The present study was designed to assess the effect of local canning process and storage time (up to 6 months) on tuna and sardine canned in olive oil and tomato sauce, respectively. The canning process affected tuna (P < 0.05) but not sardine lipid levels. Canned tuna and sardine absorbed coating oil during sterilization, inducing a higher oleic (C18:1 w9) and linoleic (C18:2 w6) acid content. Independent of fish species, the eicosapentaenoic (C20:5 w3) and docosahexaenoic (C22:6 w3) acid concentrations ranged from 2.96-6.24% and from 5.16-40.26%, respectively. The peroxide value and thiobarbituric acid index increased significantly in tuna but not in sardine flesh following the cooking step. The histamine levels increased significantly (P < 0.05) during storage but remained lower than the threshold limits. Although tuna and sardine flesh were slightly affected by the canning process, they remained good sources of w3 and w6 fatty acids. PRACTICAL APPLICATIONSIn the present study, we investigate the changes of the lipid fraction quality (fatty acids composition, peroxide value and thiobarbituric acid index) and histamine during processing and storage of two different fish species (tuna and sardine) processed during the same period. This would allow for the 3 Corresponding

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Changes in biochemical and microbiological quality of silverside during two drying process were investigated. Total fatty acid and amino acid contents in silverside were 5.42 and 10.9 g 100 g )1 fresh sample, respectively, in which, palmitic acid and glutamic acid were the most abundant. N-3 and n-6 polyunsaturated fatty acids (PUFA) levels were 0.59 and 0.62 g 100 g )1 fresh silverside respectively. After hot air and solar drying treatments, Peroxide value and thiobarbituric acid reactive substances of the total lipids increased significantly (P < 0.05) to reach 2.58 and 3.41 meq active O 2 kg )1 oil and 0.87 and 1.27 mg MA kg )1 oil, respectively. Fatty acid profile of non-polar lipid remains unchanged during experimental drying process. However, PUFA (% of total fatty acids) of polar lipid decreased significantly (P < 0.05) during both drying process with lower levels in solar drying process. Drying conditions had a significant effect on the microbiological quality. Therefore, mesophiles and total coliforms increased within drying treatment with higher counts in solar drying process.

Little tuna (Euthynnus alletteratus) is an important Mediterranean commercial fish species. In this study, the lipids of tuna filet, head, viscera, liver, and gonads fished in Tunisian waters were examined in summer and winter. Total lipid content in most organs showed a significant variation due to seasonal change. The highest lipid content was found in head in little tuna fished in winter and summer (14.2%). The lowest levels were attributed to gonads (1.5%). The major fatty acids classes were polyunsaturated fatty acids (PUFA) followed by saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). The lowest percentage of (MUFA) was recorded in winter season (9.77%). In summer, the proportion of PUFA decreased while that of SFA increased. The major contributing factor to the seasonal change of PUFA was n-3 fatty acids especially eicosapentaenoic acid (EPA) and docosahexaenoic (DHA). The lowest levels of PUFA/SFA were registered in summer. Little tuna by-products are an adequate raw material for fish oil production and excellent sources of n-3 fatty acids, the highest levels of PUFA were found during winter.

The seasonal lipid variation and fatty acids compositions were assessed in white and red muscles, head, viscera, liver and gonads of little tuna Euthynnus alletteratus. Lipid contents showed a significant variation (P < 0.05) throughout the year, the maximum level was found in the liver during winter season (27.28 g/100 g). The lowest fat contents were found in gonads during the winter and spring seasons, with levels of 1.56 and 1.49 g/100 g, respectively. White and red muscle fat levels increased significantly from winter to summer; viscera lipids, however, showed a significant decrease during the same period. Generally, the increase of the polyunsaturated fatty acids percentage in most organs was usually accompanied with a decrease of saturated fatty acids. It was shown that lipid content was higher in the head and liver compared to other compartments, and the fatty acid composition in the different organs of little tuna was significantly influenced by spawning and season. All lipids extracted contained significant amounts of docosahexaenoic acid and eicosapentaeneoic acid, which have various physiological functions. PRACTICAL APPLICATIONS Most of the available literature showed little information about biochemical composition of fillets and by‐products of some fish species and are, therefore, not complete for industrial purposes as application in food or feed nutriment. The practical application of this study was performed by the determination of fatty acids levels of little tuna fillets (white and red muscles) and by‐products (head, viscera, liver and gonads) to further explain the evolution of lipid and fatty acids throughout the year. Finally, this manuscript may provide some valuable information for other scientists working in the field of food technology.