Muscle lipids of ten fish species (freshwater: zander, whitefish, roach, burbot and crucian carp; farmed: rainbow trout and carp; and Baltic species: garfish, flounder and sprat) were analysed for fatty acids composition (GC/MS), lipid fractions (HPLC) and susceptibility to oxidation. 100 g of meat of lean freshwater and Baltic fish (roach, flounder, burbot and zander) can provide 50% less n-3 PUFAs than the meat of rainbow trout or whitefish and 4-6 times-less than sprat. The susceptibility to oxidation of freshwater fish lipids was higher than in the Baltic species of si. mi!ar PUF As content.

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.

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.

AbstractŻochowska-Kujawska J., Lachowicz K., Sobczak M., Bienkiewicz G., Tokarczyk G., Kotowicz M., Machcińska E. (2016): Compositional characteristics and nutritional quality of European beaver (Castor fiber L.) meat and its utility for sausage production. Czech J. Food Sci., 34: 87-92.The composition of European beaver (Castor fiber L.) meat and its utility for sausage production were investigated. Beaver meat has a high concentration of protein (21.44% wet weight) with the high content of available lysine (1.97 g/100 g) and tryptophan (0.29 g/100 g). The fat (5.08%) was characterised by a generally high proportion of polyunsaturated fatty acids (35%) and lower proportion of monounsaturated fatty acids (29%). Octadecenoic acid (C18:1) was a dominant monounsaturated fatty acid. Beaver muscles were characterised by generally small muscle fibres, thick perimysium and low amount of intramuscular fat, thus this raw material may be used in sausage production as an alternative to pork. The most positive effects of beaver meat addition on the texture and palatability of sausages were obtained when about 20-40% of this kind of meat was used.

The objective of the study was to investigate the application of flaxseed oil cake extract (FOCE) for oxidative stabilization of flaxseed oil in spray-dried emulsions. Two variants of powders with 10% and 20% of flaxseed oil (FO), FOCE, and wall material (maltodextrin and starch Capsul®) were produced by spray-drying process at 180 °C. The oxidative stability of FO was monitored during four weeks of storage at 4 °C by peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) measurements. Additionally, the fatty acids content (especially changes in α-linolenic acid content), radical scavenging activity, total polyphenolics content, color changes and free amino acids content were evaluated. Obtained results indicated that FOCE could be an adequate antioxidant dedicated for spray-dried emulsions, especially with a high content of FO (20%). These results have important implications for the flaxseed oil encapsulation with natural antioxidant agents obtained from plant-based agro-industrial by product, meeting the goals of circular economy and the idea of zero waste.