Batch drying of potato slices: Kinetic changes of quality parameters (colour & shrinkage) in response of uniformly distributed drying temperature

Waseem Amjad, Oliver Hensel, Anjum Munir


Uniform quality drying throughout the drying chamber of a dryer is important for a quality oriented drying process. The final quality of dried products significantly depends upon the drying temperature. A batch type dryer was developed for uniform air distribution. ANSYS-fluent was used to analyse the temperature distribution in the dryer. To assess the effect of drying temperature homogeneity on quality parameters, color and shrinkage of potato slices (6 mm thick) at 60° C were measured. The color parameters were quantified in CIELAB color space system. The shrinkage of slices (20 mm round samples) was measured using image analysis software. The rate of color change was found uniform at all sections of drying chamber with high value of R2. The kinetics of color change showed that changes in values of L*and b* fitted well to the first-order kinetic model while values of a*and ∆E followed zero order kinetic model for all sections of drying chamber. The rate of shrinkage was found uniform with an average area reduction of 43% for all sections of drying chamber. These results show that drying temperature is critical for product quality, therefore uniform distribution of drying temperature is vital to achieve spatial uniform quality of dried product. The study will be of immense benefits to researchers involved in control of quality attributes problems especially in medium scale batch food dryers.

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