Effect of Soybean Sprouting and Beta-Glucanase Treatment of Wet Milled Soybean on the Chemical Properties of Soymilk from Different Varieties of Soybean

Abstract

Soymilk samples were produced from different varieties of soybean (Samsoy 1, Samsoy 2 and TGX). One batch of each variety of soybeans was sprouted (48 h), wet milled, and treated with beta-glucanase enzyme.  An untreated batch of wet milled soybean served as control. Soymilk was  processed from each soybean variety and analyzed for reducing sugars by Fehling’s test. Sugars were also qualitatively and quantitatively analyzed  with thin layer chromatography and spectrophotometry respectively.  Proximate composition and dietary fibre of all treated soymilk from  different varieties of soybeans were also determined. Sprouting of  soybeans and beta-glucanase treatment reduced the mean glucan content  of soymilk (0.76% and 0.87% respectively) compared to the  control (1.23%). The dietary fibre of soymilk resulting from both  treatments (0.57% and 0.73% respectively) were not significantly reduced (p > 0.05) compared to the control (1.03%). Glucose, fructose, galatose,  arabinose, ribose and xylose were present in the soymilk samples and  were not significantly different (p > 0.05) among the samples from  different varieties. The concentration of the simple sugars generally  increased after beta-glucanase treatment of the soybean slurries.  Sprouting of soybeans caused a reduction of the simple sugars except for arabinose. The concentration (mg/100 ml) of the different sugars in the control (untreated) / sprouted / beta-glucanase treated soymilk are respectively as follows: glucose (12.005 / 10.987 / 28.440); fructose (10.29 / 9.49 / 18.15); galactose (0.773 / 0.753 / 1.589); arabinose (7.126 / 10.321 / 10.232); and xylose (2.065 / 1.713 / 2.678). The concentrations of glucans in the soybean varieties were similar (Samsoy 1 [0.88%], Samsoy 2 [0.98%] and TGX [1.00%]). Sprouting and treatment with beta-glucanase treatment caused hydrolysis of soybean fibre and altered the reducing sugar content of soymilk from all the selected soybean varieties.