Mesquite gum/chitosan insoluble complexes: relationship between the water state and viscoelastic properties

AbstractThe aim of this work was to form polyelectrolyte complexes (PECs) mesquite gum (MG) and chitosan (Ch), as a function of the biopolymer mixing ratio (RMG/Ch). The water state during PECs formation was monitored as a way of assessing its effect on the viscoelastic properties. The maximum difference of zeta potential values for polyelectrolyte solutions as a function of pH was found in the range from 4.0 to 5.0. PECs were obtained with zeta potential values of ∼ |< 10 mV| between R7 – R12 at a pH of 4.5. This condition was favorable for producing high insoluble-PECs yield (92.16 ± 0.56%). The viscoelastic properties and water state assessed the insoluble-PECs interactions. The insoluble-PECs exhibited a liquid-like behavior, typical of concentrated solutions. Similar loss modulus was observed independently of the RMG/Ch. (G” ∼ 20 Pa, ω = 1 rad/s). DSC analysis showed that the water content influences the water state of insoluble-PECs. Freezing water increased exponentially with the increase of the wa...