Abstract
Amino acid compositions determined by ion exchange chromatography were reported on 49 foods commonly consumed in Japan. They include cereals and pulses and their products 11, fishes and shellfishes 16, meats, milk and egg 8, and fruits and vegetables 14. Samples were acid-hydrolyzed with 6N hydrochloric acid at 110°C for 24 hours. Amino acid compositions of the hydrolyzates were determined by the automatic method with a Beckman Spinco amino acid analyzer except methionine, cystine and tryptophan. Methionine and cystine were determined with the performic acid oxidation method, and tryptophan was estimated with the microbiological method or the colorimetric method using dimethylaminobenzaldehyde.
Amino acid compositions of the 49 foods are summarized in tables in terms of mg of each amino acid per g of nitrogen.
Comparison of the amino acid composition between animal foods and plant foods showed that nutritionally important amino acids such as lysine, methionine and threonine were generally more abundant in animal foods than in plant foods, but some plant foods were rich in individual essential amino acid. Amino acid compositions of plant foods seemed to show greater variation than those of animal foods. Some plant foods contained a large amount of glutamic acid or aspartic acid, and the presence of such large amount of single amino acid lowers another amino acid contents of plant foods when expressed in terms of mg per g of nitrogen. Among animal foods, there is no important difference of amino acid composition between fishes and meats except histidine. Data obtained indicate that fishes and meats are equally good animal protein sources from the standpoint of the human nutrition.
