Plasma amino acid response to single test meals in humans. III. Supplementary effect of dried skim milk and L-methionine on a vegetable protein mixture.

Abstract

The plasma amino acid response to single test meals in young adults was used for human biological evaluation of the supplementary effect of dried skim milk powder (DSM) and synthetic L-methionine on a vegetable protein mixture. The protein sources in the vegetable mixture were wheat flour, defatted soya bean flour and pea flour. The plasma amino acid responses were evaluated both as PAA ratios (a modification of the Longenecker and Hause method), and as delta MR% (percentage change in the postprandial essential amino acid molar ratios according to Graham and Placko). Both evaluation methods indicated that there was an adequate supply of all the essential amino acids in the basic vegetable mixture, except for a small deficit of methionine. Supplementation (5% and 10%) with DSM did not significantly improve the low plasma amino acid response of methionine. The addition of synthetic L-methionine proved to be very effective in this respect. 1 g of L-methionine per 100 g of proteins from the vegetable mixture gave a plasma methionine response similar to that of the other essential amino acids. This implies that the deficit of methionine in the basic wheat/soya bean/pea mixture was about 30%.