Factors affecting the in vitro protein digestibility of chickpea albumins

In vitro protein digestibility (IVPD) of chickpea albumins and its possible relationship to their structure and the presence of trypsin inhibitor acti vity (TIA) have been studied. Trypsin digestion of the albumin fraction und er non-reducing conditions was incomplete, while the reduction of inter- an d intramolecular disulphide bonds caused an improvement in the accessibilit y of sites susceptible to trypsin digestion. Trypsin inhibitor activity in the chickpea albumin fraction was dependent upon both temperature and heati ng time. Although heating the albumin fraction at 100 degrees C for 30 min reduced the TIA by more than 50% with respect to the initial activity, an i mportant TIA rate was attributable to heat-resistant trypsin inhibitor. The TIA decrease was not related to an increase in the rate of IVPD. However, we observed a significant (P less than or equal to 0.05) increment in IVPD in the presence of beta-ME, confirming the essential role of disulphide bon ds in stabilising the protein structure of the albumin fraction. (C) 2000 S ociety of Chemical Industry.