Constant and decreasing periods of pineapple slices dried by infrared

Abstract

The aim of the present study is to model the dehydration process of pineapple slices through infrared drying, as well as to determine the critical moisture content and the critical time to the dehydration process. Pineapple slices were cut 5.0 mm thick and 2.0 cm diameter, and dried by an infrared heating source equipped with a built-in scale at accuracy of 0.001 g, under the temperatures of 50, 60, 70, 80, 90 and 100 °C, until constant weight was reached. Mass variation readings were taken at 1.0 min intervals. The mathematical models met the experimental data. The modified model by Henderson and Pabis best represented the data about the drying process. The higher drying temperature led to higher critical moisture content (from 2.205 to 2.450 kgw kgdm-1) and to decreased critical time (18.00 to 5.99 min). The coefficient of effective diffusion increased due to temperature (2.848 x 10-15 to 1.439 x 10-14). The activation energy of the drying process was 33.632 kJ mol-1.