Supercritical Extraction of Omega-3 Rich Oil from Trout Waste

In this paper the extraction of oils from trout waste is investigated. Trout heads, viscera and spine, obtained from a fish-processing company, have been separately freeze-dried and then extracted. Two different solvent extraction techniques have been utilized and compared: the common soxhlet extraction, which utilizes n-hexane at atmospheric pressure as solvent, and the supercritical CO2 extraction. To maximize the solubility of the oil into the solvent, the supercritical extraction tests have been conducted at 500 bar and 60 °C. During the supercritical extraction, the collected oil has been sequentially separated into several fractions, in order to verify possible variations in composition for the same fractions. The results are the following: 1) for each substrate the oil yield was significantly higher by using supercritical extraction than via soxhlet apparatus. 2) The fatty acid profile was similar for the various substrates (which were mainly constituted by TAGs) and practically independent on the extraction technique utilized, but crude oil obtained from viscera contains significant amount (13%) of DAGs and FFA. 3) The fatty acid profile testified an important presence of the most important omega-3 fatty acids (DHA and EPA) in the oil from fish waste (comparable with their amount in the oil from fresh fish filet). 4) Presence of lipids with omega-1 polyunsaturated fatty chains was observed in all the samples, although in low relative amount (about 3%) 5) The composition of the oil showed a slight dependence on the extraction time: for instance, the last oil fractions contained more DHA than the first fractions. Actually, the differences in compositions are small and therefore fractionating in this way did not result very effective.