The effect of slow-cooking on the trypsin inhibitor and hemagglutinating activities and in vitro digestibility of brown beans (Phaseolus vulgaris,var.Stella) and kidney beans (Phaseolus vulgaris,var.Montcalm)

Brown beans and kidney beans were subjected to two modes of cooking in a household slow cooker: (A), a fixed low setting for 10 h, and (B), a high setting for 2.5 h and a low setting for 7.5 h. Temperature changes in the beans were recorded. With treatment A over 90% of the hemagglutinating and trypsin inhibitor activities occurred after 6 h at which time the temperature had reached 80°C. With treatment B inactivation of these activities was almost complete at the end of 2 h when a maximum temperature of 100°C had been attained. The in vitro digestibility of the bean protein was considerably increased by either treatment. By way of contrast, only 20 min of heating was required to destroy these activities when the beans were brought to a boil in an open vessel.