Abstract:

In this study, soybean hull was first subjected to sequential pretreatment with an aqueous sodium hydroxide solution followed by an aqueous ammonium oxalate solution for the removal of protein and pectin and then hydrolyzed with xylanase to prepare xylooligosacccharides. To maximize total sugar content in soybean hull hydrolysate, this study emphatically focused on optimizing hydrolysis process of soybean hull. Effects of hydrolysis parameters including hydrolysis temperature and time, pH, ratio of solid to liquid and xylanase amount on total sugar content in soybean hull hydrolysate were analyzed by single factor and orthogonal array design methods. Results indicated that the optimal values of these parameters were as follows: hydrolysis for 2 h at 40 ℃, pH 5.3, a ratio of solid to liquid of 1:15 and an enzyme amount of 0.3%. The total sugar content in soybean hull hydrolysate obtained under such conditions was 5.74 mg/mL. Ion chromatographic detection revealed that the predominant monosaccharide in soybean hull hydrolysate was xylose with a relative content of 54.99%.

Key words: soybean hull, xylooligosacccharides, enzymatic hydrolysis, ion chromatography