Mathematical modeling and thermodynamic adjustment of drying kinetics and determination of total carotenoids in dried tropical fruit residues from the Brazilian Amazon

Abstract In this study, drying kinetics and their influence on the total carotenoid content in pineapple (AB), Barbados cherry (AC), and passion fruit (MA) pulp residues from Cooperativa Agrícola de Tomé–Açú (CAMTA) in Pará, Brazil, were evaluated with the goal of facilitating the application of these byproducts as functional vegetable flours. To this end, conversion drying was conducted in an air circulation oven at 60 and 70 °C for a total time of 180 min. On the basis of the experimental data of the kinetic process, eleven mathematical models were analyzed, which were evaluated via the coefficient of determination (R 2 ), chi-square (X 2 ), estimated error (SE), and root mean square error (RMSE), and the model that best predicted the results was subsequently identified. The kinetic curves for the residues indicated similar behaviors. However, at 70 °C, the moisture ratio decreased more rapidly. The total carotenoid content in the AB residues was higher at 70 °C than those in the other fruit pulp residues. In contrast, the total carotenoid contents in the AC and MA residues did not significantly differ between the two temperatures ( p > 0.05). Among the models considered, the Midilli model best fit the drying behaviors of all tropical fruit residues. Notably, the Midilli model optimally captured the drying kinetics data, and the thermodynamic parameters determined with this model were accurate. Thus, agroindustrial fruit pulp residues can serve as alternatives in vegetable flour production, thereby retaining a functional component after the drying process at the studied temperatures, which can facilitate the potential application of these fruit byproducts in various food system matrices. Graphical abstract