Effect of debittering treatment on the composition and protein components of lupin seed (Lupinus termis) flour.

In the traditional Egyptian practice, lupin seed is debittered by steeping in water overnight followed by boiling for 20 min, soaking in water for 4 days, and addition of NaCl. About 15% of TS are leached out in this method. The protein, available lysine, and ash content increased due to debittering, but the sugar and tannin content decreased. The lupin seed or debittered lupin seed flour did not show trypsin and alpha-amylase inhibitor activity and hemagglutinin activity. Lupin seed flour showed caseinolytic activity, but the debittered flour did not have this activity. The nitrogen solubility of the debittered flour was lower in water and 1M NaCl solution (12.6%) but nearly the same in 0.02M NaOH (92.6%). The in vitro digestibility of debittered lupin seed proteins with pepsin/pancreatin was slightly higher. Debittering treatment denatured lupin seed proteins and also dissociated the high mol. wt. protein component.