RU2573784C1 - Method of pre-sterilisation preparation of grain obtaining grain spawn of fungi - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: method comprises preparing the substrate till the moment of autoclaving. And in the process flowsheet of preparation of grain spawn of higher fungi the step of grain boiling is completely eliminated. At the step pre-sterilisation preparation of grain the presoaking of grain is used for 8-24 hours in lime water which is obtained by adding to water of calcium lime (CaO) at a concentration of 0.05-2.5%. Moistened grain is packed in heat-resistant containers for further autoclaving process.

EFFECT: method enables to reduce the number of steps of pre-sterilisation preparation of grain and to increase the quality of grain spawn of higher fungi.

Description

The invention relates to biotechnology, and in particular to methods for preparing cereal mycelium of mushrooms for subsequent use in the cultivation of fruiting bodies of these mushrooms. Grain mycelium producers create their own substrate formulas for growing mycelium of higher fungi. Mycelium of higher fungi grown on grain has a fairly high growth activity, since it practically does not lose its ability to grow during storage of such mycelium. An additional benefit from the use of cereal grains as a carrier of higher mycelium mycelium is the fact that the mycelium on the grain during storage and during transportation to the customer can be stored for a sufficiently long time with virtually no significant loss of activity and viability, since all the necessary substrates of the fungus mycelium are taken from available grains. It is known that to obtain grain mycelium of higher fungi, the process of autoclaving grain is universally used to achieve its sterility in containers that can withstand prolonged heat treatment. Before autoclaving, dry grain is poured into water, then it is boiled (or blanched), then the excess water is drained, and then the grain is surface dried. After drying, mineral additives are usually added to the grain (gypsum and chalk in a ratio of 4: 1 - 3: 1). Then the grain thus prepared is poured into heat-resistant containers and placed in autoclaves. The required time for grain autoclaving is established empirically for containers of various volumes (usually this time reaches 1 hour when using containers of small volume (1 l) and up to 5 hours when using containers of up to 10 l) and pressure up to 1-1.5 atm (Stamets P. Growing gourmet medical mushrooms. // Hong Kong: ten Speed Press, 1993. p. 130-131, 141).

The advantage of this method according to Stamets P. (1993), which is a combination of liquid fermentation of mycelium and the traditional "grain" method of producing mycelium, can be recognized as the speed of obtaining a large amount of maternal mycelium. In this case, the initial accumulation of a pure fermenter culture of mycelium of fungi is carried out, followed by its sowing in sterile grain.

The disadvantage of this method is that it requires special expensive equipment, high qualifications and skills of working specialists, and this, of course, increases the cost of the resulting grain mycelium. Another disadvantage is that despite the quickness of the initial seed material obtained (4-7 days), it actually replaces only the original maternal culture of mycelium from Petri dishes or from tubes with beveled agar, and the subsequent stages of work are similar to those for obtaining further grain mycelium of I, II and III generations.

In technological schemes for the production of mycelium used in Russia, the most common is practically the same technological scheme that was presented above, for example:

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In this process, there are necessarily stages:

• cooking grain;

• packaging in containers for growing: cans (2- or 3-liter) or polypropylene bags;

• sterilization;

• inoculation;

• incubation;

• bagging (in case the cultivation was carried out in a glass container);

• incubation (growing);

• storage in the refrigerator;

• implementation.

In pre-sterilization preparation of grain, cooking (blanching) of grain is always used as an obligatory step in all known technological schemes for growing mycelium of higher fungi. In any case, water is poured into containers containing grain, and then the grain is heated and boiled.

Cooking time is determined approximately - “by eye” to the subjective degree of grain readiness, or the time interval after working out the entire cooking process until the grain is ready for a particular device. This process requires approximately 30-40 minutes (it all depends on the amount of grain and the volume of the container in which the grain is cooked).

The moisture content of the grain when changing the time from 30 to 40 minutes of cooking does not change very much, for example from 54% (when cooking 30 minutes) to 56% (when cooking 40 minutes). Usually, grain is considered finished when separate, boiled grains appear on the surface, they should be about 5-7% of the total mass. A well-cooked grain when pressed has a soft consistency. In addition, you must constantly monitor so that the grain does not stick to the bottom of the tank and is not digested. It’s better not to digest the grain than to digest it, thereby turning it into a kind of porridge, which the growing mycelium is not able to assimilate (due to the coalesced grains in the total mass).

Having examined the entire technological process of preparing grain until it is sterilized, we can state that the shortcomings of these methods of presterilizing preparation of grain when obtaining grain mycelium of higher mushrooms are the multi-link process, its high economic cost, and also quite a lot of labor input as a whole. In general terms, for most technological schemes for growing cereal mycelium of higher fungi, it looks like this:

1) packing of dry grain in the tank,

2) filling these tanks with grain with a sufficient volume of water,

3) boiling (cooking or blanching) of grain in a container,

4) draining excess hot water from boiled grain,

5) repetition of grain on flat surfaces for surface drying,

6) the introduction of buffer additives (gypsum and chalk) to increase the aggregation of grain, improve the acid balance (towards alkaline reaction),

7) filling the tanks with welded grain with buffer additives for subsequent sterilization.

