Dry Shiitake Production Process
1) Raw shiitake treatment
For the shiitake harvest, it must seize the best time to have a picking up. When the shiitake is with the rim curled and pointing down while the velum is clearly visible, it’s the best harvest time. Now the shiitake moisture content is around 75% ~ 80% which is good for have a drying treatment. If pick up the shiitake on the rainy day, its moisture content is too much which will cause a longer drying time.
2) Picking method
The thumb and forefinger hold the base of the shiitake, and then, give them a twist at the very bottom of shiitake (keep the shiitake complete). After picking up, shiitake sorting, cutting its stalk and leave it less than 1 cm length is enough. Then sort them out according to the various species and different quality. They can be sorted into flower mushroom, thick mushroom, thin mushrooms etc. Then classify these 3 types of mushroom respectively again based on its cap size, thickness, moisture content.
3) Drying equipment
Load the well sorted mushroom on the drying tray and make it flat, the quantity is based on easily pulling on a tray by a single person, then push the trays into the drying furnace, keep them approximately at about 13 ~ 15 layers so that the hot air in the furnace can flow freely, let them heated evenly, thus moisture removal effect is quite good. The moisture content will drop to 15 ~ 20% after drying under the temperature of 35 ℃ hot air about 1 ~ 6 hours. At the beginning, control the temperature at 35 ℃ and drying for 3 ~ 4 hours. Then gradually rise to 40 ℃ and keep drying for 4~5 hours, now the water in the body and on the surface is evaporated basically at the equal speed. When the temperature is between 40~50℃, the fresh mushroom is gradually softened, then the body moisture is evaporated, the pileus rim will shrink and curl in, but at this stage the mushroom core is still with some moisture. When the temperature up to 50 ℃, the mushroom color won’t turn to pale yellow. In the last period of drying, the moisture in the mushroom body has a substantial reduction. Now reduce the ventilation strength and keep the drying temperature to around 50 to 55 ℃ for 2 ~ 3 hours. After that, the color of the mushroom turns slowly to be pale yellow, and the fragrance created. In order to remove the residual moisture in the mushroom body, the set the temperature up to 55 ~ 60 ℃ and keep drying at 1 ~ 2 hours, in this period the acid and the enzyme in the mushroom body create a chemical reaction to produce the aroma, and the drying process is ended.
4) Drying standard
When the water content of the dry shiitake is at around 11~13%, it can reach the storage standard. Inspect the dry shiitake, if it meets the conditions below, then it will be qualified: Press the pileus and break the stalk by hands gently, if it breaks easily with the sound of crisp, the fungus skirt is upright, shiitake keeps the original shape in golden color with faint scent.
The dry shiitake easily get damp if it absorbs the water from moisture air. So, the dry shiitake must be packed within 6 hours after drying treatment. We pack them manually.
6) Storage condition
The Dried mushroom must be moved into the cold storage with temperature for 10 ~ 20 ℃, while generally it can be validly stored for 6 ~ 12 months.