Effect of catching season in the North Adriatic sea on selected fatty acid response to cooking and ensuing true retention values in the edible portion from four species of fatty fish

The objective of this study was to determine if the behaviour of the most important fatty acids in four species of fatty fish and their true retention values upon cooking were in any way affected by the season of catch. For each of the following species: anchovy (Engraulis encrasicolus, EE), sardine (Sardina pilchardus, SP), sprat (Sprattus sprattus, SS), and scad (Trachurus trachurus, TT), four batches were acquired at local wholesale fish markets either in fall 2006 (anchovy, 105 specimens on the whole; sardine, 80; scad, 27) or in winter 2006 (sprat, 110), and four more batches in spring 2007 (anchovy, 120; sardine, 78; sprat, 75; scad, 34). Within batch, one fillet per fish was retained to constitute the pooled raw reference, while their counterparts were oven baked in a partially covered baking tin and pooled. Raw and cooked samples were analysed in duplicate for lipids, and fatty acid composition (% fatty acid methyl esters) and content (mg/100 g edible portion). The season of catch significantly affected both the lipid content and its retention value (RV) upon baking for EE, SP, and SS, the first and the third species being fattier, the second leaner in spring. Fall EE had higher saturated (SFA) and n-6 polyunsaturated (n-6 PUFA) fatty acid percentages, while having significantly lower percentages of C20:5 n-3 (EPA), C22:5 n-3 (DPA), C22:6 n-3 (DHA), n-3 PUFA, and total PUFA, without substantial differences between the raw and the cooked state, SFA excepted. TT was the only other species where a season effect on fatty acid composition was evident, especially on the members of the n-3 PUFA family which were significantly more abundant in spring. Except for TT, RV for lipids were inversely related to the lipid content. RV for n-6 and n-3 PUFA were not affected by the season of catch.