Preparation of horsegram protein concentrate with improved protein quality, in vitro digestibility and available lysine

Abstract

Horsegram (Macrotyloma uniflorum or Dolichos biflorus), an inexpensive pulse crop with high lysine and iron contents, is underutilized due to the presence of antinutrients like lectin and trypsin inhibitors, which limit protein digestibility and availability. Horsegram protein concentrate (HGPC) was prepared, which had 80.4 ± 3.5% protein and 94.2 ± 1.4% in vitro protein digestibility compared to dehulled horsegram flour (22.8 ± 0.8% and 82.3 ± 1.2%, respectively). Available lysine content in concentrate was increased by 64% compared to dehulled horsegram flour. The trypsin inhibitory activity in the protein concentrate decreased by 51% from 36.6 ± 3.5 TIU/mg in horsegram flour to 17.6 ± 2.5 TIU/mg in HGPC. Nutritional indices, including PDCAAS values for different age groups, were calculated and found to be slightly lower due to the loss of methionine and tryptophan in the concentrate. However, branched amino acids and lysine contents were higher. Thus, a vegetarian source with high protein digestibility and available lysine content could be prepared as a protein ingredient for the food industry.