Kinetics of L-Ascorbic Acid Degradation in Pineapple Drying under Ethanolic Atmosphere

The kinetics of L-ascorbic acid degradation during drying of pineapple in normal and modified atmosphere was studied. Drying experiments were carried out in a tunnel dryer at two drying temperatures and air velocities. The drying atmosphere was modified by the addition of ethanol (0.5%v/v). The presence of ethanol in the drying atmosphere promoted a more intense water evaporation compared to the conventional process. Although the L-ascorbic acid degradation rate during the pineapple drying (final moisture content of 27% wet basis) under ethanolic atmosphere was higher, these samples retained higher amounts of L-ascorbic acid. Moreover, the Weibull model was applied to fit the kinetics data.