| Rice bran is the main by-product of rice(Oryza sativa)processing,which is a rich and renewable plant resource in China.Although the output of rice bran in China ranks first in the world,the research of deep development and application and the corresponding theory of rice bran is still at a low level Only a small part of rice bran is used to extract oil or higher value products such as inositol and oryzanol.There is still a certain distance from the comprehensive utilization level and the level of product development of rice bran in developed countries.In this paper,the crude product of rice bran polysaccharides obtained by spray drying was used as raw material,and the ultrafiltration and fractionation of rice bran polysaccharides were carried out.On the basis of which,the antioxidant activity in vitro and the composition of monosaccharide were determined,and the optimum ultrasonic degradation conditions were determined by orthogonal test.The research of this subject has very important practical significance and academic value for the industrial production of rice bran polysaccharide,improving the bioavailability of rice bran polysaccharide and enriching the basic theory of polysaccharide composition.The main research results are as follows:(1)Using the spray dried rice bran polysaccharide as raw material,the ratio of liquid to material was 1:30,the extraction temperature was 100 C,the extraction time was 15 min,and the redissolution of polysaccharide reached the maximum.The relative molecular mass of polysaccharide was measured between 25kDa-852kDa by high performance liquid chromatography-eighteen-angle laser light scattering detector(HPLC-MALLS),and three kinds of ultrafiltration membranes with molecular weight of 100k,50k and 10k were selected to intercept rice bran polysaccharide in turn.Three kinds of polysaccharides with different molecular weight,RBP-?,RBP-? and RBP-III,were obtained,the contents of which were 3.68%,4.48%and 5.66%,respectively.Compared with traditional methods,the purity of polysaccharides obtained by membrane separation method reached 53.96%,and the treatment time of the two methods was shorter than that of traditional vacuum concentration method,and the conditions were mild,the operation was convenient and suit for industrialization.(2)DPPH free radical scavenging,hydroxyl radical scavenging and superoxide anion radical scavenging experiments were carried out on rice bran polysaccharides RBP-?,RBP-? and RBP-III with different molecular weights.The antioxidant capacity of RBP-?,RBP-? and RBP-? showed a dose-effect relationship,and the antioxidant capacity was related to RBP-?>RBP-?>RBP-?.(3)The monosaccharide composition of rice bran polysaccharide with different molecular weight was determined.The monosaccharide composition of RBP-?,RBP-?and RBP-? was determined by PMP pre-column derivatization and high performance liquid chromatography(HPLC).The results showed that RBP-I,RBP-? and RBP-?were mainly composed of glucose,galactose,xylose and arabinose.The ratio of substance to RBP-? was 1.597:0.930:0.356:1.382,RBP-? was 1.690:0.912:0.441:1.321;RBP-? was 1.630:0.993:0.423:1.291,their monosaccharide composition and the composition ratio was basically the same.(4)Rice bran polysaccharide RBP-? was extracted by ultrasonic degradation,and the optimum ultrasonic degradation process of rice bran polysaccharide was studied.The effects of material-liquid ratio,ultrasonic temperature and ultrasonic time on the content of rice bran polysaccharide RBP-? were studied by orthogonal design.The results showed that the optimum ultrasonic degradation process was A2BlC3.i.e.the ratio of material to liquid was 1:15,the ultrasonic time was 30 min,and the ultrasonic temperature was 35?,the content of RBP-? was 6.60%under these conditions,which was 16.6%higher than that of RBP-? before degradation. |
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