Biochemical and nutritional evaluation of Jatropha protein isolate prepared by steam injection heating for reduction of toxic and antinutritional factors

BACKGROUND: Jatropha kernel contains 400-600 g oil kg(-1), and the cake obtained after oil extraction is rich in protein. The use of Jatropha cake/meal in food or feed is limited owing to the presence of toxic and antinutritional constituents. The main objective of the present study was to prepare protein isolates with reduced toxic and antinutritional factors and improved nutritional quality. RESULTS: The yield of protein isolates was 70-77%, with a protein content of 955-970 g kg(-1). The trypsin inhibitor activity was reduced by 90-97% and the phytate, tannin and saponin contents were reduced by 90, 85 and 98% respectively in the isolates, while phorbol esters and cyanogenic glucosides decreased to undetectable levels. The chemical scores for the meals and isolates were similar; methionine and cystine were the limiting amino acids. The in vitro digestibility and calculated nutritional indices (essential amino acid index, predicted biological value, nutritional index and computed protein efficiency ratio) of the protein isolates were higher than those of the meals. Protein quality as indicated by the protein digestibility-corrected amino acid score was 1.0. CONCLUSION: Jatropha protein isolate prepared by steam injection has markedly reduced toxic and antinutritional constituents and hence has great potential as a rich source of protein. (C) 2008 Society of Chemical Industry.