## 3 Results and Discussion
### Linear Regression Analysis  
The potential of LF-NMR as predictor of quality characteristics has received substantial research interest and it has been perceived as an efficient technique to assess the freshness of aquatic products. Previous researches have also confirmed that LF-NMR measurements were associated with quality parameters, such as WHC, drip loss, color, and so on [16; 27; 28]. In the current study, the relationship between LF-NMR relaxation parameters and quality indexes was investigated during refrigerated storage (Table 2). Obviously, no relationship was detected among pT\({}_{21}\) and the physicochemical parameters, suggesting that the value of pT\({}_{21}\) was barely high enough to predict the quality characteristics of HTS fillets. However, a good correlation between pT\({}_{22}\), pT\({}_{23}\), and physicochemical parameters were detected. Briefly, the pT\({}_{22}\) showed excellent correlation with R\({}^{2}\) in the range of 0.79631-0.98873 with water contents, fat contents, and the activities of Ca\({}^{2+}\)-ATPase. While the TVB-N values and MDA values showed relatively poor relationship correlation with pT\({}_{22}\). It also can be concluded that there was no relationship between pT\({}_{22}\) and K values in all samples. By comparison, there was a significantly good correlation between pT\({}_{23}\) and TVB-N, K value and MDA (\(p\) < 0.01). However, a poor relationship was detected between pT\({}_{23}\) and water content or the activity of Ca\({}^{2+}\)-ATPase. No correlation was detected between pT\({}_{23}\) and fat content. In general, pT\({}_{22}\) plays a more important role in the evaluation of water contents, fat contents, and the activities of Ca\({}^{2+}\)-ATPase changes, while pT\({}_{23}\) is more effective in assessing the qualities of TVB-N, K value, and MDA.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Groups** & **T\({}_{2}\)** & & **TVB-N** & **K Value** & \begin{tabular}{c} **Moisture** \\ **Content** \\ \end{tabular} & \begin{tabular}{c} **Fat** \\ **Content** \\ \end{tabular} & \
\begin{tabular}{c} **Activity of** \\ **Ca\({}^{2+}\)-ATPase** \\ \end{tabular} &
\begin{tabular}{c} **MDA** \\ \end{tabular} \\ \hline CK1 & pT\({}_{21}\) & R & \(-\)0.116 & \(-\)0.252 & 0.376 & 0.257 & 0.334 & \(-\)0.356 \\  & R\({}^{2}\) & 0.01346 & 0.06351 & 0.14138 & 0.02146 & 0.111556 & 0.12674 \\  & P & ns & ns & ns & ns & ns & ns \\  & P\({}_{22}\) & R & 0.95119 & 0.29514 & 0.92732 & 0.98812 & 0.98214 & 0.99312 \\  & R\({}^{2}\) & 0.90476 & 0.08711 & 0.85992 & 0.97638 & 0.9646 & 0.98629 \\  & P & 0.05 & ns & 0.01 & 0.01 & 0.01 & 0.05 \\  & P\({}_{23}\) & R & 0.86271 & 0.94352 & 0.84978 & 0.22136 & 0.94675 & 0.94978 \\  & R\({}^{2}\) & 0.74427 & 0.89023 & 0.72213 & 0.0449 & 0.89634 & 0.90208 \\  & P & 0.01 & 0.01 & 0.05 & ns & 0.05 & 0.01 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Linear regression analysis of HTS fillets with different treatment during refrigerated storage.  
Figure 3: Results of magnetic resonance imaging (MRI) of samples under different treatments during refrigerated storage (CK1: distilled water + air packing; CK2: edible coating + air packing; C1: edible coating + MAP (60% CO\({}_{2}\)/40% N\({}_{2}\)); C2: edible coating + MAP (65% CO\({}_{2}\)/35% N\({}_{2}\)); C3: edible coating + MAP (70% CO\({}_{2}\)/30% N\({}_{2}\))).