Heat Pump Drying Characteristics of Agaricus bisporus Based on Weibull Distribution Function

In order to improve the quality of dried products of Agaricus bisporus, heat pump cold air drying was used in it's dehydrate process, the hot air drying and freeze drying of Agaricus bisporus were used as controlled experiments. The drying time, energy consumption, product hardness and product whiteness were determined during all drying processes. Meanwhile, the Weibull distribution function was used to analysis the diffusion mechanism of Agaricus bisporus during heat pump cooling air drying. The weight comprehensive evaluation of Agaricus bisporus was carried out based on the indexes of drying efficiency and product quality. Results showed that, when the inlet air velocity was accelerated and drying temperature was raised, the minimum time of Agaricus bisporus cold air drying time were 9.09% and 27.27% lower than the maximum respectively. Drying temperature had a more significant effect on the time consumption, energy consumption, product hardness and product whiteness of Agaricus bisporus (p<0.05). Weibull distribution function could accurately (R²>0.99) describe the heat pump cold air drying process of Agaricus bisporus. Under different drying conditions, the shape parameters of cold drying of Agaricus bisporus were all less than 1, and the whole drying was mainly controlled by internal water diffusion.Compared with freeze-drying, the drying time and energy consumption of Agaricus bisporus cold air drying decreased to 50% and 26.35% respectively. Compared with hot air drying, cold air drying technology reduced the hardness of dried products of Agaricus bisporus by 13.44%, while the whiteness of dried products increased by 59.92%. The optimum drying conditions for the cold air drying of Agaricus bisporus were 25℃ and 2 m/s inlet air velocity. Conclusion:Heat pump cold air drying technology could improve the quality of dried products of Agaricus bisporus and reduce drying time and energy consumption at the same time.