The effect of autoclaving on the dispersibility and stability of three neutral polysaccharides in dilute aqueous solutions
2001
Wang, Q. | Wood, P.J. | Cui, W. | Ross-Murphy, S.B.
The dispersibility of three neutral polysaccharides, oat beta-glucan, detarium xyloglucan and dextran in a dilute water-cadoxen mixture was studied by viscosity measurement. It was found that intrinsic viscosity measurement, with water-cadoxen mixtures as solvents, is a useful tool to distinguish polymer degradation from disruption of supramolecular aggregates. This approach, in conjunction with size exclusion chromatography, was used to study the effects of heat and pressure treatment on the dispersibility and stability of three polysaccharides in aqueous solutions. Autoclaving treatment at 121 degrees C for 15 min may reduce the degree of aggregation. Following autoclaving in aqueous solution, the Huggins constants decreased from 0.66 to 0.42 for oat beta-glucan and from 0.63 to 0.56 for detarium xyloglucan. It remains the same for dextran, indicating good solubility of this polymer in water. The current treatment did not cause evident changes in molecular weight and structures to detarium xyloglucan and dextran. However, degradation occurred with oat beta-glucan. The Burchard-Stockmayer-Fixman approach was applied to estimate the unperturbed dimension of oat beta-glucan and detarium xyloglucan on samples after autoclaving. The characteristic ratio C(infinity) was found to be 7.3 for detarium xyloglucan and 4.7 for oat beta-glucan, corresponding to the Kratky-Porod persistence lengths of 2.0 and 1.2 nm, respectively.
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