Changes in some components of the muscle lipids of three freshwater fish species under natural extreme cold and temperate conditions

Abstract

Fatty acid composition, conjugated linoleic acid and cholesterol contents in the muscles of three freshwater fish species (Barbus plebejus escherichi, Capoeta capoeta capoeta and Rutilus rutilus) were determined under natural extreme temperate (July) and cold (January) conditions. The aim of the study was to determine whether there were differences in these components of the muscle lipids among these three fish species under extreme natural conditions. Samples were analyzed using gas chromatography. Palmitic, oleic, docosahexaenoic and eicosapentaenoic acids were the predominant fatty acids in all fish in both months. The percentages of polyunsaturated fatty acids, n - 3 polyunsaturated fatty acids, n - 6 polyunsaturated fatty acids and eicosapentaenoic + docosahexaenoic acids in the muscle of B. plebejus escherichi and C. capoeta capoeta were significantly higher in January (P < 0.05) than in July. The ratio of n - 6 to n - 3 polyunsaturated fatty acids was lower than 0.60 in all fish species, with C. capoeta capoeta showing the lowest ratio in January (0.36). The levels of cholesterol and conjugated linoleic acid ranged from 103.46 to 150.10 mg/100 g oil and from 16.27 to 35.45 mg/100 g oil, respectively, for all samples in both months. There were no statistical differences in cholesterol levels among the three fish species in July and January. Conjugated linoleic acid contents were significantly higher in January in B. plebejus escherichi and C. capoeta capoeta. Of the three species tested, the extreme temperate and cold conditions affected B. plebejus escherichi the most.

A comparative study on the fatty acid profiles of total lipid, neutral and polar lipids in the liver and muscle ofCapoeta sieboldii(Steindachner, 1864) andCapoeta baliki(Turan, Kottelat, Ekmekçi, Imamoğlu, 2006) from Tödürge lake (Sivas, Turkey)

“…The highest and lowest levels of this acid in the NL fractions were determined in the livers of C. sieboldii (3.18%) and C. baliki (0.98%), respectively. This result seems compatible with the data that phospholipids are depots of C20:4 n-6 in the biological membranes (TOCHER et al, 2008) and the metabolism of this acid, participating in cell signalling events, results in the production of pharmacologically active eicosanoids (UYSAL et al, 2008;LE et al, 2009). However, C18:2 n-6 was other notable fatty acid exceeding 1% in the NL fractions of all groups.…”

Determination of fatty acid profiles of total, neutral, and polar lipids in different tissues of Vimba vimba (L., 1758) from Eğirdir Lake (Isparta, Turkey)

“…C18:1 n-7 levels varied between 4.73% (liver) and 5.98% (intestine). Rahnan et al (1995) and Uysal et al (2008) revealed that MUFA concentrations in freshwater fish were higher than the proportions of PUFAs and SFAs and that C18:1 n-9 was the major component of the MUFA fraction. Kalyoncu et al (2009) reported similar results in the muscle of V. vimba, in which MUFA levels were found to be higher than PUFAs and SFAs in all seasons investigated.…”

“…However, higher levels of DHA were determined in the PLs of the liver (5.67%), muscle (17.37%), and intestine (4.35%). High levels of DHA in the PLs can be explained by considering that PLs are the main resources used by fish to adapt to environmental changes by ensuring constant fluidity of the biological membranes, and one of the strongest candidates for this purpose is specifically DHA (Uysal et al, 2008). The n-3/n-6 ratios in the NLs were determined to be 1.33 in the liver, 1.56 in the muscle, and 1.25 in the intestine.…”

“…Many studies have emphasized that the fatty acid profiles of fish tissues show great variation depending on external and internal factors such as age, rations, climatic conditions, sex, water temperature, season, and reproduction period (Kiessling et al, 2001;Uysal et al, 2006;Görgün and Akpınar, 2007;Sushchik et al, 2007;Uysal et al, 2008;Kalyoncu et al, 2009;Görgün and Akpınar, 2012). Among the fatty acids in fish tissues, EPA and DHA were the primary candidates in which the most remarkable changes were observed (Szlinder-Richert et al, 2010).…”

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“…In our study, average n-6/n-3 was found as 0.27. Comparing to some marine fish species studied by Özoğul and Özoğul (2007a) bogue (boops boops) (0.05), mullet (mugil cephalus) (0.12), sardine (sardinella aurita) (0.11) and scad (trachurus mediterraneous) (0.04) and some fresh water species studied by Uysal et al, (2008) Barbus plebejus escherichi (0.37) Capoeta capoeta capoeta (0.37) and Rutilus rutilus (0.56) n-6/n-3 ratio of our study was higher than marine species, lower than freshwater species, as a result, being under the maximum recommended value, consumption of pearl mullet has an advantageous impact on maintaining the necessary dietary n-6/n-3 ratio at the recommended level. Revealing the nutritional value of fish, n-3/n-6 is recommended as a good index (Pigott and Tucker, 1990).…”