Zbigniew Borejszo

The composition of fatty acids in muscles of six freshwater fish species from the Mazurian Great Lakes (Northeastern Poland)

The Composition of Fatty Acids in Muscles of Six Freshwater Fish Species from the Mazurian Great Lakes (Northeastern Poland) Lipid content and fatty acids composition of non-predatory fish: roach, Rutilus rutilus (L.), bream, Abramis brama (L.), vendace, Coregonus albula (L.), and of predatory fish: Eurasian perch, Perca fluviatilis L., pike, Esox lucius L. and burbot, Lota lota (L.) were examined. These fish were caught from three lakes of Mazurian Great Lakes (Kisajno, Dargin, Niegocin). The content of total lipid and some fatty acids varied widely within and among species. Generally, the lipid content was low (0.56-2.78%). Among the saturated and monounsaturated fatty acids, the predominant fatty acids were palmitic C16:0 (19.24-33.44%), stearic C18:0 (4.37-6.87%), palmitoleic C16:1 (4.51-12.93%), and oleic C18:1 n-9 (6.85-14.49%). Arachidonic C20:4 n-6 (3.17-6.55%), eicosapentaenoic C20:5 n-3 (4.14-8.91%), and docosahexaenoic C22:6 n-3 (5.91-24.67%) acids were the most abundant polyunsaturated fatty acids. In the case of all the freshwater fish, with the exception of bream, higher contents of saturated fatty acids than monounsaturated fatty acids were noted. Among the fish studied, the highest value of total n-3 polyunsaturated fatty acids (43.86%) was noted in vendace, whereas bream contained the highest content of total n-6 polyunsaturated fatty acids (11.21%). The ratio of n-3/n-6 ranged between 1.50 (burbot) and 4.40 (vendace). Differences in the content of fatty acids in fish with different feeding strategies (non-predatory and predatory) were measured. Non-predatory fish were found to have lower values of saturated fatty acids than predatory fish (P ≤ 0.05). Non-predatory fish contained significantly more eicosapentaenoic acid (EPA) than predatory fish (P ≤ 0.01), whereas the amounts of monounsaturated and n-3 and n-6 polyunsaturated fatty acids in non-predatory and predatory fish were not statistically significant (P > 0.05). The total n-3 polyunsaturated fatty acids was higher in non-predatory fish, but not statistically significant (P > 0.05). Similarly, the differences in DHA and n-3/n-6 ratio in muscles of predatory and non-predatory fish were not statistically significant (P > 0.05). Zawartość Kwasów Tłuszczowych w Mięéniach Sześciu Gatunków Ryb Słodkowodnych z Wielkich Jezior Mazurskich (Północno-Wschodnia Polska) Określono zawartość tłuszczu oraz skład kwasów tłuszczowych lipidów tkanki mięśniowej płoci, Rutilus rutilus (L.), leszcza, Abramis brama (L.), sielawy, Coregonus albula (L.), okonia, Perca fluviatilis L., szczupaka, Esox lucius L. i miętusa, Lota lota (L.). Ryby odławiano z trzech Wielkich Jezior Mazurskich (Kisajno, Dargin i Niegocin). Stwierdzono różnice wewnątrz- i międzygatunkowe zawartości tłuszczu oraz składu kwasów tłuszczowych. Zawartość tłuszczu mieściła się w zakresie od 0,56 do 2,78%. Wśród nasyconych i monoenowych kwasów tłuszczowych dominowały kwasy: palmitynowy C16:0 (19,24-33,44%), stearynowy C18:0 (4,37-6,87%), palmitooleinowy C16:1 (4,51-12,93%) i oleinowy C18:1 n-9 (6,85-14,49%) (tab. 1). Wśród kwasów polienowych dominowały kwasy: arachidonowy C20:4 n-6 (3,17-6,55%), eikozapentaenowy C20:5 n-3 (4,14-8,91%) i dokozaheksaenowy C22:6 n-3 (5,91-24,67%) (tab. 1). W przypadku wszystkich ryb, z wyjątkiem leszcza, odnotowano, że procentowy udział nasyconych kwasów tłuszczowych był wyższy niż monoenowych kwasów tłuszczowych (rys. 1). Najwyższą zawartość kwasów z grupy n-3 zaobserwowano w tłuszczu sielawy (43,86%), natomiast leszcze zawierały najwięcej kwasów z grupy n-6 (11,21%) (rys. 1). Stosunek polienowych kwasów tłuszczowych z grupy n-3 do kwasów tłuszczowych z grupy n-6 wynosił od 1,50 (miętus) do 4,40 (sielawa). Niższą zawartość nasyconych kwasów tłuszczowych odnotowano w przypadku ryb spokojnego żeru (P < 0,05) w porównaniu z rybami drapieżnymi (tab. 2). Ryby spokojnego żeru zawierały więcej kwasu eikozapentaenowego niż ryby drapieżne (P < 0,01). Nie stwierdzono istotnych różnic w zawartości monoenowych oraz n-3 i n-6 polienowych kwasów tłuszczowych pomiędzy rybami spokojnego żeru i rybami drapieżnymi (P > 0,05). Podobnie, zawartość kwasu dokozaheksaenowego oraz stosunek kwasów n-3/n-6 w mięśniach ryb drapieżnych i spokojnego żeru nie różniły się istotnie (P > 0,05).

Fatty Acid Profile of Muscles of Freshwater Fish from Olsztyn Markets

Fatty Acid Profile of Muscles of Freshwater Fish from Olsztyn Markets The aim of the present study was to determine the profile of fatty acids in muscle lipids of freshwater fish: carp (Cyprinus carpio L.), rainbow trout (Oncorhynchus mykiss Walb.), bream (Abramis brama L.) and tench (Tinca tinca L.) from markets of Olsztyn (north-eastern Poland). Separation and identification of fatty acids were made using gas chromatography. The content of some fatty acids varied among species. Generally, palmitic acid (15.6%-19.5%) was the most abundant saturated fatty acid (SFA). The main monounsaturated fatty acid (MUFA) was oleic acid (20.7%-42.7%). Linoleic (4.6%-8.0%), arachidonic (AA) (0.8%-6.6%), docosahexaenoic (DHA) (1.7%-15.9%) and eicosapentaenoic (EPA) (1.2%-8.8%) acids were the predominant polyunsaturated fatty acids (PUFA). There were no significant differences (p>0.05) in the content of SFA (24.3%-28.7%) among the fish species. The content of MUFA in muscle lipids of carp (55.0%) was significantly higher (p≤0.01) than in the lipids of the other fish examined (35.8%-38.3%). Bream and rainbow trout (26.6% and 27.7%, respectively) contained significant more n-3 PUFA than carp (4.7%) and tench (20.5%) (p≤0.01). Total n-6 PUFA ranged between 8.4% (rainbow trout) and 12.9% (tench). Significant differences in n-6 PUFA content were only observed in the case of these fish (p≤0.01). The differences in the n-3/n-6 ratio (rainbow trout (3.3) > bream (2.6) > tench (1.6) > carp (0.4)) were statistically significant (p≤0.01).