Assessment the Potential of Supercritical Carbon Dioxide on Extraction of Oil from Tuna By-products and Comparison with Wet Pressing Method

Fish oil is one of the most valuable marine products. It is used as unrefined oil in animal, poultry and aquatic organisms feed. Also, fish oil has high amount of Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) and can be used as a food supplement by human. The purpose of this project was oil extraction by supercritical fluid extraction (SFE) and wet pressing (WP) methods from by-products of canned tuna factories. Yield (%) and quality of obtained oil were studied (with focus on human consumption). For this aim, extracted oil from raw materials were evaluated to determine different indices, formed compounds as results of lipid peroxidation and pollutant content based on toxic metals. Yield (%) and moisture content of oils did not show significant different in both methods. Some of volatile components such as aldehydes were detected in WP method and the number of detected alkanes in WP treatment was higher than SFE. On the contrary, acetic acid as a non-lipid acid was detected in SFE treatment. DMA as responsible for the highest level of fishy odor was detected in SFE and WP. Neutral lipids (such as wax esters, TAG, FFA and CHOL) and acidity value did not show significant different between treatments. The amount of DHA in fatty acids profile was higher in SFE methods in comparison with WP. Also, the amounts of toxic metals such as Hg, As, Cd and Pb in SFE treatment were significantly lower than WP. Thus, the results of this study showed tuna by-products have appropriate potential to extract oil for human consumption and SFE is a good process to extract it.