Analysis of Freeze-Drying of Tropical Fruits

Abstract

Freeze-drying is a process recommended for drying of heat-sensitive products. Some advantages of this technique are that it allows the shrinkage and the degrading reactions in the material, which are common in conventional drying operations, to be minimized. The knowledge of drying kinetics is essential for modeling and optimization of a freeze-drying process. In this work, drying kinetics for pineapple, guava, and mango pulps were investigated using five empirical equations commonly applied for convective drying of foodstuffs. Increasing constant- and falling-rate periods were observed during the drying of such pulps. The best fittings for the drying kinetics of all the materials were obtained using the Page and Chen and Douglas equations.

Keywords:

• Tropical fruits
• Freeze drying
• Drying kinetics
• Freezing curves

ACKNOWLEDGMENT

The authors thank the Brazilian funding agencies FAPESP/Proc:04/04815-0 and CNPq/PRONEX for their financial support.