esters. GM has announced that it will start using Hydrofluoroolefin, HFO-1234yf, in all of its brands by 2013. Dimethyl ether (DME) is also gaining popularity as a refrigerant, but like propane, it is also dangerously flammable.
Some refrigerants are seeing rising use as recreational drugs, leading to an extremely dangerous phenomenon known as inhalant abuse.
As of July 1, 1992 it is illegal in the United States to release refrigerants into the atmosphere (intentional or accidental). When refrigerants are removed they should be recycled to clean out any contaminants and return them to a usable condition. Refrigerants should never be mixed together outside of facilities licensed to do so for the purpose of producing blends. Some refrigerants must be managed as hazardous waste even if recycled, and special precautions are required for their transport, depending on the legislation of the country's government.
Refrigerants may be divided into three classes according to their manner of absorption or extraction of heat from the substances to be refrigerated:
The R-# numbering system was developed by DuPont corporation (which owns the Freon trademark) and systematically identifies the molecular structure of refrigerants made with a single halogenated hydrocarbon. The meaning of the codes is as follows:
For example, R-134a has 2 carbon atoms, 2 hydrogen atoms, and 4 fluorine atoms, an empirical formula of tetrafluoroethane. The "a" suffix indicates that the isomer is unbalanced by one atom, giving 1,1,1,2-Tetrafluoroethane. R-134 (without the "a" suffix) would have a molecular structure of 1,1,2,2-Tetrafluoroethane—a compound not especially effective as a refrigerant.
The same numbers are used with an R- prefix for generic refrigerants, with a "Propellant" prefix (e.g., "Propellant 12") for the same chemical used as a propellant for an aerosol spray, and with trade names for the compounds, such as "Freon 12". Recently, a practice of using HFC- for hydrofluorocarbons, CFC- for chlorofluorocarbons, and HCFC- for hydrochlorofluorocarbons has arisen, because of the regulatory differences among these groups.
Below are some notable blended HFC mixtures. There exist many more (see list of refrigerants). All R-400 (R-4xx) and R-500 (R-5xx) hydroflurocarbons are blends, as noted above.
"Air cycle is not a new technology. At the turn of the century air cycle or 'cold air machines' were available from companies such as J & E Hall... These were used on board ships and by food producers and retailers to provide cooling for their food stores."
Air has been used for residential, automobile, and turbine-powered aircraft air-conditioning and/or cooling. The reason why air is not more widely used as a general-purpose refrigerant is the perception that the use of air is too inefficient to be practical.
Yet, with suitable compression and expansion technology, air can be a practical (albeit not the most efficient) refrigerant, free of the possibility of environmental contamination or damage, and almost completely harmless to plants and animals. An explosion could result from refrigerant type compressor lubricating oils being compressed together with the air.
The simplest refrigerant is water. Non toxic, low cost, and widely available. The simplest cooling systems, known as swamp coolers in the south-west United States, do not even need power for a compressor, merely a blower fan - evaporated water is simply vented to the living space, where it serves to increase humidity also. However, drawbacks are multiple and severe as well. The total cooling power of the unit is limited by the fact that neither coolant nor air is recirculated. A swamp cooled home will have a constant supply of fresh, not too-dry air, but if the air outside is already humid, cooling power is severely limited. This is why such units are not found in areas of frequent and high humidity, such as the south-east United States. Furthermore, if the temperature outside is severely too hot, such as over 110 degrees F or 43 °C, the unit will not cool the air sufficiently for comfort even if the dew point outside is very low.
A refrigerator (colloquially fridge) is a common household appliance that consists of a thermally insulated compartment and a heat pump (mechanical, electronic, or chemical) that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room. Refrigeration is an essential food storage technique in developed countries. Lower temperatures in a confined volume lowers the reproduction rate of bacteria, so the refrigerator reduces the rate of spoilage.
A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum temperature range for perishable food storage is 3 to 5 °C (37 to 41 °F). A similar device that maintains a temperature below the freezing point of water is called a freezer. The refrigerator replaced the icebox, which was a common household appliance for almost a century and a half prior. For this reason, a refrigerator is sometimes referred to as an icebox.
Freezer units are used in households and in industry and commerce. Food stored at or below is safe indefinitely. Most household freezers maintain temperatures from -23 to -18 °C (-9 to -0 °F), although some freezer-only units can achieve and lower. Refrigerators generally do not achieve lower than , since the same coolant loop serves both compartments: Lowering the freezer compartment temperature excessively causes difficulties in maintaining above-freezing temperature in the refrigerator compartment. Domestic freezers can be included as a separate compartment in a refrigerator, or can be a separate appliance. Domestic freezers are generally upright units resembling refrigerators, or chests (resembling upright units laid on their backs). Many upright modern freezers come with an ice dispenser built into their door. Some even more upright and new models include exact temperature changing devices and even a built in clock.
Commercial refrigerator and freezer units, which go by many other names, were in use for almost 40 years prior to the common home models. They used gas systems such as anhydrous ammonia (R-717) or sulfur dioxide (R-764), which occasionally leaked, making them unsafe for home use and industrial purposes. Practical household refrigerators were introduced in 1915 and gained wider acceptance in the United States in the 1930s as prices fell and non-toxic, non-flammable synthetic refrigerants such as Freon-12® (R-12) were introduced. However, R-12 damaged the ozone layer, causing governments to issue a ban on its use in new refrigerators and air-conditioning systems in 1994. The less harmful replacement for R-12, R-134a (tetrafluoroethane), has been in common use since 1990, but R-12 is still found in many old systems today.
Most households][ use the freezer-on-top-and-refrigerator-on-bottom style, which has been the basic style since the 1940s.
In the early 1950s most refrigerators were white, but from the mid-1950s through present day designers and manufacturers put color onto refrigerators. In the late-1950s/early-1960s, pastel colors like turquoise and pink became popular, brushed chrome-plating (similar to stainless finish) was available on some models from different brands. In the late 1960s and throughout the 1970s, earth toned colors were popular, including Harvest Gold, Avocado Green and almond. In the 1980s, black was viewed as luxurious. In the late 1990s stainless steel became stylish, and in 2009, one manufacturer introduced multi-color designs.
