GELLING-GALACTANS FROM THE ALGAL COMMUNITY OF FURCELLARIA-LUMBRICALISAND COCCOTYLUS-TRUNCATUS (THE BALTIC SEA, ESTONIA) - A STRUCTURE-PROPERTY STUDY

Extraction of Furcellaria lumbricalis by potassium hydroxide solution shows that the maximum gel strength of polysaccharides separated is at tained by extraction at concentration 0.16 M KOH. Crude extract from t his algal species has a complicated monosaccharide composition; a dras tic increase of gel strength by alkaline extraction of the polysacchar ide mixture cannot be explained through the composition of a major (ka ppa) fraction described earlier. Alkaline treatment is also suitable f or accelerating the extraction of polysaccharides from Coccotylus trun catus overlaid with thick epithelium. Viscous galactans from C. trunca tus are more stable to alkali, their composition is simpler and close to iota carrageenan. The formation of mixed kappa and iota carrageenan gels as a result of simultaneous extraction of both seaweeds causes l evelling of rheological properties of different extraction fractions. (C) 1997 Elsevier Science B.V.