## 3 Results
### Biochemical Change  
The initial TCA-soluble peptide content in the sample was 1.56 umol/g (Figure 1C). The TCA-soluble peptide concentration of samples increased continuously during storage. From day 1 to day 7, the level of samples was relatively stable, followed by a rapid increase, reaching 8.37 umol/g on day 13. This indicated that the protein had undergone serious degradation and produced a large amount of soluble peptides after the 7 th day.  
The content of TVB-N is usually used to determine the freshness of fish. As is shown in Figure 1D, the level of TVB-N showed an obvious rising trend, especially after 7 days. The concentration of TVB-N exceeded the limit (30 mgN/100 g) on day 9.  
Changes in the mussel glucose content of samples are shown in Figure 1E. The concentration of mussel glucose with the extension of storage time showed a trend of decline, especially from day 1 to day 7, with the declining rate of glucose content being faster at this stage. This indicated that glucose was the main substance used by microorganisms in prophase.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Color**} & \multicolumn{6}{c}{**Storage Time (d)**} \\ \cline{2-9}  & **0** & **1** & **3** & **5** & **7** & **9** & **11** & **13** \\ \hline L* & 43.96 \(\pm\) 2.34 \({}^{\circ}\) & 48.03 \(\pm\) 2.75 b  & 48.17 \(\pm\) 2.10 b  & 48.33 \(\pm\) 2.35 b  & 49.21 \(\pm\) 1.81 b  & 49.28 \(\pm\) 1.00 b  & 52.47 \(\pm\) 1.92 a  & 54.35 \(\pm\) 1.92 a  \\ a* & \(-\)2.13 \(\pm\) 0.21 a  & \(-\)1.75 \(\pm\) 0.11 a  & \(-\)1.92 \(\pm\) 0.37 a  & \(-\)1.64 \(\pm\) 0.30 b  & \(-\)1.31 \(\pm\) 0.22 a  & \(-\)1.32 \(\pm\) 0.18 a  & \(-\)1.20 \(\pm\) 0.31 a  & \(-\)1.71 \(\pm\) 0.40 b  & \(-\)1.71 \(\pm\) 0.40 b  \\ b* & 0.27 \(\pm\) 0.55 c  & 0.95 \(\pm\) 1.85 b  & 1.26 \(\pm\) 0.60 b [FONOTE:b]Footnote b: footnotemark: [ENDFOOTNOTE] & 1.99 \(\pm\) 1.13 a  & 2.16 \(\pm\) 1.00 b  & 1.56 \(\pm\) 0.56 b [FONOTE:b]Footnote b: footnotemark: [ENDFOOTNOTE] & 2.71 \(\pm\) 1.64 a  & 2.23 \(\pm\) 1.17 b  \\ \hline \hline \end{tabular} Note: The same lowercase letter in the same column indicates that there is no difference in color between samples at different storage times (\(p>0.05\)).  
\end{table}
Table 1: Changes in the value of color in samples during storage at 4 °C.  
Figure 1: Changes in sensory evaluation scores (**A**), total viable count (**B**), TCA-soluble peptides concentration (**C**), TVB-N concentration (**D**), mussel glucose concentration (**E**), lactic acid concentration (**F**), total sugar concentration (**G**) of flesh during cold storage (sensory acceptability scores: 4.0–5.0 = good quality, 3.0–4.0 = acceptable quality, 2.0–3.0 = unacceptable quality, 0.0–2.0 = completely spoiled and strongly disgusting).  
The lactic acid content changed little from day 1 to day 7, from 5.90 umol/g to 5.08 umol/g (Figure 1F). This may be due to the low utilization of lactic acid by microorganisms and the increase in lactic acid in glycolysis. Then, the concentration of lactic acid decreased rapidly to 3.19 umol/g on day 13. It was shown that a large number of microorganisms produced in samples accelerated the utilization of lactic acid. Notably, the rate of decline of lactic acid increased as glucose was depleted, suggesting that microbes in samples might use lactic acid as a carbon source when glucose is depleted. [PERSON] et al. [27] also demonstrated that lactic acid could be an energy source for post-glucose metabolism during spoilage in meat and seafood. As shown in Figure 1G, the initial total of sugars in the sample was 1.69 mg/g, which dropped to 0.33 mg/g on day 7, possibly due to microbial depletion of glucose in the sample. Subsequently, the total sugar content rapidly decreased to a minimum of 1.08 mg/g on day 13, indicating that the bacteria had high activity utilizing carbohydrates during spoilage. The glucose content remained low and stable after day 7; the rapid decline in total sugars might be due to the utilization of other carbohydrates by microorganisms, such as ribose and glycogen.