| Fresh rice is refered as the rice that has fresh seeds or fresh ears that are ripe at milk term.In this study,fresh rices in the five stages of pre-milk,middle,late,waxy and mature stages were studied,and the contents of soluble dietary fiber,physical and chemical properties,antioxidant activity and improvement of insulin resistance Hep G2 cells were studied.The research on the function,the accumulation rule of SDF of fresh rice was obtained,and the edible function value of soluble dietary fiber of fresh rice were explored.The test results are as follows:(1)Soluble dietary fiber extraction was carried out on rice samples(seeds,leaves,stems and rice husks)of five periods by microwave-assisted enzymatic method.The content of soluble dietary fiber in rice was determined and calculated by national standard method.The results showed that the content of SDF in stems,leaves,shells and grains of fresh rice in the middle stage of milking was significantly higher than that in other parts of the same part(P <0.05),the SDF content decreased gradually with the increase of growth time,the highest SDF content in the mid-breast was 3.40%,and the minimum SDF in the mature stage was 0.50%.(2)The physicochemical properties and monosaccharide structure of fresh rice SDF were analyzed.Physicochemical structure determination the fresh rice samples with the highest content were compared with the maturity stage.The fresh rice SDF in the mature stage had the highest water holding capacity of 3.54 g/g,and the SDF holding power in the mature stage was1.98 g/g,the SDF binding water ability in the mid-milk leaves was the strongest and significantly higher than the grain,and the SDF expansion force in the mature stem was 2.28 m L/g.SDF had the strongest cation exchange capacity in fresh rice leaves.Fourier transform infrared spectroscopy(FT-IR)analysis of molecular mass and molecular mass distribution of fresh rice SDF,and there were many characteristic peaks of carbohydrates.For the monosaccharide structure,the mid-milk grain glucose was up to 79.2%,and the monosaccharide composition of stem,leaf and shell was very similar,with glucose being 32.1%,31.9% and 34.2% and galactose30.9%,35.7% and 35.7%,respectively.The molecular mass and molecular mass distribution analysis of fresh rice SDF by high-performance size exclusion chromatography-multi-angle laser light scattering-refractive-index detector system showed that the polysaccharides of SDF in stem and grain were not uniform polysaccharides.Rice husks and leaves were homogeneous polysaccharides.There were obvious UV detection peaks in the stems,shells,grains and leaves of fresh rice respectiely,which indicated that they contain a certain amount of protein.The molecular link modes were mainly composed of glucose and 1,6-glucosidic bonds;the stems,leaves and shells were mainly composed of arabinose and glucose galactosidic bonds.(3)In vitro antioxidant activity of fresh rice SDF at different maturity stages was studied.The results showed that fresh rice SDF in leaves and stems had strong free radical scavenging ability and weaker than those in grains.The total antioxidant capacities of fresh rice leaves the weakest,which contents were 1.87 U/mg and 0.52 U/mg,respectively.The research can provide reference value and data foundation for the development of fresh rice products,the nutrition,and function for new dietary fiber.(4)The improvement effect of fresh rice SDF on insulin resistance Hep G2 was verified.Insulin resistance model was induced by using high concentration glucose to induce Hep G2 cells.The effects of cell viability,glucose consumption,malondialdehyde(MDA)content,total superoxide dismutase(T-SOD)activity,and glutathione peroxide(GSH-Px)content were determined by CCK8 method.The effects of fresh rice SDFs on insulin resistance Hep G2 cells were examined.The results showed that,compared with the resistance model group,rice dietary fibers had protective effects on cell viability after 24 h treatment,and the activity improvement was the best at 100 ?g/m L.Fresh rice SDF significantly increased glucose uptake by cells(P<0.05).The concentration of glucose consumed at 200 ?g/m L was at most 8.85 mmol·L-1;and the MDA content was significantly decreased(P<0.05),the activity of T-SOD was significantly increased(P<0.05),and GSH-Px was significantly increased(P<0.05).With the dietary fiber concentration increases,total superoxide dismutase activity and glutathione peroxidase content were also increase.The results showed that the SDF in fresh rice had a certain improvement effect on insulin-resistant Hep G2 cells,and to some extent,the that could protect the normal glucose metabolism. |
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