# Study of the Targeted Regulation of Rice Drying Characteristics and Quality
## 3 Results and Discussion
### Evaluation of Regression Model and Analysis of Variance
#### 3.2.1 Drying Characteristic Index  
(1) Influence of test factors on Dtn  
Net drying time (Dtn, total drying time minus recovery time) is a characteristic of reaction drying efficiency. The contribution rate shown in Figure 2a was drawn by the F value, and the order of factors affecting Dtn was MC \(>\) T \(>\) RH \(>\) TR \(>\) V, indicating that MC, T, and RH were the main factors affecting Dtn. The Dtn regression equation based on the variance analysis results in Table 5 after excluding insignificant terms is shown in Table 4. The coefficient of determination (R\({}^{2}\)) of the model was 0.8977, and the CV value was 3.2%. The model had good fitting ability and reliability. As shown in Figure 3a, in the low Dtn area, the effect of changing temperature and initial moisture level on the reduction of Dtn was not obvious, as in the high Dtn area. Excessively shortening Dtn and adjusting the process did not significantly improve drying efficiency but increased energy consumption and quality degradation. As shown in Figure 3b, in the high humidity area, the change in V was obvious; in the low humidity area, the change in air speed was not obvious, indicating that the higher the humidity, the more obvious the impact of air speed on Dtn. In the case of low initial moisture content, high humidity, and high recovery ratio, Dtn was short, indicating that the appropriate recovery process was beneficial to the drying process. Figure 3c shows that when SRR is high, the increase in SRR decreases Dtn, which  
Figure 10: Influence of the interaction on changes in body fat.  
Figure 9: Influence of the interaction on the amount of protein change.  
is particularly obvious at low humidity, indicating that there is a critical value for SRR and that prolonging the SRR will not improve the drying efficiency. When SRR was prolonged to a certain time, the internal moisture was basically balanced, and Dtn no longer improved. [PERSON] and [PERSON] et al. reached similar results [12; 21].  
Influence of test factors on germination rate (PG)  
The germination rate is an important indicator for evaluating the activation of rice seeds after drying. Figure 2b shows the contribution rate using the F value, and the order of factors affecting PG was MC \(>\) TR \(>\) V \(>\) RH \(>\) T. MC and TR had the greatest impact on the germination rate, while V and RH had smaller impacts. T had almost no impact on the germination rate. The regression equation of the germination rate after removing insignificant terms is shown in Table 4. R2 of the model was 0.9482, and the CV value was 0.47%. The model had good fitting ability and reliability [22; 23].  
As shown in Figure 4a, the curved surface presented the highest part of the curved area, indicating that the germination rate was best at a high air speed and low humidity and at a low air speed and high humidity. Because the evaporation rate of water on the surface of rice is slow, it is conducive to maintaining the water balance inside the rice [23]. As shown in Figure 4b,c, the germination rate was also higher when the initial moisture content was high and the slow-sudden ratio was high. This is because the water balance inside the rice and the drying process are more uniform, making the inside of the rice more active. These factors are conducive to improving germination rates. Because the hot air speed makes the moisture on the surface of rice evaporate faster, and water migration brings the internal moisture to the surface faster, it can reduce the retention time of the internal moisture of the grain and reduce the risk of mold and bacterial mildew [24; 25].