Most home refrigerators weigh between 200 pounds (91 kg) and 450 pounds (200 kg), with some models weighing up to 875 pounds (397 kg).
Before the invention of the refrigerator, icehouses were used to provide cool storage for most of the year. Placed near freshwater lakes or packed with snow and ice during the winter, they were once very common. Natural means are still used to cool foods today. On mountainsides, runoff from melting snow is a convenient way to cool drinks, and during the winter one can keep milk fresh much longer just by keeping it outdoors.
In the 11th century, Persian physicist and chemist Ibn Sina (Latinized name: Avicenna) invented the refrigerated coil, which condenses aromatic vapours.][ This was a breakthrough in distillation technology and he made use of it in his steam distillation process, which requires refrigerated tubing, to produce essential oils.][
The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. The American inventor Oliver Evans, acclaimed as the "father of refrigeration," invented the vapor-compression refrigeration machine in 1805. Heat was removed from the environment by recycling vaporized refrigerant, where it moved through a compressor and condenser, where it eventually reverted to a liquid form to repeat the process. However, Evans built no such refrigeration unit. In 1834, Jacob Perkins modified Evans' original design, building the world's first refrigerator and filing the first legal patent for refrigeration using vapor-compression. John Gorrie, an American doctor from Florida, invented the first mechanical refrigeration unit in 1841—based on Evans' original invention to make ice in—to cool air for yellow fever patients. Gorrie's mechanical refrigeration unit received a patent in 1851. American professor Alexander C. Twining of Cleveland, Ohio patented an early vapor-compression refrigerator in 1853 that was fully capable of producing a ton of ice per day.
In 1856, James Harrison, an immigrant from Scotland living in Australia, developed an ice making machine using ammonia and an ether compressor. It was used in the brewing and meat packing industries of Geelong, Victoria. Ferdinand Carré of France developed a somewhat more complex system in 1859. Unlike earlier compression-compression machines, which used air as a coolant, Carré's equipment contained rapidly expanding ammonia. In 1867, Andrew Muhl, an immigrant from France, built an ice-making machine in San Antonio, Texas, to help service the expanding beef industry before moving it to Waco in 1871. In 1873, the patent for this machine was contracted by the Columbus Iron Works, a company acquired by the W. C. Bradley Co., which produced the world's first commercial ice-makers.
Carl Paul Gottfried Linde, ennobled in 1897 as Ritter von Linde, was a German engineer who developed refrigeration and gas separation technologies. In 1890, Carl von Linde moved back to Munich where he took up his professorship once more, but was soon back at work developing new refrigeration cycles. In 1892, an order from the Guinness brewery in Dublin for a Carbon Dioxide liquefaction plant drove Linde's research into the area of low temperature refrigeration, and in 1894 he started work on a process for the liquefaction of air. In 1895, Linde first achieved success, and filed for patent protection of his process (not approved in the US until 1903). In 1901, Linde began work on a technique to obtain pure oxygen and nitrogen based on the fractional distillation of liquefied air. By 1910 coworkers including Carl's son Friedrich had developed the Linde double-column process, variants of which are still in common use today.
In 1913, refrigerators for home and domestic use were invented by Fred W. Wolf of Fort Wayne, Indiana with models consisting of a unit that was mounted on top of an ice box. In 1914, engineer Nathaniel B. Wales of Detroit, Michigan, introduced an idea for a practical electric refrigeration unit, which later became the basis for the Kelvinator. A self-contained refrigerator, with a compressor on the bottom of the cabinet was invented by Alfred Mellowes in 1916. Mellowes produced this refrigerator commercially but was bought out by William C. Durant in 1918, who started the Frigidaire Company to mass-produce refrigerators. In 1918, Kelvinator Company introduced the first refrigerator with any type of automatic control. The absorption refrigerator was invented by Baltzar von Platen and Carl Munters from Sweden in 1922, while they were still students at the Royal Institute of Technology in Stockholm. It became a worldwide success and was commercialized by Electrolux. Other pioneers included Charles Tellier, David Boyle, and Raoul Pictet. Carl von Linde was the first to patent and make a practical and compact refrigerator.
These home units usually required the installation of the mechanical parts, motor and compressor, in the basement or an adjacent room while the cold box was located in the kitchen. There was a 1922 model that consisted of a wooden cold box, water-cooled compressor, an ice cube tray and a 9-cubic-foot (0.25 m3) compartment, and cost $714. (A 1922 Model-T Ford cost about $450.) By 1923, Kelvinator held 80 percent of the market for electric refrigerators. Also in 1923 Frigidaire introduced the first self-contained unit. About this same time porcelain-covered metal cabinets began to appear. Ice cube trays were introduced more and more during the 1920s; up to this time freezing was not an auxiliary function of the modern refrigerator.
The first refrigerator to see widespread use was the General Electric "Monitor-Top" refrigerator introduced in 1927, so-called because of its resemblance to the gun turret on the ironclad warship MonitorUSS of the 1860s. The compressor assembly, which emitted a great deal of heat, was placed above the cabinet, and surrounded with a decorative ring. Over a million units were produced. As the refrigerating medium, these refrigerators used either sulfur dioxide, which is corrosive to the eyes and may cause loss of vision, painful skin burns and lesions, or methyl formate, which is highly flammable, harmful to the eyes, and toxic if inhaled or ingested. Many of these units are still functional today. These cooling systems cannot legally be recharged with the hazardous original refrigerants if they leak or break down.][
The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s and provided a safer, low-toxicity alternative to previously used refrigerants. Separate freezers became common during the 1940s, the popular term at the time for the unit was a deep freeze. These devices, or appliances, did not go into mass production for use in the home until after World War II. The 1950s and 1960s saw technical advances like automatic defrosting and automatic ice making. More efficient refrigerators were developed in the 1970s and 1980s, even though environmental issues led to the banning of very effective (Freon) refrigerants. Early refrigerator models (from 1916) had a cold compartment for ice cube trays. From the late 1920s fresh vegetables were successfully processed through freezing by the Postum Company (the forerunner of General Foods), which had acquired the technology when it bought the rights to Clarence Birdseye's successful fresh freezing methods.
