When drying, shiitake should be separated according to their size, thickness and humidity. They should be horizontally put on the drying sieve with stalk upwards. Thick and big shiitake with high water content should be put on the upper layer, thin and small shitake with low water content should be put on the lower layer. If the fresh shiitake has great water content, it should be dried with mushroom surface upwards in the sun for 1-2 hours and then be sent to the drying room for further drying.
Specific drying process for shiitake as follows:
1.Shiitake preparation and baking in the drying room.
Put shiitake on the plate and then send them to the drying shelf. Put those big and thick shiitake with high water content on the upper layer, at the same time,put those small and thin shiitake with low water content on the lower layer.There should be 8- 10 layers at most. Otherwise, the heated temperature of shiitake on each layer will be uneven. The distance between each layer should be around 30cm.
2.Intelligent technology: temperature control.
The shiitake can be sent to the dryingroom only after the temperature rises up to 35℃ in the drying room. When drying, the temperature must be gradually increased from low temperature to high temperature. The temperature can be increased by 1- 3℃ after one hour and the maximum temperature should be controlled within 80- 85℃. Generally speaking, the shiitake should be dried under 35- 40℃for 6 hours, 40- 60℃for 8- 10 hours and 80℃ for 2 hours. Higher water content the shiitake has, more drying time it demands under low temperature.
If the temperature isincreased suddenly at the very beginning of drying, the shiitake tissue willlose water too fast. As a result, the shiitake cap will deform to flat andcrack, the gill will fold inversely, the color will turn black, enzyme activity will be destroyed and the original fragrance will be lost. After sent to the drying room, the shiitake should be dried continuously until it is dry.The shiitake color will turn black and the quality will decline if it occurs interruptedheating and unstable temperature.
3. Multiple protection: dehumidification control
During the shiitake drying process, timely dehumidification is also an important part except strict heating temperature control. Basic principle for dehumidification: In the early stage of shiitake drying, when drying room temperature is 35- 40℃, the shiitake should be dehumidified by slow load. If the temperature rises up to 40- 60℃, the dehumidification process should be off and on. If the temperature is higher than 60℃, the dehumidification can be stopped. The shiitake will turn white if it is dehumidified excessively. If the dried shiitake becomes water- soaked yellow, it means dehumidification control is not good or temperature is not higher enough. This phenomenon will easily occur when the heating is stopped in the midway.
4. Quality guarantee: quality inspection
After dried for 16- 18 hours, open the drying room and check whether the shiitake dryness is qualified. When inspecting, press the joint of shiitake cap and stalk by fingers, it is qualified if it only occurs trail. If it feels soft so as the shiitake gill, it should continue to be dried. Qualified drying product characteristics: It has special fragrance for shiitake; shiitake gill is yellow, upright, complete and is not of inverse shape; Shiitake water content is no more than 13%; The shiitake keeps its original shape with round and flat cap, obtaining natural color.