Modelagem matemática da secagem convectiva e dessorção das folhas de Ora-pro-nobis (Pereskia sp.)

Abstract

The Ora-pro-nobis (Pereskia sp.) is an unconventional food plant, and brazilian native, his leaves have a high protein, ber and mineral contents. Several studies have detected others bioactive compounds, like antioxidants and vitamins, in leaves composition. This characteristics make them an alternative for improving human nutrition. The purpose of this study was to modeling the convective drying process and desorption isotherms in Ora-pro-nobis leafs, evaluating the e ect of temperature and creating technical parameters for the processing of these leaves. The equivalent moisture content was measured using the static gravimetric method under the relative humidity range of 29% to 83% and under temperature range of 40oC to 60oC. At constant water activity, an increase in temperature decrease the equivalent moisture content of Ora-pro-nobis leaves, indicatind the desorption isotherms are sensitive to the temperature. The expetimental data was analysed using tatistical data processing techniques and the results tted to di erent desorption equations. The Peleg equation show good agreements with the experimental results. To determinate the drying kinetics, Ora-pro-nobis leaves was dried using heated air in the temparature range betwen 40oC-60oC, by 5oC step. The sample mass, drying chamber temperature and humidity was recorded during the tests. The experimental data was tted to di erent empirical and semi-theoretical drying equations, using non-linear regression, and analysed using statistical data processing techniques. The Two-terms model gave better predictions than others tested models, satisfactorily describing the thin-layer drying weight loss characteristics of Ora-pro-nobis leaves.