# Influence of Pre-Treatment on the Seasonal Variation of Smoked Baltic Strat Texture and Color
## 3 Results and Discussion
### Smoked Sprat Texture
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Pre-Treatment**} & \multicolumn{3}{c}{**Moisture Content (\%)**} \\ \cline{2-4}  & **Early** & **Mid** & **Late** \\ \hline Control & 67.5 \(\pm\) 2.6 \({}^{\text{\,{\sc{a}}}}\)A & 69.2 \(\pm\) 0.8 \({}^{\text{\,{\sc{a}}}}\)A & 69.5 \(\pm\) 0.8 \({}^{\text{\,{\sc{a}}}}\)A \\ Na & 66.7 \(\pm\) 1.1 \({}^{\text{\,{\sc{a}}}}\)B & 65.8 \(\pm\) 2.1 \({}^{\text{\,{\sc{a}}}}\)B & 65.0 \(\pm\) 1.4 \({}^{\text{\,{\sc{b}}}}\)A \\
3 Na2 Ca & 62.5 \(\pm\) 1.8 \({}^{\text{\,{\sc{b}}}}\)A & 61.6 \(\pm\) 1.5 \({}^{\text{\,{\sc{c}}}}\)A & 62.2 \(\pm\) 1.2 \({}^{\text{\,{\sc{b}}}}\)A \\
2 Na3 Ca & 61.5 \(\pm\) 1.5 \({}^{\text{\,{\sc{b}}}}\)A & 60.6 \(\pm\) 0.9 \({}^{\text{\,{\sc{c}}}}\)A & 59.8 \(\pm\) 0.9 \({}^{\text{\,{\sc{b}}}}\)A \\ Ace & 65.7 \(\pm\) 2.0 \({}^{\text{\,{\sc{a}}}}\)B & 64.1 \(\pm\) 0.9 \({}^{\text{\,{\sc{b}}}}\)A & 64.0 \(\pm\) 2.5 \({}^{\text{\,{\sc{b}}}}\)B \\ NaAce & 62.9 \(\pm\) 1.6 \({}^{\text{\,{\sc{a}}}}\)B & 62.2 \(\pm\) 0.9 \({}^{\text{\,{\sc{c}}}}\)A & 58.6 \(\pm\) 1.6 \({}^{\text{\,{\sc{b}}}}\)B \\ CaAce & 61.7 \(\pm\) 2.3 \({}^{\text{\,{\sc{b}}}}\)B & 59.0 \(\pm\) 1.2 \({}^{\text{\,{\sc{d}}}}\)A & 57.0 \(\pm\) 1.1 \({}^{\text{\,{\sc{d}}}}\)B \\ \hline \hline \end{tabular} Average value (n = 9) \(\pm\) SD. For sample abbreviations, see Table 1. \({}^{\text{\,{\sc{a}}}}\)-d Different lowercase letters indicate significant differences between values in columns; \({}^{\text{\,{\sc{a}}}}\)-B different uppercase letters indicate significant differences in rows at \(p\leq\) 0.05, per [PERSON]’s test.  
\end{table} 
Table 3: The moisture content of smoked sprat, depending on the season and pre-treatment. softening in a fish from the late season may affect the appearance of smoked sprat, making it unacceptable for further processing in canned produce, fish pate, or fish snacks. Pre-treatment did not show a significant effect on the early-season fish texture (Table 5), possibly due to the higher fat content and lower water content, which resulted in the slower migration of the pre-treatment agent in the fish tissue. According to [PERSON] et al. (2015), lipids in fatty fish present a physical barrier to salt transport due to fat hydrophobicity. The hardness of smoked mid- or late-season fish increased when acetic acid was applied either alone or combined with sodium or calcium salt. [PERSON] et al. (2016) also described the hardness increase in Irish sprat after marination, attributing an increase to the protein denaturation, which may result in decreased water adsorption. [PERSON] and [PERSON] (2016) reported a reduced elasticity of Baltic herring with an increased acid concentration in the range of 1-5%. In our study, the texture analysis of sprat indicated a weak negative correlation between the cutting strength and smoked fish pH (\(-\)0.488), which is in agreement with [PERSON] et al. (2016), who revealed that the hardest texture for Irish sprat was observed at the lowest pH. Figure 2: Texture of smoked sprat depending on the season and pre-treatment: (**A**) work of shear; (**B**) cutting strength. Average values (n = 21) with the standard deviation. For sample abbreviations, see Table 1.  
The use of salts for fish pre-treatment before smoking did not significantly affect the texture of early- or mid-season sprat, whereas the application of salts in the pre-treatment of late-season fish significantly increased both the work of shear and cutting strength, indicating a harder texture. The seasonal effect may be ascribed to the higher water content (Table 2) in late-season fish and differences in the water distribution within tissue, which may vary significantly [10]. A higher water content facilitates salt migration. The role of sodium chloride in the texture formation of muscle foods is well established. According to the systematic review performed by [PERSON] et al. [17], salt plays an essential role in texture by aiding the solubilization of protein, triggering protein extraction, and enhancing the water-holding capacity.