Effect of Chemical Soaking, Toasting and Crude α-Galactosidase Enzyme Treatment on the Oligosaccharide Content of Red Gram Flour

Abstract

The effects of soaking in 1 and 2% sodium bicarbonate solution, toasting, roasting followed by boiling and crude α-galactosidase treatment on the levels of the raffinose family of sugars in red gram (Cajanus cajan, L) seeds were investigated. The percent removal of raffinose (43.05 and 73.80%), stachyose (15.80 and 70.27%) and verbascose (18.07 and 51.71%) after soaking in 1 and 2% of sodium bicarbonate solution of red gram seeds for 16 h, respectively. Roasting of red gram seeds for 20 min led to a mean reduction of 64.17% for raffinose, 61.67% for stachyose and 57.53% for verbascose and toasting followed by boiling led to a mean reduction of 19.80% for raffinose, 33.20 for stachyose and 45.58% for verbascose, respectively. The treatment of red gram flour with partially purified α-galactosidase from Aspergillus niger for 3 h was effective in reducing the levels of the raffinose family of sugars. Practical Applications The processing methods such as soaking in sodium bicarbonate solution (1 and 2%) toasting, roasting followed by boiling and crude α-galactosidase from Aspergillus niger treatment are employed to reduce the flatulence inducing raffinose family sugars in legume. Effect of soaking in 2% sodium bicarbonate solution for 16 h led to highest reduction of raffinose family sugars than that of soaking in 1% sodium bicarbonate solution. Toasting of red gram seeds for 20 min has been found to moderate reduction of raffinose family sugars. Roasting for 5 min followed by 20 min boiling found to be low levels of reduction of raffinose family sugars. Whereas the partially purified α-galactosidase from A. niger was effective in reducing the levels of the raffinose family of sugars in all the cultivars studied. Enzymatic treatment for 3 h completely removed the flatus-inducing factors, as evidenced by TLC analysis. This information could further stimulate application of these inexpensive and easy methods for the removal of raffinose family of sugars in different varieties of legume seeds.