Extraction of lipids and astaxanthin from crustacean by-products: A review on supercritical CO2 extraction

Background: Crustacean by-products are potentially a source of high-value carotenoids and lipids for use in the pharmaceutical, cosmetic, food industries, and biomaterials. Traditionally, carotenoids and lipids are extracted using energy/waste intensive processes, which can degrade the product and/or by-products, are difficult to scale up, and/or operationally complex. The development of "green" valorization processes has made recovery of bioactive compounds from shrimp processing by-products feasible. Scope and approach: In this review we outline the advances in the field of value-added carotenoid and lipid recovery from shrimp and other crustacean processing by-product with a particular focus on supercritical CO2. The pros and cons of the various processes are summarized and compared. Studies related to optimization of supercritical extraction are outlined in more detail. Key findings and conclusions: Overall, supercritical extraction using CO2 and co-solvents has the potential to increase both polar and non-polar lipid/carotenoid recovery without the negative environmental and economic disadvantages associated with traditional extraction methods. There are particular advantages using edible oils as green co-solvent in supercritical CO2 extraction as an alternative to organic co-solvents. However, there is still significant study required determining the range of ratios of solvents, developing batch extractive processes into continuous processes, balancing operating conditions (e.g. costs) with product purity, and scale-up for larger scale production.