## 3 Results and Discussion  
### Determination of Physicochemical Indices  
Under various storage conditions, rice grains can exhibit differences in their biochemical components. The current study aimed to compare the quality of rice grains stored under different conditions. Moisture content serves as a primary indicator for assessing the quality of rice grains, which is closely linked to storage practices. Excessive moisture in a paddy can potentially elevate the risk of mold formation and simultaneously undermine its germination capability. To optimize storage conditions and ensure the overall quality of rice grains, it is crucial to maintain an appropriate moisture level [30]. The moisture content of rice grains stored under normal temperature, vertical ventilation, and nitrogen gas atmosphere was 11.11%, which was the lowest compared with other storage conditions (Figure 1A). Additionally, the starch content and glutenin levels were also the lowest, at 46.93 g/100 g and 2.99 mg/g (Figure 1C,G), respectively. Moreover, the protein levels, including albumin, globulin, gliadin, and glutenin, were found to be the lowest in rice grain stored under normal temperature, vertical ventilation, and nitrogen gas atmosphere conditions (albumin: 0.47 mg/g, globulin: 1.15 mg/g, gliadin: 0.40 mg/g, glutenin: 2.99 mg/g) when compared to the other two storage conditions. Previous studies have indicated that storing rice at low temperatures and low humidity can effectively reduce enzyme activity. These studies have also shown that after 100 days of storage under such conditions, the quality of rice remains largely unchanged and comparable to the freshly harvested sample [31; 32]. This suggests that maintaining low temperature and humidity levels during storage can help preserve the quality of rice for an extended period. The respiration and enzyme activity of rice can cause changes in its quality. High temperature and humidity can accelerate these processes, leading to a deterioration in rice quality. It is important to control the temperature and humidity at lower levels during storage to minimize these effects and maintain the quality of the rice [33]. Furthermore, rice grains stored under normal temperature, horizontal ventilation, and nitrogen gas atmosphere conditions exhibited the highest starch content (56.42 g/100 g) and glutenin levels (4.06 mg/g) among the three storage environments. It is worth noting that the fatty acid value is an important indicator used to assess the freshness of rice. It is widely accepted that a higher fatty acid value indicates a more pronounced deterioration in paddy quality [34]. In the case of rice grains stored under normal temperature, horizontal ventilation, and nitrogen gas atmosphere, the fatty acid value was measured at 11.87 mg/100 g, which represents the smallest amount of deterioration in rice grain quality (Figure 1B). During rice grain storage, the variation in fatty acids was mainly caused in two ways, including oxidation and hydrolysis. During hydrolysis, the change in fatty acid value is mainly due to the combined action of the enzyme activity of the rice grain itself and molds [35]. Among the three storage conditions, the fatty acid value of rice grains stored under the conditions of normal temperature, vertical ventilation, and nitrogen gas atmosphere (19.48 mg/100 g KOH) and quasi-low temperature, horizontal ventilation, and nitrogen gas atmosphere (21.46 mg/100 g KOH) reached a higher level. It was considered that these two storage conditions were suitable for microbial growth and adverse for rice grain storage. However, in the study, the fatty acid values of rice grains stored under the three conditions did not exceed the national storage standards for suitability. This indicates that all three storage conditions provide a better assurance of maintaining the quality of rice.