Structure impact of two galactomannan fractions on their viscosity properties in dilute solution, unperturbed state and gel state

Int J Biol Macromol. 2017 Mar:96:550-559. doi: 10.1016/j.ijbiomac.2016.12.057. Epub 2016 Dec 26.

Abstract

Two fractions of carob galactomannans (GM25 and GM80) were extracted at respectively 25°C and 80°C from crude locust bean gum. Those fractions having slightly different chemical structures, previously characterized, were studied for their viscosity properties over a wide range of concentrations: diluted solution, unperturbed state and gel state. For each of the physical properties, links to the chemical fine structure could be established, expanding knowledge on the topic: in dilute solution, GM25 is more soluble in water while GM80 seems to tend to self-association due to its structure as highlighted by intrinsic viscosity measurements ([η]GM25=9.96dLg-1 and [η]GM80=4.04dLg-1). In unperturbed state, initial viscosities η0 were more important for GM80 fractions at 1% and 2% due to greater hyperentanglements (η0(GM80,1%)=9.9Pas; η0(GM80,2%)=832.0; Pa.s η0(GM25,1%)=3.1Pas; η0(GM25,2%)=45.1Pas). In gel state, hydrogels obtained from GM80 were also stronger (hardness GM80 (2%)=0.51N and hardness GM25 (2%)=0.11N), suggesting a much more important number of junction areas within the gel network. The findings discussed herein demonstrate the potential for new applications.

Keywords: Galactomannans; Rheology; Structure; Viscosity.

MeSH terms

  • Galactans / chemistry
  • Galactose / analogs & derivatives
  • Gels
  • Mannans / chemistry*
  • Plant Gums / chemistry
  • Solutions
  • Structure-Activity Relationship
  • Temperature
  • Viscosity

Substances

  • Galactans
  • Gels
  • Mannans
  • Plant Gums
  • Solutions
  • galactomannan
  • locust bean gum
  • Galactose