INVESTIGATION OF THE CARRAGEENANS EXTRACTED FROM SOLIEIRA-FILIFORMIS AND AGARDHIELLA-SUBULATA FROM MAR-PICCOLO, TARANTO

Dried samples of the red algae Solieria filiformis and Agardhiella sub ulata from Mar Piccolo, Taranto, were extracted by stirring in water a t 25 (Cold), 85 (Hot) and 120 (pressure) degrees C. For each species, six successive cold, three hot and two pressure extractions were perfo rmed and analyzed separately. Water-soluble polysaccharides were isola ted after treatment with amylase, alcohol precipitation, dialysis and freeze drying. The total, starch-free yields were 27 and 24% of the dr y weight for S. filiformis (SF) and A. subulata (AS), respectively. FT IR and NMR spectroscopic analysis showed that the different cold and h ot water extracts had a similar structural backbone, which can be char acteristic of gelling type carrageenans with a dominant iota repeating structure (DA2S-G4S). However, some irregularities were detected by N MR, which may be attributed to 6-sulphated 4-linked precursor units. T he occurrence of such and other irregularities was more frequent in th e SF samples, giving a possible explanation for the enhanced extractab ility in cold water of carrageenan polymers from this species. (C) 199 7 Elsevier Science B.V.