The tryptic inhibitor and the availability of cystine and methionine in raw and germinated soya beans

Abstract

The utilization of the nitrogen and sulphur of the proteins of raw and germinated soya beans was determined by balance studies on rats. The digestibility coefficient of the protein was 84.6 and 84.3 and the biological value was 55.3 and 51.3 for the germinated and raw soya beans respectively. The percentage absorption of total sulphur was 65.2 and 65.1 for the raw and germinated beans respectively. The average percentage retention of absorbed sulphur was slightly higher (14.5%) for the germinated bean than for the raw bean (10.3%). Analysis of the urinary sulphur showed that the rats excreted a proportionately larger amount of methionine sulphur on the raw bean diet that when they were fed the germinated beans. Analysis of the raw and germinated soya beans for their tryptic inhibitor contents showed no difference in theptic inhibitor activity.