# Study of the Targeted Regulation of Rice Drying Characteristics and Quality
## 1 Introduction  
Rice drying is a complex nonlinear process, and the drying efficiency and quality of rice are easily affected by different drying factors. In the past two decades, experts and scholars in the field of grain drying have explored various methods to ensure the quality of rice drying. China's \"14 th Five-Year Plan\" advocates the \"quality and freshness of grain\" and pays attention to the \"nutrition and health of grain\", indicating that post-production grain quality is a key issue that should be given attention in the grain industry. In the world, there are three main methods to ensure the drying quality of rice: [PERSON]. et al. introduced the analytical model of continuous and \"intermittent drying\" of fixed beds, and the results showed that intermittent drying can improve the drying efficiency and quality compared with continuous drying [1]; [PERSON], [PERSON] et al. found that, based on the glass transformation of the \"variable temperature drying\", its burst waist increase rate is significantly reduced [2]; and [PERSON], [PERSON] et al. established a model of rice qualityand cumulative temperature of drying by drying and slow drying, which improved the processing quality [3; 4]. Most scholars have explored the changes in rice indexes based on the changes in some parameters of the soothing period, such as drying period parameters and soothing period time. For example, [PERSON] et al. [5] explored the effects of two drying methods, infrared radiation and heat pump drying, and different soothing ratios on the quality of rice milling. [PERSON], [PERSON] et al. [6; 7] discussed the effects of drying and soothing temperatures on the crack rate of rice and the effects of soothing temperature, soothing ratio, and soothing time on the drying rate; [PERSON], [PERSON] et al. [8; 9] studied the effects of hot-air-assisted radio frequency combined drying technology on the thermal uniformity, drying structure characteristics, and quality of rice drying and found that it has the advantages of high drying speed and energy consumption reduction and improves the quality of rice. The main physical and chemical components of starch, protein, fat, and water in rice have a significant impact on its flavor and nutritional value [10], and the drying process can cause changes in these physical and chemical components. In research on rice drying quality, the accurate regulation of rice drying quality is challenging due to the influence of hot air and air speed, grain internal moisture gradient distribution, internal thermal stress, and other factors. In this regard, scholars from various countries have carried out many practical studies on the regulation of rice drying quality [11]. In addition, research groups have systematically carried out experimental studies on the directional regulation of high-quality rice quality in the early stage [1; 3; 12; 13]. Various physical and chemical indicators of rice are affected by the temperature, relative humidity, air speed, and hysteresis ratio of the drying medium to varying degrees, and there are mutual incentive and transformation phenomena in the drying process [4]. Based on this, a set of rice quality regression models have been established, and a theoretical system of quality directional regulation has been preliminarily constructed [3]. Therefore, in view of the few comprehensive indexes of directional regulation and the lack of drying process parameters, only processing index is a comprehensive consideration. This paper adds drying characteristic index, nutrition index, and processing index after the new test. Therefore, this study started from the drying quality change mechanism of high-quality japonica rice to study the characteristics of rice quality change, designed a response surface (RSM) experiment, analyzed the mapping relationship between drying parameters and drying quality indicators, and established a regression model.