The first successful application of frozen foods occurred when General Foods heiress Marjorie Merriweather Post (then wife of Joseph E. Davies, United States Ambassador to the Soviet Union) deployed commercial-grade freezers in Spaso House, the US Embassy in Moscow, in advance of the Davies’ arrival. Post, fearful of the USSR's food processing safety standards, fully stocked the freezers with products from General Foods' Birdseye unit. The frozen food stores allowed the Davies to entertain lavishly and serve fresh frozen foods that would otherwise be out of season. Upon returning from Moscow, Post (who resumed her maiden name after divorcing Davies) directed General Foods to market frozen product to upscale restaurants.
Home freezers as separate compartments (larger than necessary just for ice cubes), or as separate units, were introduced in the United States in 1940. Frozen foods, previously a luxury item, became commonplace.
A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers. In this cycle, a circulating refrigerant such as R134a enters a compressor as low-pressure vapor at or slightly above the temperature of the refrigerator interior. The vapor is compressed and exits the compressor as high-pressure superheated vapor. The superheated vapor travels under pressure through coils or tubes comprising the condenser, which are passively cooled by exposure to air in the room. The condenser cools the vapor, which liquefies. As the refrigerant leaves the condenser, it is still under pressure but is now only slightly above room temperature. This liquid refrigerant is forced through a metering or throttling device, also known as an expansion valve (essentially a pin-hole sized constriction in the tubing) to an area of much lower pressure. The sudden decrease in pressure results in explosive-like flash evaporation of a portion (typically about half) of the liquid. The latent heat absorbed by this flash evaporation is drawn mostly from adjacent still-liquid refrigerant, a phenomenon known as auto-refrigeration. This cold and partially vaporized refrigerant continues through the coils or tubes of the evaporator unit. A fan blows air from the refrigerator or freezer compartment ("box air") across these coils or tubes and the refrigerant completely vaporizes, drawing further latent heat from the box air. This cooled air is returned to the refrigerator or freezer compartment, and so keeps the box air cold. Note that the cool air in the refrigerator or freezer is still warmer than the refrigerant in the evaporator. Refrigerant leaves the evaporator, now fully vaporized and slightly heated, and returns to the compressor inlet to continue the cycle.
An absorption refrigerator works differently from a compressor refrigerator, using a source of heat, such as combustion of liquefied petroleum gas, solar thermal energy or an electric heating element. These heat sources are much quieter than the compressor motor in a typical refrigerator. A fan or pump might be the only mechanical moving parts; reliance on convection is considered impractical.
The Peltier effect uses electricity to pump heat directly; this type of refrigerator is sometimes used for camping, or where noise is not acceptable. They can be totally silent (if they don't include a fan for air circulation) but are less energy-efficient than other methods.
Other uses of an absorption refrigerator (or "chiller") include large systems used in office buildings or complexes such as hospitals and universities. These large systems are used to chill a brine solution that is circulated through the building.
Many modern refrigerator/freezers have the freezer on top and the refrigerator on the bottom. Most refrigerator-freezers—except for manual defrost models or cheaper units—use what appears to be two thermostats. Only the refrigerator compartment is properly temperature controlled. When the refrigerator gets too warm, the thermostat starts the cooling process and a fan circulates the air around the freezer. During this time, the refrigerator also gets colder. The freezer control knob only controls the amount of air that flows into the refrigerator via a damper system. Changing the refrigerator temperature will inadvertently change the freezer temperature in the opposite direction. Changing the freezer temperature will have no effect on the refrigerator temperature. The freezer control may also be adjusted to compensate for any refrigerator adjustment.
This means the refrigerator may become too warm. However, because only enough air is diverted to the refrigerator compartment, the freezer usually re-acquires the set temperature quickly, unless the door is opened. When a door is opened, either in the refrigerator or the freezer, the fan in some units stops immediately to prevent excessive frost build up on the freezer's evaporator coil, because this coil is cooling two areas. When the freezer reaches temperature, the unit cycles off, no matter what the refrigerator temperature is. Some people][ recommend setting the refrigerator to maximum and the freezer to a point where one's refrigerated food won't freeze. Modern computerized refrigerators do not use the damper system. The computer manages fan speed for both compartments, although air is still blown from the freezer.
Alternatives to the vapor-compression cycle not in current use include:
Newer refrigerators may include:
Early freezer units accumulated ice crystals around the freezing units. This was a result of humidity introduced into the units when the doors to the freezer were opened condensing on the cold parts, then freezing. This frost buildup required periodic thawing ("defrosting") of the units to maintain their efficiency. Manual Defrost (referred to as Cyclic) units are still available. Advances in automatic defrosting eliminating the thawing task were introduced in the 1950s, but are not universal, due to energy performance and cost. These units used a counter that only defrosted the freezer compartment (Freezer Chest) when a specific number of door openings had been made. The units were just a small timer combined with an electrical heater wire that heated the freezer's walls for a short amount of time to remove all traces of frost/frosting. Also, early units featured freezer compartments located within the larger refrigerator, and accessed by opening the refrigerator door, and then the smaller internal freezer door; units featuring an entirely separate freezer compartment were introduced in the early 1960s, becoming the industry standard by the middle of that decade. These older freezer compartments were the main cooling body of the refrigerator, and only maintained a temperature of around , which is suitable for keeping food for a week.
Later advances included automatic ice units and self compartmentalized freezing units.
An increasingly important environmental concern is the disposal of old refrigerators— initially because freon coolant damages the ozone layer—but as older generation refrigerators wear out, the destruction of CFC-bearing insulation also causes concern. Modern refrigerators usually use a refrigerant called HFC-134a (1,1,1,2-Tetrafluoroethane), which does not deplete the ozone layer, instead of Freon. A R-134a is now becoming very uncommon in Europe. Newer refrigerants are being used instead. The main refrigerant now used is R-600a, or isobutane. This refrigerant is naturally occurring, and has a smaller effect on the atmosphere if released. There have been reports of refrigerators exploding if the refrigerant leaks gas in the presence of a spark.
