Molecular weight effects on gelation and rheological properties of konjac glucomannan–xanthan mixtures

✍ Scribed by Dan Shen; Chao Wan; Shanjun Gao

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 211 KB
• Volume: 48
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/polb.21890

✦ Synopsis

Abstract

Fractions of konjac glucomannan (KGM) with various viscosity‐average molecular weights (M~v~) ranging from 4.00 × 10^5^ to 2.50 × 10^6^ were prepared by hydrolysis degradation in hydrochloride acid/ethanol. Effect of M~v~ of KGM on the critical gelation temperature (T~gel~) determined by Winter–Chambon criterion and the elasticity of KGM/xanthan mixed gels, a kind of binary gel formed by synergistic gelation, were investigated by dynamic viscoelastic measurements. It was shown that the value of T~gel~ of the gel was shifted to a higher temperature and the gel strength was enhanced when M~v~ of KGM was increased. The critical M~v~ (1.91 × 10^6^) was observed, above which the T~gel~ and elasticity of the mixed gels showed no or slight increase. It was suggested that T~gel~ and elasticity of KGM/xanthan mixed gels mainly depend on the structure of junction zones driven by the strong interaction between KGM and xanthan, which was gradually improved with increasing M~v~ of KGM. It was found that the critical strain and yield stress of the mixed gels increased monotonically with the increasing M~v~ of KGM. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 313–321, 2010