Microwave assisted hydrothermal extraction of polysaccharides from Ulva prolifera: Functional properties and bioactivities

Sulfated polysaccharides from green tide algae Ulva prolifera were effectively extracted by microwave assisted hydrothermal extraction technology. The properties and bioactivities of polysaccharides could be controlled by extraction conditions. While rhamnose, galacturonic acid and glucose were major monosaccharides at 90°C with 0.01M HCl, glucose was the major monomer at 150°C with 0.1M HCl. Sulfur content increased with temperature and acid concentration, while molecular weight decreased with temperature and concentration. Functional property analysis showed that polysaccharides extracted from 90°C, 0.05M HCl had the best water-holding capacity (41.32g/g) and oil-holding capacity (15.09g/g), and polysaccharides extracted from 150°C, 0.05M HCl had the best foaming properties (foaming capacity 143% and foaming stability 113%, respectively). In addition, polysaccharides extracted from 150°C, 0.1M HCl exhibited higher antioxidant activity and pancreatic lipase inhibition activity. The relationship between polysaccharide compositions/molecular weight and properties/bioactivities was discussed.