[Nutritional evaluation of protein concentrates of beans (Phaseolus vulgaris) and lentils (Lens esculenta)].

The composition and nutritive value were determined in navy bean meal (Phaseolus vulgaris) and lentil meal (Lens esculenta), and in their respective protein concentrates obtained through extraction followed by isoelectric precipitation. Sulfur amino acids per gram of nitrogen were lower in the concentrates than in the meals, while there was no difference for lysine and threonine. The white bean protein concentrate had a lower biological value than the meal but better digestibility, although trypsin inhibitor concentration was unchanged. Digestibility greatly improved with heating but it did not increase beyond 81% even after autoclaving. Autoclaved samples supplemented with methionine reached a biological value of 83. The lentil protein concentrate also had a lower biological value than the meal but digestibility was high for both samples (91%) and remained unchanged after heating. Trypsin inhibitors were absent. After supplementing with methionine, a biological value of only 63 was obtained, due to the low level of tryptophan, the second limiting amino acid. In spite of the concentrates' lower biological value, it was proved that they equalled the meals' potential for complementing cereal, as their content in lysine and threonine is high. The concentrates have the additional advantage of allowing effective supplementation without increasing the legume-cereal ratio.