| The moisture content of rice after harvest is usually high and above the safe storage moisture,which is not conducive to safe storage and subsequent processing.Therefore,rice needs to be dried after harvest to bring its moisture down to a safe moisture level for storage and processing.Studies have shown that different drying methods and degrees of drying have a greater impact on the quality of rice,making differences in the processing of rice.Therefore,controlling the post-harvest drying conditions of rice is beneficial for improving the palatability of rice and providing guidance for post-harvest drying of rice.In this study,the same variety of japonica rice treated by natural drying and mechanical drying was used as the main raw material to analyse the differences in appearance quality,structural characteristics and rice quality between the two drying treatments,and to explore the differences in the quality of the two types of rice through three cooking methods,with a view to providing data guidance for rice cooking enterprises.The main research contents and results are as follows:(1)The difference in the quality of rice under different soaking temperature and soaking time was analyzed by cooking characteristics,texture characteristics and taste value,and the results showed that the quality of rice was improved after soaking in the two drying methods,and the quality of the two groups of rice was the best when soaked at a water temperature of 20°C for 30 min,and the comprehensive taste value of rice was 84.73(natural drying)and 85.46(mechanical drying).(2)Through scanning electron microscopy,low-field nuclear magnetic resonance instrument and rapid viscosity analyzer,the changes in the appearance and quality of rice under the two drying methods before and after soaking,the water migration of rice after soaking and the changes in starch and other structures were explored.The results showed that the surface cracks of rice in the mechanical drying group were more,the water absorption rate was fast in the early stage of soaking,and the content of moisture content and extractable was high.The relative crystallinity of the two groups of unsoaked rice was 8.22%,and the relative crystallinity of the two groups decreased by1.03%(natural drying)and 1.98%(mechanical drying),respectively.(3)The changes of moisture content,moisture distribution,starch structure and rice color during the cooking process of rice under the two drying methods were analyzed.The results showed that when the cooking temperature reached above 60°C,the moisture content and dissolved solids content of rice increased significantly,and the water distribution results showed that the water migration rate of rice in the mechanical drying group was faster than that in the natural drying group,and the scanning electron microscopy results showed that when the cooking temperature reached 80°C,the "honeycomb" pores appeared on the surface of the rice and the natural drying group had more pores,and the XRD results showed that the relative crystallinity of the starch of the two groups decreased significantly from 29.03% to 12.89%(natural drying)during the cooking process.24.07% decreased to 11.87%(mechanical drying),the brightness and Baidu of rice in the two groups increased with the increase of cooking temperature,and the brightness and whiteness values of rice in the mechanical drying group were significantly higher than those in the natural drying group.(4)Using the three cooking methods of electric steamer,rice cooker and production line to analyze the difference in the quality of the two types of rice.The results showed that the rice cooked in the electric steamer had low hardness,high viscosity,good taste quality,and high brightness and whiteness values of the rice.In summary,this study analyzed the changes of moisture,starch structure and rice quality during the cooking process of the two drying methods,and found that mechanical drying under appropriate conditions can improve the quality of rice and reduce the difficulty of cooking. |
