## 4 Discussion  
Depending on the mixing ratio of the primary ingredients in CSPSP, the \(p\)-values for the lack-of-fit test of the response surface model equation for hardness (\(Y_{1}\)), redness (\(Y_{2}\)), and sensory texture (\(Y_{3}\)) were observed as 0.076 for hardness (\(Y_{1}\)), 0.076 for redness (\(Y_{2}\)), and 0.318 for sensory texture (\(Y_{3}\)). These values were all higher than 0.05. The coefficients of determination (R\({}^{2}\)) were found to be 0.973 for hardness (\(Y_{1}\)), 0.878 for redness (\(Y_{2}\)), and \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Items** & **RCS** & \multicolumn{2}{c}{**CSPSP**} \\ \cline{3-5}  & & & **-N (not Boiled)** & **-A (after Boiled)** \\ \hline \multirow{2}{*}{Hardness (\(\times 10^{3}\) N/m\({}^{2}\))} & Experiment method 1 & 1082.7 \(\pm\) 19.6 \({}^{\rm c}\) & \(534.2\) \(\pm\) 6.5 \({}^{\rm b}\) & 21.6 \(\pm\) 0.6 \({}^{\rm a}\) \\  & Experiment method 2 & NM & 553.6 \(\pm\) 6.0 \({}^{\rm b}\) & 27.8 \(\pm\) 0.2 \({}^{\rm a}\) \\  & Experiment method 3 & 1724.6 \(\pm\) 47.8 & NM & NM \\ \hline \multirow{3}{*}{Sensory evaluation (points)} & Appearance & 7.1 \(\pm\) 0.6 \({}^{\rm a}\) & 8.1 \(\pm\) 0.5 \({}^{\rm a}\) & 8.2 \(\pm\) 0.6 \({}^{\rm a}\) \\  & Taste & 6.5 \(\pm\) 0.4 \({}^{\rm a}\) & 8.3 \(\pm\) 0.5 \({}^{\rm b}\) & 8.7 \(\pm\) 0.5 \({}^{\rm b}\) \\ \cline{1-1}  & Flavor & 6.1 \(\pm\) 0.7 \({}^{\rm a}\) & 7.9 \(\pm\) 0.4 \({}^{\rm b}\) & 8.4 \(\pm\) 0.3 \({}^{\rm b}\) \\ \cline{1-1}  & Texture & 4.4 \(\pm\) 0.5 \({}^{\rm a}\) & 6.7 \(\pm\) 0.6 \({}^{\rm b}\) & 8.7 \(\pm\) 0.3 \({}^{\rm c}\) \\ \cline{1-1}  & Overall acceptability & 6.0 \(\pm\) 0.6 \({}^{\rm a}\) & 7.7 \(\pm\) 0.5 \({}^{\rm b}\) & 8.5 \(\pm\) 0.4 \({}^{\rm b}\) \\ \hline \end{tabular} -N (not boiled), CSPSP manufactured with RCS; -A (after boiled), CSPSP manufactured after boiling common squid; NM, not measured; Panel configurations, n = 24 (12 males and 12 females); the average age, 70 (65–75); Different superscripted letters indicate statistically significant differences (\(p<0.05\)).  
\end{table} 
Table 13: Hardness and sensory evaluation of RCS and CSPSP. Figure 2: Scanning electron microscope images (magnification: \(\times 5000\)) of raw squid muscle (a), CSPSP manufactured with RCS (b), and CSPSP manufactured after boiling common squid (c). 0.959 for sensory texture (\(Y_{3}\)), all of which were close to 1. The model values were 0.000 for hardness (\(Y_{1}\)) and sensory texture (\(Y_{3}\)) and 0.005 for redness (\(Y_{2}\)), all of which were lower than 0.05, confirming the suitability of all the designed models [42]. In summary, hardness (\(Y_{1}\)) exhibited an inverse relationship with the amount of RCS mantle added, while redness (\(Y_{2}\)) displayed a direct proportionality with the quantity of RCS mantle added. Sensory texture (\(Y_{3}\)) exhibited an increasing trend until the coded value of the independent variable reached 0.67, but then decreased until it reached 1.414. This suggests that when the RCS mantle was self-ripened (100 \({}^{\circ}\)C, 5 min) and ground with a chopper, the muscle tissue softened, resulting in a 28% reduction in hardness, from 34.9 \(\times\) 1000 N/m\({}^{2}\) to 25.1 \(\times\) 1000 N/m\({}^{2}\). These findings align with a study on the texture-softening process of jumbo squid mantle through cooking [43]. In contrast, when comparing the hardness of RCS itself, the common squid paste sausage prototype made using RCS (CSPSP-N), and the common squid paste sausage prototype made using boiled common squid (CSPSP-A), the hardness of CSPSP-A decreased by 50.7% and 98%, respectively, compared to that of raw squid and CSPS-A (\(p<\) 0.05). The texture preference of CSPS-A (8.7 points) exceeded that of raw squid (4.4 points) and CSPS-N (6.7 points), with differences of 4.3 points and 2.0 points, respectively (\(p<\) 0.05), indicating a similar trend in the preference evaluations of elderly consumers (Table 13).