Trypsin inhibitory activity of beans (Phaseolus vulgaris L.): critical evaluation of methods for determination

High values of residual trypsin inhibitory activity found for heat-treated beans indicated the occurrence of artifices due to the methodology. A critical evaluation of the methods in use and of possible interferents was performed trying to determine the most adequate way of measuring residual trypsin inhibitory activity. Results showed that extraction conditions, pH of reaction and sample preparation are responsible for significant alterations of the values found, requiring careful standardization. This is the first report about the influence of lyophilization upon residual trypsin inhibitory activity of cooked beans.