Component analysis and utilization strategy of brown macroalgae as promising feedstock for sugar platform-based marine biorefinery

Brown algae have gained attention as a sustainable feedstock for biorefineries due to their ability to sequester carbon dioxide, rapid growth, and high carbohydrate content. The carbohydrate content in brown algae has only been analyzed for a few species, and in most cases, access to fundamental data such as sugar composition is limited, which hinders the assessment of brown algal biomass-based biorefining potential. In this study, the carbohydrate composition of brown algae ( Undaria pinnatifida , Saccharina japonica , Ecklonia cava , and Ecklonia stolonifera ) was analyzed in detail and application directions were proposed. As a result, alginate and glucan were detected in all resources, and the contents (alginate and glucan wt%) were as follows: U. pinnatifida (39.6 and 4.9 wt%), S. japonica (34.0 and 6.3 wt%), E. cava (24.3 and 7.7 wt%), and E. stolonifera (39.1 and 9.7 wt%). All feedstocks contain trace amounts (2.9–4.9 wt%) or no xylan-mannan-galactan. Mannitol was detected only in S. japonica (26.7 wt%) in rich, showing high potential as a biorefinery feedstock. We highlight that the carbohydrate composition of E. cava and E. stolonifera was analyzed for the first time and the potential use of brown algal biomass in a biorefinery approach.