Studies on Drying of Purple Carrot Roots

The article compares kinetics of drying and properties of dried roots of purple carrot cultivars: Deep Purple F1 and Purple Haze F1 Bejo Zaden B.V., which differ in coloring of the core section of roots. Sliced carrots were dried by convective drying (CD), microwave-convective drying (MCD), infrared-convective drying (IRCD), and freeze drying (FD). An enhancement of convective drying due to the application of infrared or microwave radiation considerably reduced drying time. The lowest values of apparent density were recorded for freeze-dried carrots, whereas these values for carrots dried by other methods were approximately four times higher. Roots of carrot cv. Deep Purple dried markedly faster than those of cv. Purple Haze. Rehydration of freeze-dried carrots was higher than that dried by other methods. This was clearly manifested particularly in the initial stage of rehydration. Kinetics of rehydration were comparable for carrot dried by other methods. Cultivars did not have a noticeable effect on the analyzed physical properties apparent density and reconstitution properties. Dried carrots of cv. Deep Purple were characterized by an approximately 2.5 times higher antioxidant capacity and higher contents of anthocyanins and polyphenols than dried carrots of cv. Purple Haze.