Study On The Composition And Activity Of Non-starch Polysaccharides In Fresh Edible Rice Seeds

Fresh edible rice refers to the rice harvested and utilized between the milk ripening stage and the full ripening stage.At present,fresh edible whole grains have attracted much attention,but fresh rice is still relatively weak,which of these substances have biological activity remains to be further explored.In this experiment,the milk ripening(early,middle and late),wax ripening,and full ripening stage seeds of rice were used as raw materials.Firstly,the effects of ultrasonic time,extraction temperature,microwave power and the ratio of liquid to solid on the extraction rate of polysaccharides were explored by single factor experiments,optimization of extraction process by response surface methodology,the impurities were removed by enzymatic method,Sevage method and dialysis method,determination of polysaccharide content in different periods by Ultraviolet and visible spectrophotometry.Secondly,the composition of monosaccharide was determined by High performance liquid chromatography,structure determination of polysaccharides by fourier transform infrared spectrometer,determination of molecular weight and its distribution by high-performance size-exclusion chromatography-multi-angle laser light-scattering-RI.Finally,the total reducing power of polysaccharides,ABTS+ free radical,DPPH free radical,superoxide anion,hydroxyl radical scavenging capacity were studied to determine the antioxidant capacity of polysaccharides,exploring the inhibitory ability of polysaccharides to Staphylococcus aureus,Salmonella,Shigella and Escherichia coli by determining the minimum inhibitory concentration,Cell Counting Kit-8 method was used to detect the effect of polysaccharide on lung cancer cells and normal cells.The main results are as follows1.The single factor optimum extraction conditions were as follows:ultrasonic time:2 h,extraction temperature:60?,microwave power:600 W and liquid-solid ratio:15 mL·g-1 Response surface experiments were designed to obtain the optimal extraction conditions ultrasonic time:100 min,extraction temperature:60?,microwave power:620 W and liquid-solid ratio:17.50 mL·g-1,extraction result:(46.98±1.13)mg·g-1.After removing impurities,the content of polysaccharides increased first and then decreased with the extension of growth time,and the highest content of polysaccharides was 46.89 mg·g-1 in the late milk ripening stage,and the lowest content was 22.32 mg·g-1 in the full ripening stage2.Fresh edible rice seeds polysaccharides mainly consist of mannose,rhamnose,glucuronic acid,galacturonic acid,glucose,galactose,xylose,arabinose and fucose,mannose and fucose were not detected in wax ripening and full ripening stage.The polysaccharide contain hydrogen bond,O-H,C-H,C=O,C-O-C,furan ring,?-glycosidic,a-D-xylopyranose and so on.The molecular weight and the radius of gyration of the polysaccharides increased with the ripening time,and the maximum value was(217.3±9.5)×104 u,399.6±15.2 nm at the full ripening stage3.All the polysaccharides had certain antioxidant activity,and the effect was the best in the later milk ripening stage,its total reducing power,ABTS+ radical,DPPH radical,superoxide anion and hydroxyl radical scavenging capacity were 0.93,86.18%,56.81%,41.69%,75.62%,and significantly higher than the antioxidant capacity at full maturity(0.81,73.56%,42.14%,35.78%,64.95%).Fresh edible rice seeds polysaccharides had good antibacterial activity,especially in the middle milk ripening stage and late milk ripening stage,the minimum inhibitory concentration for Staphylococcus aureus,Salmonella,Shigella and Escherichia coli were 1.875 mg·mL-1,1.875 mg·mL-1,3.75 mg·mL-1,3.75 mg·mL-1.The results of CCK-8 experiment showed that the fresh edible rice seeds polysaccharides had killing effect on lung cancer cells and had no side effect on human embryo lung fibroblast cellsThe content,composition and activity of fresh edible rice seeds polysaccharides were detected,and the relationship between composition and biological activity was analyzed to explore its practical application value.It lays a good theoretical foundation for the research and development and utilization of rice products,and also provides data support for the development of fresh cereals,which will play a certain role in promoting the intensive processing of agricultural products.