Preparation Of Oligosaccharides Based On Wheat Bran Arabinoxylans Alkali Enzyme Combination

oligosaccharides(AXOs)with many functional properties was a degradation product of wheat bran pentosan,which was widely concerned by domestic and foreign scholars.As the preparation of AXOS was the main factor affecting the structure and function of AXOs.In this paper,alkali enzyme method was used to prepare functional AXOs to systematically research the effects of alkali extraction conditions on the yield and properties of pentosan(Arabianxylan: AX)the substate in the preparation of AXOs.Further enzyme hydrolysis AX was used to prepare AXOs with high potency activities and analyze the relationship between AXOs structure and prebiotic activity.And the AXOs was applied to in steamed bun products to analyze its impact to provide theoretical basis for the effective preparation and utilization of AXOs.(1)Using alkaline method to extract AX from wheat bran,we studied the effects of extraction temperature,extraction time,NaOH concentration and ratio of material to liquid on the yield of AX,the products monosaccharide components and relative molecular weight of the products.The results showed that with the extension of the extraction time,increasing of extraction temperature,the NaOH concentration and ratio of material to liquid,AX yield significantly increased,but the yield rise slowly or not rise when a certain condition.Different extraction conditions resulting AX products are mainly composed of arabinose,glucose,galactose and xylose four kinds of monosaccharides;Extend the extraction time,increasing the reaction temperature,NaOH concentration and ratio of material to liquid,arabinose and xylose relative content increased,glucose is relatively decreased.The change of extraction conditions had no significant effect on the relative molecular weight of AX,and had a certain effect on the total sugar concentration of AX in different molecular weight regions.In a word,the extraction conditions were determined by AX yield,which could not only guarantee the AX yield but also get the AX product with high relative molecular weight.(2)Considering the result of extraction conditions effect on the yield and properties of wheat bran AX,the orthogonal experiment was optimized with the AX yield as the index.The results showed that the most optimum extraction conditions were as follows: extraction temperature 85?,extraction time 3.5h,ratio of material to liquid 1:12 and NaOH concentration 0.25 mol / L,the AX yield reached 6.56%,and the influence degree of each factor on AX yield was : NaOH concentration > the ratio of material to liquid > temperature> time.(3)Using wheat bran AX as materials for preparation of AXOs by enzymatic hydrolysis,the effect of enzymolysis temperature,enzymolysis time and enzyme dosage on the content of AXOs,prebiotic activity and structural properties were studied.The results showed that the content of AXOs increased following the extension of enzymolysis time and the increasing of enzymolysis temperature and enzyme dosage.When Bifidobacterium adolescentis was cultured with AXOs obtained under different enzymolysis conditions,the concentration of Bt increased by different extents.The metabolites of fermentation broth contained lactic acid,acetic acid and propionic acid,and the content of acetic acid was the highest.The trend of acid production was consistent with the concentration of bacteria;To the content and prebiotic activity of AXOs as an indicator for preparation of AXOs could conclude that the multiplication of cell concentration was up to 5.65 times when the enzymolysis temperature was 50?,the time of enzymolysis was 2h and the amount of enzyme was 1g/L.When the results of the prebiotic activity and structural properties were taken into account,it could be drawn that the prebiotic activity of AXOs was the optimal,and the average degree of polymerization tended to be minimal,the relative content ratio of xylose,xylotriose and xylotetraose was the smallest.(4)Based on the effect of enzyme hydrolysis on the prebiotic activity of AXOs,The effects of AXOs prepared with enzymatic hydrolysis time of 2h,enzymolysis temperature of 50? and enzyme dosage of 1g/L were compared with that of inulin.The results showed that AXOs medium conditions prepared cell concentration accounted for 92.96% inulin medium,The amount of acetic acid and propionic acid produced by the AXOs media was more.(5)The effects of different amounts of AXOs on the sensory evaluation and texture characteristics of bread products were studied.The results showed that the addition of AXOs not only increased the specific volume and volume of the steamed bun products,but also improves the sensory score;It could greatly reduce the steamed bun 's chewiness and hardness,increase adhesion and flexibility.By combining two indicators to determine the best addition of AXOs to the bread product was 2%.