Ultrasonic degradation kinetics and rheological profiles of a food polysaccharide (konjac glucomannan) in water

By Jing Li, Bin Li, Ping Geng, A. Song, Jian-yong Wu. 2017

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Abstract This study was carried out to evaluate the effects of power ultrasound (US) on the molecular weight and rheological properties of a food polysaccharide, konjac glucomannan (KGM). Upon the exposure of KGM solution (1% w/v in water) to US at a relatively high power intensity (50 W/cm 2 ), the apparent viscosity decreased rapidly from about 50 Pa s to a negligible level within 10–20 min. The intrinsic viscosity ([η]) of KGM solution decreased gradually during the US exposure with a time course closely fitted to the first-order polymer degradation kinetics (random chain scission). The US treatment also caused a significant reduction of particle size (Z avg ) of KGM aggregates and changes in the rheological properties including the decrease of storage modulus (G′) and loss modulus (G″), and the increase in phase angle (tan δ = G″/G′). Nevertheless, no change in primary structure was detected by Fourier transformation infrared (FT-IR) analysis. The results suggested that high intensity US was an effective means for KGM degradation without significant structural destruction.

Subfields: Biomaterials, Food Science, Plant Science

View Paper: https://www.semanticscholar.org/paper/211ae799686042c0dc04b5f4e0f4b9d24f58af74