Disposal of discarded refrigerators is regulated, often mandating the removal of doors; children playing hide-and-seek have been asphyxiated while hiding inside discarded refrigerators, particularly older models with latching doors. Since August 2, 1956, under U.S. federal law, refrigerator doors are no longer permitted to lock from the inside. More modern units use a magnetic door gasket that holds the door sealed but can be pushed open from the inside. This gasket was invented by Herman C. Ells Sr.
Domestic refrigerators and freezers for food storage are made in a range of sizes. Among the smallest is a 4 L Peltier refrigerator advertised as being able to hold 6 cans of beer. A large domestic refrigerator stands as tall as a person and may be about 1 m wide with a capacity of 600 L. Some models for small households fit under kitchen work surfaces, usually about 86 cm high. Refrigerators may be combined with freezers, either stacked with refrigerator or freezer above, below, or side by side. A refrigerator without a frozen food storage compartment may have a small section just to make ice cubes. Freezers may have drawers to store food in, or they may have no divisions (chest freezers).
Refrigerators and freezers may be free-standing, or built into a kitchen.
Other specialised cooling mechanisms may be used for cooling, but have not been applied to domestic refrigerators.
In the past, refrigerators consumed more energy than any other home appliance][, but in the last 20 years progress has been made to design, manufacture, and encourage the sale of refrigerators with improved energy efficiency. In the early 1990s a competition was held among the major manufacturers to encourage energy efficiency. Current US models that are Energy Star qualified use 50 percent less energy than the average models made in 1974. The most energy-efficient unit made in the US consumes about half a kilowatt-hour per day (20 W). But even ordinary units are quite efficient; some smaller units use less than 0.2 kWh per day (8 W). Larger units, especially those with large freezers and icemakers, may use as much as 4 kW·h per day (170 W). The European Union uses a letter-based mandatory energy efficiency rating label instead of the Energy Star; thus EU refrigerators at the point of sale are labelled according to how energy-efficient they are.
For US refrigerators, the Consortium on Energy Efficiency (CEE) further differentiates between Energy Star qualified refrigerators. Tier 1 refrigerators are those that are 20% to 24.9% more efficient than the Federal minimum standards set by the National Appliance Energy Conservation Act (NAECA). Tier 2 are those that are 25% to 29.9% more efficient. Tier 3 is the highest qualification, for those refrigerators that are at least 30% more efficient than Federal standards. About 82% of the Energy Star qualified refrigerators are Tier 1, with 13% qualifying as Tier 2, and just 5% at Tier 3.
Besides the standard style of compressor refrigeration used in normal household refrigerators and freezers, there are technologies such as absorption refrigeration and magnetic refrigeration. Although these designs generally use a much larger amount of energy compared to compressor refrigeration, other qualities such as silent operation or the ability to use gas can favor these refrigeration units in small enclosures, a mobile environment or in environments where unit failure would lead to devastating consequences.
Among the different models of refrigerators, top-freezer models are more efficient than bottom-freezer models of the same capacity, which are in turn more efficient than side-freezer models. Models with through-the-door ice units are less efficient than those without. Dr. Tom Chalko in Australia has developed an external thermostat to convert any][ chest freezer into a chest refrigerator using only about 0.1kWh per day—the amount of energy used by a 100 watt light bulb in one hour. A similar device is manufactured by Johnson Controls. Scientists at Oxford University have reconstructed a refrigerator invented in 1930 by Leó Szilárd and Albert Einstein in their efforts to replace current technologies with energy efficient green technology. The Einstein refrigerator operates without electricity and uses no moving parts or greenhouse gases.
Many refrigerators made in the 1930s and 1940s were far more efficient than most that were made later. This is partly attributable to the addition of new features, such as auto-defrost, that reduced efficiency. Additionally, post World War 2, refrigerator style became more important than efficiency. This was especially true in the 1970s, when side by side models with ice dispensers and water chillers became popular. However, the reduction in efficiency also comes partly from cost cutting (less insulation). Due to the introduction of new energy requirements, refrigerators made today are much more efficient than those made in the 1930s; they consume the same amount of energy while being three times as large.
The efficiency of older refrigerators can be improved by defrosting (if the unit is manual defrost) and cleaning them regularly, replacing old and worn door seals with new ones, adjusting the thermostat to accommodate the actual contents (a refrigerator needn't be colder than to store drinks and non-perishable items) and also replacing insulation, where applicable. Some sites recommend you clean condenser coils every month or so on units with coils on the rear. It has been proved that this does very little for improving efficiency,][ however, the unit should be able to "breathe" with adequate spaces around the front, back, sides and above the unit. If the refrigerator uses a fan to keep the condenser cool, then this must be cleaned, at the very least, yearly.][
Frost-free refrigerators or freezers use electric fans to cool the appropriate compartment. This could be called a "fan forced" refrigerator, whereas manual defrost units rely on colder air lying at the bottom, versus the warm air at the top to achieve adequate cooling. The air is drawn in through an inlet duct and passed through the evaporator where it is cooled, the air is then circulated throughout the cabinet via a series of ducts and vents. Because the air passing the evaporator is supposedly warm and moist, frost begins to form on the evaporator (especially on a freezer's evaporator). In cheaper and/or older models, a defrost cycle is controlled via a mechanical timer. This timer is set to shut off the compressor and fan and energize a heating element located near or around the evaporator for about 15 to 30 minutes at every 6 to 12 hours. This melts any frost or ice build up and allows the refrigerator to work normally once more. It is believed that frost free units have a lower tolerance for frost, due to their air-conditioner like evaporator coils. Therefore, if a door is left open accidentally (especially the freezer), the defrost system may not remove all frost, in this case, the freezer (or refrigerator) must be defrosted.][
If the defrosting system melts all the ice before the timed defrosting period ends, then a small device (called a defrost limiter) acts like a thermostat and shuts off the heating element to prevent too large a temperature fluctuation, it also prevents hot blasts of air when the system starts again, should it finish defrosting early. On some early frost-free models, the defrost limiter also sends a signal to the defrost timer to start the compressor and fan as soon as it shuts off the heating element before the timed defrost cycle ends. When the defrost cycle is completed, the compressor and fan are allowed to cycle back on.][
Frost free refrigerators, and some early frost free refrigerator/freezers that used a cold plate in their refrigerator section instead of airflow from the freezer section generally don't shut off their refrigerator fans during defrosting. This allows consumers to leave food in the main refrigerator compartment uncovered, and also helps keep vegetables moist. This method also helps reduce energy consumption, because the refrigerator is above freeze point and can pass the warmer-than-freezing air through the evaporator or cold plate to aid the defrosting cycle.
