Micronized-Enzymatic Modification Of Rice Bran Dietary Fibre And Changes Of Its Physicochemical And Functional Properties

In this thesis,the enzymatic modification was researched in view of the low content of soluble dietary fiber and poor functional properties of defatted rice bran dietary fiber(DRBDF).So in experiment,defatted rice bran dietary fibre(DRBDF)was used as raw material to extract DF,and the DRBDF was studied by means of enzymatic modification.The aims were to improve the content of SDF and the functional properties of DF in DRBDF.Firstly,the high temperature of alpha amylase and alkaline protease were used to remove the starch and protein in the defatted rice bran,and then to superfine grinding DRBDF with cellulase and xylanase enzyme hydrolysis DRBDF.Then,by single-factor tests and response surface method determined that the optimum conditions were:the amount of cellulase enzymatic was EGU/63.1g,xylanase enzyme amount was 30.6 FXU/g,enzymolysis time was 4.1 h,the range of sample particle sizes was 100?150 ?m,the pH value was 4.5,enzyme solution temperature was 55 ?.Under these conditions,the yield of SDF was 8.32%.The water holding capacity of the TDF and IDF obtained by enzymatic hydrolysis reached 5.19g/g and 5.47g/g respectively,and the oil holding capacity reached 5.26g/g and 5.39g/g.Compared with DRBDF,the water holding capacity of TDF increased to 1.32 times,the oil holding capacity increased to 2.21 times,and the water holding capacity of IDF increased to 1.40 times,and the oil holding capacity increased to 2.26 times.After the enzymatic hydrolysis,the swelling force of DF decreased.The TDF and IDF had 78.6%and 87.1%swelling force of DRBDF,respectively.By infra-red spectrum,the analysis of physical and chemical properties of DF modified discovery.All of DF had the typical carbohydrate absorption peaks.The SDF had the absorption peak of phenolic benzene ring.The capacities of SDF and TDF to adsorb glucose were higher than that of DRBDF(p<0.05)significantly,and the highest was SDF,the value reached to 134.19mg/g.At pH 7.0,the capacity of SDF and TDF to adsorb cholesterol was up to 30.86mg/g and 24.37mg/g.Compared with DRBDF,that enhanced 45%and 14.5%,respectively.However,the adsorption capacity of IDF on cholesterol decreased.After enzymatic hydrolysis,the clearance ability of SDF to N02 was significantly higher than that of DRBDF,while IDF was essentially the same as that of DRBDF.After enzymatic hydrolysis,the content of phenolic compounds in each DF increased significantly.The total phenolic content of SDF and TDF reached 20.03 mg gallic acid equivalent/g and 4.52 mg gallic acid equivalent/g,respectively.They were 9.36 times and 8.82 times as much as DRBDF.The total antioxidant capacity of SDF and TDF were 37.16?pmol Trolox equivalent/g and 16.22 ?mol Trolox equivalent/g,that were 4.97 times and 2.17 times as much as DRBDF.The total phenolic content and total antioxidant capacity of IDF were higher than DRBDF.The best zymolysis condition of rice bran fibre yogurt were the amount of SDF liquid was 5%,the amount of sugar was 5g/100mL,the amount of inoculation was 4mL/100mL,the zymolysis temperature was 42? the zymolysis time was 5h.