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Title: Physico-chemical characterisation of water soluble non-starch polysaccharides
Author: Wang, Qi
ISNI:       0000 0001 3560 7812
Awarding Body: University of London
Current Institution: King's College London (University of London)
Date of Award: 1998
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This thesis is concerned with the development of physico-chemical techniques to characterise the properties of water soluble non-starch polysaccharides (s-NSP). The first part of this project was to characterise the structure and solution properties of s- NSP extracted from a plant, Detarium senegalense Gmelin. The extracted s-NSP was analysed by GLC and found to be similar in structure to tamarind xyloglucan. This was confirmed by comparing the oligosaccharides released on enzymatic digestion with those obtained from tamarind xyloglucan. Histochernical examination of detariurn seed showed the presence of xyloglucan in highly thickened cell walls. The intrinsic viscosity of detariurn gum was found to be high, indicating that the sample was of high molecular weight. The semi-dilute solution characteristics investigated by steady and dynamic shear rheometry, suggest that detarium gum is a well behaved linear polymer entanglement system. Static light scattering was also successfully applied to examine the molecular weight and architecture of the detarium xyloglucan macromolecules. The physiological behaviour of s-NSP when consumed is critically dependent on their physico-chemicapl roperties,i ncluding the rate and degreeo f hydration. In the second part of the project a method for determining the hydration rate of a powdered form of s- NSP was developed. A logarithmic model for describing the hydration kinetics of guar gum was also establishedT. his model was used to investigatet he effects of polymer concentration (C), molecular weight (M), and particle size on the hydration rate of guar gum. The results showed that there was a significant inverse relationship between hydration rate and M and mean particle size, respectively. The hydration rate increased with increasingC at a low concentrationr ange,b ut decreasedw hen C>1.2% (w/w). The pH in the lumen of the gastrointestinal tract of human is acidic, usually between 2.0 and 1.5 after a meal. The stability of guar gum in acidic conditions was investigated at temperatures 25,37 and 50'C. The results indicated that there was unlikely to be significant acidic degradation of guar gum in the human gastrointes final tract. The pH condition was also found to influence the hydration rate of guar gum. In general, the hydration rate was lower in an acid environment than it was in neutral conditions
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Physical chemistry