Production Technology Research Of Xyloologosaccharidies From Corncobs By Enzyme System

Xylooligosaccharide is an important basic material of functional food, which regulates the intestinal flora. It can also promote the growth of probiotics and restrain the excessive reproduction of harmful intestinal bacteria. Xylooligosaccharide is usually obtained from the hydrolysis, separation and purification of corncobs, bagasse, husk and straw. This study aims to optimize the production of Xylooligosaccharide based on corncobs, including the optimization of corncob pretreatment and enzymolysis, xylanase preparation, and the purification of xylooligosaccharide.l.The optimization on the preparation of xylanase and pretreatment of corncobsThe xylanase was attained by the solid fermentation of Trichoderma koningii Lys-368. The test of a single factor indicated that xylanase activities reached 8.2 IU/g under the following optimal conditions:corncobs (8.0 g), wheat bran (2.0 g), ammonium sulfate (0.5 g), water (20.0 mL), pH scale (5.5-6.2), temperature (30?) for 4 days of fomentation. The optimal pretreatment conditions contained 80 meshes of smashed corncobs, the ratio of corncob powder to water(1:8), NaOH (1.0%), and pressurization at 110? for 20 minutes, in which the amount of reducing sugar extracted reached 61.5 ? mol/mL.2.The optimization of process corncob powder by method of enzymatic hydrolysis.2.The optimization on the production of corncob enzymolysisBased on the optimal conditions of corncob pretreatment,this study conducted a single factor experiment on how to optimize the corncob enzymolysis and it turned out that the best conditions covered pH scale(5.0), the temperature of enzymolysis (45?),12 hours of enzymolysis and the enzyme dosage(4.0 IU/mL). Through three levels of orthogonal experiments targeted on these four factors(alkali pretreatment, enzymolysis time as well as temperature, the ratio of solid to liquid),this research confirmed that the optimal combinations of the corncob enzymolysis were as follows:the content of NaOH 0.8% for pretreatment of corncobs, the ratio of and ratio of material to solvent (1:15),50? for 24 hours of enzymolysis, producing the reducing sugar(58.2 ? mol/mL).3.The Separation and purification of xylooligosaccharidesFirst of all, the crude enzyme fluid was ultrafiltrated to get rid of impure protein.After 30 kDa of filtration membrane,the yield of crude enzyme liquid was 91.9%, but its yield after 6 kDa of filtration membrane rate is as high as 97.1%, and its total yield was 89.2%.Enzymolysis liquid was decolored by activated carbon.Then five kinds of activated carbon were preliminarily screened.The result showed that activated carbon 10006619 of China National Medicines Corporation Ltd. was considered as the best variety.And the single-factor experiment towards decoloring conditions proved the optimum decoloring conditions,which include pH scale(4.0), the temperature (60?), activated carbon(2.0 g/L).Under such circumstances, the decolorization rate was 93.5% and finally, the rate of xylooligosaccharide yield was 88.0%.