THE EFFECT OF PHASE-TRANSITIONS ON RELEASE OF N-PROPANOL ENTRAPPED INCARBOHYDRATE GLASSES

The mobility of an organic volatile probe (1-n-propanol), incorporated in two types of amorphous carbohydrate glasses, was evaluated by meas uring probe retention as a function of time. Retention was found to de pend on temperature, moisture content and the degree of matrix collaps e. In sucrose glasses, crystallization and probe release occur simulta neously and both crystallization and release depend on the temperature above T-g, as predicted by the William-Landel-Ferry (WLF) equation. I n sucrose:raffinose systems held above T-g, initial rapid release of t he probe ('fast' release) is observed coinciding with, and presumably due to, matrix flow during collapse, followed by a much slower diffusi onal release. Relaxation times for collapse (tau(c)), and 'fast' relea se (tau(FR)) above T-g were calculated They were found to be dependent on T-T-g and moisture content. Dependence of relaxation times on (T-T -g) was found to be well predicted by the WLF equation.