Effect of Dehulling and Germination on Physicochemical and Pasting Properties of Black Beans (Phaseolus vulgaris L.)

Dehulled and/or germinated black bean flours were physicochemically characterized, including pasting properties, along with the trypsin inhibitor and antioxidant phenolics. To our best knowledge, this is the first study that, using nonparametric correlations and principal component analysis, identifies the parameters affecting the pasting properties of germinated black bean flour. The carbohydrate loss observed after black bean germination was indirectly correlated with the crude fiber content. Therefore, germination increased the protein and crude fiber contents compared with raw seeds (from 19.1 and 2.4% to 24.0 and 5.1%, respectively). Additionally, the highest protein digestibility was obtained in dehulled germinated black bean flour (78.4%), followed by whole germinated seed flour (74.1%). The dehulling process increased the total starch content 13.5 and 18.8% compared with raw and germinated whole bean flours, respectively. Dehulling decreased both trypsin inhibitor activity and antioxidant phenolics. Germination reduced by twofold the peak and final viscosities of black bean flours. Interestingly, both viscosities were negatively correlated with protein and positively correlated with fat and insoluble dietary fiber. Although resistant starch content was not affected by germination or dehulling, its interactions with fat and insoluble dietary fiber were responsible of the changes observed in pasting properties of germinated black bean flour.