Study On The Preparation Of Xylooligosaccharides From Sweet Corncobs By Enzyme System

The experiment takes sweet corncob as raw material, the xylan extraction and xylanase degradation process were studied systematically from sweet corncob. The cooking and pectinase treatment were applied to design different retort and enzymatic treatment conditions on the extraction rate of hydrolysis of xylan, the paper mainly studied the effects of different conditions on the hydrolysis yield of xylobiose during the xylanase degradation process. Xylan hydrolyzate was purified by gelchromatography which aim to increase the content of xylobiose of xylooligosaccharides. The main works are as following:1. Pretreatment:the acid treatment and heat extraction after dehydration treatment, crush and fine grinding were investigated grinding granularity, extraction time and temperature effect on the extraction pretreatment were used by anthrone colorimetric to indicate the yield of total sugar, finally, the result was that:under the optimum conditions of maximum yield of soluble sugar at120mesh, temperature110℃, extraction time35min, which reaehed53.17%.2. Pectinase treatment:the effect of degree of hydrolysis were used by changing hydrolysis temperature, time, pH, enzyme dosage, the final results showed that:hydrolysis temperature60℃, time90min, pH value5.0, enzyme dosage76U/g when D-galacturonic acid content was2.398mg, the degree could reach45.98%.3. The experiment studied the technological parameter of xylobiose extraction and took the yield of xylan as a target to make sure whether Sweet corncob paste would be pectinase hydrolyzed or not. The factors of enzyme technology were discussed by the single-factor experiment and orthogonal experiment to choose the optimum extraction process from sweet corncobs. The paste was pretreated and1.0g/1H2SO4at60℃for24h,5000r/min centrifugal20min, ratio of solid to liquid (W/V)1:11, pH value6, temperature100℃, time70min, under this condition, the extraction rate of xylan was60.95%, however, the rate was39.12%when the sweet corncob paste were not hydrolyzed.4. The processing of the sweet corncob xylan extraction was established as the followings:15g/100NaOH, ratio of1:16(W/V), temperature85℃, time180min, under this condition, the extraction rate of xylan was50.75%.5. The yield of xylobiose was discussed by the single-factor experiment and orthogonal experiment to choose the optimum extraction process, the final results showed that:enzyme dosage149U/g, temperature45℃, time5.5h, pH value4.9when the yield reached10.71%.6. The method of activated carbon removed pigment, ion exchange resin D-301, sevage removing protein and sephadexG-25chromatography were used in the separation and purification of xylooligosaccharides. Finally, the degree was reached more90%, the content of xylobiose was90.45%, which the rate to total sugar was57.19%.