Influence of osmotic pretreatment and convective drying temperature on the drying and rehydration kinetics of pear slices (Pyrus communis)

Abstract

This research evaluated the impact of osmotic dehydration (OD) pretreatment at 40°Brix for 0, 1.5, and 3 min, and convective drying temperatures (40°C, 60°C, and 80°C), on the drying kinetics, color changes, and rehydration kinetics of pear slices. Drying efficiency was found to increase significantly with increasing osmotic pretreatment temperature and time. The most efficient moisture removal condition was drying at 80°C with 3 min of OD, the kinetics of which were described by the Page model (R2 ≥ 0.99). However, the application of OD under some conditions intensified browning, although a 3-min OD pretreatment followed by convective drying at 80°C resulted in the least browned sample. Regarding rehydration kinetics, the Peleg model parameters (R2 ≥ 0.92) indicated that a shorter osmotic dehydration (OD) time and lower drying temperature favored the rate of water absorption, while a higher drying temperature without OD application favored water retention. Therefore, the application of an osmotic pretreatment at 40 °Brix for 3 min followed by drying at 80 °C is suggested, as it allows for a rapid drying process with less browning and moderate rehydration capacity.