The Preparation Of Xylooligosaccharides By Enzymes Hydrolyzing From Soybean Hull

Xylooligosaccharides are oligasaccharides composed of xylose units linked byβ-1,4-xylosidete bonds.They are highly-effective Bifidobacteria improver and have good physiological activities and were widely studied all over the world.This dissertation systemically studied the processing of the xylooligosaccharides production with enzyme,including the extraction xylan from soybean hull,the hydrolization of xylan by xylanase,the refinery of the raw xylooligosaccharides solution and the components of xylooligosaccharides.The variables which affected extraction were:alkaline(NaOH)concentration,the ratio of solid to liquid,extraction temperature and extraction time.The better extractive conditions were obtained alkaline concentration was 2.5%(w/v), the ration of solid to liquid 1:15, extraction time was 80min, temperature was 80℃. The yield of xylan from soybean hull was 8.63%. Ion chromatography showed a single sugar test, xylose was the mainly single sugar of alkaline extraction of soybean hull. Xylose sugar content was 54.99%.Through the hydrolysis of single factor experiments and orthogonal test to determine the optimal conditions for hydrolysis. The most important factor was the amount of enzyme added, followed by the hydrolysis time and solid to liquid ratio, temperature and pH value of relatively insignificant. The optimal conditions for orthogonal were enzyme dosage of 0.3%(w/v) xylanase and solid to liquid ratio of 1:15 on pH 4.3,40℃for 2 h.Optimal conditions for hydrolysis by the program to obtain the total sugar content 5.74 mg/mL, higher than the orthogonal condition in the content, so the priority programs selected orthogonal conditions for the best conditions for hydrolysis.Through the decolorization of activated charcoal of single factor experiments and orthogonal test to determine the optimal conditions. Under the premise of decolorizati on rate and sugar retention, the optimal conditions were activated carbon dosage 0.5%, pH value of 3.5 on 60℃for 40 min.In this condition, the decolorization rate was 86.4%,sugar retention rate was 81.3%.With the anion exchange resin of 12 static screening results, we select 001×7 and 201×7 ratio of 1:1 by volume on the bleaching sugar desalination. The handling capacity was 3 times of the column volume. After desalting column series treatment, solution conductivity approached less than 95us/cm. The composition of the desalination sugar was detected by HPLC. The chromatographic conditions were Agilent 1100 serises, Agilent ZORBAX Carbohydrate(4.6×250 mm,5um),colu-mn temperature of 30℃, mobile phase of acetonitrile:water=70:30, flow rate 0.8 mL/min, injection volume was lOuL. The detector was a differential refractive index detector. Known by the HPLC profiles, there are X2-X5 in the hydrolysis sugar. The content of Xylooligosaccharides was 36.73%.