Protein: Preparation and Digestion

Protein is digested by digestive enzymes (themselves proteins) which can break the peptide bonds that connect the amino acid links. This can happen only if the enzyme can physically reach a link. In some proteins few or no links are exposed, so the protein is indigestible. However, proteins can also be broken up by hydrolysis, the action of water, which proceeds more quickly at high temperatures and in acid conditions. Once the protein has begun to disintegrate, more links are revealed for the enzymes to work on. This is how cooking makes meat digestible. Hydrolysis also goes on in the strongly acid digestive juices of the stomach.