Effect of hot air drying on quality characteristics and physicochemical properties of bee pollen

Abstract 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 (Deff) values ranged from 1.38 × 10 −10 to 4.00 × 10−10 m2/s, and the activation energy (Ea) 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 (Δ E) 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.

摘要
本研究旨在探究热风干燥对蜂花粉品质特性、理化性质、形态结构及感官特性的影响，并计算蜂花粉热风干燥过程中的有效水分扩散系数（Effective Moisture Diffusivity, Deff）与活化能（Activation Energy, Ea）。本实验将蜂花粉样品分别置于40、45、50、55及60℃条件下进行干燥处理。有效水分扩散系数（Deff）取值范围为1.38×10^-10 至4.00×10^-10 m²/s，活化能（Ea）经测定为42.96 kJ/mol。蜂花粉中的蛋白质、脂肪、总碳水化合物及维生素C均受干燥温度影响。干燥后的蜂花粉样品具备较高的溶解度指数，且相较于新鲜蜂花粉，其L*值与b*值更低。总色差（ΔE）在40℃干燥的蜂花粉样品中最低。干燥后蜂花粉表面的形态变化随干燥温度升高而加剧。40℃干燥的蜂花粉感官评分最高，且相较于45、50、55及60℃干燥的蜂花粉样品，其品质属性保留更为完整。推荐采用40℃热风干燥工艺进行蜂花粉干燥。