Comparison of oil yield and quality obtained by different extraction procedures from salmon (Salmo salar) processing byproducts

The content and composition of lipids in different byproducts (skins, heads, and backbones) from mechanically processed farmed Atlantic salmon were determined and compared with that obtained from wild salmon. Three different procedures were used to establish the optimal conditions of oil extraction (at high temperature -95 degrees C, cold extraction at temperature not exceeding 15 degrees C and enzyme assisted with Alcalase). Cold extraction at temperature not exceeding 15 degrees C was very efficient, yielding almost 95% of the oil from skins. In the case of heads the obtained yield of about 71% was not lower than that from extraction performed at 95 degrees C or extraction supported by enzyme treatment. The peroxide value of oil isolated from the heads using cold extraction was at the same level as in oil of the enzyme assisted process, but four times lower than in oil extracted at high temperature. The results showed that the content of lipids from in the farmed salmon byproducts the content of lipids was about 45-55% higher than in byproducts of wild salmon, however the EPA+DHA content was 10-33% lower. Practical applications: With cold extraction heating which is commonly used for oil recovery in the fish industry could be eliminated and thus the cost of the process would be lower and oxidative changes in the oil reduced. Furthermore, this method based on rules of green chemistry can be more attractive and alternative procedure of oil isolation from fatty fish byproducts than those using organic solvents. The fatty fish byproducts such as heads, skins, and backbones may be used as a source of valuable oils rich in PUFA. The remaining material after oil isolation can be a source of collagen and gelatin used in the food, pharmaceutical, and cosmetic industries and finally of minerals preparation (in the case of heads and backbones) used for enriching animal feed.