Fractionation of extracted Madagascan Gracilaria corticata polysaccharides: Structure and properties

Polysaccharides were sequentially extracted from Gracilaria corticata which is collected from south-west coast of Madagascar. Chemical analysis combined with 1H, 13C NMR and Fourier transform infrared spectroscopies showed that the fraction extracted with water/ethanol 60% (v/v) as solvent has low methoxyl and pyruvate contents and a great ability to form relatively strong physical gels in the presence of KCl. Rheological properties of extracted fractions are discussed as well as the ionic selectivity.