Studies on the New Applications of Amino Acids in Food Industries

Abstract

Rice is deteriorated with storage at high temperature for long period by the oxidation of fat resulting in the production of volatile carbonyl compounds and volatile carboxylic acids such as npropanal, n-hexanal, n-valeric acid and so on. Therefore, it was tried to eliminate the rancid odor in boiling rice by the addition of cystein, cystine, DL-alanine, L-leucine, L-histidine, L-lysine hydrochloride, L-glutamic acid and mono-sodium glutamate. Only L-lysine hydrochloride was effective for this purpose. Hence, the mechanisms of this phenomenon were investigted by gas chromatographic procedure as follows; the dilute aqueous solutions of n-propanal were heated with free Llysine, L-lysine hydrochloride, DL-alanine, L-ornitine, L-arginine and L-lysine hydrochloride containing calcium carbonate, and then, each 10μl of thus heated solutions were injected directly to gas chromatography. The original peak of n-propanal disappeared by the heating with free L-lysine, L-lysine, L-ornitine, L-arginine and L-lysine hydrochloride containing calcium carbonate. On these results, it was able to presume that the elimination of rancid odor in rice was caused by the reaction of e-amino residue in L-lysine with volatile carbonyl compounds. Volatile carboxylic acids in rancid odor were also changed into non-volatile one with the same mechanisms.