Canning
Canning is a method of
preserving food by first heating it to a temperature that destroys contaminating
microorganisms, and then sealing it in air-tight jars, cans or pouches. Because of the danger of botulism and other pathogens, the only safe method of canning most foods is under conditions of both high heat and pressure, normally at temperatures of 240-250F . Foods that must be
pressure canned include most
vegetables,
meats,
seafood,
poultry, and
dairy products. The only foods that may be safely canned in a boiling water bath are highly acidic foods with a pH below 4.6, such as
fruits,
pickled vegetables, or other foods to which acid has been added.
Encyclopedia
Canning is a method of
preserving food by first heating it to a temperature that destroys contaminating
microorganisms, and then sealing it in air-tight jars, cans or pouches. Because of the danger of botulism and other pathogens, the only safe method of canning most foods is under conditions of both high heat and pressure, normally at temperatures of 240-250°F . Foods that must be
pressure canned include most
vegetables,
meats,
seafood,
poultry, and
dairy products. The only foods that may be safely canned in a boiling water bath are highly acidic foods with a pH below 4.6, such as
fruits,
pickled vegetables, or other foods to which acid has been added.
History
Bottling
During the early
Revolutionary Wars, the notable
French newspaper
Monde, prompted by the government, offered a hefty cash award of 12,000 Francs to any inventor who could come up with a cheap and effective method of preserving large amounts of food. The massive armies of the period required regular supplies of quality food, and so preservation became a necessity. In 1809, the French confectioner Nicolas François Appert developed a method of
vacuum-sealing food inside glass jars. However, glass containers were unsuitable for transportation.
Tinning
Glass jars were replaced with cylindrical tin or steel cans. Tin-openers were not to be invented for another thirty years — at first, soldiers had to cut the cans open with
bayonets. The French Army began experimenting with issuing tinned foods to its soldiers, but the slow process of tinning foods and the even slower development stage prevented the army from shipping large amounts around the Empire, and the war ended before the process could be perfected. Unfortunately for Appert, the factory which he had built with his prize money was burned down in 1814 by Allied soldiers invading
France. Following the end of the
Napoleonic Wars, the process was gradually put into practice in other European countries and in the United States. Based on Appert's methods of food preservation the packaging of food in sealed airtight tin-plated wrought-iron cans was first patented by an Englishman, Peter Durand, in 1810. Initially, the canning process was slow and labour-intensive, making the tinned food too expensive for ordinary people to buy. However, increasing mechanisation of the process, coupled with a huge increase in urban populations across Europe, resulted in a rising demand for tinned food. Early methods employed poisonous
lead solder for sealing the tins, which had disastrous consequences for the 1845
Franklin expedition to the
Arctic ocean.
A number of inventions and improvements followed, and by the 1860s, the time to process food in a can reduced from six hours to 30 minutes. Thomas Kensett established the first U.S. cannery for oysters, meats, fruits and vegetables in
New York in 1812 and also patented an improved tin canister method. Urban populations in
Victorian era Britain demanded ever-increasing quantities of cheap, varied, good-quality food that they could keep on the shelves at home without having to go to the shops every day for fresh produce. In response, companies such as
Nestlé, Heinz, and others emerged to provide shops with good-quality tinned food for sale to ordinary working class city-dwellers. Demand for tinned food skyrocketed during the
First World War, as military commanders searched for cheap, high-
calorie food which could be transported safely, would survive trench conditions, and which would not spoil in between the factory and the front lines. Complete meals in a tin appeared in 1916, but throughout the war soldiers generally subsisted on very low-quality tinned foodstuffs, such as the British "Bully Beef" and
Pork and Beans produced by the MacConnaughy Corporation. Shortages of tinned food in the British Army in 1917 led to the government issuing
cigarettes and even
amphetamines to soldiers to suppress their appetites. After the war, companies that had supplied tinned food to national militaries improved the quality of their goods for sale on the civilian market. Canned foods were soon commonplace. Today, tin-coated steel is the material most commonly used. Laminate vacuum pouches are also now used for canning, such as those found in an
MRE.
Other home food preservation methods
Canning companies
External links
-
- from Allrecipes
-
-
- from the Agricultural Extension Office
See also
Incidents and accidents related to tinned foods
Famous canned foods
