Modeling the drying behavior and mass transfer phenomena in osmotically dehydrated tomatoes

Abstract

This study investigated the drying behavior of tomato slices subjected to osmotic pretreatment. The slices were immersed for 30 min in one of five solutions: 0.2 % KMS, 0.2 % KMS + 1 % CaCl₂, 65 °Brix Sucrose solution, 1 % CaCl₂, or 1 % CaCl₂ + 55 % Sucrose, alongside untreated controls. The convective drying conditions were 65 °C temperature, 30 % relative humidity, and 3 m/s air velocity. Results indicated that the pretreatment process substantially influenced drying rates, facilitating faster moisture removal relative to untreated samples. Among the four mathematical models evaluated, Henderson and Pabi’s model demonstrated a strong capacity to describe the drying behavior of tomatoes at 65 °C. The effective moisture diffusivity values for the pretreated sample groups were found in the range between 1.45×10⁻⁹ m²/s and 1.61×10⁻⁹ m²/s, higher compared to the control at 1.36×10⁻⁹ m²/s. In terms of mass transfer models, between the Peleg and Weibull models, the Weibull model was found to be more suitable for describing the water loss pattern. Overall, the combination of osmotic pretreatment and controlled-air convection drying produced dried tomato products with reduced moisture content and enhanced stability. Thus, the insights obtained from this research can be applied directly to enhance the efficiency, safety, consistency, and diversification in the production of dried tomato products, which can benefit both the industries involved and the end consumers.