Effect of soaking, cooking and crude α-galactosidase treatment on the oligosaccharide content of red gram flour

The contents of sucrose, raffinose, stachyose, verbascose, total soluble sugars and reducing sugars in whole seeds of 14 cultivars of red gram (Cajanus cajan) grown in Karnataka state were determined. The effects of soaking, cooking and crude α-galactosidase treatment on the levels of the raffinose family of sugars were investigated. The percent losses of raffinose, stachyose and verbascose after soaking the red gram seeds for 16 h were 54.6, 55.4 and 33.3%, respectively. Cooking the red gram seeds for 60 min resulted in a decrease of 80.2% for raffinose, 87.2% for stachyose and 81.6% for verbascose. Thin-layer chromatographic analyses of 4 h enzyme-treated samples revealed complete hydrolysis of galactooligosaccharides. Therefore, α-galactosidase from Cassia sericea could have potential use in the food industry.