Study On Storage Stability And Processing Characteristics Of Rice Bran Based On Water Activity Regulation

Rice bran,which has lots of the nutrients,is a by-product of rice producing with great development value.Rice bran is rich in dietary fiber and beneficial to people's health,but it is not fully utilized in food.Because it bad characters such as rough taste and poor processing properties and its susceptibility to rancidity due to a large amount of fatty.In order to improve the utilization rate of rice bran,rice bran stabilization research and application and food processing are effective ways to develop rice bran resources.In this paper,not only the water activity of rice bran was modified by both the microwave method and air convection method,but also the effect of stabilization was studied,and the water activity of rice bran which is most suitable for storage was obtained.Meanwhile,the kinetic model of effective storage period of rice bran was established,and the stabilized rice bran was added.The study on tensile properties,texture properties and micro-structure of rice bran-wheat mixed dough provides theoretical research for the storage and development of rice bran.The main research results are showed as follows:1.Microwave and convection air are applied to rice bran.By reducing the water activity of rice bran,inhibiting the hydrolysis degree of lipase and prolonging the shelf life of rice bran,the water activity of rice bran with the best stabilizing effect is obtained with a value of 0.165.The long-term storage test showed that the stabilization treatment process for adjusting the water activity of rice bran can extend the storage period of rice bran to three times of what the storage time of raw rice bran is,which proves that the stabilization effect of rice bran based on water activity modified is remarkable.2.Arrhenius theory was applied to obtain the oxidation rates of raw rice bran with a water activity of 0.508 and that of rice treated by stabilizing method with a water activity of 0.165,which are kAw0.508=828.15exp(3194.2/T)?KAw0.165=100.51exp(2841.3/T).The oxidation rate equation of rice bran is that after adjusting the water activity of rice bran,the oxidation rate is reduced by 8.24 times compared with that of raw rice bran.Therefore,the rate of oxidation can be significantly delayed by adjusting the water activity.3.The storage period of the raw rice bran with water activity of 0.508 is as follows:tAw0.508=lnAV??/AV0×cxp(3194.2/T)/828.15,the model of stable rice bran storage period with water activity of 0.165 is:tAw0.165=lnAV??/AV0×exp(2841.3/T)/100.51,after fuzzy sensory evaluation combined with the acid value of rice bran,23.01 can be used as the critical value of rice bran acid price.At the end point,after determining the initial acid value AV0 of the rice bran and determining the storage temperature T,the storage period model can be used to predict the storage time of the rice bran.4.Rice bran and wheat flour were mixed in order to improve the rough taste and poor processing properties of rice bran.The results of electron microscopy showed that there were significant differences in the micro structure of the mixed dough formed by different particle size and rice bran addition.The internal micro-structure continuity of the rice bran through the 80 mesh sieve is poor at 5%,10%,15%,20%,the pores are relatively large and uneven,and the rice mesh is 120%for 5%,10%,and 15 The internal structure of rice bran mixed dough with the addition of 20%and 20%is more compact and uniform,with smaller pores,better stability and less difference with the internal structure of wheat dough.Therefore,the smaller the particle size of rice bran,the more stable the internal structure is,which is beneficial to the later food processing.5.The tensile properties of mixed dough showed that the stretching distance,tensile resistance,draw ratio and tensile area of rice bran-wheat mixed dough showed a decreasing trend with the increase of rice bran addition.The decrease of the particle size shows an increasing trend.Compared with the tensile characteristic parameters of the wheat flour itself,the amount of rice bran added is not more than 20%and the size of rice meshed of 120 mesh sieve is selected.6.The experimental results of the texture of the mixed dough show that the dough added with rice bran powder has certain changes in hardness,elasticity,chewiness and recovery.With the increase of the amount of rice bran powder,the hardness of the dough is mixed.Both the chewing degree and the chewing degree were improved,and the elasticity and recovery of the mixed dough were not obvious,and the tendency was slightly decreased.As the particle size of rice bran decreased,the hardness and chewiness increased,and the difference of recovery and elasticity was small.