1. Protein is a major component of meats, poultry, fish, eggs, milk, and milk products. It is present in smaller amounts in nuts, beans, and grains.
2. Coagulation. Proteins consist of long chains of components called amino acids. These chains normally form tight coils. As proteins are heated, the coils gradually unwind.At this point, the protein is said to be denatured.
For the cook, the important fact about denaturing is that, when the protein coils unwind, they become attracted to each other and form bonds.This bonding is called coagulation.The coagulated proteins form a solid network of these bonds and become firm.As the temperature increases,the proteins shrink,become firmer, and lose more moisture. Exposure of proteins to excessive heat toughens them and makes them dry. Most proteins complete coagulation or are cooked at 160F to 185F (71C to 85C).
3. Many protein foods, such as meats, contain small quantities of carbohydrates.When proteins are heated to about 310F (154C),the amino acids in the protein chains react with carbohydrate molecules and undergo a complex chemical reaction.The result is that they turn brown and develop richer flavors.This reaction is called the Maillard reaction. It is what happens when meat browns. Because of the high temperature required for this reaction, the Maillard reaction takes place only on the dry surface. Because of its water content, the interior of the meat cannot get this hot.
4. Connective tissues are special proteins that are present in meats. Meats with a great deal of connective tissue are tough, but some connective tissues are dissolved when cooked slowly with moisture. Cooking tough meats properly, therefore, makes them more tender.These techniques are explained in Chapter 10.
5. Acids, such as lemon juice,vinegar, and tomato products, do two things to proteins:
• They speed coagulation.
• They help dissolve some connective tissues.
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