Determination of lipid quality and mercury levels of sardine and rainbow trout cooked with different methods

This study aimed to investigate the effects of baking and pan-frying methods on the lipid quality and mercury (Hg) levels of two important fish species in Türkiye, namely, fileted sardine (Sardina pilchardus) and rainbow trout (Oncorhynchus mykiss). The results revealed that sardines significantly decreased n-3 fatty acids depending on the cooking process, while the best n-6/n-3 ratio was observed in baked sardines, with higher rates found in pan-fried fish. Notably, pan-fried rainbow trout cooked with butter showed the highest atherogenic index (AI) of 0.71±0.32 and thrombogenic index (TI) of 0.61±1.43, as well as a hypocholesterolemic/hypercholesterolemic index (HH) of 0.79 ± 0.17. Conversely, fried sardines exhibited lower atherogenic and thrombogenic scores, with fried sardines cooked in sunflower oil having a hypocholesterolemic/hypercholesterolemic index of 4.85 ± 0.3. There were no significant variations in Hg content between raw and cooked fish. However, when compared to the raw control, the rise in Hg content for baked fish was substantial (p < 0.05) (baked rainbow trout 0.18 mg/kg and sardine 0.29 mg/kg). The decrease in FAs (Fatty Acids) due to cooking methods can be ordered as follows: Raw sardine > baked > fried. Conversely, the increase in FAs due to the cooking methods can be ordered as follows: fried > baked > raw sardine. Baked rainbow trout had much lower levels of palmitic acid, stearic acid, and myristic acid than the raw material. However, these levels were significantly increased in rainbow trout cooked in a frying pan. Additionally, oleic acid levels in fried rainbow trout were detected to be lower than in other preparations, whereas they were equivalent in baked rainbow trout.