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

Abstract

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.

Keywords:

• Ethanol
• Fruit drying
• Modified atmosphere
• Pineapple
• Vitamin C

ACKNOWLEDGEMENTS

The authors acknowledge the State of São Paulo Research Foundation (FAPESP) for the M.Sc. scholarship granted to P.H.S. Santos (Process no. 2006/05282-0).

Notes

^a RH_calculated is the relative humidity calculated considering the presence of ethanol as an ideal gas.

X₀ and X_f are the moisture content of fresh and dried samples on wet basis, respectively.