Characterisation of the lipid fractions obtained by proteolytic and chemical extractions from rainbow trout (Oncorhynchus mykiss) roe

Lipids from rainbow trout (Oncorhynchus mykiss) roe were extracted by chemical and enzymatic methods. Enzymatic hydrolysis by Alcalase®, Neutrase® and Protamex® yielded three fractions after centrifugation: a light phase (oil), an intermediate fraction (water-soluble material) and a residual heavy phase. Best results were obtained with Alcalase® where the roe proteins hydrolysis degree was 7.8% compared with 19% for trout fillets. The difference was explained by the particular composition of the proteins of the fish egg chorion. The yield of oil extracted after proteolysis was 3.7% vs. 9.6% by chemical technique. The polyunsaturated fatty acids (PUFAs) amount in the oil phase was high (41.8%) with 34.7% n−3 PUFA accounting for total lipids. High-concentration of PUFA was found in the polar lipid fraction of the heavy phase where docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) accounted for 25.6 and 10.9% of total lipids, respectively.