By Harold McGee
Three aspects of amino acids are especially important to the cook. First, amino acids participate in the browning reactions that generate flavor at high cooking temperatures. Second, many single amino acids and short peptides have tastes of their own, and in foods where proteins have been partly broken down— aged cheeses, cured hams, soy sauce—these tastes can contribute to the overall flavor. Most tasty amino acids are either sweet or bitter to some degree, and a number of peptides are also bitter. But glutamic acid, better known in its concentrated commercial form MSG (monosodium glutamate), and some peptides have a unique taste that is designated by such words as savory, brothy, and umami (Japanese for “delicious”). They lend an added dimension of flavor to foods that are rich in them, including tomatoes and certain seaweeds as well as salt-cured and fermented products. When heated, sulfur-containing amino acids break down and contribute eggy, meaty aroma notes.