The b-carotene content in freeze-dried mangoes decreases over
time during storage. To compare the degradation of b-carotene
among different storage RVP values, the rate constants were plotted
as a function of storage RVP (Fig. 5). Fig. 5 also shows the state
of samples at 25 C. Freeze-dried mango powder was in a glassy
state while stored at 11.3% RVP, whereas it was plasticized by
water and subsequently rendered into a rubbery state while stored
above an RVP of 11.3%. The decrease in the rate constant was found
at higher levels of storage RVP of up to 43.2%, which coincided with
the transition into the rubbery state. This was in agreement with
Prado et al. (2006), who observed a decrease in the rate constant
of b-carotene degradation in the encapsulated freeze-dried polymeric
matrix when stored at higher RVP levels. In the glassy state,
the rate constant of b-carotene degradation was determined to