The Effects of Heat on the Nutritive Value of Protein Hydrolysates with Dextrose

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Abstract
The effects of heat on the nutritive value of fibrin hydrolysate and dextrose solutions were studied. A significant decrease in rat repletion response was noted when: (1) the amino nitrogen had shown about a 6 to 8% decrease; (2) fluorescence had decreased to a low value following an early maximum; (3) color had developed to a marked degree following an initial induction period. Microbiological assay of the heat-darkened hydrolysate with dextrose indicated progressive loss of many of the individual essential amino acids. The greatest individual loss was in tryptophan. All amino acids except tryptophan were largely recoverable upon complete acid hydrolysis. Prolonged heating produced changes in the hydrolysate-glucose solutions which were not overcome by replacement of tryptophan alone. The amino acid composition of heat-damaged hydrolysate-glucose solutions determined by microbiological assay does not give a true index of nutritive value.