Temperature and viscosity for structural collapse and crystallization of amorphous carbohydrate solutions

Abstract

Temperatures and bulk viscosities, at which certain changes in the physical state take place, were examined in various amorphous, supersaturated carbohydrate solutions. The glass transition temperature (Tg) of these aqueous sugar glasses ranged from 181 K to 381 K. Temperatures of physical state changes, such as glass-softening, structural collapse, water and solute crystallization, are quite predictable. They are primarily dependent on the T(g) (less or little dependent on the type of carbohydrates), and occur consistently at certain temperatures above the T(g). Bulk viscosities of amorphous carbohydrate solutions, at which the structural collapse, glass-softening, devitrification and solute crystallization take place, are predicted to be of the order of 108-11, 107-10, 105-7 and 103-6 Pa s, respectively. These values may also serve as reference points for other amorphous systems.