Hybrid and intermittent drying of carrot (Daucus carota var. Nantes)

[EN] A combination of high power airborne ultrasound and microwaves in hot air drying was developed to investigate the effect of intermittent mode on process effectiveness and quality of carrot. The drying experiments were carried out in an innovative hybrid dryer. The course of moisture ratio, drying rate, specific energy and water consumption, colour, water activity and shrinkage were discussed. The results showed that intermittent ultrasound and microwaves in convective drying accelerate the heat and mass transfer, leading to shorter drying time and faster drying rate. It was found that hybrid-intermittent drying can improve the energy efficiency and product quality.