The Effect of Drying Kinetic on Shrinkage and Colour of Potato Slices in the Vacuum- Infrared Drying Method

Abstract

The influence of drying conditions on the shrinkage and colour distribution of potato slices in a vacuum- infrared drying system was studied. In this work, the effect of the infrared radiation powers (100, 150 and 200 W) and vacuum levels (20, 80, 140 mmHg and atmosphere pressure) at different thickness (1, 2 and 3 mm) on bulk volumetric shrinkage were investigated. Colour changes were evaluated by image analysis. Data analysis showed that shrinkage percentage increased with increase of sample thickness. This means that maximum of shrinkage percentage (85.31%) and minimum of shrinkage percentage (61.79%) was computed at thickness of 3mm and 1 mm, respectively. It was found that either thickness or IR power had any significant effects ( p <0.01) on shrinkage of potato slices in this drying system. Maximum colour changes (44.31%) and minimum colour changes (6.86%) were obtained at thickness of 3 mm and 1 mm, respectively. Also, results imply that neither IR power nor air vacuum had any significant effects ( p <0.01) on colour changes of potato slices.