Performance evaluation of an infrared heating-assisted fluidized bed dryer for processing bee-pollen grains

Bee pollen has high antioxidant properties and therefore attracts interest in applications such as functional food or ingredient in food, cosmetic and pharmaceutical industries. Drying during pollen processing ensures physical and microbiological stability. This paper investigates the performance of an infrared (IR) heating assisted fluidized bed dryer for drying pollen grains. Physical characterization of the material and fluid dynamic tests were performed to choose dryer operating conditions. Drying kinetics, power consumption and product quality for hybrid drying was compared to those from conventional fluidized bed dryer and isolated IR dryer for pollen processing. The effective moisture diffusivity value in the hybrid drying was approximately 30 % higher and specific energy consumption was 52 % lower than those of conventional fluidized bed drying. In addition, the smoother drying conditions than thin-layer IR drying prevented colour degradation of bee pollen, thus conserving product quality. Therefore, this study shows that the combination of IR radiation with fluidization presents interesting synergistic effect for the processing of bee pollen grains.