Effects of Salts on the Initial Thermal Degradation of Concentrated Aqueous Solutions of Sucrose¹

Abstract

Abstract The effects of salts and other solutes on the degradation of highly pure sucrose in concentrated aqueous solutions (∼65°Brix or % dissolved solids) at 100°C were investigated. Polarimetry and ion chromatography with pulsed amperometric detection (ICIPAD) were used to quantify sucrose degradation. Pseudo-first order kinetic constants of initial degradation rates were calculated. Salt and solute effects were first considered with relation to their effect on water structure around the sucrose molecule. Na+, Mg2+ and Ca2+, which act to enhance water structure, slightly increased initial degradation; the latter two ions significantly increased subsequent accelerated degradation. Highly charged, small cations, e.g., Al3+, significantly increased sucrose degradation through polarized hydrated ions/acidic pH effects. Larger cations, e.g., K+, which act to reduce water structure, significantly increased degradation. The Hofmeister (lyotropic) anion order was not followed for sucrose thermal degradation effects, which indicated that anion binding to hydrophobic sites on the sucrose molecule is not critical. Other possible mechanisms of salt-induced sucrose thermal degradation are discussed.