LAUSR

Abstract Herein, deep eutectic solvent combined with subcritical water extraction of seaweed polysaccharides were investigated from Saccharina japonica. In this regard, a deep eutectic solvent was added with sufficient amount of water and it was used as an extraction medium. To optimize, a Box–Behnken design was used to study the influences of the temperature (100 °C–150 °C), pressure (10–50 bar), water content (50%–70%), and liquid/solid (L/S) ratio (30–50 mL/g). The optimal conditions were 150 °C, 19.85 bar, and 70% water content, and L/S ratio of 36.81 mL/g showed a high yield of alginate (28.12%) and fucoidan (14.93%). FTIR, TGA, and DSC measurements confirmed that the extracted polysaccharides had the features of alginate and fucoidan. 1H NMR data revealed that extracted alginate had an M/G ratio of 4.5 and η