Seasonal Variation of Chemical and Fatty Acids Composition in Atlantic Mackerel from the Tunisian Northern-East Coast

Abstract

Seasonal variation of chemical and fatty acids composition of Atlantic Mackerel populations from the Northern-East coast of Tunisia were investigated in order to assess the best period for its consumption. Fresh specimens were purchased monthly from Bizerte fishing port located in the north-east coast of Tunisia. It was noted that total lipids and protein contents levels varied significantly (P<0.05) according to the season. The highest protein level was registered in autumn (27.6%), while the lowest was in spring (18.7%). Total fat content decreased significantly (P<0.05) from (11.1%) in spring to (4.5%) in summer. The major fatty acids in each season were 16:0 and18:0 (palmitic and stearic) acids as saturated; 16:1 and 18:1 (palmitoleic and oleic) acids as monounsaturated; and 20:4 (arachidonic acid), 20:5 Eicosapentanoic (EPA), 22:6 Docosahexanoic (DHA)as polyunsaturated. These components varied significantly (P<0.05) during the sampling period. It was shown that high PUFA values are related to the high n-3 PUFA proportions, mainly represented by EPA and DHA. Docosahexanoic acid was the most abundant (P 0.05) was observed in autumn (40.1%). It was noted that n-6 PUFA proportions were very low comparatively to those of n-3 PUFA series. The highest level of n-6 PUFA series corresponded to arachidonic acid in autumn (3.9%). The best (n-3)/(n-6) ratio was registered in spring (10.81).