Drying is a single operation employed to prolong the life of a large quantity of vegetables. Carrot (Daucus carota) drying has been the subject of many studies. This plant has been highlighted in the human diet for having high nutritional value, mainly due to the high content of β-carotene. In this work, carrot drying behavior was studied in a regular microwave dryer and a vacuum microwave dryer. A vacuum of 450 mmHg was applied for drying of carrot in different geometrical shapes (cubes, discs and sticks). The samples were dried at power ratings of 1.0 W/g, 1.5 W/g and 2.0 W/g for both methods of drying. The evolution of physical properties such as density, volume and porosity was monitored and related to the moisture content of the sample and to the method of drying and power rating used. The geometric shape of the sample influenced the drying kinetics and it was verified that the cubic form was responsible for a slower drying. The application of vacuum showed no major changes in the drying kinetics in microwave but influenced the physical properties of the material. The influence of power ratings on the content of β-carotene was also evaluated and discussed. The main difference observed was the lower shrinkage of the samples dried in the vacuum microwave compared to those dried only in microwave.

The main objective of this study was to evaluate the effect of the drying process on the vitamin C levels and physical properties of dedo-de-moça pepper. The drying kinetics and the structural properties were determined as a function of moisture content. Convective drying was compared with freeze-drying in terms of product quality, structural properties, retention of vitamin C and rehydration characteristics. Empirical and semi-empirical equations were used to describe the drying and rehydration kinetics. Nonlinear analysis applied to results of convective drying, based on curvature measures and bias measures, showed that the only equation that gives good inference results based on least squares estimators is the Overhults equation. The characterization of the rehydration process was done by determining the indexes that take into account the water absorption capacity and solutes losses. The material dried by lyophilization show greater potential to rehydrate.