Isolation and thermostability of trypsin inhibitors from black bean (Phaseolus vulgaris)

Abstract

In the present work, trypsin inhibitors were isolated from black beans (P. vulgaris) and their thermal stability was evaluated. The inhibitors were isolated by affinity chromatography, obtaining, for the two tests carried out, 0.0020 and 0.0029 g of inhibited, with purification factors of 71.42 and 67.61, respectively. The product obtained was subjected to electrophoresis, determining that almost all of the proteins present in the original extract that did not have antitryptic activity had been removed in the isolated product. However, the electrophoretic pattern of the obtained product did not coincide with that of the original extract. To evaluate thermal stability, the electrophoretic bands obtained from beans cooked at atmospheric pressure at 0, 30, 60, 90 and 120 min were compared. In parallel, an antitryptic activity test was carried out for the same bean samples. With both methods, the electrophoretic (qualitative) and the competition (quantitative) methods, it was determined that after 30 min. After cooking the trypsin inhibitors had already been destroyed.     From the work carried out, it was concluded that the trypsin inhibitors of black beans (P. vulgaris) are multiple, isolating 7 bands with different electrophoretic behavior and that the trypsin inhibitors are unstable to a cooking treatment at atmospheric pressure starting from 30 min.