The Effects of Heat on Protein in Foods

All living things, including the food we eat, contain protein molecules. But the amount of protein that actually makes it into our bodies is dependent on a variety of factors, including how much heat is used to cook it and how long it is cooked, as some varieties offer the most nutritional value when they are raw.

Protein Molecules

• Whenever you cook food, the heat first breaks and then "unfolds" the proteins within. Protein molecules are long chains of 100 or more amino acids all linked together that usually form a coil called an alpha helix.
  When a protein is "stressed," as it is when it is heated or cooked, it begins to "uncoil" and changes, losing or altering some of its properties.

Protein Denaturing, or Cooking

• When the molecules of protein in food are "stressed" by the heat of cooking, the process is called protein denaturing. There are physical and chemical changes to the structure of the protein as it is being cooked, some of which are beneficial and others that are not.

To Cook or Not to Cook

• Overcooking creates chemical changes that can alter or destroy protein in plant and animal tissue. Excess heat breaks down proteins, causing them to lose essential amino acids and up to 50 percent of their vitamins and minerals. Also, the higher the temperature, the more cancer-causing chemicals are produced. Meat, fish and poultry cooked on a gas grill create nitrosamines, which are carcinogens. Sizzling fat on a grill also generates carcinogens, such as nitrosamines, hydrocarbons and benzopyrene. When meat is charred, polycyclic hydrocarbons and free radicals are created.

Benefits of a Raw Vegan Diet

• There is scientific evidence, including a study done by the United Kingdom's National Health Service, that indicates that a raw vegan diet can decrease toxic products in the colon and bacterial enzymes throughout the body, as well as lower the risk of breast and colon cancers.

Reasons to Cook

• On the other hand, some foods should never be eaten raw. Meat and poultry, in particular, and fish should be cooked to prevent infection from salmonella, E. coli and other harmful bacteria. At the same time, how you cook what you cook is also important.

Cooking Methods that Benefit Protein in Foods

• Instead of frying or grilling, try baking meat and chicken and poaching fish or steaming it in parchment. Cooking methods using a steady medium temperature over a longer period of time also helps keep proteins in meat, chicken or fish more viable and cancer-causing chemicals to a minimum. Lightly steaming vegetables will ensure that their proteins (and other nutrients and fiber) remain at their best.