Amino Acid

amino acid. (uh-mee'-no ae'sid)

    Any of the organic acids whose molecules contain one or more acidic carboxyl groups (COOH) and one or more amino groups (NH₂) and that polymerize to form peptides and proteins. Proteins are macromolecules composed of combinations of large numbers of the twenty different natural amino acids. During the beermaking process, amino acids are formed by the natural enzymatic degradation of such proteins. During kilning, amino acids combine with simple sugars to form colored compounds called melanoidins. Of the twenty amino acids found in nature, eight are considered to be essential in the diet (essential amino acids are identified by an asterisk in the following table); the other twelve are considered nonessential. The crucial issue associated with amino acids is their rate of uptake by yeast and the role they play in metabolism. Others are essential in the sense that can come only from malt. All amino acids are used by yeast as nutrients at different parts of the fermentation process.