Nutritional quality of rice bran protein in comparison to animal and vegetable protein.

Rice bran protein (RBP) was prepared by alkali extraction and isoelectric precipitation from defatted rice bran. The protein quality of RPB was evaluated and compared to two vegetable proteins [soy protein (ISP) and rice endosperm protein (REP)] and two animal proteins [whey protein (WPI) and casein]. RPB contained 74.93% of protein and its pepsin digestibility and KOH solubility were 89.8% and 91.5%, respectively. In Sprague-Dawley rats, RBP showed protein efficiency ratio, net protein ratio, net protein utilisation, and biological value of 2.39, 3.77, 70.7, and 72.6, which were comparable to the qualities of animal proteins. The true digestibility of RBP (94.8%) was significantly higher than that of REP (90.8%), ISP (91.7%) and WPI (92.8%) and the same as that of casein. Protein digestibility corrected amino acid score (PDCAAS) of RBP was 0.90. These results suggest that rice bran protein appears to be a promising protein source with good biological values and digestibility.