National Committee on Marine Sciences (NCMS)

Browse

Now showing 1 - 1 of 1

Highly methylated agar from Gracilaria edulis (Gracilariales, Rhodophyta)
Villanueva, Ronald; Montaño, Nemesio (Springer, 1999-04)
The structure and gelling properties of alkali-modified agar from Gracilaria edulis were investigated. 1H and 13C NMR experiments revealed a basic repeating unit of alternating 3-linked 6- O-methyl-β-D-galactopyranose and 4-linked 3,6-anhydro-α-L-galactopyranose. Partial methylation at O-2 of the anhydrogalactose moiety was also revealed. Meanwhile, the O-4 of the methylated galactose residue was detected to exhibit partial sulfation by NMR and FT-IR spectroscopy. The gel strength and syneresis index of the extracted agar were considerably enhanced by the addition of sodium, potassium, and calcium ions. The ion-driven gelation and peculiar sulfate position conferred the agar's similarity to κ-carrageenan.