Effects Of Biological Treatment On Quality Characteristics Of Rice Bran Instant Powder And Development Of High Dietary Fiber Rice Bran Compound Powder

Rice bran is occurring in the process of rice processing by-products,rich in protein,dietary fiber,minerals,vitamins and other nutrients.My country is rich in rice bran resources and the rice bran is highest among the world now.However,the rice bran contains large amounts of fatty oxidase and peroxidase,which makes it easy to rancidity and difficult to store,and high crude fiber content in rice bran,taste rough.The human body lacks cellulase,therefore,rice bran can not be directly used as food materials for processing.To depth development of rice bran in order to improve its utilization and economic value,in this paper,four layers of rice bran(1#-4#)obtained after rice milling were treated by biological technology(enzymatic hydrolysis and biological fermentation).To improve the machinability and edible,and explore different processing methods on layered rice bran instant powder's influence on the quality characteristics.And develop high dietary fiber rice bran compound powder.The specific research contents are as follows:(1)Taking the yield of rice bran as an indicator,compound enzymatic hydrolysis technology(?-amylase and alkaline protease=1?1)was used to treat four layers of rice bran.The optimal enzymatic hydrolysis temperature,enzyme addition amount,enzymatic hydrolysis time and solid-liquid ratio were determined by single factor and orthogonal optimization test,and the process parameters with the highest yield of rice bran were selected.The optimal enzymatic hydrolysis temperature of rice bran 1#to 4#was 60?,55?,55?and 50?,respectively.Enzyme addition amount was 1.0%,1.0%,1.5%and 1.5%,respectively.The enzymatic hydrolysis time was 120 min.The solid-liquid ratio was 1?20,and the powder yield under the optimal condition was24.8%,30.0%,33.1%and 38.9%,respectively.(2)With glucose equivalent(DE)value and soluble solids as evaluation indexes,biological fermentation method(Lactobacillus acidophilus and Bacillus subtilis MK20)was adopted,and the optimal inoculation ratio,inoculation amount,fermentation time and fermentation temperature were determined by single factor and orthogonal optimization test.The results showed that the optimal inoculation ratio of rice bran 1#to 4#was 1?2,1?2,1?1,1?1,respectively.The optimal inoculation amount was3%,3%,4%and 2%,respectively.The optimal fermentation time was 12 h,16 h,16 h,24 h,respectively.The optimal fermentation temperature was 28?,28?,28?and34?,respectively.(3)Based on these studies,further analyses of the physical and chemical properties,powder characteristics,microstructure and antioxidant characteristics of the rice bran instant powder were treated by enzymatic hydrolysis and biological fermentation of four layers of rice bran(1#-4#).First,the correlation analysis was carried out with the content of functional factors(total phenol,soluble dietary fiber),antioxidant capacity(DPPH·clearance,ABTS⁺·clearance,OH·clearance,O₂^-clearance,Fe²⁺chelation rate)and powder properties(water holding capacity,oil holding capacity,water solubility,angle of rerest and slip angle)as evaluation indexes.Secondly,principal component analysis(PCA)was used to construct the quality evaluation model of rice bran powder.Finally,the effects of enzymatic hydrolysis and biological fermentation on the microstructure of rice bran powder were discussed.PCA clearly revealed the correlation of all parameters.Compared with other groups,the quality characteristics of M1#rice bran instant powder were significantly improved.The peak temperature of enzymatic hydrolysis and biological fermentation was significantly increased,and the peak temperature of enzymatic hydrolysis was relatively higher,which enhanced the thermal stability of rice bran powder.After enzymatic hydrolysis and biological fermentation,the particle size of the four layers of rice bran powder was reduced to varying degrees,and the surface of rice bran powder was damaged to different degrees.The structure of the rice bran powder was loose and the gap was significantly increased,which was conducive to promoting the release of active substances.Thus the antioxidant activity of rice bran powder was improved.In addition,the functional groups of rice bran protein molecular structure were significantly changed by biological fermentation.After enzymatic hydrolysis and biological fermentation,the?-helix of rice bran protein molecular structure disappeared,and the?-fold of rice bran protein decreased from32.9%to 29.0%due to enzymatic hydrolysis,while the?-fold increased from 32.9%to 38.3%due to biological fermentation.The change of?-rotation angle was not significant,and the random curl increased to 50.0%and 32.0%,respectively.(4)According to the AI,the linear planning method was adopted,and the raw material ratio of energy,protein,fat,carbohydrate,dietary fiber nutrient content was accurately calculated to prepare high dietary fiber rice bran compound powder.Under the restriction of dietary fiber content not less than 13%of the total weight and price not more than 6 yuan/part,the formula of high dietary fiber rice bran compound powder was obtained.Then five formulations were further optimized.Among these formulations,formula two(rice bran 1#30 g,rice bran 2#30 g,rice bran 3#98.68 g,rice bran 4#34 g,soybean 22 g,purple rice 26 g,mushroom 14 g,corn 10 g,sweet potato 18 g,red jujube 30 g)had the highest dietary fiber content and the lowest price,sensory score,hydration properties and dispersity were relatively good.In addition,formula 2 also had the highest antioxidant capacity.Therefore,formula 2 was the best formula of high dietary fiber rice bran compound powder.