Evaluation of the freezing kinetics of araçá-boi pulp formulated with different maltodextrin concentrations

This study aimed to evaluate the freezing kinetics of araçá-boi pulp at −30°C with different concentrations of maltodextrin. Formulations containing different concentrations (0, 7, 14, and 21%) of dextrose equivalent 10 maltodextrins were prepared. The pulps were characterized based on the following parameters: soluble solids, pH, titratable acidity, soluble solids/titratable acidity ratio, vitamin C, flavonoids, diffusion coefficient, model coefficient, effective diffusivity, average effective diffusivity, coefficient of determination, standard error of estimate, and mean relative error. For the freezing kinetics, a hole was made in the geometric center of the samples, and a thermocouple was inserted to monitor the internal temperature, while another thermocouple was placed inside the freezing unit to monitor the freezing medium, determining the thermal equilibrium point at −30°C. The Fourier model applied to the experimental data showed coefficients of determination above 98% and low standard error of estimate and mean relative error values. The pH increased with higher maltodextrin concentrations, ranging from 2.46 to 2.55. Vitamin C content decreased as maltodextrin concentration increased, with the 14 and 21% formulations showing the lowest vitamin C values. The freezing curve was similar to that observed for pure water, allowing for the identification of the three stages involved in the water-to-ice phase transition. The freezing time increased proportionally with the addition of maltodextrin, with the longest times observed for the 21% maltodextrin formulation and the shortest for the control (0% maltodextrin) at −30°C.