Regarding total life-cycle costs, many governments offer incentives to encourage recycling of old refrigerators. One example is the Phoenix refrigerator program launched in Australia. This government incentive picked up old refrigerators, paying their owners for "donating" the refrigerator. The refrigerator was then refurbished, with new door seals, a thorough cleaning and the removal of items, such as the cover that is strapped to the back of many older units. The resulting refrigerators, now over 10% more efficient, were then distributed to low income families.][
The refrigerator allows the modern family to keep food fresh for longer than before. This, along with the modern supermarket, allows most families, without a sizable garden in which to grow vegetables and raise animals, a vastly more varied diet and improved health resulting from improved nutrition.][ Dairy products, meats, fish, poultry and vegetables can be kept refrigerated in the same space within the kitchen (although raw meat should be kept separate from other foodstuffs for reasons of hygiene).
The refrigerator lets people eat more salads, fresh fruits and vegetables, without having to own a garden or an orchard. Exotic foodstuffs from far-off countries that have been imported by means of refrigeration can be enjoyed in the home because of domestic refrigeration.
While storing healthier foods for longer times, more refrigerators and freezers are stocked with processed, quick-cook foods that are less healthy. Studies that correlate frozen foods and obesity have proven that easy access to a wide variety of products such as frozen dairy products, can lead to a general decline in overall health.
Freezers allow people to buy food in bulk and eat it at leisure, and bulk purchases save money. Ice cream, a popular commodity of the 20th century, was previously only obtained by traveling to where the product was made fresh. Consumers had to eat it on the spot. Now it is a common food item. Ice on demand not only adds to the enjoyment of cold drinks, but is useful for first-aid, and for cold packs that can be kept frozen for picnics or in case of emergency.
Some refrigerators are now divided into four zones to store different types of food:
The capacity of a refrigerator is measured in either litres or cubic feet. Typically the volume of a combined refrigerator-freezer is split to 100 litres (3.53 cubic feet) for the freezer and 140 litres (4.94 cubic feet) for the refrigerator, although these values are highly variable.
Temperature settings for refrigerator and freezer compartments are often given arbitrary numbers by manufacturers (for example, 1 through 9, warmest to coldest), but generally 3 to 5 °C (37 to 41 °F) is ideal for the refrigerator compartment and for the freezer. Some refrigerators must be within certain external temperature parameters to run properly. This can be an issue when placing units in an unfinished area, such as a garage. European freezers, and refrigerators with a freezer compartment, have a four star rating system to grade freezers.
Although both the three and four star ratings specify the same storage times and same minimum temperature of , only a four star freezer is intended for freezing fresh food, and may include a "fast freeze" function (runs the compressor continually, down to as low as ) to facilitate this. Three (or fewer) stars are used for frozen food compartments that are only suitable for storing frozen food; introducing fresh food into such a compartment is likely to result in unacceptable temperature rises. This difference in categorisation is shown in the design of the 4-star logo, where the "standard" three stars are displayed in a box using "positive" colours, denoting the same normal operation as a 3-star freezer, and the fourth star showing the additional fresh food/fast freeze function is prefixed to the box in "negative" colours or with other distinct formatting.
Most European refrigerators include a moist cold refrigerator section (which does require (automatic) defrosting at irregular intervals) and a (rarely frost free) freezer section.
Old refrigerators have been adapted to create low cost passive solar water heating systems. Also, many refrigerators have been refurbished for low-income families in eastern Australia via the Phoenix refrigerator program (see energy efficiency)][
In Mexico the Federal Government has created the program Cambia Tu Viejo Por Uno Nuevo — Change Your Old Refrigerator For A New One. The old refrigerators are recycled to recover their components — refrigerant gas, copper, glass, iron, etc.
A soft drink (also called soda, pop, coke, soda pop, fizzy drink, tonic, seltzer, mineral, sparkling water, lolly water, or carbonated beverage) is a beverage that typically contains water (often, but not always, carbonated water), usually a sweetener, and usually a flavoring agent. The sweetener may be sugar, high-fructose corn syrup, fruit juice, sugar substitutes (in the case of diet drinks) or some combination of these. Soft drinks may also contain caffeine, colorings, preservatives and other ingredients.
Soft drinks are called "soft" in contrast to "hard drinks" (alcoholic beverages). Small amounts of alcohol may be present in a soft drink, but the alcohol content must be less than 0.5% of the total volume if the drink is to be considered non-alcoholic. Fruit juice, tea, and other such non-alcoholic beverages are technically soft drinks by this definition but are not generally referred to as such.
Soft drinks may be served chilled or at room temperature, and some, such as Dr Pepper, can be served warm.
The first marketed soft drinks in the Western world appeared in the 17th century. They were made of water and lemon juice sweetened with honey. In 1676, the Compagnie des Limonadiers of Paris was granted a monopoly for the sale of lemonade soft drinks. Vendors carried tanks of lemonade on their backs and dispensed cups of the soft drink to thirsty Parisians.
In the late 18th century, scientists made important progress in replicating naturally carbonated mineral waters. In 1767, Englishman Joseph Priestley first discovered a method of infusing water with carbon dioxide to make carbonated water when he suspended a bowl of distilled water above a beer vat at a local brewery in Leeds, England. His invention of carbonated water (also known as soda water) is the major and defining component of most soft drinks.
Priestley found that water treated in this manner had a pleasant taste, and he offered it to friends as a refreshing drink. In 1772, Priestley published a paper entitled Impregnating Water with Fixed Air in which he describes dripping oil of vitriol (or sulfuric acid as it is now called) onto chalk to produce carbon dioxide gas, and encouraging the gas to dissolve into an agitated bowl of water.
