Effect of fermentation substrates on enzyme production and degradation of oligosaccharides in pinto bean flour as affected by particle size

Different substrate combinations and different fungal species were screened for the production of α-galactosidases. Particle sizes of pinto bean flour, activities of enzyme solution and incubation times of enzyme treatment were tested to get the optimum processing conditions to eliminate raffinose oligosaccharides in pinto bean flour. Okara and tofu whey at 2:1 (w/v) and wheat bran and tofu whey at 1:1 (w/v) were used as the substrates for enzyme production. Aspergillus awamori NRRL 4869 was used to produce enzyme. Pinto bean flour (passed through 60 mesh screen) incubated with enzyme solution (60 Gal U/mL) most effectively eliminated the raffinose oligosaccharides. A. awamori NRRL 4869, wheat bran and tofu whey substrates at 1:1 (w/v), particle size 60 mesh and enzyme activity 60 Gal U/mL were the best conditions for enzymatic degradation of oligosaccharides in pinto bean flours. Dry edible beans are highly nutritious and healthy foods. One of the obstacles for the utilization of dry beans is the presence of flatulence factors, especially the raffinose oligosaccharides, which are well known to produce flatulence in man and animals. The flatulence causes some social problems in adults and may cause discomfort in infants and young children. The elimination or reduction of the flatulence factors present in beans suggests an increased acceptability by consumers. This subsequently contributes to human health. Treatment of beans with preparations rich in α-galactosidase produced by microorganisms on agricultural by-products can reduce the raffinose oligosaccharide content. The present investigation provided the optimum processing conditions for fungal enzymatic treatment for eliminating oligosaccharides in pinto bean flour. Enzymatic treatment was effective for eliminating the raffinose oligosaccharides, and hence, crude α-galactosidases from fungi have potential use in the food industry.