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Essential Amino Acids That Are Destroyed by Cooking

by Cindy Hill

Amino acids are the building blocks of protein that help form muscles and other body tissue. Essential amino acids are those that must be consumed every day to support optimal health. Cooking foods destroys some essential amino acids they contain, but the negative effects vary depending on which cooking method is used. Short cooking times, and incorporating the cooking liquid into the finished dish, help to preserve the most essential amino acids in most foods.

Essential Amino Acids

Twenty different amino acids are necessary to build protein tissue and aid in metabolism, according to the University of Arizona Biology Project. Ten amino acids can be manufactured by the human body. The other 10 -- arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine -- are called essential amino acids. These amino acids must be consumed daily in food, as the human body can neither produce them nor store them. Meat, fish, eggs, dairy products, whole grains, beans and vegetables all contain protein and varying levels of these 10 essential amino acids.

Losses

Destruction of essential amino acids varies between different amino acids as well as between different cooking methods. Levels of the essential amino acid lysine dropped significantly in sweet potatoes that were canned or dehydrated, and not as severely in sweet potatoes that were baked, according to a 1982 report published in the Journal of Agriculture and Food Chemistry. Methionine levels dropped in sweet potatoes that were dehydrated, but did not drop much in those which were canned or baked. Raw flageolet beans contained higher quantities of amino acids than those that were cooked, according to researchers from the Agricultural University of Krakow, Poland, but short cooking methods preserved more of the essential amino acids than sterilizing the beans through canning.

Cooking Liquid

Some of the essential amino acids lost in cooking may not totally degrade, but rather be leached into the cooking liquid. Some amino acids and other nutrients leach from sweet potatoes into their surrounding syrup during the canning process. More amino acids are retained in a traditionally cooked potato stew than in potatoes that were fried or boiled, according to researchers from the College of Agricultural Studies at the Sudan University of Science and Technology. When the syrup or broth in which food items are cooked is consumed along with the food, such as in stew, soup or canning syrup, the essential amino acids and other nutrients which have leached out during cooking continue to provide their healthful benefits to the dish.

Benefits

Cooking meats in broth releases amino acids that convey positive health effects. Cooking chicken in broth releases amino acids from the meat which may contribute to the cold-fighting properties of chicken soup, according to chef Aran Essig of the University of Northern Colorado. Some essential amino acids are also concentrated in the food product when cooking reduces the food's mass. Canned sweet potatoes had higher concentrations of the essential amino acid leucine than was found in sweet potatoes that were baked or dehydrated, according to researchers from the U.S. Department of Agriculture and North Carolina State University.

About the Author

A freelance writer since 1978 and attorney since 1981, Cindy Hill has won awards for articles on organic agriculture and wild foods, and has published widely in the areas of law, public policy, local foods and gardening. She holds a B.A. in political science from State University of New York and a Master of Environmental Law and a J.D. from Vermont Law School.

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