| This topic selected wheat bran as raw material, which was the by-product of flour processing. Removed the starch in wheat bran by enzymolysis of high temperature alpha-amylase and glucoamylase. Alkaline protease, papain, flavourzyme were chosen to dispose of protein in wheat bran. In the process, enzymolysis technology was studied and the optimum hydrolysis conditions were acquired to extract wheat bran dietary fiber; Utilize the method of ultra high pressure with xylanase to extract oligosaccharides in wheat bran. And oligosaccharide power was got by vacuum concentration, activated carbon decolorization and freeze drying. The wheat bran oligosaccharides with different concentrations were made to study antibacterial effect. Filter paper method and turbidimetric method were used to measure the diameter of inhibition zone and MIC of E.coli, S aureus, B sub, Penicillium, Rhizopus. It had a certain practical value and laid the theoretical foundation for the development and utilization of wheat bran functional components. The main research results are as follows:1.wheat bran contain the major components:23.08% starch,17.96% protein, 17.32% pentosan. For the extraction of oligosaccharides, the starch and protein in wheat bran should be removed to make for xylanase degradation.2.After the enzymolysis of high temperature alpha amylase and glucoamylase, residual starch in wheat bran was 0.21%(23.12% in raw materials). It indicated these two enzymes could wipe off starch basically.And through the optimization conditions of orthogonal experiment were:high temperature alpha amylase (temperature was 95℃, enzyme concentration was 1.5%, solid-liquid ratio was 1:12, hydrolysis time was 30min). Glucose amylase (enzymolysis temperature was 65℃, the enzyme concentration was 2.5%, solid-liquid ratio was 1:15, the hydrolysis time was 150min). The remaining amount of starch was 0.21% after the 2 enzymes.3.Mixing with flavor protease, alkaline protease, papain to get optimized ratio, which was 1:2:1. And in this condition, the remaining protein amount of wheat bran was 2.67%. solid-liquid ratio was 1:15, the time was 2.5h, the temperature was 65℃, the enzymolysis pH was 7.0. The remaining protein amount of wheat bran was 2.25% after removing test.4.Various influencing factors on extraction percentage of wheat bran oligosaccharides were compared under the condition of ultra high pressure and normal pressure. It contained solid-liquid ratio, enzyme concentration, pressure, temperature, holding time. In a proper range, with the increasing of the ratio of material to liquid and enzyme concentration, extraction rate increased gradually. And the amplitude decreases gradually, finally it tended to be stable; Pressure size had an greater effect on extraction efficiency, which was mainly due to the pressure increasing enzyme activity or the spatial structure of wheat bran changing more loose to contribute to enzyme reaction; Enzymolysis temperature and reaction time of xylanase in certain ranges affected the enzymolysis effect as well.5.The optimizing conditions by the response surface method was:solid-liquid ratio was 33ml/g, enzyme concentration was 3.0g/L, pressure was 225 MPa, pressure temperature was 30℃, the holding time was 30min. The predicted value of wheat bran oligosaccharides of extraction rate under the optimal technology was 88.21%. And the actual value in the verification testing was 88.10%.6.Determination of antibacterial activity of wheat bran oligosaccharides by filter paper method, it had inhibitory effect on E.coli, S.aureus, B.sub. But it had no obvious effect on Penicillium and Rhizopus, even enlarging additive amount, the colony number of mould was more than the negative control group. This may be due to the mould exploited wheat bran oligosaccharides to carry on metabolism, which accelerated the growth of molud. MIC were measured by turbidimetric method, the results showed that the MIC of E.coli was lOOmg/ml, the MIC of B.sub was 100mg/ml, S.aureus was 60mg/ml. |
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