The Diversity of Four Anti-nutritional Factors in Common Bean

Anti-nutritional factors such as lectins, saponin, trypsin inhibitor and phytic acid are endogenous substances in the common bean (Phaseolus vulgaris L.). In this study, the contents or activities of these anti-nutritional factors in fresh pods were detected in 56 selected cultivars. The results revealed significant difference within each factor in the tested cultivar population. The mean value of lectin content and the activity of trypsin inhibitor were 1.743 mg ⋅ g−1 and 1.680 mg ⋅ g−1 respectively. Their coefficients of variation (CV) were both more than 100% and each of the cultivar frequency distribution curve showed a main peak, but the discontinuous distributions in the extremely high and low areas indicate hierarchic cultivars. However, the mean contents of saponin and phytic acid were 3.730 mg ⋅ g−1 and 3.102 mg ⋅ g−1, respectively, with CV less than 41%. Each showed a main peak in its normal distribution curve and low frequency continuous distribution in dual tails. Meanwhile, statistic analysis demonstrated a positive correlation between the lectin content and trypsin inhibitor activity in fresh pods. Furthermore, all 56 tested cultivars were clustered into three groups based on their four anti-nutritional factor levels: 80% of them into medium level group, and 12% of them into low level group. The endogenous edible toxic compounds, such as lectin and trypsin inhibitor, are closely related to insect resistance in the field. This study suggests that it is possible to screen the cultivars containing less lectin and other factors but with reduced pest resistance in the field.