Enhanced extraction and antioxidant potential of astaxanthin from crawfish and shrimp byproducts using ultrasound-assisted extraction with flaxseed oil

Abstract

Crawfish and shrimp byproducts (CB and SB) are rich in bioactive compounds like astaxanthin (AX), an antioxidant with applications in the food industry. This study extracted AX from CB and SB using flaxseed oil (FO) as the solvent, comparing conventional extraction with closed-continuous-ultrasound-assisted extraction (UAE). SB and CB were collected, frozen, and analyzed for proximate composition and total extractable AX content. Based on AX content, only CB were selected for UAE. For conventional extraction, freeze-thawed or freeze-dried CB were heated with FO at 60 °C for 60 min. UAE was conducted with freeze-dried CB using a 1:8 blend of FO and ethanol, pumped through a closed continuous system, and sonicated for 20 min. Physicochemical properties, AX content, and oxidative stability were assessed for conventionally extracted AX from SB-(FOSBAX), CB-(FOCBAX), and UAE-processed CB-(FOCBAXUAE). Results showed FOCBAXUAE using 25 g CB and 25 g FO achieved a significantly higher concentration of AX, 1.9 mg AX g⁻¹ FO from freeze-dried CB, compared to FOCBAX and FOSBAX, 0.092 mg AX g⁻¹ FO and 0.054 mg AX g⁻¹ FO, a 20.6- and 35.1-fold increase, respectively (P < 0.05). FOCBAXUAE exhibited superior color properties, lower moisture content (0.15 %), and enhanced oxidative stability, with the lowest peroxide value (0.56 mEqO₂/kg) and free fatty acid content (1.96 %). Additionally, FOCBAXUAE had the highest DPPH• scavenging activity (85.85 %). In conclusion, UAE combined with ethanol and FO in a closed continuous system was highly effective in enhancing AX extraction and improving oxidative stability. Using freeze-dried CB in UAE yielded the highest antioxidant capacity, demonstrating the potential of this method for value-added utilization of CB.