Determination of Some Essential Amino Acids in Several Uncooked and Cooked Mexican Foodstuffs

Abstract
Nine essential amino acids were determined in corn, tortillas, beans (cooked and uncooked), rice (cooked and uncooked), and pulque, using the microbiological method. Compared with whole egg, the corn, tortillas, and uncooked rice were deficient in lysine. Corn and tortillas were also deficient in tryptophan, and beans in methionine. In preparing tortillas considerable changes occur in the tryptophan, histidine, threonine, and arginine content of the corn as determined by microbiological analysis, using Streptococcus faecalis. Beans when cooked show practically no such changes. Similarly, rice remains essentially the same on being cooked. Appreciable quantities of amino acids, especially lysine, were found in pulque.