As a prototype, the method of preparation of cereal mycelium of higher mushrooms according to Lemke G. (Lemke G. Praktische Erfahrungen bei der Champignonbrutherstellung. Der Champignon, 1972, 126, p. 5-23.) Is selected, where the preparation of mycelium occurs in stages through the following stages:

1. To 10 kg of wheat grain add 15 l of water, the mixture is boiled for 15-20 minutes on low heat.

2. After boiling, the water is drained through a sieve, the grain is dried "superficially", then 120 g of gypsum and 30 g of chalk are added. These additives regulate the pH of the medium, acting as a buffer, gypsum also prevents the bonding of grain.

3. Grain is poured into 1-liter milk bottles, filling them in 2/3. The vessels are closed with cotton plugs and sterilized at a temperature of 121 degrees Celsius and a pressure of 101.325 KPa for 1.5 hours. After autoclaving, the pH of the medium is 6.5-6.7.

4. The substrate is cooled to the temperature of sowing - 24-26 degrees Celsius.

5. Inoculation is made with sterile uterine mycelium grown in test tubes on an agar medium. To inoculate one bottle (vessel), use one tube with uterine mycelium.

6. After sowing the mycelium, the bottles are incubated in a thermostat at a temperature of 24-26 degrees Celsius, inspecting after 3 days for the absence of competitive microflora.

7. 7-10 days after sowing the mycelium on the grain substrate, the contents of the vessels are shaken. This prevents gluing of the grain and accelerates the growth of the mycelium.

8. 3-4 weeks after sowing, the mycelium is ready for use.

9. Prior to sowing, fully sprouted mycelium is stored in a refrigerator at a temperature of 2-4 degrees Celsius.

The disadvantages of this method is the high and unpredictable rejection of the sown batch of vessels (an average of 20-40%, and sometimes up to 60%!) Due to the defeat of the grain in them with lower fungi after passing through the above stages according to Lemke G., which ultimately leads to significant losses of cereals used, their re-sterilization to destroy the developed mold fungi and, thus, to significant labor costs.

The technical result of the proposed method consists in the complete elimination in the technological scheme for preparing grain mycelium of higher mushrooms of the grain cooking stage while simultaneously abandoning the use of special mineral additives (gypsum and chalk) due to the use of quicklime (CaO) during the soaking of grain in water, reducing the number of stages pre-sterilization preparation, reduction of labor and financial costs with a guarantee of the quality obtained at the end of the final product - grain mycelium of higher mushrooms. In addition, the absence at the pre-sterilization preparation stage of grain masking the development of mycelium of mineral additives of gypsum and chalk becomes visually better and allows you to quickly assess the purity of the mycelium developing on caryopsis, which, in turn, guarantees the quality of grain mycelium of higher fungi.

The proposed method of pre-sterilization preparation of grain in the technology for preparing cereal mycelium of edible mushrooms is also implemented in stages in the following way:

1. Dry grain is packaged in flexible perforated open containers on one side of a large volume (up to 50 l), for example a polypropylene bag.

2. These containers with grain are placed in containers filled with water, to which quicklime was previously added and mixed in a concentration of 0.05-2.5%. The containers are positioned so that the water covers the containers with grain and is about 8-10 cm higher than its edge, since when the dry grain swells, the latter increases its volume by about one and a half times.

3. Tanks with grain are left for 8-24 hours in water with the addition of lime to soak the grain and initiate the germination of spores of lower fungi, ie transfer from a resting state to the vegetative phase of development.

After this time or later (a delay of 6-8 hours is possible) - the water is drained from the tanks (the grain can be left wet in the tanks for another day).

4. A flexible container with wet grain open on one side, perforated over the entire area, is placed in an autoclave and sterilized at a pressure of 1 ÷ 1.5 atm and sterilization time from 30 minutes to 1-1.5 hours, depending on the volume of grain to be sterilized in containers ( determined empirically).

5. The grain after autoclaving in hot form is packaged from a flexible container, perforated over the entire area, open on one side, into other containers, for example bags, cans.

6. The containers with grain are closed and the grain is cooled to a temperature that does not damage the seed uterine mycelium.

7. After sowing the uterine mycelium, the containers are incubated in a thermostat at a temperature of 24-26 ° C or at room temperature in special rooms on shelves.

8. After 3-5 days, the containers with sprouted mycelium are shaken to prevent gluing of the grain and to activate the growth of the mycelium.

9. After shaking, the containers (bags, cans) continue to incubate under the same conditions as in paragraph 7. The final readiness of the mycelium is determined visually - the mycelium grows and connects the grains together into a single solid white briquette.

10. Before seeding into the mass of the prepared substrate, the mycelium is stored in a refrigerator at a low temperature of -2-4 ° C.

Claims (1)

A method of presterilizing preparation of grain for the preparation of higher mycelium grain mycelium, including preparation of a substrate prior to autoclaving, characterized in that in the technological scheme for preparing higher-fungal grain mycelium, the stage of grain cooking is completely eliminated using pre-soaking of grain at the stage of grain pre-sterilization preparation for 8-24 hours in lime water, which is obtained by adding quicklime (CaO) to the water at a concentration of 0.05-2.5%, followed by packaging moistened grain in heat-resistant containers for the further autoclaving process.