## 3 Results and Discussion
### Oscillatory Dynamic Rheology  
The physicochemical parameters that link to gelation, which is the basis for texture creation, can be determined using rheology [33]. Figure 2 depicts the dynamic viscoelastic behavior of unwashed mackerel mince and surimi generated by varying the number of washing cycles during the temperature transition from sol to gel. Gel formation was measured using the storage modulus (G') (Figure 2a). An increase in G' indicated that the sample's rigidity had increased as a result of the development of an elastic structure [34]. In all samples, the G' was gradually increased from around 35 \({}^{\circ}\)C to approximately 45 \({}^{\circ}\)C, as shown in Figure 2a, with the exception of W3, which was elevated continuously. The creation of the initial protein network structure was referred to as the \"gel setting\" step. Myosin would unfold at this point to allow for ordered polymerization, and the initial elasticity of proteins would be lost [35]. According to [PERSON] et al. [36], the development of protein networks via weak connections between protein molecules, such as hydrogen bonds, falls within this spectrum. The setting phenomenon may be reduced in W3, which has been washed excessively, resulting in a larger elimination of endogenous transglutaminase (TGase). As TGase is a water-soluble protein, it can be washed away. Followingthat, G' dropped rapidly, reaching its lowest point about 48 \({}^{\circ}\)C, indicating gel weakening. This was mostly owing to the activity of residual proteases at this temperature, which can hasten myosin degradation, and interfere with gel formation [37]. The majority of heat activated fish proteinases are triggered between 50 and 60 \({}^{\circ}\)C, which is close to their optimal temperature [37]. Furthermore, increased surimi paste mobility due to actomyosin dissociation, unfolding, and denaturation can be another explanation for decreased G' value [31]. [PERSON] et al. [38] also claimed that the drop in G' was caused by the coil transformation of the \(\alpha\)-helix, in which the fluidity of the protein increased and the viscoelasticity decreased; this also explained why G\" decreased (Figure 2b). G' of surimi from Pacific whiting achieved a minimum value of 55 \({}^{\circ}\)C, according to [PERSON] et al. [39]. Nonetheless, the W3 sample did not show a decrease in G' in this range. This corresponded to the lowest TCA-soluble peptide content (Table 1), owing to the effectiveness of adequate washing, which can remove endogenous protease enzymes. To avoid gel weakening caused by leftover proteases, the surimi preparation was set at 40 \({}^{\circ}\)C, and cooked at 90 \({}^{\circ}\)C. Myosin denatures and aggregates more at 48 \({}^{\circ}\)C, eventually producing a stable gel [40]. The G' was then increased once again, peaking around 65-69 \({}^{\circ}\)C, suggesting the establishment of a strong gel network due to higher attractive forces (e.g., disulfide bond, and hydrophobic interaction). During this \"gel strengthening\" stage, the primary cross-linking and aggregates of myosin occurred. The unwashed mince provided the lowest G' throughout the heating process, while the W3 sample had the greatest G', followed by W2 and W1 samples, respectively, notably at temperatures above 50 \({}^{\circ}\)C. This was in line with the same breaking force pattern (see Section 3.4.1). The construction of a thermo-irreversible gel network was most likely owing to the covalent cross-links among dissociated protein molecules. While SH groups were oxidized, a disulfide bridge might have been produced, and hydrophobic domains may have joined via hydrophobic-hydrophobic interaction [41]. G' was then reduced one more. This could be because hydrogen bonding breaks off at high temperatures [31]. The viscosity modulus (G\") curves of unwashed mince and surimi were often similar to G' (Figure 2a).