Biological and chemical evaluation of chick pea seed proteins as affected by germination, extraction and alpha-amylase treatment.

Abstract

The effects of germination, extraction (double extraction with 70% ethanol and water at isoelectric point) and alpha-amylase treatments of chick pea seed flours on crude protein, total carbohydrate, protein efficiency ratio (PER), biological value (BV), true digestibility (TD), net protein utilization (NPU), essential amino acid composition, in-vitro protein digestibility (IVPD) and actual amino acid indices (essential amino acid index or amino acid score) were evaluated. Crude protein content was increased (8-149%), while total carbohydrate was decreased (11-62%) by germination, extraction and alpha-amylase treatments. Alpha-amylase treatment was more efficient in reducing total carbohydrate and increasing the protein content than that of extraction treatment. The protein quality of chick pea flours as measured by PER, BV, TD, NPU, IVPD and corrected amino acid indices (actual amino acid indices x IVPD) was significantly improved by these treatments. The protein quality of germinated-alpha-amylase treatment was comparable with casein, while germinated-alpha-amylase treaded seeds appeared nutritionally superior to casein. The results indicate that the germinated-alpha-amylase and germinated-alpha-amylase-extracted treatments could be used successfully as a source of concentrated high quality protein for baby food production. The corrected amino acid indices gave better prediction of PER, BV, TD and NPU (r = 93 to 97) than actual amino acid indices (r = 45 to 71). PER was highly correlated with corrected amino acid score (r = 0.93). The PER could be predicted from the following simple regression equation: PER = -1.827 + 0.0561 x corrected amino acid score.