## 3 Results and Discussion
### Bio-Physico-Chemical Properties  
#### 3.2.1 pH  
The pH of unwashed mince was 6.31 at the beginning, and the pH of surimi increased significantly as the number of washing cycles increased (\(p<0.05\); Table 1). Surimi has a higher pH than unwashed mince, which could be attributed to the removal of water-soluble acidic compounds (e.g., free acidic amino acids and other endogenous acids) during the washing process. It has been reported that organic compounds, including acidic substances, can be removed from fish mince during the washing process [6; 7; 8]. According to [PERSON] et al. [18], the ultimate pH is generally between 6.2 and 6.6. The pH of the surimi may be modified by the leaching efficiency, and related to the pH of the medium utilized [9]. However, the same medium was employed in this investigation, which was  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Unwashed** & **W1** & **W2** & **W3** \\ \hline Yield (\%) & - & 89.57 \(\pm\) 4.32a & 83.43 \(\pm\) 3.77b & 79.74 \(\pm\) 2.46c \\ pH & 6.31 \(\pm\) 0.01d & 6.45 \(\pm\) 0.01c & 6.62 \(\pm\) 0.01b & 6.75 \(\pm\) 0.01a \\ Lipid reduction (\%) & - & 52.76 \(\pm\) 1.31b & 54.36 \(\pm\) 0.76 ab & 56.43 \(\pm\) 1.24a \\ Myoglobin content & 6.77 \(\pm\) 0.72a & 2.56 \(\pm\) 0.15b & 1.63 \(\pm\) 0.01c & 1.61 \(\pm\) 0.06c \\ (mg/g sample) & & & & \\ Myoglobin derivatives & & & & \\ Deoxymyoglobin (\%) & 17.59 \(\pm\) 0.23d & 18.92 \(\pm\) 0.33c & 20.96 \(\pm\) 0.85b & 22.56 \(\pm\) 0.32a \\ Oxymyoglobin (\%) & 6.29 \(\pm\) 0.09a & 5.23 \(\pm\) 0.65a & 5.27 \(\pm\) 0.65a & 4.61 \(\pm\) 0.76a \\ Metmyoglobin (\%) & 75.12 \(\pm\) 0.13a & 75.85 \(\pm\) 0.92a & 73.78 \(\pm\) 0.78b & 72.83 \(\pm\) 0.45b \\ Ca2+-ATase activity & 2.27 \(\pm\) 0.03a & 2.17 \(\pm\) 0.04b & 2.12 \(\pm\) 0.03b & 2.10 \(\pm\) 0.02b \\ (umol/mg protein/min) & & & & \\ Reactive SH content & & & & \\ (mol/10\({}^{8}\) g protein) & 6.14 \(\pm\) 0.05b & 6.29 \(\pm\) 0.02 ab & 6.48 \(\pm\) 0.09a & 6.49 \(\pm\) 0.20a \\ Surface hydrophobicity & 30.43 \(\pm\) 1.42d & 41.42 \(\pm\) 2.48c & 49.43 \(\pm\) 2.86b & 57.61 \(\pm\) 0.33a \\ (BPB bound (ug)) & & & & \\ TCA-soluble peptide content & & & & \\ (umol tyrosine/g sample) & 0.79 \(\pm\) 0.03a & 0.43 \(\pm\) 0.05b & 0.31 \(\pm\) 0.03c & 0.19 \(\pm\) 0.03d \\ \hline \hline \end{tabular} Values are given as mean \(\pm\) standard deviation from triplicate determinations. Different letters in the same row indicate significant differences (\(p<0.05\)). W1 = one washing cycle, W2 = two washing cycles, W3 = three washing cycle, and BPB = bromophenol blue. Lipid content of unwashed mince was 0.61%, wet weight. In the unwashed mince, the yield and lipid reduction were not calculated.  
\end{table}
Table 1: Yield and bio-physico-chemical properties of Indian mackerel unwashed mince and surimi prepared by different washing cycles.  
cold water. The only difference between the treatments was the washing cycle. As a result, the washing cycle can influence the pH of the surimi. During the washing process, both alkaline and acidic substances can be washed out of the minced fish, resulting in a new pH equilibrium in the washed mince [7; 9; 15].