## 2 Experimental Materials and Test Methods
### Changes in the Secondary Structure of Protein in the Interfacial Adductor Muscle of Scallops  
There is a phenylalanine ring at 1004 cm\({}^{-1}\), whose structure is not affected by protein structure, was used as the internal standard to normalize the data. After processing, Alix computing software was used to carry out deconvolution, second-order derivation and curve fitting for the processed Raman spectrum data, and then the Raman spectrum was divided into peaks. According to the obtained peak area, the secondary structure of the protein was calculated, and the influence of different ultra-high pressure treatment conditions on the secondary structure of the protein in the adductor muscle at the interface of the scallop was analyzed, as shown in Figure 3.  
By comparing the peak areas corresponding to \(\alpha\)-helix, \(\beta\)-sheet, \(\beta\)-turn and random coil in proteins, according to the peak segmentation and iterative fitting curve of the adductor muscle on the scallop interface in the amide I region as shown in Figure 3, the relative contents of each secondary structure contained in the protein of the adductor muscle at the interface of the scallop were obtained. The relative contents of the main secondary structure of the protein were shown in Figure 4 under the condition of different holding time. \begin{table}
\begin{tabular}{c c} \hline
**Wave Number/cm\({}^{-1}\)** & **Band Attribution Information** \\ \hline
509 & Stretching vibration of S-S \\
755 & Stretching vibration of Tyyptophan \\
830/853 & The fundamental and overtone Fermi resonances of tyrosine \\
1004 & Respiratory vibration of Phenylalanine ring \\
1333 & III band of amide \\
1657 & I band of amide \\
2945 & Telescopic vibration of C-H \\ \hline \end{tabular}
\end{table} 
Table 2: Identification of Raman Spectral Characteristic Bands in the adductor muscle of Scallops. Figure 2: Raman spectra of adductor muscle of scallop under different holding times. Figure 4: Effect of holding time on secondary structure of protein in adductor muscle of scallops. Figure 3: Distinct peaks and iterative fitting curves of scallop closed-shell muscle protein amide I with different holding times (**a**) 1 min (**b**) 2 min (**c**) 3 min (**d**) 4 min. As can be seen in Figure 3, the mass fraction of \(\alpha\)-helix structure decreased, and the mass fractions of \(\beta\)-sheet, \(\beta\)-turn, and random coil increased in the protein secondary structure of the adductor muscle of scallops under UHP force compared with that of the adductor muscle of scallops untreated. However, as far as the UHP treatment was concerned, the mass fraction of \(\alpha\)-helix increased with the increase of the holding time; the mass fractions of the other three structures gradually decreased. According to the results obtained from the split-peak fitting calculation, the mass fraction of \(\alpha\)-helix decreased by 29.29% when the holding time was 1 min, while the mass fraction of \(\alpha\)-helix only decreased by 13.70% compared with the untreated ones when the holding time was 3 min. The \(\alpha\)-helix structure is connected by hydrogen bonding, and the increase in its mass fraction indicates less damage to the hydrogen bonding by the action of UHP; the trend in the mass fraction of the \(\alpha\)-helix versus the \(\beta\)-sheet is shown in the results calculated using split-peak fitting. The mass fractions of \(\beta\)-sheet of the adductor muscle of scallops increased by 447.14%, 276.87%, and 173.23%, respectively, under the treatments with different holding pressure times; the mass fractions of \(\beta\)-turn increased by 21.97%, 21.15% and 13.17%, respectively; and the mass fraction of the random coil also increased by 14.76%, 11.01% and 6.94%, respectively, under different holding times. In conclusion, the protein structure of the adductor muscle changed significantly under different holding times, which lays a foundation for the further elaboration of the reasons for the changes in the texture of the adductor muscle of scallops.