Background. The aquaculture rainbow trout may be a valuable source of long chain n-3 polyunsaturated fatty acid (LC n-3 PUFA). In the retail these fish are mainly present as a whole or gutted. The present study was aimed at comparing changes occurring in lipids of whole and gutted rainbow trout stored in ice. Materials and Methods. The analysis were performed after 0, 3, 7, and 14 days of storage in ice at 2°C and the following assays were carried out: proximate composition; lipid composition high pressure liquid chromatography (HPLC); fatty acid composition gas chromatography /mass spectrometry (GC/MS) by direct tissue saponification; contents of lipids extracted, using the Bligh-Dyer technique; UV-VIS, IR, and fluorescence lipid spectra; peroxide value (PV); anisidine value (AsV); and acid value (AC). Results. Gutting prior to storage made it possible to extend the sensory shelf-life by about 2-3 days and affected the quantitative fatty acid composition and oxidation level during storage in ice. The rainbow trout lipids are resistant to oxidation; oxidation product decomposition rather than lipid oxidation proceeds during storage, the decomposition being more intensive in whole than in gutted fish. It is only when the fish lose their eating quality (2 weeks) that a small increase in the level of oxidation occurs, accompanied by an about 15% loss of n-3 PUFA and a 20% loss of DHA, but only in the whole fish. Conclusion. Gutting rainbow trout prior to storage in ice is appropriate by the extending the shelf-life by about 2-3 days and keeping stable amount of n-3 PUFA during 2 weeks of storage.

Seafood (fish in particular) is one of the main food groups in nutrition models with proven health benefits. Seafood has long been considered a very valuable dietary component, mainly due to presence of n-3 polyunsaturated fatty acids (n-3 PUFA) but it is also an important source of protein (including collagen), anserine, taurine, iodine, selenium, vitamin A, vitamin K, vitamin D, tocopherols, B vitamins and astaxanthin. Considering the beneficial effects of these ingredients on blood pressure, lipid profile and the inflammatory process, seafood should be an essential component of the diet. Non-communicable diseases (NCD) such as cardiovascular diseases, cancer, diabetes and mental disorder, chronic respiratory diseases are common diseases associated with advanced age. Promotion of a healthy lifestyle (including proper nutritional behavior) and prevention of diseases are the most effective and efficient ways to decrease premature mortality from NCD and to maintain mental health and well-being. This review article shows the potential preventive and therapeutic effects of seafood with an emphasis on fish. Our narrative review presents the results of systematic reviews and meta-analysis.

Lipid composition (HPLC), fatty acid composition (GC/MS), lipid oxidation (peroxide value, anisidine value), UV-VIS and fluorescence spectra (Ex 365 nm), and susceptibility of lipids to oxidation (photooxidation test) as well as heavy metal, PCB, and DDT contents were determined in canned, raw, and thermally treated cod liver (separately in the released oil and in the solids). Canned products of three manufacturers were examined. Mean contents of n-3 polyunsaturated fatty acids (n-3 PUFAs) in the oil and solids were 31.91 +/- 1.83 and 16.59 +/- 7.48 g/100 g, respectively, the respective contents of docosahexaenoic acid (DHA) being 17.88 +/- 1.69 and 8.79 +/- 3.67 g/100 g. Lipid resistance to oxidation was found to decrease after thermal treatment of livers. However, the lipid oxidation level in canned liver stored for 3-8 months was not high and averaged, for the entire can content, 0.47 +/- 0.4 Meq O, the oil being more susceptible to oxidation that the solids. It is concluded that canned cod liver is a very good source of n-3 PUFA, particularly with respect to DHA. Heavy metal, DDT, and PCB contamination and the presence of lipid oxidation products in the canned products tested remain at a level producing no perceivable health hazard and could in no way interfere with consumption of recommended amounts of n-3 PUFAs.

Effects of rainbow trout freshness on n-3 polyunsaturated fatty acids in fish offalThe effects of rainbow trout cold storage on the quality of offal left after fish processing to fillets with skin were determined. The intact farmed rainbow trout were kept at 2 7C in ice for 0, 4, 7, and 14 days of storage. The offal was, immediately after processing, frozen at 220 7C and analysed after a month-long frozen storage; fillets (non-frozen) were analysed as well. Non-protein nitrogen, volatile bases, trimethylamine, lipid oxidation (peroxide value, anisidine value, UV-VIS spectra, and fluorescence) and fatty acid composition were determined. The offal consists in 15% of protein and in about 20% of chloroform/methanol-extractable lipids, with n-3 polyunsaturated fatty acids (n-3 PUFA) accounting for 20.37 6 1.25% of the fatty acids. The fish storage duration was found to exert a significant (p = 0.05) effect on the changes in lipids and nitrogen compounds. No losses of long-chain n-3 PUFA in the offal were detected during the 2 wk of storage in ice plus 1 month at 220 7C. The rainbow trout offal is a valuable -rich and stable -source of n-3 PUFA.

Summary In this study, analyses were carried out to establish the impact of heating three species of fatty fish: trouts, herrings and sprats, on the lipids oxidation and on contents of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The comminuted fish tissue was heated at restricted access of oxygen at temperature of 60, 100 and 160 °C for 15–120 min. Lipids, extracted with the Bligh‐Dyer method, were determined for peroxide value (PV) and anisidine value (AV). The Fatty acid methyl esters were prepared directly from the tissue, whereas contents of EPA and DHA were determined with the GC/MS method. Depending on the temperature applied, 15‐min heating of fish meat tissue caused 30–80% decrease of PN and 20–40% decrease of AV, on average. Generally, the continued heat treatment caused successive decreases in both PV and AV and the rate of this process was observed to increase along with an increasing temperature. The heating of trout and sprats at temperature of 60, 100 and 160 °C even for 1–2 h did not evoke losses either in EPA or in DHA content. In turn, in the case of herring caught during the pre‐spawning season, ca. 90–120 min of heat treatment contributed to ca. 20–25% decrease in contents of these fatty acids.