This thesis presents results suggesting that polymannuronate – one of two possible forms of homogeneous alginate, referred to as “polyM” – cross-links when subjected to rapid water loss during spray-drying. This insight is important since the consensus of the field is that polymannuronate does not form cross-links to any significant extent. The research supporting the conclusion that polyMs do not cross-link is typically carried out at non-dynamic conditions (i.e., steady temperatures around 25 °C, constant pressure around 1 atm, and without rapid water loss). Spray-drying conditions are quite different than these standard conditions.
Molecular dynamics studies meant to gain insight into why polymannuronate cross-links during spray-drying were performed. The results of the simulations suggest that rapid water loss increases the attraction between individual polyM chains and Ca2+ ions, between polyM chains and water, and between polyM chains and polyM chains. This increased attraction was seen up until the point of approximately 95% water loss, at which point the trend is reversed. 95% water loss matches the conditions achieved during spray-drying. Additionally, with increased water loss polyM was observed to behave more like polyguluronate – the other form of homogeneous alginate referred to as “polyG” – which is known to cross-link effectively.
The cross-linking of polymannuronate during spray-drying suggests that in forming cross-linked alginate microcapsules (CLAMs) during spray-drying, alginate composition may be a much less significant parameter than previously thought. If so, then the production of microcapsules by spray-drying may be a more cost-effective means of encapsulation than previously thought.
|Commitee:||Fan, Zhiliang, Upadhyaya, Shrinivasa|
|School:||University of California, Davis|
|Department:||Biological Systems Engineering|
|School Location:||United States -- California|
|Source:||MAI 81/4(E), Masters Abstracts International|
|Keywords:||alginate, cross-linking, molecular dynamics, polymannuronate|
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