Amino Acids

amino acids, the basic building blocks of proteins, chemicals essential to all living systems. There are 20 amino acids involved in constructing thousands of proteins of living materials. When these proteins act as catalysts for specific biochemical reactions, they are called enzymes.

In ripe grapes, nitrogen-containing compounds constitute about 1 g/l of juice, of which amino acids make up about half. The most common are proline, arginine, and glutamic acid (see umami). During grape ripening, the concentrations of amino acids increase, arginine and proline especially; proline increases more than arginine if the fruit is exposed to light. High concentrations of arginine, resulting from soils with a high nitrogen content, present the danger of production of the carcinogen urethane (ethyl carbamate) in wine.