The drying process of king oyster mushroom slices is very similar to most Chinese herbal medicines and flowers. It starts from the low temperature section, and then slowly adjusts the temperature. According to the size and water content of the mushroom slices, the whole drying time varies from 15-20 hours. According to the experience, under the conditions of fixed wind speed, material size and material accumulation layer, the drying time of King Oyster Mushroom is shortened with the increase of hot air temperature, especially in the medium temperature range. Within this range, the higher the temperature, the faster the heat transfer rate, the shorter the drying time.
According to the material characteristics, you should adjust the temperature and humidity, adopt the drying mode of air source heat pump gradient cooling, drying at 60 °C for 3 hours, and then reducing the temperature to 55 °C for 3 hours. Finally, when the drying temperature is set at 50°C, the king oyster mushrooms were dried to constant weight. The advantages of drying by this way are as follows: the freshly picked king oyster mushrooms have a higher moisture content, and the gradual heating and cooling method can ensure that the surface of the king oyster mushrooms does not wrinkle. The hot air drying method with gradient cooling has low energy consumption and reduces production costs. Taking a 6P machine as an example, it can hold about 750 kg of fresh king oyster mushroom slices. The drying time for each batch is 15-20 hours. The moisture content of the dried king oyster mushroom slices is about 10%, the shape is complete, and the color is milky white with slightly yellow, meanwhile, it is with a faint fragrance.