Effect of polysaccharide chain conformation on ultrasonic degradation of curdlan in alkaline solution

• Published in: Carbohydrate polymers Vol. 195; pp. 298 - 302
• Main Authors: Cheung, Yi-Ching, Yin, Junyi, Wu, Jian-Yong
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.09.2018
• Subjects: beta-glucans; Chain conformation; Curdlan; Intrinsic viscosity; Kinetics; Molecular weight; molybdenum; sodium hydroxide; solubility; Ultrasonic degradation; ultrasonics; Chain conformation; Curdlan; Kinetics; Ultrasonic degradation; Intrinsic viscosity; Molecular weight
• ISSN: 0144-8617; 1879-1344; 1879-1344
• DOI: 10.1016/j.carbpol.2018.04.118

•Power ultrasound (US) was applied for partial degradation of curdlan in alkaline solution.•US caused conformation changes in addition to molecular weight reduction.•US degradation rate increased with the US power intensity and NaOH concentration.•Random coil was more liable to US degradation than helical conformation. This study was to investigate the effects of polysaccharide chain conformation on ultrasonic degradation of curdlan, a high MW β-glucan with wide applications. The ultrasonic degradation was performed in alkaline solution at 0.1 M and 0.3 M NaOH, in which the curdlan chain was mainly in triple helical conformation and random coil form, respectively. The degradation rate was represented by the kinetic model, 1/Mt − 1/Mo = kt, with the rate constant k increasing with the ultrasonic power. The degradation rate was much higher in 0.3 M NaOH than in 0.1 M NaOH, suggesting that curdlan in random coil conformation was more liable to degradation than in helical conformation. Curdlan in 0.1 M NaOH was changed from triple helices to single helices and eventually to random coils with a higher solubility. In summary, ultrasonic degradation of curdlan in alkaline solution had a close and complex relationship to the chain conformation changes.