## 3 Results and Discussion
### pH Value Analysis  
The changes in pH values for HHP, HHP+SV and the control are given in Table 1. The initial pH value of largemouth bass fillets was 6.98. [PERSON] et al. [28] found that the initial pH value of fresh largemouth bass fillets was 6.80 and that the pH value was gradually increased (7.04 \(\pm\) 0.01) during 2 days of storage. HHP-0, HHP-10, HHP-0+SV and HHP-10+SV showed a comparable level of pH on day 0, 6.97 \(\pm\) 0.01, 6.92 \(\pm\) 0.01, 6.89 \(\pm\) 0.02 and 6.85 \(\pm\) 0.04, respectively. However, the pH value started increasing after 6 days of storage. Presumably due to the volatile alkaline components produced by spoilage bacteria, such as alkaline amines (trimethylamine and other volatile amines) produced by fish-spoiling bacteria [29]. The pH of largemouth bass fillets was sharply decreased after one week of storage. The decrease in pH value may be due to the release of lactic acid produced by the anaerobic glycolysis of glucose and inorganic phosphate produced by ATP degradation [30]. On the 30 th day of storage, HHP and HHP+SV treatment resulted in pH values of 6.4 and 6.8 for largemouth bass fillets, respectively. In this study, HHP+SV treatment contributed to keeping the pH level of largemouth bass fillets slowly changing since it may reduce the growth of bacteria that produce volatile basic components (for example, alcohols and ketones). The pH value of largemouth bass fillets treated with HHP+SV was higher than that of the control and HHP. The increase in the pH value of fish meat during cooking was owed to the formation of disulphide bonds during the cooking process.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & \multicolumn{5}{c}{**Storage Time (Days)**} \\ \cline{2-6}  & **0** & **2** & **4** & **6** & – & – \\ \hline Control & 6.98 \(\pm\) 0.01 \({}^{\text{b}}\) & 7.04 \(\pm\) 0.01 \({}^{\text{a}}\) & 6.74 \(\pm\) 0.01 \({}^{\text{c}}\) & 6.56 \(\pm\) 0.01 \({}^{\text{d}}\) & – & – \\ \hline \multirow{2}{*}{**Treatment**} & \multicolumn{5}{c}{**Storage time (days)**} \\ \cline{2-6}  & **0** & **6** & **12** & **18** & **24** & **30** \\ \hline HHP-0 & 6.97 \(\pm\) 0.01 \({}^{\text{Ab}}\) & 7.02 \(\pm\) 0.01 \({}^{\text{Ca}}\) & 6.87 \(\pm\) 0.01 \({}^{\text{Dc}}\) & 6.60 \(\pm\) 0.01 \({}^{\text{Dd}}\) & 6.51 \(\pm\) 0.01 \({}^{\text{De}}\) & 6.40 \(\pm\) 0.01 \({}^{\text{Df}}\) \\ HHP-10 & 6.92 \(\pm\) 0.01 \({}^{\text{Bc}}\) & 6.97 \(\pm\) 0.01 \({}^{\text{Da}}\) & 6.94 \(\pm\) 0.01 \({}^{\text{Cb}}\) & 6.86 \(\pm\) 0.01 \({}^{\text{Cd}}\) & 6.60 \(\pm\) 0.01 \({}^{\text{Ce}}\) & 6.43 \(\pm\) 0.01 \({}^{\text{Cf}}\) \\ HHP-0+SV & 6.89 \(\pm\) 0.02 \({}^{\text{Ce}}\) & 7.12 \(\pm\) 0.01 \({}^{\text{Aa}}\) & 7.07 \(\pm\) 0.01 \({}^{\text{Ab}}\) & 6.89 \(\pm\) 0.01 \({}^{\text{Bc}}\) & 6.81 \(\pm\) 0.01 \({}^{\text{Bd}}\) & 6.75 \(\pm\) 0.01 \({}^{\text{Be}}\) \\ HHP-10+SV & 6.85 \(\pm\) 0.04 \({}^{\text{De}}\) & 7.05 \(\pm\) 0.01 \({}^{\text{Ba}}\) & 7.01 \(\pm\) 0.01 \({}^{\text{Bb}}\) & 6.97 \(\pm\) 0.01 \({}^{\text{Ac}}\) & 6.89 \(\pm\) 0.01 \({}^{\text{Ad}}\) & 6.85 \(\pm\) 0.01 \({}^{\text{Ae}}\) \\ \hline \hline \end{tabular}  
* A–D: Differences between different treatment groups; a–f. Differences in treatment groups during storage.  
\end{table}
Table 1: Effects of different treatments on the pH value of largemouth bass during storage.  
Figure 1: The effect of different treatments on the number of TVC of largemouth bass during storage. A–D: Differences between different treatment groups; a–f. Differences in treatment groups during storage.