Moisture sorption isotherms of reduced-sugar confectionery coatings elaborated with stevia: Mathematical modeling and thermodynamic analysis

Abstract

This work was focused on the study of the adsorption phenomena in reduced-sugar confectionery coatings elaborated with a high-intensity sweetener (stevia) as a sucrose substitute. Formulations with different sucrose/stevia contents were elaborated and dried by casting method (60°C for 24 h). Films with dispersed/continuous phase ratios ((Figure presented.)) ranging from 5 (60% sugar) to 2 (0% sugar) were obtained and stored at different temperatures ((Figure presented.)) (5, 25, and 40°C) and water activities (0.206–0.963). Equilibrium moisture contents ((Figure presented.)) were determined by a gravimetric method (drying at 70°C for 6 h and 0.01 atm). The experimental data and phenomena (net isosteric heat and entropy of adsorption) were successfully described through the theoretically-based generalized D'Arcy and Watt model. An antithetical temperature effect on (Figure presented.) was observed between 25 and 40°C. Two crossover points were found and affected by (Figure presented.) and (Figure presented.). Novel and industrially-useful information on reduced-sugar confectionery coatings was obtained. Practical Application: The sorption of water vapor by foods has received much attention because it is important for evaluating quality changes during storage and for modeling industrial processes. The development of new reduced-sugar and free-sugar products is increasing, due to consumers awareness of their well-being and health. This work presents original research on the mathematical description of the sorption process of reduced-sugar confectionery coatings elaborated with stevia (a high-intensity natural sweetener). Four levels of sucrose replacement by stevia and a wide range of storage temperatures (5–40°C) and water activities (0.206–0.963) were analyzed. The information obtained in this work could be useful for researchers and technicians to estimate and control the moisture adsorption performance of sweetened coatings elaborated with traditional (sucrose) and alternative (natural sweeteners) ingredients in practical situations, such as storage and processing.