Another Englishman, John Mervin Nooth, improved Priestley's design and sold his apparatus for commercial use in pharmacies. Swedish chemist Torbern Bergman invented a generating apparatus that made carbonated water from chalk by the use of sulfuric acid. Bergman's apparatus allowed imitation mineral water to be produced in large amounts. Swedish chemist Jöns Jacob Berzelius started to add flavors (spices, juices, and wine) to carbonated water in the late eighteenth century.
A variant of soda in the United States called "phosphate soda" appeared in the late 1870s. It became one of the most popular soda fountain drinks from 1900 through the 1930s, with the lemon or orange phosphate being the most basic. The drink consists of 1 US fl oz (30 ml) fruit syrup, 1/2 teaspoon of phosphoric acid, and enough carbonated water and ice to fill a glass. This drink was commonly served in pharmacies.
Artificial mineral waters, usually called "soda water", and the soda fountain were mostly popular in the United States.][ Beginning in 1806, Yale University chemistry professor Benjamin Silliman sold soda waters in New Haven, Connecticut. He used a Nooth apparatus to produce his waters. Businessmen in Philadelphia and New York City also began selling soda water in the early 19th century. In the 1830s, John Matthews of New York City and John Lippincott of Philadelphia began manufacturing soda fountains. Both men were successful and built large factories for fabricating fountains.
In 19th century America, the drinking of either natural or artificial mineral water was considered a healthy practice. The American pharmacists selling mineral waters began to add herbs and chemicals to unflavored mineral water. They used birch bark (see birch beer), dandelion, sarsaparilla, fruit extracts, and other substances. Flavorings were also added to improve the taste. Pharmacies with soda fountains became a popular part of American culture. Many Americans frequented the soda fountain on a daily basis. Due to problems in the U.S. glass industry, bottled drinks were a small portion of the market in the 19th century. (However, they were known in England. In The Tenant of Wildfell Hall, published in 1848, the caddish Huntingdon, recovering from months of debauchery, wakes at noon and gulps a bottle of soda-water.) In America, most soft drinks were dispensed and consumed at a soda fountain, usually in a drugstore or ice cream parlor. In the early 20th century, sales of bottled soda increased exponentially. In the second half of the 20th century, canned soft drinks became an important share of the market.
Over 1,500 U.S. patents were filed for either a cork, cap, or lid for the carbonated drink bottle tops during the early days of the bottling industry. Carbonated drink bottles are under great pressure from the gas. Inventors were trying to find the best way to prevent the carbon dioxide or bubbles from escaping. In 1892, the "Crown Cork Bottle Seal" was patented by William Painter, a Baltimore, Maryland machine shop operator. It was the first very successful method of keeping the bubbles in the bottle.
In 1899, the first patent was issued for a glass-blowing machine for the automatic production of glass bottles. Earlier glass bottles had all been hand-blown. Four years later, the new bottle-blowing machine was in operation. It was first operated by the inventor, Michael Owens, an employee of Libby Glass Company. Within a few years, glass bottle production increased from 1,400 bottles a day to about 58,000 bottles a day.
During the 1920s, "Home-Paks" were invented. "Home-Paks" are the familiar six-pack cartons made from cardboard. Vending machines also began to appear in the 1920s. Since then, soft drink vending machines have become increasingly popular. Both hot and cold drinks are sold in these self-service machines throughout the world.
Soft drinks are made by mixing dry ingredients and/or fresh ingredients (for example, lemons, oranges, etc.) with water. Production of soft drinks can be done at factories or at home.
Soft drinks can be made at home by mixing either a syrup or dry ingredients with carbonated water. Carbonated water is made using a soda siphon or a home carbonation system or by dropping dry ice into water. Syrups are commercially sold by companies such as Soda-Club; dry ingredients are often sold in pouches, in the style of the popular U.S. drink mix Kool-Aid.
Drinks like ginger ale and root beer are often brewed using yeast to cause carbonation.
Of most importance is that the ingredient meets the agreed specification on all major parameters. This is not only the functional parameter (in other words, the level of the major constituent), but the level of impurities, the microbiological status, and physical parameters such as color, particle size, etc.
A report in October 2006 demonstrated that some soft drinks contain measurable amounts of alcohol. In some older preparations, this resulted from natural fermentation used to build the carbonation. In the United States, soft drinks (as well as other beverages such as non-alcoholic beer) are allowed by law to contain up to 0.5% alcohol by volume. Modern drinks introduce carbon dioxide for carbonation, but there is some speculation that alcohol might result from fermentation of sugars in an unsterile environment. A small amount of alcohol is introduced in some soft drinks where alcohol is used in the preparation of the flavoring extracts such as vanilla extract.
The consumption of sugar-sweetened soft drinks is associated with obesity, type 2 diabetes, dental caries, and low nutrient levels. Experimental studies tend to support a causal role for sugar-sweetened soft drinks in these ailments, though this is challenged by other researchers. "Sugar-sweetened" includes drinks that use high-fructose corn syrup, as well as those using sucrose.
Many soft drinks contain ingredients that are themselves sources of concern: caffeine is linked to anxiety and sleep disruption when consumed in excess, and some critics question the health effects of added sugars and artificial sweeteners Sodium benzoate has been investigated by researchers at University of Sheffield as a possible cause of DNA damage and hyperactivity. Other substances have negative health effects, but are present in such small quantities that they are unlikely to pose any substantial health risk provided that the beverages are consumed only in moderation.
In 1998, the Center for Science in the Public Interest published a report titled Liquid Candy: How Soft Drinks are Harming Americans' Health. The report examined statistics relating to the increase in soft drink consumption and claimed that consumption is "likely contributing to health problems." It also criticized marketing efforts by soft drink companies.
From 1977 to 2002, Americans doubled their consumption of sweetened beverages—a trend that was paralleled by doubling the prevalence of obesity. The consumption of sugar-sweetened beverages is associated with weight and obesity, and changes in consumption can help predict changes in weight. One study followed 548 schoolchildren over 19 months and found that changes in soft drink consumption were associated with changes in body mass index (BMI). Each soft drink that a child added to his or her daily consumption was accompanied by an increase in BMI of 0.24 kg/m2. Similarly, an 8-year study of 50,000 female nurses compared women who went from drinking almost no soft drinks to drinking more than one a day to women who went from drinking more than one soft drink a day to drinking almost no soft drinks. The women who increased their consumption of soft drinks gained 8.0 kg over the course of the study while the women who decreased their consumption gained only 2.8 kg. In each of these studies, the absolute number of soft drinks consumed per day was also positively associated with weight gain.
