Control of Solids Uptake by Convective Drying Prior to Osmotic Processing of Foods

Abstract

Solute impregnation constitutes a major drawback to the commercial use of osmotic dehydration of food and several methods to control solute uptake have been proposed. In this work the effect of a convective drying step before osmotic treatment in minimizing solute uptake by the material is analyzed. Results indicate that the initial convective step is a useful way to control solute uptake of apple without increasing total operation time. Reduction of solute uptake using an initial convective step of 30 min varied between 75 and 85% with respect to the samples submitted to a single osmotic treatment with the same duration. It was determined that an initial convective treatment of 30–60 min does not modify total operating time and provides an efficient control of solute gain by the material. This combined dehydration process may be an attractive alternative for producing a new generation of vegetable snacks.

Keywords:

• Combined methods
• Dehydration kinetics
• Mass transfer
• Solids gain

Acknowledgments

The authors acknowledge the financial support of EU's TMR project CT96-0082 “Quality in Drying (QUID).”