Osmotic Dehydration of Tomato Assisted by Ultrasound: Evaluation of the Liquid Media on Mass Transfer and Product Quality

The treatment of a food in liquid media involves mass transfer and could aid to preserve some food properties. The assistance of ultrasound (US) could even improve the process. Therefore, the aim of this study was to evaluate US (frequency 25 kHz, powder intensity 8 kW m(-3)) in tomato treatment in sucrose and NaCl solutions, common osmotic agents. Moreover, for testing the influence of the media, distilled water and maltodextrin solution completed the set of tested liquids. Water loss (WL), solid gain (SG), water activity (a(w)), color parameters, like the total color difference (Delta E) and microstructure were evaluated. The advantages of NaCl and sucrose solutions were the high WL and SG values besides low a(w) and Delta E. The alterations in the microstructure of US-treated samples in distilled water or maltodextrin suggested that a product with low solid incorporation and reduced drying time could be obtained in a further drying.