Extraction of Omega-3 Fatty Acids from Atlantic Sea Cucumber (Cucumaria frondosa) Viscera Using Supercritical Carbon Dioxide

Abstract

This study explores the potential of Cucumaria frondosa (C. frondosa) viscera as a natural source of omega-3 FAs using supercritical carbon dioxide (scCO₂) extraction. The extraction conditions were optimized using a response surface design, and the optimal parameters were identified as 75 °C and 45 MPa, with a 20 min static and a 30 min dynamic extraction, and a 2:1 ethanol to feedstock mass ratio. Under these conditions, the scCO₂ extraction yielded higher FAs than the solvent-based Bligh and Dyer method. The comparative analysis demonstrated that scCO₂ extraction (16.30 g of FAs/100 g of dried samples) yielded more fatty acids than the conventional Bligh and Dyer method (9.02 g, or 13.59 g of FAs/100 g of dried samples with ultrasonic assistance), indicating that scCO₂ extraction is a viable, green alternative to traditional solvent-based techniques for recovering fatty acids. The pre-treatment effects, including drying methods and ethanol-soaking, were investigated. Freeze-drying significantly enhanced FA yields to almost 100% recovery, while ethanol-soaked viscera tripled the FA yields compared to fresh samples, achieving similar EPA and DHA levels to hot-air-dried samples. These findings highlight the potential of sea cucumber viscera as an efficient source of omega-3 FA extraction and offer an alternative to traditional extraction procedures.

Keywords: Cucumaria frondosa; ethanol-soaking pre-treatment; green extraction; omega-3 fatty acids; sea cucumber by-products; supercritical carbon dioxide; supercritical fluid extraction.

Figure 1

The structure of sea cucumber, C. frondosa (fresh sea cucumber entirety and dehydrated parts). Adapted from Hossain et al. (2020) [3]; the pictures of dehydrated parts were taken on samples provided by AKSO Marine Biotech Inc. (Hacketts Cove, NS, Canada).

Figure 2

Contour plots for FA yields (g/100 g of feedstock on a dry weight basis) from scCO₂ extraction of hot-air-dried C. frondosa viscera. Non-targeted variables were maintained at their median values, with the temperature at 55 °C, pressure at 35 MPa, dynamic extraction time at 50 min, and the co-solvent/feedstock mass ratio at 1.

Figure 3

Contour plots for the selected omega-3 FA yields (g/100 g of feedstock on a dry weight basis) from scCO₂ extraction of hot-air-dried C. frondosa viscera. Non-targeted variables were maintained at their median values, with the temperature at 55 °C, pressure at 35 MPa, dynamic extraction time at 50 min, and the co-solvent/feedstock mass ratio at 1.

Figure 4

SEM images of hot-air-dried C. frondosa viscera (a) before and (b) after scCO₂ extraction under the optimal conditions and freeze-dried viscera (c) before and (d) after extraction under the optimal conditions.