The aim of this study was to investigate the effect of hot air drying on quality characteristics, physicochemical properties, morphological structure and organoleptic characteristics of bee pollen, and compute the effective moisture diffusivity and activation energy during hot air drying of bee pollen. Bee pollen samples were dried at 40, 45, 50, 55 and 60 °C. Effective moisture diffusivity (D eff) values ranged from 1.38 × 10 −10 to 4.00 × 10 −10 m 2 /s, and the activation energy (E a) was found to be 42.96 kJ/mol. Protein, fat, total carbohydrates and vitamin C of bee pollen were affected by the drying temperature. Dried bee pollen samples had high solubility index, and had lower L* and b* values as compared with those of the fresh bee pollen. Total color difference (ΔE) was the lowest for the bee pollen dried at 40 °C. Morphological changes on dried bee pollen surfaces increased with increasing the drying temperature. Bee pollen dried at 40 °C took the highest sensory scores and retained its quality attributes better than the bee pollen samples dried at 45, 50, 55 and 60 °C. Hot air drying at 40 °C is recommended for the drying of bee pollen.

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Infrared radiation drying being one of the innovative drying methods was chosen to perform comparative study at different infrared power levels at 50, 62, 74 and 88 W. Quality attributes such as protein, fat, ash, carbohydrate, vitamin C content, solubility index and colour of infrared dried bee pollen samples were evaluated. The infrared power has a significant effect on the drying and quality characteristics especially colour. Drying time was reduced from 170 to 50 min when the infrared power level increased from 50 W to 88 W. Morphological changes on the surface of bee pollen grains increased with increasing the infrared power. The bee pollen infrared dried at 50 W retained its quality characteristics better than the bee pollens infrared dried at other power levels.