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Thermal and Rheological Properties of a Family of Botryosphaerans Produced by Botryosphaeria rhodina MAMB-05
Department of Physics, Chemistry and Biology, Faculty of Science and Technology, University Estadual Paulista, Presidente Prudente 19060900, Brazil
Biorefining Research Initiative, Lakehead University, Thunder Bay, ON, P7B 5E1, Canada
Department of Biochemistry and Biotechnology, CCE, State University of Londrina, Londrina 86051990, Brazil
Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba 81531990, Brazil
* Author to whom correspondence should be addressed.
Received: 12 July 2011; in revised form: 18 August 2011 / Accepted: 23 August 2011 / Published: 2 September 2011
Abstract: Differential scanning calorimetry (DSC), thermogravimetry (TG) and Fourier-transform 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.
Keywords: b-glucans; botryosphaeran; thermal analysis; FT-IR spectroscopy; rheology
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Fonseca, P.R.; Dekker, R.F.; Barbosa, A.M.; Silveira, J.L.; Vasconcelos, A.F.; Monteiro, N.K.; Aranda-Selverio, G.; Da Silva, M.L.C. Thermal and Rheological Properties of a Family of Botryosphaerans Produced by Botryosphaeria rhodina MAMB-05. Molecules 2011, 16, 7488-7501.
Fonseca PR, Dekker RF, Barbosa AM, Silveira JL, Vasconcelos AF, Monteiro NK, Aranda-Selverio G, Da Silva MLC. Thermal and Rheological Properties of a Family of Botryosphaerans Produced by Botryosphaeria rhodina MAMB-05. Molecules. 2011; 16(9):7488-7501.
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. 2011. "Thermal and Rheological Properties of a Family of Botryosphaerans Produced by Botryosphaeria rhodina MAMB-05." Molecules 16, no. 9: 7488-7501.