Study Of Reasonably Processing Technology And Quality Of Indica Rice

As an important staple food,indica rice is favored by southerners in China because of its sweet taste and low sticky mouthfeel.Now it is over milled popularly,causing high broken rice rate,more nutritients loss,low rate of milled rice and a series of current situations.Three kinds of indica rice were selected as raw material,to study the comprehensive influence law of effect of milling degree on the processing appearance,nutrition and sensory qualities of,and the brown rice mechanical characteristics,combining with the microstructure of milled rice,and to explore their correlation with processing quality,providing theoretical basis for reduction of milled grinding process of broken.Finally,this research optimized the milling parameters,based on reasonable milling processing,to reduce the breakage rate,to provide theoretical basis for reasonable processing of indica rice.The main research contents of this paper are as follows:Firstly,this paper studied the effect of milling degree on the processing qualities,microscopic change,through the preparation of the reduction rate of 0%-16%the rice samples.The results showed that whiteness value increased,broken rice rate increased,with the increase of the milling degree,and higher milling degree could significantly increase the rate of broken rice,the rate of remained germ decreased,but among 8%-12%of milling rate,the rate of remained germ change was not significant,and kept high germ rate(15%-78%).The mean values of grain length,width,thickness and length-width ratio showed a decreasing trend during milling of rice(P<0.05).The distribution chart showed that the variation of grain length was significantly greater than that of width and thickness,and the variation of thickness was more obvious than that of width.The microscopic observation of grain cross section showed when the milling rate was 8%,the whole aleurone layer and a small amount of aleurone layer were retained,and when the milling rate was 14%,the aleurone layer was completely removed.It was assumed that the milling rate was 0%-6%,and a small amount of aleurone layer and a small amount of aleurone layer were crushed with the milling rate of 8%-12%,and the endosperm layer was ground with the milling rate of 14%-16%.Compared with japonica rice,indica rice cultivars had deeper folds in cross section and more obvious groove marks,which were not beneficial to the surface grinding.Moreover,the aleurone layer thickness of indica rice was thinner than that of japonica rice,which resulted in the difference of nutrient content between indica rice and japonica rice.Secondly,The effects of milling degree of rice on nutritional quality and sensory food quality of three kinds of indica rice were investigated.Studies have shown that with the increase of milling rate reduction,various nutrients(fat,protein,dietary fiber,minerals and vitamin B₁)all showed a trend of decreased significantly(P<0.05),when milling rate was0-4%,protein content decreased significantly,and in 8%-12%,protein content decreased slow,when milling rate was greater than 12%(rice bran layer basic grinding except)levels continued to decline.From brown rice between bran and aleurone layer,protein content showed a trend of decrease,and protein was not evenly distributed in the endosperm.On the other hand,the dietary fiber content of the three types of brown rice was 4%-5%.When the milling rate was greater than 8%,the dietary fiber content of the three types of indica rice gradually changed and the content was between 1.00%-2.18%,indicating that the brown rice layer was basically crushed.The three kinds of brown rice were rich in phosphorus,magnesium and potassium,while the content of calcium was relatively low,which mainly exists in the bran and embryo of brown rice,and the content in the endosperm was very small and uneven.The higher milling degree,the lower the mineral content would be.Among them,the phosphorus content of the three kinds of brown rice ranged from 3230mg/kg,-3990 mg/kg,the milling rate was 14%-16%,the phosphorus content ranged from1450 mg/kg-1790 mg/kg,and the magnesium content ranged from 1310 mg/kg-1390 mg/kg,which were 55%-64%and 73%-81%lower than that of the brown rice,respectively.The potassium content is similar to that of magnesium with the increase of milling rate,but its content decreased more.The distribution of calcium content was relatively uneven.The back energy spectra of the cross sections of rice with different precision showed that Mg,P and K mainly accumulated in the aleurone layer,and the content of carbon and oxygen was higher in the endosperm.When the grinding rate was 4%-8%,the three kinds of brown rice retained more calcium.Vitamin B₁content of three kinds of brown rice in 0.172 mg/100 g-0.205mg/100 g,milling rate was 0%-6%,bran was run over to gradually,but the content of vitamin B₁ had a small change,run over 14%-16%reduction rate and bran was almost run over to fully,reduced the content of vitamin B₁,vitamin B₁ content of only 0.081 mg/100 g-0.132 mg/100 g,in endosperm layer vitamin B₁ content was less,mainly exist in the aleurone layer and the aleurone layer.Sensory evaluation results showed that the sensory score gradually rose,the increase of the machining accuracy in machining high milling degree(milling rate of 12%or more,leaving skin degree of 2.15%or less)after scoring change was not significant(P<0.05),with reasonable machining accuracy and grinding(reduction rate of 8%-12%,leave skin degree of 1.45%-8.50%),flavor and taste increased,the overall score was higher also,and compared with the high machining accuracy kept a high nutritional quality of rice.Finally,according to the research on the three factors influencing the mechanical properties of brown rice(water content and size of brown rice),it was found that the water content of brown rice significantly reduced the crushing force values of compression force,shear force and three-point bending force,and the crushing displacement gradually decreased,especially when the water content of brown rice was?16.56%,and the change trend was obvious.Under the same compressive force value,the higher the water content of brown rice,the greater the grain displacement caused by the force,indicating that the increase of water content increased the capacity of brown rice to withstand deformation,which was conducive to the effective milling of brown rice bran to a certain extent.The thickness of brown rice was correlated with the three-point bending force to some extent,and the larger the thickness was,the greater the three-point bending force was,and the crushing rate was reduced to a certain extent.When the three kinds of brown rice were milled with the same milling degree,the breakage rate of Meixiangzhan and Tianlongyihao with larger thickness distribution was lower than that of Sharuanzhan with smaller thickness distribution.In conclusion,from the overall analysis of the structure,nutrition,taste and material characteristics of indica rice,reasonable processing was not only to reduce the milling degree of rice,but more important should be suitable for rice,and remian good edible quality.Based on reasonable processing,the rate of broken rice could be reduced and the rate of rice yield could be improved.On the basis of moderate processing,in order to reduce the rate of broken rice,the water content of brown rice,the handling amount of brown rice and the milling time of brown rice were optimized,and the regression model of broken rice rate and the optimal parameter combination were obtained.The experimental results showed that the water content of brown rice was 15.19�0.05%,the handling amount of brown rice was 144g,the milling time was 77 s,the broken rice rate was 11.50�0.72%,and the skin retention was 6.13�0.23%.