Fucoidan, a sulfated polysaccharide from brown algae, exhibits a wide range of biological activities that depend on its chemical structure and are closely correlated with the extraction technique used. The conventional extraction technique (CE) is time consuming and requires high temperatures, so the use of advanced extraction techniques is a promising alternative. The aim of this study was to extract polysaccharides from the brown algae Fucus virsoides and Cystoseira barbata using 5 different extraction techniques (CE, microwave-assisted extraction (MAE), pressurised liquid extraction (PLE), ultrasound-assisted extraction (UAE), and non-thermal plasma (NTP)) under previously defined optimal conditions. The influence of these techniques on polysaccharide yield (%PS), chemical structure (fucose, sulfate groups, uronic acids), molecular properties (weight average molecular weight (Mw), number average molecular weight (Mn), polydispersity index (PDI)) and antioxidant capacity (ORAC) was studied
The highest %PS for both algae was obtained with PLE and the lowest with NTP. The highest antioxidant capacity was obtained with MAE, while UAE had the highest Mw and, together with NTP, the highest sulfate group content and the lowest concentration of uronic acids. The application of PLE and MAE reduced the extraction time from 3 hours to 30 minutes.