Debittering of lupin (Lupinus luteus L) protein by calcium alginate and nutritional evaluation

A new process for debittering lupin (Lupinus luteus L) proteins by coagulating in an aqueous medium was developed. The proteins of whole bitter yellow lupin seed (BYL) were solubilized in an aqueous medium with alginic acid then coagulated in a bath of calcium chloride. This process was also applied to sweet yellow lupin seeds and sweet white lupin, which are low alkaloid varieties. Crude protein content of the concentrates from the three varieties of lupin seeds and the yield at different pH levels were determined. The protein efficiency ratio of the low alkaloid protein concentrate (LAPC) from BYL was determined. The daily protein intake of LAPC diet was close to that of the untreated bitter seed diet. However, the weight gain was lower (0·23 ± 0·16 compared to 0·35 ± 0·17 g day−1). Weight gains for both lupin diets were considerably less than for rats fed a casein diet (4·74 ± 0·49 g day−1). Protein intake of LAPC supplemented with 2% (w/w) DL‐methionine was comparable to that of casein (1·5 g day−1). However, the weight gain and the PER were significantly different: 3·66 ± 0·62 g day−1 and 2·02 ± 0·20 g day−1, respectively, for rats on the low alkaloid protein diet supplemented with methionine compared with 4·74 ± 0·49 g day−1 and 2·50 ± 0·15 g day−1 for rats on the casein diet.