# Influence of Pre-Treatment on the Seasonal Variation of Smoked Baltic Strat Texture and Color
## 3 Results and Discussion
### Smoked Sprat Color  
In the smoking process, fish undergo a process of thermal treatment and drying, leading to non-enzymatic browning reactions, contributing to the color of the final product. The smoked sprat color components in the CIE Lab system of the lightness (L*) and the redness (a*) were stable through the catching season, whereas the yellowness (b*) tended \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Item**} & \multirow{2}{*}{**Treatment**} & **Treatment** & **Season** & **Treatment \(\times\) Season** \\  & & **One-Way ANOVA** & **One-Way ANOVA** & **Three by Seven Factorial Design** \\  & & **(Post Hoc Tukey)** & **(Post Hoc Tukey)** & **ANOVA (Post Hoc LSD)** \\ \hline \multirow{8}{*}{Work of shear} & Control & & & F (12; 161) = 3.48, \\  & Na & F (6; 153) = 4.05, & & \(p\) \(<\) 0.001 \\  & 3 Na2 Ca & \(p\) = 0.001 & F (2; 157) = 11.09, & Control: ns \\  & 2 Na3 Ca & Ace * \textgreater{} Control & \(p\) \textless{} 0.05 & Na: S3 \textgreater{} S1 **, S2 ** \\  & Ace & 3 Na2 Ca *, 2 Na3 Ca *, & S3 \textgreater{} S1 **, S2 ** & 3 Na2 Ca: S1 \textless{} S2 ***, S3 ** \\  & NaAce & Ace ** \textgreater{} Na & & 2 Na3 Ca: S3 \textgreater{} S1 ***, S2 *** \\  & CaAce & & & Acc: ns \\  & & & & NaAce: ns \\  & & & & CaAce: S1 \textless{} S3 ** \\ \hline \multirow{8}{*}{Cutting strength} & Control & & & F (12; 161) = 3.89, \\  & Na & F (6; 153) = 4.26, & & \(p\) \textless{} 0.001 \\  & 3 Na2 Ca & \(p\) = 0.001 & F (2; 157) = 10.08, & Control: ns \\  & 2 Na3 Ca & Ace * \textgreater{} Control & \(p\) \textless{} 0.001 & Na: S2 \textless{} S3 ** \\  & Ace & 2 Na3 Ca **, Ace **, & S3 \textgreater{} S1 ***, S2 ** & 3 Na2 Ca: S1 \textless{} S2 *** \\  & NaAce & CaAce * \textgreater{} Na & & 2 Na3 Ca: S3 \textgreater{} S1 ***, S2 ** \\  & & & & Acc: S3 \textgreater{} S2 ** \\  & CaAce & & & NaAce: ns \\  & & & CaAce: S1 \textless{} S3 ** \\ \hline \hline \end{tabular} For sample abbreviations, see Table 1. S1—early-season (September/October); S2—mid-season (November/December); S3—late-season (March/April). Statistically significant differences are marked with * \(p\)\(<\) 0.05; **\(p\)\(<\) 0.01; and **\(p\)\(<\) 0.001. ns—no significant differences.  
\end{table} 
Table 5: The significance of the season and pre-treatment effect on the smoked sprat texture. to decrease towards the end of the catching season (Figure 3), possibly due to the reduced fat content. Pre-treatment only affected the lightness of the early-season fish samples (Table 6). It did not affect the lightness of the pre-treated samples in the mid- or late-season. Treatment with acetic acid combined either with sodium salt or calcium salt made the sprat surface darker. A moderate negative correlation existed between the fat content and L* value (lightness) for smoked sprat (r = -0.646). A weak positive correlation was found between the fat content and color component a* (redness) and the fat content and color component b* (yellowness). Figure 3: Color of smoked sprat depending on the season and pre-treatment: (**A**) color component L* black–white; (**B**) color component a* green–red; (**C**) color component b* blue–yellow. Average values (n = 30) with standard deviation. For sample abbreviations, see Table 1.  
The most important values are color component L* because it shows the lightness of the sample and yellowness (b*), which appears as a golden skin color. The smoked sprat produced from early-season fish after one year of frozen storage, irrespective of the treatment method, was redder and less yellow. The reduced yellowness in the late-season sprat may be observed due to the lower content of carotenoid astaxanthin, a fat-soluble pigment [24]. Acetic acid possibly acts as a solvent, releasing pigment and improving the yellowness of smoked fish skin. However, the color was pre-treatment material-dependent. The application of the pre-treatment with acetic acid for late-season sprat allowed for increasing the surface yellowness compared to the sample without pre-treatment.