| Arabinoxylan(AX)is an important non-starch polysaccharides in wheat bran, which accounts forabout20%in wheat bran. It not only has an important impact on the quality of the processing of cerealproducts, but also has many important physiological activities. Thus, arabinoxylan has an enormouspotential for developmentIn order to understand the quality status of wheat bran resources in China, We firstly did the initialinvestigation about the nutritional quality and safety indexes of domestic wheat bran samples.12wheatbran samples were collected from nine wheat major production areas in China. The measurementindexes included components of dietary fiber, arabinoxylan, crude protein, total starch, amino acid,pesticide residue, heavy metal residue, and mycotoxins. The results showed that in the nutritionalcomposition of the collected samples, the average dietary fiber content44.20%, arabinoxylan content (inpentosan meter)35.33%, crude protein content17.62%, total starch content20.60%. There weredifferences in nutritional characteristic indexes among different samples, the contents of total starch andsoluble dietary fiber had the first and second largest variation and the variation coefficients were35.31%and24.23%, respectively. Amino acid components analysis showed glutamic acid had the largest contentand the average content of lysine as the first limiting amino acid was0.64%. In the safety quality indexes,the contents of heavy metal residue complied with the limit standard, and pesticide residues were notdetected. In the mycotoxin indexes, the DON content of one sample from Hebei exceeded its limit range.From the utilization of wheat bran arabinoxylan, four superior samples such as samples came fromBinzhou, Shandong province;Bayannur, Inner Mongolia province; Taizhou, Jiangsu province and Beijingcould be used for the next step of polysaccharide extraction as raw materials, because of their highercontent of arabinoxylan, lower content of starch and better sanitary status.This study confirmed the extraction processes of wheat bran arabinoxylan. Polysaccharide extractionprocess was optimized by quadratic regression orthogonal rotary design. The optimum parameters werethat the concentration of sodium hydroxide and hydrogen peroxide and temperature were0.67mol/L and0.88%and68℃, respectively. The yield was the max (26.59%) and the purity of the product was69.67%.What’s more, comparative study on processes of ultrasound-assisted extraction andmicrowave-assisted extraction was discussed The results showed that the appropriate conditions ofultrasound-assisted extraction were that extraction time of20min, power500W, ratio of solid to liquid1:30, the yield of polysaccharide was13.58%. The appropriate conditions of microwave-assistedextraction were that extraction time of4min, power550W, the ratio of solid to liquid1:30, the yield ofpolysaccharide was14.77%. In addition, the molecular weight of the ultrasound-assisted extractionproduct were much higher than microwave-assisted extraction’s This paper introduced the degradation of alkaline extraction of arabinoxylan(hereafter referred asAX) through enzymatic and acidhydrolysis, meanwhile, studied the average molecular weight (Mw) anddistribution of the degradation products though High Performance Size Exclusion ChromatographyMultiangle Laser Light Scattering (HPSEC-MALLS). The results showed that molecular weight of theenzymatic hydrolyzed AX samples decreased significantly. The main component part of80%ethanolprecipitation’s Mw concentrated in5.277×104Da. But lower than80%ethanol treatment resulted inpoorer fractionation. While among acid hydrolyzed AX samples, both hydrochloric acid and citric acidcould effectively reduce the AX’s Mw and the Mw of the main component could be reduced to10~3orders of magnitude, instead, the effect of acetic acid hydrolysis AX was very weak. In the condition of95℃for2hours, the Mw of HCl treatment AX was7.501×10~3Da with peak area percentage of84.10%,but the distribution was board (Mw/Mn=11.88); the Mw of citric acid degradation product was8.997×10~3Da with peak area percentage of56.70%, and the samples had good homogeneity(Mw/Mn=1.673). This study preliminarily revealed that citric acid, as a weak acid, had its certainadvantage on effectively reducing the AX’s molecular weight, compared with the hydrochloric acid andenzymatic degradation.Vitro fermentation method was used to simulate the human intestinal environment to research thesedifferent molecular weight fragments arabinoxylan samples’s prebiotic activity. The study found that allarabinoxylan samples and the inulin could promote the proliferation of bifidobacteria. Compared withglucose medium, the log value increased from1.05to1.31magnitude. The prebiotic activity scores ofinulin and arabinoxylan samples were greater than0, which indicated that they all had prebiotic activity.What’s more, the higher of the samples’s degradation degree, the better of prebiotic activity... |
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