Effects of sun-drying on the lipid quality and fatty acid composition of blue whiting (Micromesistius poutassou)

Abstract

The effects of sun-drying on the chemical composition, lipid quality, and fatty acid profile of blue whiting (Micromesistius poutassou) were investigated. Fifty fresh fish (300–400 g per fish) were eviscerated and randomly assigned to two groups: raw (control) and sun-dried. Fish designated for drying were exposed to sunlight for two consecutive days (08:00–17:00 h) until a final moisture content of 12.19 ± 0.81% was attained. Data were analysed using an independent-samples t-test, with statistical significance set at p < 0.05. Sun-drying significantly reduced the moisture content of blue whiting while increasing the relative concentrations of crude protein, crude fat, and ash. Oil extracted from sun-dried fish exhibited significantly higher peroxide value (9.76 vs. 4.95 meq O₂/kg), acid value (17.76 vs. 11.22 mg KOH/g), and free fatty acid content (9.03 vs. 5.64% oleic acid), but a lower iodine value (8.88 vs. 10.79 g I₂/100 g) than oil from raw fish, consistent with increased lipid oxidation and hydrolysis during drying. Sun-drying also significantly altered the fatty acid composition, increasing the relative proportion of saturated fatty acids while reducing the proportions of monounsaturated and polyunsaturated fatty acids. Overall, sun-drying effectively reduced the moisture content of blue whiting but was associated with deterioration in lipid quality and changes in the relative fatty acid composition. These changes may have implications for the nutritional quality and stability of dried blue whiting.