Drying kinetics and colour change of lemon slices

The effect of microwave-convective heating on drying characteristics and colour change of lemon slices was investigated. The drying experiments were carried out at 180, 360, 540 and 720 W and at 22 degrees C, with air velocity of 1 ms(-1). The values of effective moisture diffusivity were found to be in the range between 1.87 10(-8) and 3.95 10(-8) m(2) s(-1), and the activation energy was estimated to be 10.91 Wg(-1). The drying data were fitted with six mathematical models available in the literature. The model describing drying kinetics of lemon slices in the best way was found. The colour change of the dried lemon slices was analysed and considered as a quality index affecting the drying quality of the product. The values of lightness/darkness, yellowness/blueness and hue angle increased, while the value of redness/greenness decreased with increasing microwave power.