# Effect of a Hypoxia-Controlled Atmosphere Box on Egg Respiration Intensity and Quality
## 4 Discussion
The decrease in O\({}_{2}\) volume fraction in the storage environment inhibits the respiration intensity of eggs (Figure 2), effectively slowing down the changes in the protein structure of the egg white. We also found that the pH of eggs stored at an O\({}_{2}\) concentration of <15% increased faster in the early stages. However, the pH of eggs stored in an O\({}_{2}\) concentration >15% increased faster in the later stages. The possible reason is that the breathing intensity of eggs is inhibited in a low O\({}_{2}\) content of the storage environment. At this time, anaerobic respiration occurs in eggs and the product of anaerobic respiration is an oxidized inorganic substance. The microorganisms in the eggs from Groups D and E were mainly aerobes, and the organic matter was oxidized to CO\({}_{2}\) and water (H\({}_{2}\)O) during aerobic respiration. The organic components degraded during this process may include carbohydrates, lipids, and organic acids. This process consumes O\({}_{2}\) via a series of enzymatic reactions. Glycolysis, tricarboxylic acid cycle, and the electron transfer system are the metabolic pathways of aerobic respiration. The reaction product of CO\({}_{2}\) and H\({}_{2}\)O is acidic [38]; thus, the pH of eggs that underwent aerobic respiration was lower than that of eggs that did not, explaining the lower pH of eggs in Groups D and E in the early stages. Secondly, the pH of eggs has a certain relationship with freshness. From the initial stage of storage to the deterioration of fresh eggs, the trend in pH changes mainly showed an upward trend. The freshness of eggs in Group E was the lowest (Table 2). Therefore, the pH of eggs in Group E increased in the later period likely due to a change in their freshness. The results show that O\({}_{2}\) and N\({}_{2}\) in the storage environment affect the growth and reproduction of microorganisms, which is consistent with the results reported by [PERSON] et al. [39]. N\({}_{2}\) is inert, does not react with the contents of eggs [40], and has little effect on the metabolic reactions in eggs. However, the anaerobic environment created by N\({}_{2}\) has a selective effect on anaerobic and O\({}_{2}\)-tolerant lactic acid bacteria [41]. O\({}_{2}\) accelerates the proliferation of aerobic bacteria and inhibits the proliferation of anaerobic bacteria [42]. Therefore, the control of O\({}_{2}\) levels during egg storage is of great significance to inhibit the respiration of eggs and microbial growth within the egg and prevent deterioration. The source of N\({}_{2}\) gas used for conditioning is generally atmospheric air. N\({}_{2}\)-production equipment and N\({}_{2}\)-filling operations are relatively simple and are associated with fairly low costs. The volume of N\({}_{2}\) required to fill the air-conditioning box in this study for 1200 s was about 0.54 m\({}^{3}\). For manufacturers, using this method to store eggs helps reduce low-temperature damage to eggs and inhibit the growth of microbial colonies, thereby effectively increasing the storage time. Moreover, this method entails an easily manageable temperature requirement and does not necessitate temperature control or changes during spring, autumn, and winter. Thus, our method could be an effective and low-cost option for egg storage and shows potential to be developed further for use in a real-world setting and in production. Studies have reported that different batches of agricultural products may show a 10% difference in RR [43], while different varieties may show a difference of up to 60% [44]. Our next study will focus on studying the storage of other varieties of eggs in an environment of low O\({}_{2}\) to better promote this technology. We also intend to develop and optimize storage control equipment for the air-conditioning technology, which can monitor multiple air-conditioning boxes in real-time and conveniently maintain gas concentrations in the storage environment and meet industrial application standards.