EFFECT OF HEAT TREATMENT ON THE QUALITY AND UTILIZATION BY THE RAT OF PROTEIN IN WHEAT GERM MEAL

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Abstract
Five samples of wheat germ meal (WGM): raw, toasted 45 min, autoclaved 20, 45, or 90 min were analyzed for amino acids. Arginine and lysine were decreased by all treatments; the greatest loss was of lysine in 45- and 90-min autoclaved samples. Digestibility of protein and absorption of amino acids, determined with rats, was decreased by autoclaving. Decreased amino acid content and protein digestibility was reflected in lower weight gain and protein efficiency ratio (PER). Experimentally determined protein digestibilities of mixtures of raw and 90-min autoclaved WGM showed that the digestibility values of the two components were additive. Supplementation of raw WGM with amino acids showed that only methionine improved growth and PER. By these criteria, methionine-supplemented raw WGM was superior to methionine-supplemented soybean meal. Raw WGM exhibited no toxicity for the rat. The results confirm the excellent quality of protein in WGM. It is suggested that heat treatments applied during processing should be kept at a minimum.