EFFECTS OF SALTS ON THE INITIAL THERMAL-DEGRADATION OF CONCENTRATED AQUEOUS-SOLUTIONS OF SUCROSE

The effects of salts and other solutes on the degradation of highly pu re sucrose in concentrated aqueous solutions (similar to 65 degrees Br ix or % dissolved solids) at 100 degrees C were investigated. Polarime try and ion chromatography with pulsed amperometric detection (IC-IPAD ) were used to quantify sucrose degradation. Pseudo-first order kineti c constants of initial degradation rates were calculated. Salt and sol ute effects were first considered with relation to their effect on wat er structure around the sucrose molecule. Na+, Mg2+ and Ca2+, which ac t to enhance water structure, slightly increased initial degradation; the latter two ions significantly increased subsequent accelerated deg radation. Highly charged, small cations, e.g., Al3+, significantly inc reased sucrose degradation through polarized hydrated ions/acidic pH e ffects. 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 mole cule is not critical. Other possible mechanisms of salt-induced sucros e thermal degradation are discussed.