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The role of rice bran, soybean skin and beet residue in the culture medium of edible and medicinal fungi

Rice bran.

Rice bran, also known as fine bran and green bran, is a carbon and nitrogen source, and can be directly used by mycelium. High-quality rice bran must be fresh, odorless, fragrant, sweet and smooth without residue, crude protein ≥ 12.5%, moisture ≤ 13%, and free of impurities. Rice bran contains germ. The quality standard requires that the particle size above 20 mesh should not exceed 10%, light yellow, sweet, and easy to eat. Packing 50 kg/piece. For fungi with short cultivation cycles such as Flammulina velutipes, it only takes 48 to 50 days from inoculation to harvest. Mycelium is difficult to absorb nutrients directly from sawdust, but can quickly absorb nutrients from corn cobs, rice bran, etc., to achieve rapid fruiting and high yield.

For fungi with longer cultivation cycles, such as velvet antler mushrooms and white jade mushrooms, some sawdust needs to be added to extend the cultivation cycle and maintain its taste, quality and yield.

【Discussion】

Rice bran begins to oxidize, produce oil, and become rancid 1 week after it is hulled. Large enterprises should control the amount of rice bran used to 3-5 days. Rice bran should be used immediately after it is delivered, and examined under a microscope to determine whether the particle shape is similar. High-quality rice bran has a small amount of white germ. Use oil-absorbing paper to rub the rice bran, observe the oil content and hand-feeling lubricity, or take a sample to test the nitrogen content, which should be higher than the national third-level rice bran standard. Poor-quality rice bran heats up, sours, clumps, and is mixed with impurities. It can be determined by testing the crude ash content. The crude ash content of unadulterated rice bran should be <8%.

Soybean skin and beet pulp

Soybean skin is a by-product of soybean processing. It contains about 12.2% crude protein and is a high-quality plant protein. Its crude fiber content is 38%, and its lignin content is about 2%. It is also rich in vitamins C, E, B group and minerals such as phosphorus, iron, zinc, calcium, magnesium, etc. In the cultivation of fungi such as Flammulina velutipes, soybean skin is widely used as a protein supplement. Beet pulp is the shredded beet after sugar production. It has a high water content and is baked in running water to become a dry powder for the market. Although the price is high, it is used by the edible and medicinal fungi industry to increase the water content of the culture medium due to its good water absorption performance (water absorption rate up to 600%).