Abstract
The red seaweeds Gelidiella acerosa and Gracilaria mammillaris growing along the coast of Venezuela were investigated as potential economic sources of agar. Agar extracted from Gracilaria mammillaris accounted for 27% of the algal dry weight but had quite a poor gelling ability because of the presence of alkali-stable sulphate groups on the D-galactose residue. However, the gel strength of its aqueous solutions was considerably enhanced by the addition of potassium, sodium and calcium ions (up to 1N). On the contrary, the galactan from Gelidiella acerosa (yield of about 20% w/w) exhibited quite good properties. In particular, the gel strength was comparable to that of commercial agaroses. Sulphate esters were not detectable by chemical methods and NMR spectroscopy revealed an agarose backbone with a high degree of methylation on both D and L-galactose residues.
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Murano, E., Toffanin, R., Pedersini, C. et al. Structure and properties of agar from two unexploited agarophytes from Venezuela. Hydrobiologia 326, 497–500 (1996). https://doi.org/10.1007/BF00047851
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DOI: https://doi.org/10.1007/BF00047851