Calorimetric Solution Properties of Simple Saccharides and Their Significance for the Stabilization of Biological Structure and Function

Abstract

Thermodynamic and kinetic quantities were measured for 13 common saccharides: cellobiose, gentiobiose, glucose, lactose, lactulose, leucrose, maltose, melibiose, palatinose, raffinose, sucrose, trehalose, and turanose. Thermodynamic data included heats of solution (in water) of the amorphous and crystalline solids and melting temperatures. The glass transition temperature (Tg) and the increase in heat capacity at Tg were measured for each rigorously dried product. Many of these data were previously unavailable. We provided an interpretation of the heat of solution of the amorphous saccharides in terms of their capacity to hydrogen bond to water. A correlation was noted between the heats of solution of the amorphous carbohydrates and their Tg values. Furthermore, a thermodynamic analysis was performed to obtain values of the Gibbs free energy change for the amorphous-to-crystalline transformation at 25 °C.