Studies Of Preparation Process And The Edible Quality Of Instant Brown Rice Powder Through The Method Of Combining Extrusion Technology And Enzymolysis Technology

Based on Northeast japonica rice as raw material, application of extrusion technologyand biological technology for treatment of brown rice, and then using spray drying technologyto produce instant brown rice powder were studied in this paper.The study focused on theoptimum parameters of the extrusion process of brown rice, enzymolysis conditions of brownrice and puffed brown rice powder, influence of varying degrees of enzyme liquid on thequality of instant brown rice powder and the quality improvement of instant brown ricepowder.Firstly, the brown rice was used as raw material to study the effect of the of extrusionparameters, containing particle size, the moisture content, screw speed, extrusion temperature,on the target parameters of brown rice power. The experiment was designed by Box-Behnkendesign, in which the gelatinization degree of brown rice starch and the Soluble Dietary Fiber(SDF) yield were the target parameters. The response surface methodology was used tooptimize the extrusion processing of brown rice. The result showed the optimal extrusionparameters for brown rice were the particle size60mesh，moisture content20.1%，screwspeed135r/min, and temperature168℃. While the gelatinization degree of extrudate starchwas92.15%, the SDF yield was1.540%.Secondly, after enzymatic hydrolysis of brown rice and optimal puffed rice powder, theoptimal enzymatic hydrolysis conditions were determined. And then enzymatic hydrolysatewas provided feed for spray drying. Thermostable α-amylase and cellulose enzyme were usedfor enzyme liquid of brown rice in two steps. The response surface methodology experimentwas used to get the optimal thermostable α-amylase hydrolysis parameters of brown rice. Theoptimal reaction conditions of thermostable α-amylase were reaction temperature90°C, PHvalue6.5, enzyme concentration70u/g, time100min and substrate concentration of4%.Thenthe cellulose was added to the thermostable α-amylase hydrolysate. The orthogonal test wasused to get the best cellulose hydrolysis parameters of brown rice. The optimal reactionconditions of cellulose enzyme were reaction temperature50°C, enzyme concentration0.12%,time120min and PH value5.0. Medium temperature α-amylase and cellulose enzyme wereused for enzyme liquid of optimal puffed rice powder in two steps. The response surfacemethodology experiment was used to get the optimal medium temperature α-amylasehydrolysis parameters of brown rice. The optimal reaction conditions of medium temperatureα-amylase were enzyme concentration25u/g, time49min PH value5.5, reaction temperature 54°C and the ratio of brown rice to water1︰11(w︰w).The cellulose was added to themedium temperature α-amylase hydrolysate. The orthogonal test was used to get the bestcellulose hydrolysis parameters of optimal puffed rice powder. The optimal reactionconditions of cellulose enzyme were reaction temperature50°C, enzyme concentration0.08%,time100min and PH value5.0.Thirdly, enzymatic hydrolysate of brown rice and optimal brown puffed rice powder indifferent enzymatic hydrolysis degrees were used for spray drying to get instant brown ricepowder under the optimal process parameters of spray drying. The effect of degree ofenzymatic hydrolysis on quality evaluation and sensory evaluation of instant brown ricepowder was studied. The better instant brown rice powder was choosed by comparing thecomprehensive evaluation scores and sensory evaluation scores. The results showed that thequality of the instant brown rice powder which derived from enzymatic hydrolysate ofoptimal puffed rice powder was better.Finally, because of light flavor and taste of the better instant brown rice powder, thebetter instant brown rice powder from the fourth chapter was mixed with optimal brownpuffed rice powder in different proportions in order to improve the quality of instant brownrice powder. The results showed that when the mix ratio was1:3, the best flavor of instantbrown rice powder was the best and its viscosity was the most suitable for people of taste.And then the sensory evaluation score is up to92points.