Enzymatic hydrolysis of farmed Atlantic salmon by-products: Investigation of operational parameters on extracted oil yield and quality

Six operational parameters (fish part, antioxidant addition, water addition, enzyme species, enzyme concentration and hydrolysis time) were studied for their effect on yield and quality of enzymatically extracted oil from farmed Atlantic salmon by-products. The highest oil yield of 26.0% (93.6% recovery) was obtained from salmon viscera using 1% Flavourzyme for 2 h without addition of water or the antioxidant. Averagely, salmon viscera produced more oil compared to mixture of salmon heads and frames. However, viscera oil had higher levels of oxidation and hydrolysis, indicating inferior quality. The use of Alcalase resulted in the highest oil quality compared to Flavourzyme and SEBPro, due to less oil oxidation and free fatty acids in the alkaline environment using Alcalase (pH 8). The enzyme concentration studied (0.1 and 1%) didn?t have any significant effect on oil yield or oxidation. At 1% enzyme concentration, the oil extracted from 4 h hydrolysis had higher levels of oxidation but lower level of free fatty acids compared to the oil extracted from 2 h hydrolysis. Addition of water significantly decreased both oil yield and quality. The use of antioxidant (0.15%) didn?t affect oil yield but significantly inhibited oil oxidation.