Study On The Physicochemical Properties And Hypolipidemic Function Of Dietary Fiber From Rice Bran Meal With Three Oil Production Processes

In this paper,rice bran meal was prepared from rice bran as raw material,and rice bran meal dietary fiber was prepared by enzymatic method using response surface optimization of hydraulic pressing method,organic solvent leaching method and water enzymatic method to produce rice bran oil process conditions.Then the basic components of the three rice bran meals and rice bran meal dietary fibers were determined,and the structural characterization,physicochemical properties and functional properties of the three rice bran meal dietary fibers were compared.Finally,the hypolipidemic effect of rice bran meal dietary fiber of three oil production processes on rats with hyperlipidemia was investigated through animal experiments,and the main findings were as follows.(1)The optimal process of three oil production methods(hydraulic pressing,organic solvent extraction and hydroenzymatic method)and their effects on the basic composition of dietary fiber of rice bran meal were optimized by single-factor and response surface experiments:the optimal process conditions of hydraulic pressing method were 20 min of baking time,20 min of steam treatment time and 110℃ of baking temperature,and the oil yield of rice bran was 53.44%under this condition.The best extraction process of organic solvent extraction method was the extraction temperature was 60℃,the material-liquid ratio was 1:8 g/mL,the extraction time was 2 h,and the oil yield of rice bran was 93.31%under this condition.The optimum process conditions for the aqueous enzyme method were 4%enzyme addition,3 h enzymatic digestion time,1:10 g/mL material-liquid ratio,and 65.24%oil yield of rice bran under these conditions.The dietary fiber contents of hydraulic pressed rice bran meal dietary fiber(H-RBDF),N-hexane leached rice bran meal dietary fiber(NRBDF)and Enzyme method rice bran meal dietary fiber(E-RBDF)were 63.32%,57.03%and 71.12%for insoluble dietary fiber(IDF)and 5.39%,6.68%and 5.88%for soluble dietary fiber(SDF),respectively.(2)The effect of three kinds of oil making methods on the physicochemical characteristics of rice bran meal dietary fiber:after testing and analysis,the particle size distribution of three kinds of rice bran meal dietary fiber showed that N-RBDF had the smallest D50,indicating that the particle size of N-RBDF was the smallest,but the particle size span(Span)of water E-RBDF was the smallest,indicating that the particle size distribution of E-RBDF was the narrowest.Scanning electron micrographs showed that all three dietary fibers had irregular flakes with a small amount of protein particles on the surface,with H-RBDF having the largest particles,E-RBDF the second largest,and NRBDF the smallest,which was consistent with the particle size results.The FTIR spectra showed no change in the position and number of characteristic absorption peaks for the three dietary fibers,only differences in the intensity of some peaks.X-ray diffraction(XRD)results showed that the crystallinity of H-RBDF,N-RBDF and E-RBDF were 31.98%,20.27%and 29.80%,respectively.The results of thermogravimetric analysis showed that all three dietary fibers had the same location of pyrolysis peaks,but there were significant differences in peak intensities.The water-holding capacity,water-holding capacity and peak intensity of E-RBDF were the same as those of RBDF.RBDF had 1.56 times,1.28 times,1.33 times,and 1.29 times,1.10 times,and 1.34 times of H-RBDF and N-RBDF,respectively.The cation exchange capacity of N-RBDF was 1.30 times that of H-RBDF and 1.27 times that of E-RBDF;the adsorption of cholesterol by E-RBDF reached 3.39 mg/g at pH=7,which was 1.78 and 1.89 times higher than that of H-RBDF and N-RBDF,respectively,and the adsorption of sodium glycocholate and sodium taurocholate by ERBDF was 4.95 mg/g and 11.77 mg/g,which were 2.03 and 1.68 times higher than that of H-RBDF and 1.43 and 1.57 times higher than that of N-RBDF,respectively.However,the E-RBDF inhibited pancreatic lipase 0.82 and 0.65 times more than H-RBDF and N-RBDF,respectively.(3)The results of the lipid-lowering experiments of three kinds of rice bran meal dietary fiber on hyperlipidemic rats showed that rice bran meal dietary fiber had a hypolipidemic effect on hyperlipidemic rats.All three types of rice bran dietary fiber significantly(p<0.05)reduced the serum triacylglycerol(TG)level,total cholesterol(TC)level and low-density lipoprotein cholesterin(LDL-C)level,as well as the activity of alanine aminotransferase(ALT)and aspartate aminotransferase(AST),and increased the serum high-density lipoprotein cholesterin(HDL-C)level in rats,among which E-RBDF reduced serum TG,TC,LDL-C,ALT and AST in rats by 61.42%,25.10%,10.84%,5.44%and 6.77%,respectively.Meanwhile,the three rice bran meal dietary fibers also significantly(p<0.01)reduced TG,TC,LDL-C and malondialdehyde(MDA),and increased HDL-C and total superoxide dismutase(Total superoxide dismutase,T-SOD)and(Glutathione peroxidase,GSH-Px)activities in rat liver.It also improved the steatosis of the liver and reduced the atherogenic index(AI)in hyperlipidemic rats.Among them,E-RBDF decreased TG,TC,LDL-C and MDA in rat liver by 49.70%,31.40%,50.86%and 57.94%,respectively,and elevated T-SOD and GSH-Px by 38.82%and 61.46%,respectively.And The effect of ERBDF group was the best,H-RBDF group was the second and N-RBDF group was the least obvious,so all three kinds of rice bran meal dietary fiber had good hypolipidemic function,among which E-RBDF had the best effect.