The Drying Constant and its Effect on the Shrinkage Constant of Different-Shaped Food Particulates

Experiments were undertaken to study the relationship between the drying constant and the shrinkage constant of food products during drying. Three particular geometrical shapes of parallelepiped, cylindrical and spheres were selected from potatoes (aspect ratio = 1:1, 2:1, 3:1), cut beans (length: diameter = 1:1, 2:1, 3:1) and peas, respectively. The volumetric shrinkage behaviour and drying behaviour of food particulates were studied in a batch fluidised bed dryer connected to a heat pump dehumidifier system at three different drying temperatures of 30, 40 and 50 ◦C. Shrinkage constant was evaluated with non-dimensional moisture and compared with the drying constant for all materials at these three temperatures to understand the effects of the drying constant on the shrinkage constant for each material under investigated drying conditions. Simple mathematical models were obtained for the relationship between the volumetric shrinkage constant and the drying constant.