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

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 Mg2+/trehalose solutions cannot be considered viscoelastic in nature but as a fluid‐like system.