Effect Of Exogeneous Enzyme Hydrolysis Of Soybean (Glycine Max) Cell-Wall Materials On The Chemical Properties Of Soymilk

ABSTRACT 

The effect of cell wall enzymes on the sugar composition of soymilk was investigated using High Performance Liquid Chromatography (HPLC) and UV/Visible spectrophotometer. Soymilk was extracted from wet milled soybean slurry from three different varieties of soybean (Samsoy1, Samsoy 2 and TGX). Different cell-wall degrading enzymes (glucanase, cellulase. arabanase, hemicellulase and xylanase) were applied to  each batch of soybean slurry before extraction  of soymilk. The enzymes which were contained in four different commercial brands were applied separately and in different combinations. Soymilk from each enzyme treated sample and control (untreated) were evaluated for Total Dissolved Solids (TDS) and different sugars (glucose, raffinose, sucrose, fructose, xylose, maltose, lactose, stachyose, starch, galactose, methyl cellulose and gum arabic) using HPLC and UV- Visible Spectrophotometer. The proximate composition of all treatment samples and control from the three varieties were also analyzed. The mean TDS of all enzyme- treated soymilk samples (235.8 – 268.3 ppm) was significantly (p≤0.05) higher than the control (167.8 ppm) and it also increased significantly (p≤0.05) after sterilization from 227.9 ppm to 256.6 ppm. The regressed data of the various sugar composition from UV – Visible Spectrophotometer and HPLC analysis showed high correlation with TDS (both before and after sterilization). The amount of the sugars present in the enzyme-hydrolyzed soymilk samples were significantly (p≤0.05) different from the control.  Sucrose content was depleted after enzyme treatment. The changes in content of simple sugars (glucose, xylose, fructose, maltose, raffinose, starchyose) in enzyme-hydrolyzed soymilk has high correlation with TDS. Chemical modification of some sugars impaired their detection using HPLC and UV-Visible Spectrophotometer despite increases in TDS. The use of TDS as a quality parameter for the rapid monitoring of enzyme hydrolysis of soybean cell-wallsugars for soymilk is feasible.