## 3 Results
### Response Surface Plot Analysis
Figure 5 shows that in the case of low relative humidity drying, AC is weakly decreasing and then increasing all the time as the drying temperature increases; in the case of high relative humidity drying, AC is negatively correlated with the drying temperature. The lowest values of AC appeared when the temperature was around 45-50 \({}^{\circ}\)C and the relative humidity was 42-46% [41], while the peak values of AC appeared at a low temperature and high relative humidity, and a high temperature and low relative humidity. Drying rice grains at a high temperature and low relative humidity promotes the activity of starch synthase and accelerates the process of starch synthesis, thus increasing the content of the dry grain. Figure 4: The influence of the interaction of fat. Note: The red value of the response surface diagram is larger, and the blue value is smaller. straight-chain starch. Whereas, drying at a high temperature and high relative humidity slows down the activity of starch synthase and inhibits the starch synthesis process, leading to a decrease in the content of straight-chain starch. [PERSON] et al. [42] studied the effects of high temperature on starch morphological changes and expression related to starch biosynthesis and degradation. This study provides an important reference for us to understand the effect of temperature changes on the structural characteristics and internal components of rice, especially the effect of temperature on the starch change of rice. Therefore, high temperature and low relative humidity promoted the formation of straight-chain starch, while high temperature and dry conditions with high relative humidity;, on the contrary, inhibited the formation of straight-chain starch. The main increase is in soluble straight-chain amylopectin, the relatively high content (13-20%) of which gives rice a good texture when cooked. A rice with a high content (13-20%) has a good texture [38; 41; 42]. According to China's national standard GB/T 19266-2008 [43] for high-quality round-grained rice, a straight-chain starch content of 13% to 20% gives a better taste; a straight-chain starch content of more than 20% results in rice that is viscous, small, with a hard texture, no luster and poor taste; if the straight-chain starch content is too low, then the rice is soft, sticky and greasy, and elasticity is poor. (4) Response analysis of amylopectin (APC)  
Amylopectin content can affect the nutritional quality of rice. According to the result of Table 5, Figure 2, the F value reflects the influence degree of each factor on the response to the influencing factors of AC in the following order: RH > TR > T > V > MC. The regression equation of the protein content is as shown in Table 3; the model of the decision coefficient R\({}^{2}\) is 0.9625; the CV value is 1.32%; the model has good fitting capability and reliability. Figure 5: Effect of A \(\times\) B interaction on amylose. Note: The red value of the response surface diagram is larger, and the blue value is smaller. It can be seen from Figure 6 that, within the scope of the test scheme, the interaction of temperature, humidity and tempering ratio of rice in the drying process has a significant impact on amylose content. Figure 6a,b shows that the drying temperature is 45 \({}^{\circ}\)C and humidity is 42%, and the amylopectin content reaches its peak. At a high relative humidity, TR was negatively correlated with amylopectin content. In the case of a high tempering ratio and low relative humidity, the correlation is positive. The content of amylopectin was the highest under the condition of a low humidity and high tempering ratio. The reasons are the slow water migration in rice, more crystallized starch particles and inhibition of starch synthase activity. The activity of starch synthetase may be inhibited to a certain extent, thus slowing down the speed of starch synthesis. This leads to a relative increase in amylopectin content at the same time as starch synthesis because amylopectin synthesis usually takes precedence over amylose synthesis.