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Food Science Basics: Denaturing Proteins

Food Science Basics: Denaturing Proteins

The Culinary Institute of America

At the molecular level, natural proteins are shaped like coils or springs. When natural proteins are exposed to heat, salt, or acid, they denature—that is, their coils unwind.

When proteins denature, they tend to bond together, or coagulate, and form solid clumps. An example of this is a cooked egg white, which changes from a transparent fluid to an opaque solid. As proteins coagulate, they lose some of their capacity to hold water, which is why protein-rich foods give off moisture as they cook, even if they are steamed or poached.

Fortunately, some heat-induced denaturation is reversible through cooling. This is why roasted foods should be allowed to rest before carving; as the temperature falls, some of the water (“juice”) that was forced into spaces between the proteins is reabsorbed and the food becomes moister. Denatured proteins are easier to digest than natural proteins.

Reprinted by permission from The Culinary Institute of America, The Professional Chef, 8th Edition (John Wiley & Sons, Inc. 2006).