## 4 Discussion
(2016) [37], which used a slightly acidic type (pH 6.0-6.5, ORP 880-900 mV, ACC 20 mg/L), the ACC decreased to below 10 mg/L after 21 days under L\({}_{\text{RT}}\), while under S\({}_{\text{RT}}\), it only slightly decreased and remained above 15 mg/L. After 21 days of storage, the ACC of NW\({}_{25}\) decreased only slightly, at 16 mg/L under L\({}_{\text{RT}}\) and 23 mg/L under S\({}_{\text{RT}}\). Although detailed comparisons are difficult due to subtle differences in the initial ACC and storage environment, it was confirmed that NW has greater storage stability compared with the acidic type, which is more prone to ACC reduction due to the release of chlorine gas. In contrast, high-concentration NW preparations (NW\({}_{100}\), NW\({}_{200}\), NW\({}_{300}\), NW\({}_{500}\), and NW\({}_{1000}\)) maintained higher ACC levels, but also exhibited rapid declines in L\({}_{\text{RT}}\), with NW\({}_{1000}\) showing an over 50% reduction in ACC under all storage conditions. Thesefindings are in line with other researchers, who reported that ACC in electrolyzed water tends to degrade quickly when stored at room temperature and exposed to light, making refrigerated and shaded conditions essential for storing chlorine content and ensuring long-term bactericidal efficacy [33; 34; 38; 39]. The results of this study indicate that storage conditions play a crucial role in determining the stability of NW. Standard-concentration NW preparations were relatively stable over 126 days when stored in \(\mathrm{S_{LW}}\). However, high-concentration NW preparations showed significant degradation of both ACC and pH, even under the optimal condition (\(\mathrm{S_{LW}}\)). Therefore, high-concentration NW preparations (\(\mathrm{NW_{500}}\), \(\mathrm{NW_{1000}}\)) should be used within shorter timeframes or stored under highly controlled conditions to maintain their efficacy. These findings are consistent with previous research, which found that room temperature and light exposure lead to rapid declines in both pH and ACC, resulting in reduced bactericidal activity [25; 38; 39]. In practice, NW should be stored under shaded and refrigerated conditions to maintain its chemical properties and disinfectant efficacy, especially when using high-concentration types. The chlorine odor, which is only slightly noticeable at the standard concentration, is pronounced and unpleasant at \(\mathrm{NW_{1000}}\), making it unsuitable for long-term storage. Furthermore, the PET containers storing \(\mathrm{NW_{1000}}\) at room temperature showed slight whitening if shaded or lost transparency and turned cloudy white inside if not shaded. PET can be degraded by physical, chemical, or biological methods. Under certain acidic conditions, it can be degraded to ethylene glycol and terephthalatic acid via hydrolysis [40; 41]. [PERSON] et al. (2020)[40] have reported that immersion tests of biodegradable PET at pH 3.0 to 10.5 for up to 4 weeks at 80 \({}^{\circ}\)C revealed significant differences in decomposition behavior in alkaline and acidic solutions, with a significant decrease in the molecular weight observed in dilute sulfuric acid (pH 3.0). In the PET containers used to store the test NW preparations in our study, the interaction of prolonged contact with high concentrations of free available chlorine, increased acidity of \(\mathrm{NW_{1000}}\) during storage (pH \(<\) 3 in the 126-day storage period under \(\mathrm{L_{RT}}\)), and lack of light shielding may have exceeded the limits of the chemical and weather resistance of PET. The change in appearance inside the PET container, which was particularly noticeable in the \(\mathrm{L_{RT}}\) affected by both light and temperature, is inferred to be mainly due to acid hydrolysis on the PET surface caused by contact with the remarkably increased acidity of \(\mathrm{NW_{1000}}\) during storage. HOCI molecules, which are the main microbicidal components of electrolyzed water, are not chemically stable.