| Dry edible beans are highly nutritious. However, one of the limitations for their utilization is the presence of flatulence factors, especially the raffinose family of oligosaccharides. Removal of the raffinose oligosaccharides would encourage consumption of bean-based foods. The objective of this study was to investigate the effect of processing methods, including soaking, cooking, autoclaving, different acidities of the cooking media, and enzymatic methods, on oligosaccharide content in pinto beans. Crude enzyme preparations were produced from six fungal species grown on wheat bran- and okara-based substrates with soy tofu whey. The identification and quantitative determination of oligosaccharides were conducted using high-performance liquid chromatography.;The loss of raffinose oligosaccharides was 10% after soaking pinto beans for 16 h, 52% after cooking for 90 min, 58% after autoclaving for 30 min, 62% after autoclaving for 30 min in an acid medium, and 64% after cooking for 90 min in an acid medium. In contrast, treatment of bean flour using crude α-galactosidase (60 Gal U/mL) produced by Aspergillus awamori NRRL 4869 for 2 h completely eliminated raffinose oligosaccharides. Acid used in flavoring beans in cooking may enhance the degradation of oligosaccharides. The enzymatic treatment was the most effective among various processing methods tested for removing raffinose oligosaccharides.;Sensory characteristics of the low-oligosaccharide pinto bean paste were tested by a descriptive flavor intensity method. Results showed that color, raw beany off-flavor, bitterness, and astringency increased significantly after the enzymatic treatment. The overall sensory quality characteristics of enzyme-treated bean paste were greatly decreased. Lipoxygenase and typsin inhibitor activity were greatly inhibited by all processes (P<0.05).;Crude fungal α-galactosidases completely eliminated raffinose oligosaccharides and have potential use in the food industry. However, the crude enzymes also contained other types of enzymes that catalyzed undesirable reactions to produce low sensory quality products. Hence, more specific enzymatic methods for producing good sensory characteristics of bean paste need to be developed before commercialization. |