It remains possible that the correlation is due to a third factor: people who lead unhealthy lifestyles might consume more soft drinks. If so, then the association between soft drink consumption and weight gain could reflect the consequences of an unhealthy lifestyle rather than the consequences of consuming soft drinks. Experimental evidence is needed to definitively establish the causal role of soft drink consumption. Reviews of the experimental evidence suggest that soft drink consumption does cause weight gain, but the effect is often small except for overweight individuals.
Many of these experiments examined the influence of sugar-sweetened soft drinks on weight gain in children and adolescents. In one experiment, adolescents replaced sugar-sweetened soft drinks in their diet with artificially sweetened soft drinks that were sent to their homes over 25 weeks. Compared with children in a control group, children who received the artificially sweetened drinks saw a smaller increase in their BMI (by −.14 kg/m2), but this effect was only statistically significant among the heaviest children (who saw a benefit of −.75 kg/m2). In another study, an educational program encouraged schoolchildren to consume fewer soft drinks. During the school year, the prevalence of obesity decreased among children in the program by 0.2%, compared to a 7.5% increase among children in the control group.
Sugar-sweetened drinks have also been speculated to cause weight gain in adults. In one study, overweight individuals consumed a daily supplement of sucrose-sweetened or artificially sweetened drinks or foods for a 10 week period. Most of the supplement was in the form of soft drinks. Individuals in the sucrose group gained 1.6 kg, and individuals in the artificial-sweetener group lost 1.0 kg. A two week study had participants supplement their diet with sugar-sweetened soft drinks, artificially sweetened soft drinks, or neither. Although the participants gained the most weight when consuming the sugar-sweetened drinks, some of the differences were unreliable: the differences between men who consumed sugar-sweetened drinks or no drinks was not statistically significant.
Other research suggests that soft drinks could play a special role in weight gain. One four-week experiment compared a 450 calorie/day supplement of sugar-sweetened soft drinks to a 450 calorie/day supplement of jelly beans. The jelly bean supplement did not lead to weight gain, but the soft drink supplement did. The likely reason for the difference in weight gain is that people who consumed the jelly beans lowered their caloric intake at subsequent meals, while people who consumed soft drinks did not. Thus, the low levels of satiety provided by sugar-sweetened soft drinks may explain their association with obesity. That is, people who consume calories in sugar-sweetened beverages may fail to adequately reduce their intake of calories from other sources. Indeed, people consume more total calories in meals and on days when they are given sugar-sweetened beverages than when they are given artificially sweetened beverages or water. However, these results are contradicted by a study by Adam Drewnowski published in 2004, in which "32 subjects consumed a 300-calorie snack of fat-free raspberry cookies or regular cola on two occasions each – either two hours (“early”) or 20 minutes (“late”) before lunch." It found that "...the calories eaten at lunch were not affected by whether the snack was cookies or cola."
A study by Purdue University reported that no-calorie sweeteners were linked to an increase in body weight. The experiment compared rats who were fed saccharin-sweetened yogurt and glucose-sweetened yogurt. The saccharin group eventually consumed more calories, gained more weight and more body fat, and did not compensate later by cutting back.
The consumption of sugar-sweetened soft drinks can also be associated with many weight-related diseases, including diabetes, metabolic syndrome and cardiovascular risk factors, and elevated blood pressure.
According to research presented at the American Heart Association's Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2013 Scientific Sessions by researchers at the Harvard School of Public Health, sugar-sweetened beverages may be responsible for 180,000 deaths every year worldwide.
Most soft drinks contain high concentration of simple carbohydrates: glucose, fructose, sucrose and other simple sugars. Oral bacteria ferment carbohydrates and produce acid, which dissolves tooth enamel during the dental decay process; thus, sweetened drinks are likely to increase risk of dental caries. The risk is greater if the frequency of consumption is high. This has led to dentists referring to soft drinks as "liquid chainsaws".
A large number of soft drinks are acidic, and some may have a pH of 3.0 or even lower. Drinking acidic drinks over a long period of time and continuous sipping can therefore erode the tooth enamel. However, under normal conditions, scientific evidence indicates Coca-Cola's acidity causes no immediate harm.
Using a drinking straw is often advised by dentists as the drink does not come into as much contact with the teeth. It has also been suggested that brushing teeth right after drinking soft drinks should be avoided as this can result in additional erosion to the teeth due to the presence of acid.
There have been a handful of published reports describing individuals with severe hypokalemia (low potassium levels) related to chronic extreme consumption (4-10 L/day) of colas.
In a meta-analysis of 88 studies, drinking soda correlates with a decrease in milk consumption along with the vitamin D, vitamin B6, vitamin B12, calcium, protein and other micronutrients. Phosphorus, a micronutrient, can be found in cola-type beverages, but there may be a risk in consuming too much. Phosphorus and calcium are used in the body to create calcium-phosphate, which is the main component of bone. However, the combination of too much phosphorus with too little calcium in the body can lead to a degeneration of bone mass. Research suggests a statistically significant inverse relationship between consumption of carbonated beverages and bone mineral density in young girls, which places them at increased risk of suffering fractures in the future.
One hypothesis to explain this relationship is that the phosphoric acid contained in some soft drinks (colas) displaces calcium from the bones, lowering bone density of the skeleton and leading to weakened bones, or osteoporosis. However, calcium metabolism studies by Dr. Robert Heaney suggested that the net effect of carbonated soft drinks, (including colas, which use phosphoric acid as the acidulent) on calcium excretion in urine was negligible. Heaney concluded that carbonated soft drinks, which do not contain the nutrients needed for bone health, may displace other foods which do, and that the real issue is that people who drink a lot of soft drinks also tend to have an overall diet that is low in calcium. In the 1950s and 1960s there were attempts in France and Japan to ban the sale of Coca-Cola as dangerous since phosphates can block calcium absorption. However, these were unsuccessful as the amounts of phosphate were shown to be too small to have a significant effect.
