Study On Preparation Of Xylooligosaccharides From Wheat Bran

Wheat bran, main byproduct of wheat flour milling, contains about 20% pentosans. The objective of this paper is to extract the xylooligosaccharide from wheat bran by biological technique. Besides of cellulose and hemicellulose, wheat bran contents lots of starch, protein, phytic acid and antioxidants etc.The composition of wheat bran was analysized as 22.16% starch, 18.75% protein, 17.27% pentosans, 4.82% fat. First of all, we separated starch and protein by enzymic hydrolysis to get WBDF which includes a lot of xylan, so that we can extract effeciently xylooligosaccharide by xylanase hydrolysis. Taking the residual of starch and protein of hydrolyzed wheat bran as review target, we investigate the factor effecting hydrolysis by One-way analysis of variance and ANVOA to optimize parameters. The residual of starch is reduced to 0.21% from original 22.16% and the residual of protein is to 4.76% from 18.75%. The optimum conditions ofα-amylase digestion were as follows: the temperature was 100°C, the ratio of stuff and liquid was 1:12, digestion time was 20min,and enzyme concentration was 1.5% wheat bran starch, The optimum conditions of alkaline protease digestion were as follows: the temperature was 50°C, the ratio of stuff and liquid was 1:12, digest time was 120min, and enzyme concentration was 3% wheat bran protein. Insoluble wheat bran dietary fibre with 40% of yield was prepared from wheat bran by treatment withα-amylase and protease. The wheat bran that has been discared starch and protein contents 42.62% pentosans.Protein was removed with enzyme digestion and ultrasonicwave treatment after starch removed. The effect of ultrasonic treatment and the ratio of stuff and liquid on removing protein were studied. The optimum conditions were determined. The components of wheat bran after enzymatic hydrolysis were analyzed. The results showed that the optimal conditions of removing protein were as follows: 300W of the ultrasonic power, 80 minutes action duration, the ratio of stuff and liquid 1:12, the temperature 50°C. Insoluble wheat bran dietary fibre with 36~40% of yield was extracted from wheat bran,The content of pentosans is 45% .In this study characteristics of several xylanases were studied and xylanases H was screened out as hydrolase. Factors effecting production of xylooligosaccharides was analyzed by One-way analysis of Variance and was optimized by using response surface methodology employing a five-level,five-variable central composite rotatable design.The optimum reaction conditions were as follows: substrate concentration, 60 g·L-1; enzyme concentration, 3.5 g·L-1, reaction time, 26h; temperature, 55°C; pH, 5.6. The yield of xylooligosaccharide is 26.58%.Pilot trial of xylooligosaccharide was studied: the result was consistent with experiment. After enzymatic hydrolysis the yield of xylooligosaccharide was 10.82% and the purity was up to 70.83%, the relative content of xylobiose and xylotriose and xylotetraose achieved 50.17% of xylooligosaccharide.