Practical Guide to Fresh-keeping and Processing Techniques for Shiitake Mushrooms

1. Drying equipment:

Although shiitake drying equipment at home and abroad differs in form, scale and technical level, its principle is basically the same. Generally there are the following models:

(1) forced circulation dryer;

(2) forced ventilation parallel-flow dryer;

(3) heat pump dryer.

2. Drying methods

(1) Raw material handling

Before drying, trim off the mushroom stalks or stem bases from the freshly picked mushrooms, remove impurities, and process after grading. Mushrooms picked on rainy days or with high moisture content should first be spread out to air-dry, so that the moisture content drops from 90% to 75%-80% before drying.

(2) Loading the raw materials into the machine

Mushrooms picked on the same day must be dried on the same day. Place the fresh mushrooms arranged on trays into the tray racks, and when the temperature inside the machine rises to 40°C-45°C, spread the tray racks loaded with mushrooms into the dryer.

(3) Drying temperature

Controlling the temperature well is the key technique in drying and processing. For the forced ventilation type, the temperature can be gradually raised from 40°C to 60°C; for the natural ventilation type, use 35°C-60°C. The temperature must rise slowly; generally, dehydration and drying at an evaporation rate of 6% per hour is appropriate. If the temperature is too high, the surface evaporation intensity is strengthened while internal diffusion cannot keep up, the inside of the shiitake becomes gelatinous, and the central part of the mushroom cap is often boiled black, reducing product quality.

(4) Ventilation and exhaust

In order to achieve a certain degree of air exchange during the drying process, the wind speed at the moisture-exhaust tail end of the drying equipment should preferably reach 0.5-1 m/s. At the same time, pay attention to the relationship between temperature and ventilation volume.