Chemical and rheological characterization of the carrageenans from Hypnea musciformis (Wulfen) Lamoroux

COSENZA V.A.; NAVARRO D.A. ; FISSORE E.N.; ROJAS A.M.; STORTZ C.A.

CARBOHYDRATE POLYMERS

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2014 vol. 102 p. 780 - 789

0144-8617

This work reports a chemical and rheological study of the carrageenans from Hypnea musciformis, a red seaweed commercially known for its production of K-carrageenan. The polysaccharides were extracted with water both at room temperature and at 90 ºC: the yield of the latter was about six times as large as the former. Fractionation with KCl yielded a large proportion (50-67%) of a precipitate with 0.125M of this salt for both extracts, with characteristics of a nearly pure K-carrageenan, as determined by methylation analysis and NMR spectroscopy. Smaller amounts of fractions precipitating at higher concentrations showed a basic K-carrageenan structure,but included some i-carrageenan character. The KCl-soluble polysaccharides showed a larger complexity, containing D- and L-galactans or D/L-hybrids. Some differences in the rheological properties of these carrageenans have been found. Although all KCl precipitating polysaccharides form true gels at 10 ºC in presence of KCl, those extracted with hot water form more elastics gels than those extracted at room temperature. Both purified K-carrageenans show lower gelling and melting temperature than the whole polysaccharides from which they become.