Screening for synergistic interactions in dilute polysaccharide solutions

Goycoolea, F.M., Morris, E.R. and Gidley, M.J. (1995) Screening for synergistic interactions in dilute polysaccharide solutions. Carbohydrate Polymers, 28 4: 351-358. doi:10.1016/0144-8617(95)00098-4


Author Goycoolea, F.M.
Morris, E.R.
Gidley, M.J.
Title Screening for synergistic interactions in dilute polysaccharide solutions
Journal name Carbohydrate Polymers   Check publisher's open access policy
ISSN 0144-8617
1879-1344
Publication date 1995-12
Sub-type Article (original research)
DOI 10.1016/0144-8617(95)00098-4
Volume 28
Issue 4
Start page 351
End page 358
Total pages 8
Place of publication Oxford, United Kingdom
Publisher Pergamon
Language eng
Formatted abstract
A simple viscometric approach has been used to screen for binding interactions between different polysaccharides in very dilute solution where exclusion effects should be negligible. The method involves preparing stock solutions to approximately the same, low, viscosity (ηsp≈1), dialysing to identical ionic conditions, mixing in various proportions, and looking for departures from the initial common viscosity. Mixtures of xanthan or de-acetylated xanthan with locust bean gum (LBG) or konjac glucomannan (KM) show massive enhancement of viscosity, as anticipated from the formation of synergistic gels at higher concentrations. However, no viscosity changes on mixing with LBG or KM were observed for other conformationally ordered bacterial polysaccharides (welan and rhamsan) or for alginate and pectin with sufficient Ca2+ to induce almost complete conversion to the dimeric 'egg box' form, demonstrating that conformational rigidity is not, in itself, sufficient for other polysaccharides to form heterotypic junctions with mannan or glucomannan chains. Interactions of carrageenans with LBG appear to depend on both conformation and the extent of aggregation. Mixtures of LBG with K+ kappa carrageenan in 100mM KCl (which is known to promote extensive aggregation of double helices) gave erratic values for rotational viscosity and showed typical gel-like mechanical spectra under low-amplitude oscillation. Disordered carrageenans (K+ kappa in water and lambda in 100mM KCl) showed no evidence of interaction with LBG. Negative results were also obtained for iota carrageenan under ionic conditions believed to promote ordering without significant aggregation (100mM KCl). However, under conditions where limited aggregation might be expected (iota carrageenan in 90 mM CaCl2; Me4N+ kappa carrageenan in 150 mM Me4NI), significant reductions in viscosity were observed on mixing with LBG, which may indicate some intermolecular association but without the formation of an extended network structure.
Keyword Kappa carrageenan
Pectins
Model
Conformation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Nutrition and Food Sciences Publications
 
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Created: Wed, 16 Mar 2011, 20:34:26 EST