Preservatives

**Preservatives 8th Grade Exit Project** **Julia H.** //Canning// Canning food is the use of preserving foods in an airtight container through heat. Preservation by canning is possible because the long periods of heat treatment that inactivates enzymes and kills microorganisms that would cause food to spoil during storage. The airtight seal protects food from re-contamination following sterilization, which allows the canned food to be stored at room temperature for many months without spoiling. (Hinchman, Alison D., and Megan K. Bellue. "Historic Preservation." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 15 Mar. 2012.) **History** The canning process was developed in the response to the problem of feeding military forces in the field. Addressing the problem of food spoilage, a prize was offered by the French in 1795 for inventing a way to keep food safe for the troops. Nichols Appert, a chef in Paris, accepted the challenge and developed the canning process. Using bottles closed with cork and wire, he won the prize for the canning process in 1810. At about the same time, the tin-coated metal can was patented in England, giving the rise to the term //canning//. Today, virtually all types of food can be canned, and the products are available in all types of can sizes. **Techniques** The canning process is basically the same for home or industrial canning, although the mechanics are different. The process begins with a nice supply of fresh produce. The produce is washed, sorted, and prepared for canning. After it has been peeled and seeds and other wastes have been removed, the product is placed in the canning container(a glass jar or metal can) in pieces of the desired shape and size. Water or syrup is sometimes added to, leaving spaces in the container. The remaining air is removed by heating the can for a few minutes. Then the container is closed in preparation for the heating process. The heating process is vital to the safety of the product. The food must be heated to a high enough temperature to ensure that all the microorganisms that are present have been killed. Many fruits have high acid, and the microorganisms present in them will be killed by processing the cans or jars in boiling water for about half an hour, depending on the food. Meat, fish, poultry and vegetables, however, are low in acid and must be heated to at least 115.5º C for periods of half an hour or longer, again, depending on the food. The temperature can be reached only by processing under pressure. Even when canned under pressure, home-canned meats and vegetables should be boiled for 20 minutes before even tasting them, in order to prevent food poisoning. **Containers** The typical food container used in commercial canning is made with glass or tin-coated steel sheets and is made to withstand very high temperature and pressures. Since the early 1960s, cans made of aluminum have been used increasingly for canning liquids. They are die-stamped in a one-piece, seamless cylinder form with a separate, sealed top. Metal cans are cut from a metal sheet and then rolled and seemed into cylinder shape. (McWilliams, Margaret E. "Canning." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 8 Mar. 2012.) //Dehydration// The art of preserving certain foods by drying them is, apart from cooking, the oldest known method of food processing. Fruits that are high in sugar content, such as dates and grapes, have been sun-dried in warm climates since they were first cultivated. This was also the most simplest method of preserving fish, and in some cultures, of preserving meat. Modern methods of dehydration can preserve a far greater range of foods. In tunnel-drying, food in moved through an enclosed airstream heated to 71º C. In microwave drying, liquids are evaporated by internal heating of food, whereas in freeze-drying, quick-frozen food is placed in a vacuum chamber where water is drawn out into a vapor. Spray-drying employs a stream of hot air. Foam-drying uses liquids that have been foamed and dried in a vacuum. <span style="font-family: Times New Roman,serif;">All dehydration methods prevent microbial growth. Processes that use heat may change the flavor of some foods. <span style="font-family: Times New Roman,serif;">("Dehydration (food)." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 14 Mar. 2012.)

<span style="font-family: Times New Roman,serif;">//Food Additives// <span style="font-family: Times New Roman,serif;">A food additive is a non-food substance added to the food during its processing to preserve it or to enhance its color, taste, texture or value. Iron, minerals, and vitamins are regularly introduced into food to compensate for losses during processing or to provide additional nutrient value. Flavoring agents make up the largest single class of additives and includes salts, spices, essential oils, and natural and synthetic flavors. Additives that improve texture include emulsifiers, stabilizers, and thickeners. <span style="font-family: Times New Roman,serif;">("Food Additives." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 14 Mar. 2012.)

<span style="font-family: Times New Roman,serif;">//**How Does This Deal With Chemicals**// <span style="font-family: Times New Roman,serif;">Preservation deals with chemicals because some foods have additives added to them and that causes the chemicals in the food to react and last longer. When you dehydrate food, it helps to get rid of the organisms that are in the food that causes it to decompose. When you can it, it help to keep the food sealed tight so that bacteria cant get into the food to destroy it. When you add additives to the food, it enhances the foods qualities and that also helps it to last longer. <span style="font-family: Times New Roman,serif;">(Peterson, Martin Severin. "Food Preservation." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 15 Mar. 2012.)

<span style="font-family: Times New Roman,serif;">Work Sited Page
 * "Dehydration (food)." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 14 Mar. 2012. ||


 * "Food Additives." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 14 Mar. 2012. ||


 * Hinchman, Alison D., and Megan K. Bellue. "Historic Preservation." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 15 Mar. 2012. ||


 * McWilliams, Margaret E. "Canning." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 8 Mar. 2012. ||


 * Peterson, Martin Severin. "Food Preservation." //Grolier Multimedia Encyclopedia.// Grolier Online, 2012. Web. 15 Mar. 2012. ||