The effect of glucose and invert sugar impregnation on the convective drying rate of pineapple and the suitability of nine mathematical models to describe the drying curves were investigated. Tests were conducted using fresh pineapple rings and samples which were pre-treated by osmotic dehydration in sucrose solutions (0.40, 0.44, and 0.47 g mL-1) and in invert sugar syrup. Osmotic pre-treatments were performed at 40 and 50 ºC for 2 hours at 60 min-1. The convective drying was performed in a tray cabinet dryer using heated ambient air at 60 ºC and 1.25 m.s-1. The adjustment levels of the models were based on the correlation coefficient, the root mean square error, mean absolute percentage error, and residual plot analysis. The highest rates of convective drying were obtained for the fresh samples. In the osmotically pre-treated fruits, with both temperatures, an increase in the solution concentration was followed by a decrease in the convective drying rate. The Wang and Singh model was considered the most adequate in describing the convective drying of pineapple rings.
Ananas comosus (L.) Merrill; osmotic dehydration; dried fruits
