Supercritical Carbon Dioxide Extraction of Fatty Acids from Atlantic Sea Cucumber (Cucumaria frondosa) Viscera

Abstract

Omega-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), play important roles in human health. Omega-3 PUFAs-enriched nutraceuticals are highly recommended as supplements for daily diets. Currently, EPA and DHA are mainly obtained from fish and its processing by-products through extraction and fractionation. Besides those traditional sources, some marine organisms’ by-products, like see cucumber (Cucumaria frondosa) viscera, also exhibit potential as natural supplies of Omega-3 PUFAs. Supercritical carbon dioxide (scCO2) extraction technique has attracted increasing interests as a promising green technology for lipids extraction from marine organisms for biofuel production or pharmaceutical development. In order to establish a clean and efficient recovery process, this study applied scCO2 extraction to extract lipids from Cucumaria frondosa viscera. Through a response surface design, the extraction process variables, such as temperature (35-75 ˚C), pressure (20-50 MPa), dynamic extraction time (30-70 min), and co-solvents to biomass ratio (0:1-2:1), were evaluated and optimized to obtain the highest yields of EPA and DHA in the extracted product. Temperature of 75 ˚C, pressure of 45 MPa, dynamic extraction time of 30 min, and mass ratio of co-solvent to biomass as 2:1 was determined as the optimal levels, achieving 88% of fatty acids recovery and 80 % of combined EPA and DHA recovery in comparison to maximum contents obtained in in-situ transesterification. The effect of pre-treatment methods (hot air drying and freeze drying) on lipid extraction yield was also investigated. It was found the freeze-dried samples yielded significantly more fatty acids but insignificantly different selected Omega-3 fatty acids. However, the cost and energy consumption of freeze drying equipment and the statistically insignificant difference of Omega-3 fatty acids yields still suggested it was not necessary to switch to commercial freeze dryers for fatty acids extraction at the industrial level.