Mathematical Modeling And Thermodynamic Properties Of The Drying Kinetics Of Trapia Residues

Trapia (Crataeva tapia L.) is an edible, arboreal fruit species found in Brazil, of which the pulp is suitable for industrialization. The residual peel and seeds are sources of bioactive compounds and can be used after appropriate treatment. Such fruit parts have been introduced as ingredients in various applications to reduce waste in agricultural production and take advantage of the presence of nutrients, but to make them viable for industrial use, the moisture content of the product should be reduced, enabling it to be conserved at room temperature and transformed into powder or flour. The objective of this study was to assess the convective drying of residual trapia peel and seeds in 0.6 cm thick layers at temperatures of 50, 60, 70, and 80 degrees C, and to fit 10 mathematical models to the experimental data. In addition, the activation energy for the drying of the residues and the thermodynamic properties were also determined. Of the models tested, the Midilli model best fitted the drying kinetics of the residues, with a coefficient of determination (R-2) >= .9960. The effective diffusivity increased with the drying temperature, ranging from 5 x 10(-10) to 16.1 x 10(-10) m(2) s(-1), and the activation energy (E-a) varied between 18 and 24.2 kJ mol(-1), with lower E-a values for the peel and higher values for the seeds. Gibbs free energy variation increased with increasing temperature and was considered a nonspontaneous process, while the enthalpy and entropy decreased. Practical Applications The use of the data presented here for the drying kinetics and thermodynamic properties provides support for the use of the dried trapia residues (previously discarded) in the production of new foods, due to knowledge of the processing time and physical behavior of the sample. The trapia powder, rich in bioactive compounds, could be incorporated into various food formulations in the bakery and yogurt segments, among others.