Preparation method of secondary spawn and production spawn of straw mushroom
Secondary spawn is the spawn made by transferring primary spawn into secondary spawn substrate. Secondary spawn can be used directly as production spawn. Generally, secondary spawn is transferred to the same kind of substrate for expanded culture to become production spawn. Secondary spawn is generally placed in 750 ml mushroom bottles or plastic bags.
(1) Preparation of substrate
Formula 1: rice straw 90%, bran (rice bran) 9%, gypsum powder 1%. The preparation method is to select golden-yellow, non-moldy dry rice straw, cut it into 3 cm lengths, soak it in clean water for about 12 hours so that it fully absorbs water (only rice straw that has absorbed water thoroughly is easy to sterilize completely), scoop it out and squeeze out the excess water, add bran and gypsum powder in proportion, and mix thoroughly. The moisture level is suitable when water droplets continuously drip from a handful. Then put it into bottles, pressing it firmly with a wooden stick while filling, with the tightness uniform and moderate; generally a 750 ml bottle is filled with 75 g of dry straw. It is best to fill the substrate to about 5 cm from the bottle mouth, and it should not be too full. Next, use a pointed wooden stick to make a small hole in the center, extending to the middle of the bottle, to facilitate inoculation. Wash off the culture medium attached inside and outside the bottle mouth, wipe the inner wall of the bottle mouth dry, insert a cotton plug, and sterilize.
Formula 2: cottonseed hull 94%, bran 5%, gypsum powder 1%, lime 6%. Preparation method: pre-wet the cottonseed hulls, then add the auxiliary materials; when the water content is about 60%, it can be bottled (bagged).
Formula 3: wheat grains 98.5%, gypsum powder 1%, calcium carbonate 0.5%. Preparation method: first soak the wheat grains in 12%-15% lime water for about 10 hours, heat and boil for 15 minutes, then filter, let the wheat grains dry slightly, mix in gypsum powder and calcium carbonate after cooling, and bottle immediately. When bottling, place a thin layer of rice chaff with a moisture content of 30%-40% at the bottom of the bottle, and place a thin layer of cottonseed hulls or rice chaff at the shoulder of the bottle as sealing material to reduce contamination by foreign bacteria. The bottling method for the rest of the substrate is the same as Formula 1. This method is suitable for making secondary spawn; if used for production spawn, it is likely to cause contamination because of its better nutrition.
(2) Sterilization. Bottles (bags) filled with substrate must be sterilized the same day to avoid fermentation and spoilage of the substrate. The sterilization pressure is 137-147 kPa, and sterilization lasts 1.5-2 hours. If a normal-pressure sterilization stove is used, the water must be boiled and then kept for 8 hours, followed by leaving it sealed overnight, which can also achieve the purpose of sterilization.
(3) Inoculation. After sterilization, immediately take out the spawn bottles (bags) and send them to an inoculation box or clean bench; inoculate after cooling. Generally, each primary spawn is used to inoculate 4-8 bottles of secondary spawn, and each bottle of secondary spawn is used to inoculate about 60 bottles of production spawn.
(4) Cultivation. After inoculation, move all the spawn to an incubator or culture room. The room temperature is preferably 30-32°C, and it can be checked after 24 hours. Before the mycelium seals the surface, it is best to check once a day and promptly remove contaminated spawn. Three to five days after the spawn fully covers the bottle is the most suitable spawn age; the spawn age for a 750 ml mushroom bottle is 25-30 days. In particular, the culture room must be clean and ventilated, and the outdoor environment must also be clean.