The effects of temperature, pH, and cations on the rheological properties of the extracellular polysaccharides of medicinal species of genus Tremella Pers. (Heterobasidiomycetes)

Proma Khondkar, Kofi E. Aidoo, Richard F. Tester

Research output: Contribution to journalArticle

Abstract

Extracellular polysaccharides were produced from nine Tremella species using the malt-yeast (MY) media. The rheological properties of the polysaccharide solution were examined by the Power-law model. The extracellular polysaccharide solutions showed shear-thinning (pseudoplastic) behavior. The pseudoplasticity was more pronounced for 5% polysaccharide solutions. T. cinnabarina and T. indecorata polysaccharide solutions (0.1% w/v) gave the highest and lowest viscosities—9.18 and 1.73 mPa, respectively—at 25°C and at a shear rate of 150 s-1. The effects of chemical and physical factors on solution viscosity were studied. The viscosity of solutions decreased with an increase in temperature and also at extreme pH values. Rheological analysis revealed that divalent cations (calcium and zinc) did not increase the viscosity of polysaccharides, but monovalent cations (sodium and potassium) did, which suggests that ionic bridging occurred between polymer chains. A synergistic increase in the viscosity of the solution was observed when the polysaccharides were mixed with xanthan.

Original languageEnglish
Pages (from-to)73-85
Number of pages13
JournalInternational Journal for Medicinal Mushrooms
Volume12
Issue number1
DOIs
Publication statusPublished - 1 Jan 2010

Keywords

  • extracellular polysaccharides
  • fungi
  • Tremella

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