Effect of freeze–thaw cycles on the physicochemical, water–holding properties, and histology of Sardinella aurita

This study investigates the impact of freeze–thaw cycles on samples of Sardinella aurita, focusing on the examination of physicochemical properties, water–holding capacity, color changes, and histological alterations in fish meat. The present findings indicate significant variations in the studied parameters, i.e., pH, water activity, lightness (L*), redness (a*), yellowness (b*), protein solubility (mg·g-1), moisture content (%), thawing loss (%), centrifugation loss (%), cooking loss (%), underscoring the importance of comprehending the consequences of freezing–thawing in the fishing and food processing industry. Initially, a statistically significant decrease in pH levels was observed (T0: 6.23 ± 0.1, T4: 6.19 ± 0.1), followed by a notable increase after the fifth freeze–thaw cycle (T5: 6.47 ± 0.1), possibly due to chemical and microbiological composition shifts. Water activity exhibited a gradual decrease (T0: 0.911 ± 0.009, T4: 0.899 ± 0.01), likely attributed to water loss during freezing–thawing (P<0.05). Colorimetry results demonstrated a significant decrease in brightness (L*) and a slight increase in yellow hue (b*) throughout the cycles, with values ranging from 63.51 (T0) to 33.64 (T5) for L* and from 26.74 (T0) to 17.28 (T5) for b*. These variations highlight notable and significant changes in the product’s color over the freeze–thaw cycles (P<0.05). Histological analysis revealed structural changes, including muscle fiber dehydration. These observed changes hold implications for product quality and consumer perception. It is essential to recognize that various factors, such as fish size, seasonality, and environmental conditions influence these results. Further research is needed to delve deeper into these aspects. In essence, this study offers valuable insights for industry professionals, aiding them in making informed decisions regarding seafood products subjected to freezing–thawing cycles. This not only ensures product quality and safety but also helps prevent food fraud and provides consumers with high–quality products.