Step by step extraction of bio-actives from the brown seaweeds, Carpophyllum flexuosum, Carpophyllum plumosum, Ecklonia radiata and Undaria pinnatifida

Abstract The biorefinery concept is a framework to address the concerns raised by single product extraction from renewable resources. Whereas single product extraction can involve high costs and generate large amounts of waste, the biorefinery process aims to fully utilise the biomass to produce multiple products and energy together. In this study, the step-by-step extraction of pigments, mannitol, phlorotannins, carbohydrates, alginates and residual seaweed from four species of brown seaweeds Carpophyllum flexuosum, Carpophyllum plumosum, Ecklonia radiata and Undaria pinnatifida was investigated. The yields, calculated based on algal dry weight of each product in each species of seaweed, were between 3.4 and 9.8% (pigments), 22.2–30.7% (mannitol), 0.1–5.1% (phlorotannins), 5.2–15.5% (alginates), 12.2–18.5% (other carbohydrates) and 13.5–19.5% (residual seaweed). The characterisation of each product fraction was performed and their potential applications are discussed. The results indicate that brown seaweeds are potential candidates for a biorefinery process to produce both value-added bio-materials and bio-energy.