Effects of Salts on Crystallization Kinetics and Rheological Behavior of Concentrated α,α-Trehalose Solutions

Abstract

The effect of addition of CaCl2 · 2H2O and MgCl2 · 6H2O on crystallization kinetics and the rheological behavior of a 70% trehalose solution was studied by polarized light microscopy and dynamic oscillatory rheometry. Salts caused a delay on nucleation with induction times for crystallization longer for Mg2+ than for Ca2+. Divalent cations were incorporated into crystals, changing the growth of certain faces preferentially, which resulted in changes in morphology. Addition of CaCl2 · 2H2O in a high salt/trehalose molar ratio dramatically increased complex modulus (G*), indicating a stronger viscoelastic behavior. A gel-like structure was formed when Ca2+ was added to trehalose solution. The behavior of Mg 2+/trehalose solutions cannot be considered viscoelastic in nature but as a fluid-like system.