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- Title
Thermal and Rheological Properties of a Family of Botryosphaerans Produced by Botryosphaeria rhodina MAMB-05.
- Authors
Fonseca, Paulo R. M. S.; Dekker, Robert F. H.; Barbosa, Aneli M.; Silveira, Joana L. M.; Vasconcelos, Ana F. D.; Monteiro, Nilson K.; Aranda-Selverio, Gabriel; da Silva, Maria de Lourdes Corradi
- Abstract
Differential scanning calorimetry (DSC), thermogravimetry (TG) and Fouriertransform infra-red spectroscopy (FT-IR) analyses were performed to investigate changes in the physico-chemical properties of botryosphaerans, a family of exopolysaccharides (EPS) produced by the fungus Botryosphaeria rhodina MAMB-05 grown on glucose (EPSGLC), sucrose (EPSSUC) and fructose (EPSFRU). A slight endothermic transition and small mass loss attributable to the removal of water of hydration were observed in the DSC and TG analyses, respectively, for the three EPS samples. The FT-IR spectra confirmed no structural changes occurred during thermal treatment. Viscometry was utilized to obtain information on the rheological behaviour of the EPS in aqueous solutions. The Power Law and Cross Equations determined the natural pseudoplastic characteristics of the EPS. Comparatively, results obtained for EPS produced when B. rhodina MAMB-05 was grown on each of the three carbohydrate sources demonstrated similar apparent viscosity values for EPSGLC and EPSSUC, while EPSFRU displayed the lowest apparent viscosity of the three botryosphaerans, suggesting a higher degree of ramification and lower Mw. EPSGLC and EPSSUC possessed similar degrees of ramification. The slight differences found in their viscosities can be explained by the differences in the type of branching among the three botryosphaerans, thus varying the strength of intermolecular interactions and consequently, consistency and viscosity. The physico-chemical studies of botryosphaerans represent the originality of this work, and the knowledge of these properties is an important criterion for potential applications.
- Subjects
BOTRYOSPHAERIA; CALORIMETRY; THERMOGRAVIMETRY; INFRARED spectroscopy; MICROBIAL exopolysaccharides
- Publication
Molecules, 2011, Vol 16, Issue 9, p7488
- ISSN
1420-3049
- Publication type
Article
- DOI
10.3390/molecules16097488