CHARACTERIZING SEMIREFINED IOTA-CARRAGEENAN NETWORKS BY ATOMIC-FORCE MICROSCOPY

Samples of PNG iota carrageenan have been studied by X-ray diffraction and Atomic Force Microscopy (AFM). Aqueous preparations of PNG iota c arrageenan can be fractionated into water soluble and water insoluble components. The water soluble component is largely composed of iota ca rrageenan containing small amounts of cellulose. AFM studies reveal th at this component forms network structures very similar to those obtai ned for refined iota carrageenan. Some swollen cellulosic networks wer e observed in the PNG samples. The water insoluble fraction has been s hown to be predominately partially crystalline cellulose I. AFM reveal s that the cellulose is present as a fibrous network similar to that f ound for bacterial cellulose or the cellulosic component of plant cell walls. In the PNG samples the lateral ordering of the cellulose micro fibrils has been disrupted presumably during the extraction of the PNG carrageenan from the seaweed. The AFM imaging conditions used to stud y the insoluble component would not permit imaging of any iota carrage enan networks which may be present in this sample. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.