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.