Color, microstructure, physicochemical, textural and sensory properties with the retention of secondary metabolites in convective-, microwave- and freeze-dried carrot (Daucus carota) slices

Purpose This work was undertaken to evaluate the impact of different drying methods (convective, microwave and freeze drying) on color, selected secondary metabolites (total phenolic substances, ascorbic acid, beta-carotene and antioxidant capacity), texture (hardness), sensory properties and microstructure of carrot slices. Design/methodology/approach Convective drying at three different temperatures (55, 65 and 75 °C), microwave drying at two different power levels (100 and 200 W) and freeze drying were applied. Findings Significant differences were found among fresh and dried-carrot slices. Convective-dried carrots showed better quality characteristics in comparison with microwave-dried carrots. The convective-dried carrots at 65 °C exhibited the highest retention of bioactive compounds and best color among all convective drying conditions. The microwave-dried carrot slices at lower power (100 W) showed higher quality characteristics compared to the dried carrots at 200 W. The freeze-dried carrots exhibited the highest retention of secondary metabolites, sensory properties and best color among all drying methods. Originality/value The results from this study are significant for the processing of dried carrots by optimizing the conditions to obtain a high-quality product. Overall, freeze drying is a promising application as shown in the present study by its capability to better retention carrot quality underlying color, sensory, texture, microstructure and secondary metabolites.