Dehulling and selected physical characteristics of Canadian dry bean (Phaseolus vulgaris L.) cultivars

The tangential abrasive dehulling device (TADD) was used to evaluate the dehulling properties of 13 dry bean cultivars from five market classes. Hull yield or percent kernel removed was cultivar dependent and increased linearly (r2 ⩾ 0.984) as dehulling time increased from 30 to 120 s. Hull yield was significantly different within cultivars of great northern and pink bean market classes and there were no significant (p < 0.05) differences within black and pinto bean cultivars. Bean cultivars differed significantly in dehulling parameters–rate coefficient (RC) and abrasive hardness index (AHI), although the differences were small. Cluster analysis, based on dehulling parameters, segregated the cultivars into three major groups; AC Black Violet, AC Black Diamond, CDC Jet, and subgroup AC Resolute and AC Agrinto (AHI, 12.7–14.9 s); Othello, AC Early Rose and AC Polaris and the subgroup CDC Minto and Winchester (AHI, 11.7–12.5 s); and AC Redbond and Viva (AHI < 11 s). Black beans were the hardest to dehull since the longest time (928 s) was required to completely remove the hulls by abrading on average, 50 g/100 g seed. Multiple regression analysis showed that dehulling parameters were not related to any seed characteristics, although seed length, width, thickness and weight were highly correlated (r2 ⩾ 0.786, p < 0.005).