The USDA's recommended daily intake (RDI) of added sugars is less than 10 teaspoons per day for a 2,000-calorie diet. High caloric intake contributes to obesity if not balanced with exercise, with a large amount of exercise being required to offset even small but calorie-rich food and drinks.
Until 1985, most of the calories in soft drinks came from sugar or corn syrup. As of 2010, in the United States high-fructose corn syrup (HFCS) is used nearly exclusively as a sweetener because of its lower cost, while in Europe, sucrose dominates, because EU agricultural policies favor production of sugar beets in Europe proper and sugarcane in the former colonies over the production of corn. HFCS has been criticized as having a number of detrimental effects on human health, such as promoting diabetes, hyperactivity, hypertension, and a host of other problems. Although anecdotal evidence has been presented to support such claims, it is well known that the human body breaks sucrose down into glucose and fructose before it is absorbed by the intestines. Simple sugars such as fructose are converted into the same intermediates as in glucose metabolism. However, metabolism of fructose is extremely rapid and is initiated by fructokinase. Fructokinase activity is not regulated by metabolism or hormones and proceeds rapidly after intake of fructose. While the intermediates of fructose metabolism are similar to those of glucose, the rates of formation are excessive. This fact promotes fatty acid and triglyceride synthesis in the liver, leading to accumulation of fat throughout the body and possibly non-alcoholic fatty liver disease. Increased blood lipid levels also seem to follow fructose ingestion over time. A sugar drink or high-sugar drink may refer to any beverage consisting primarily of water and sugar (often cane sugar or high-fructose corn syrup), including some soft drinks, some fruit juices, and energy drinks.
In 2006, the United Kingdom Food Standards Agency published the results of its survey of benzene levels in soft drinks, which tested 150 products and found that four contained benzene levels above the World Health Organization (WHO) guidelines for drinking water.
The United States Food and Drug Administration released its own test results of several soft drinks containing benzoates and ascorbic or erythorbic acid. Five tested drinks contained benzene levels above the Environmental Protection Agency's recommended standard of 5 ppb. The Environmental Working Group has uncovered additional FDA test results that showed the following results: Of 24 samples of diet soda tested between 1995 and 2001 for the presence of benzene, 19 (79%) had amounts of benzene in excess of the federal tap water standard of 5 ppb. Average benzene levels were 19 ppb, about four times tap water standard. One sample contained 55 ppb of benzene, 11 fold tap water standards. Despite these findings, as of 2006, the FDA stated its belief that "the levels of benzene found in soft drinks and other beverages to date do not pose a safety concern for consumers".
In 2003, the Delhi non-profit Centre for Science and Environment published a disputed report finding pesticide levels in Coke and Pepsi soft drinks sold in India at levels 30 times that considered safe by the European Economic Commission. This was found in primarily 12 cold drink brands sold in and around New Delhi. The Indian Health Minister said the CSE tests were inaccurate, and said that the government's tests found pesticide levels within India's standards but above EU standards.
A similar CSE report in August 2006 prompted many state governments to have issued a ban of the sale of soft drinks in schools. Kerala issued a complete ban on the sale or manufacture of soft drinks altogether. (These were later struck down in court.) In return, the soft drink companies like Coca-Cola and Pepsi have issued ads in the media regarding the safety of consumption of the drinks.
The UK-based Central Science Laboratory, commissioned by Coke, found its products met EU standards in 2006. Coke and the University of Michigan commissioned an independent study of its bottling plants by The Energy and Resources Institute (TERI), which reported in 2008 no unsafe chemicals in the water supply used.
In recent years, debate on whether high-calorie soft drink vending machines should be allowed in schools has been on the rise. Opponents of the (soft drink) vending machines believe that soft drinks are a significant contributor to childhood obesity and tooth decay, and that allowing soft drink sales in schools encourages children to believe they are safe to consume in moderate to large quantities. Opponents argue that schools have a responsibility to look after the health of the children in their care, and that allowing children easy access to soft drinks violates that responsibility. Vending machine proponents believe that obesity is a complex issue and soft drinks are not the only cause. They also note the immense amount of funding that soft drink sales bring to schools. Some people][ take a more moderate stance, saying that soft drink machines should be allowed in schools, but that they should not be the only option available. They propose that when soft drink vending machines are made available on school grounds, the schools should be required to provide children with a choice of alternative drinks (such as fruit juice, flavored water and milk) at a comparable price. Some lawmakers debating the issue in different states have argued that parents—not the government—should be responsible for children's beverage choices.
On May 3, 2006, the Alliance for a Healthier Generation, Cadbury Schweppes, Coca-Cola, PepsiCo, and the American Beverage Association announced new School Beverage Guidelines that will voluntarily remove high-calorie soft drinks from all U.S. schools.
On 19 May 2006, the British Education Secretary, Alan Johnson, announced new minimum nutrition standards for school food. Amongst a wide range of measures, from September 2006, school lunches will be free from carbonated drinks. Schools will also end the sale of junk food (including carbonated drinks) in vending machines and tuck shops.
In the United States and elsewhere, legislators, health experts and consumer advocates are considering levying higher taxes on the sale of soft drinks and other sweetened beverages to help curb the epidemic of obesity among Americans, and its harmful impact on overall health. Some speculate that higher taxes could help reduce soda consumption. Others say that taxes could help fund education to increase consumer awareness of the unhealthy effects of excessive soft drink consumption, and also help cover costs of caring for conditions resulting from overconsumption. The food and beverage industry holds considerable clout in Washington, DC, as it has contributed more than $50 million to legislators since 2000.
In January 2013, a British lobby group called for the price of sugary fizzy drinks to be increased, with the money raised (an estimated £1 billion at 20p per litre) to be put towards a "Children's Future Fund", overseen by an independent body, which would encourage children to eat healthily in school.
In March 2013, New York City's mayor Michael Bloomberg proposed to ban the sale of non-diet soft drinks larger than 16 ounces, except in convenience stores and supermarkets. A lawsuit against the ban was upheld by a state judge, who voiced concerns that the ban was "fraught with arbitrary and capricious consequences". Bloomberg announced that he would be appealing the verdict.