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

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.