Preparation Of Xylooligosaccharides From Soybean Hull

Xylooligosaccharides have been a research hotspot at home and abroad. The soybeanhull is good material preparation for xylooligosaccharides, since it is rich in hemicellulose.This paper systemically studied the producing and preparing technology of thexylooligosaccharides from soybean hull. The pretreatment method on soybean hull and alkalisolution were determined, the extraction of soybean hull xylan, the acid and enzymatichydrolysis of xylan and the decolorization of hydrolysates were investigated, in addition, thecomponents of xylooligosaccharides were detected by HPLC. The main results were asfollows:1. The pretreatment method on soybean hull and alkali solution were discussed. Soybeanhull firstly swollen at60℃for16h in water was the best pretreatment method, and NaOHwas the most suitable extraction solvent.2. The most optimal parameters of extraction process were determined as: materialpartical size60mesh, solid-to-liquid ratio1:12(g:mL), extraction temperature92℃,extraction time119min, and alkali concentration1.58%. Under these conditions theexperimental yield of xylan was9.55%；3. The most optimal parameters of acid hydrolysis process were determined as: acidconcentration0.2mol/L, reaction time40min, substrate concentration2.5%and reactiontemperature95℃. Under these conditions, the concentration of reducing sugar was4.467mg/mL, the DP of xylooligosaccharides solution was2.17.4. The most optimal parameters of enzymatic hydrolysis process were determinedas:additive amount of xylanase4.5g/L, reaction temperature50℃, reaction time10h,substrate concentration7.5%and pH value5.0. Under these conditions, the concentration ofreducing sugar was3.926mg/mL, the DP of xylooligosaccharides solution was2.36. 5. The most optimal parameters of e decolorization process were determined as: dosageof activated carbon3.5%, reaction temperature70℃, reaction time50min, pH value5.0.Under these conditions, the decolorization rate was87.96%, the sugar retention rate was89.03%.6. The main components of the xylooligosaccharides solution was wood sugar (xylose),wood two sugar (xylobiose), wood three sugar (xylotriose) and wood four sugar. The contentof xylooligosaccharides accounted for about53.23%among total sugar after acid hydrolysis,while it accounted for about70.37%after enzymatic hydrolysis.