Key Points of Sterilization Technology for Oyster Mushroom Cultivation and an Introduction to Common Methods

Sterilization technology for oyster mushroom cultivation refers to a complete set of operating methods for sterilizing prepared growing substrate, with the aim of killing all kinds of contaminant microorganisms carried in the raw materials. Oyster mushroom substrate consists mainly of agricultural and forestry by-products such as cottonseed hulls, corn cobs, and sawdust. These raw materials themselves carry large numbers of mold spores, and if they are not thoroughly treated, the substrate is highly prone to contamination after mycelium inoculation, directly affecting mushroom production.

The sterilization methods commonly used in production fall into two categories: atmospheric-pressure steam sterilization and high-pressure steam sterilization. Atmospheric-pressure sterilization usually uses an earthen steaming stove or steam piped into the stove, and after the substrate temperature rises to about 100 degrees Celsius, it is maintained for several hours. The equipment is simple, and a relatively large number of substrate bags can be processed at one time. High-pressure sterilization is carried out in a sealed sterilization chamber, with higher temperatures and shorter processing time, giving more thorough sterilization, but the equipment investment is relatively larger. Some growers also use the fermentation heap method, allowing the substrate to heat up naturally and adjusting the pH with lime to reduce the base level of contaminant microorganisms.

To achieve the ideal sterilization effect, the moisture content during substrate mixing should be moderate, and the various raw materials need to be mixed evenly. After bagging, the bags should be placed in the stove promptly to avoid the substrate being piled too long, heating up, and turning sour. When the substrate bags are arranged in the stove, gaps should be left between them so that steam can circulate fully and sterilization dead zones are prevented. After sterilization is finished, it is best not to open the door and remove the bags in a hurry; the bags can be allowed to cool slowly inside the stove for a period before being moved to a clean place to cool.

Incomplete sterilization is a common cause of contamination by green mold, Neurospora, and other contaminant microorganisms in oyster mushroom production. Sterilized substrate bags should be placed in a clean cooling room to cool down, and inoculation should be carried out in accordance with aseptic requirements, so that the finished-product rate can be effectively raised and a good foundation laid for subsequent mycelial growth and mushroom production.