Ultrasound, microwave and enzyme-assisted multiproduct biorefinery of Ascophyllum nodosum

Abstract

This study investigated the multiproduct (fucoidans, β-glucans, proteins, carotenoids, fatty acids, amino acids and polyphenols) valorization of the invasive macroalgae Ascophyllum nodosum within a green biorefinery concept using ultrasound (US), microwave (MW) treatment followed by supercritical CO₂ (SC-CO₂) with co-solvent and enzymatic extraction. Water and 50% aqueous ethanol were used as green extraction solvents. The extraction methods using 50% ethanol as extraction solvent improved the yields of phenolic compounds and glucan and enhanced in vitro antioxidant activity. The characterization of SC-CO₂ extracts revealed that pretreatment with US and MW improved the 2-fold yield of carotenoids, total phenolics and fatty acids. However, US/MW pretreatment and enzymatic extraction did not improve the yields of proteins and free amino acids. Overall, using concurrent green US/MW-assisted extraction methods enhanced the yields of the bioactive compounds in a short duration and provided extracts with a better antioxidant capacity in the field of food applications.

Keywords: Amino acid; Ascophyllum nodosum; Bioactive compounds; Biorefinery; Brown seaweed; Microwave; Supercritical CO(2); Ultrasound.