JPH0681570B2 - Manufacturing method of culture medium for mushroom cultivation - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a culture medium for mushroom cultivation, and more specifically, to shorten the sterilization time in retort sterilization treatment and uniform sterilization to change the medium water content. The present invention relates to a method for producing a culture medium for mushroom cultivation, which can be carried out without performing it.

(Prior Art) Conventionally, a so-called mushroom cultivation medium for producing mushrooms such as shiitake mushrooms grown in mushrooms artificially and in large quantities has been carried out. For example, in mushroom cultivation such as shiitake mushrooms, it is possible to make a culture medium for mushroom cultivation using sawdust, rice bran and other medium raw materials, inoculate the mushroom culture medium for mushroom cultivation, incubate and culture shiitake mushrooms. Has been done. In addition, bottle cultivation is carried out in hiratake and enokitake. This series of steps will be described in more detail. As for the mushroom culture medium base, a polypropylene culture bag (4) is filled with a predetermined amount of the culture medium raw material (1) such as sawdust and rice bran as shown in FIG. The bag opening is closed with a screw lid (2) having a vent (3) or filled in a polypropylene bottle, and stored in a retort kettle in that state, and retort sterilized at 110 to 130 ° C. It is manufactured by applying. In addition, the present inventors, before the retort sterilization process, by the retort kettle body and the vacuum device integrally connected thereto,
Method of reducing the pressure inside the retort kettle (Japanese Patent Laid-Open No. 63-209516)
Issue gazette).

However, the medium is generally made of sawdust, rice bran, etc., and air remains in the culture container filled with the medium. Therefore, under high pressure in the retort sterilization process, the temperature in the culture container is unlikely to rise due to the adiabatic action of the air remaining in the culture container without being deaerated.
Further, the shape of the culture container is generally a lump such as a columnar shape, and it is difficult to raise the temperature in the center of the culture container from the viewpoint of heat conduction. That is, including the method of reducing the pressure inside the retort kettle prior to the retort sterilization treatment, the air in the culture container is not sufficiently degassed, and the temperature inside the culture container is difficult to rise. At present, it takes a long time of 5 hours. Further, since the temperature of the central part in the culture container is less likely to rise than that of the peripheral part, uniform retort sterilization treatment cannot be performed, and there is a great risk that an unsterilized part is generated in the culture container. As a result, in the subsequent culturing step, the probability of contamination of various bacteria increases, and the incidence of defective culture medium increases.

As described above, in the conventional retort sterilization treatment method, since the retort sterilization treatment takes a long time, it leads to a decrease in production efficiency in a factory where mass production is performed, and because of uneven heating in the culture vessel, the yield is high. It also leads to a decrease in
At present, a method for deaerating the air in the culture vessel to quickly raise the temperature inside the culture vessel to shorten the treatment time has not been developed.

(Problems to be Solved by the Invention) The present invention has been made in view of such circumstances, and an object of the present invention is to speed up and homogenize retort sterilization treatment, and to maintain a medium water content. It is to provide a method for producing a cultivating substrate for mushroom cultivation that can be performed.

(Means for Solving the Problem) The above-mentioned object is to put a container filled with a medium raw material for mushroom cultivation in a retort kettle to perform retort sterilization, decompress the inside of the retort kettle and fill the container with the above medium. The process of degassing the internal air and the process of supplying steam of 100 ° C or higher to the retort kettle at a pressure of 10 kg / cm ² or less and sending the steam into the container are sequentially repeated, and the second and subsequent times. The method for producing a culture medium for mushroom cultivation is characterized in that the pressure for depressurizing the inside of the retort kettle is set to a saturated vapor pressure with respect to the medium temperature at that time, or a pressure slightly higher than that.

That is, the manufacturing method of the present invention, during the retort sterilization treatment, forcibly deaerating the air from the culture container by reducing the pressure in the retort kettle, and supplying steam to the retort kettle in the culture container. Rapidly replacing air with steam is repeated to raise the temperature, and in this case, the pressure reduction state in the retort kettle after the second time is saturated vapor pressure with respect to the culture medium temperature at that time, or slightly higher. By applying a pressure, the retort sterilization treatment is performed uniformly in a short time while maintaining the water content of the medium.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 is an explanatory view showing an example of the retort sterilization / vacuum suction device used in the present invention.

In the figure, (5) is a pot main body, and (12) is a steam blowing pipe provided on the ceiling thereof. (10) is a steam pipe for supplying steam to the blow-out pipe (12), and an opening / closing valve (11) is provided in the middle. Reference numeral (13) is a vacuum suction pipe having an opening at the bottom of the pot main body (5), which is connected to the vacuum pump (7) and provided with an opening / closing valve (14) therebetween. (17) is an air intake pipe having an opening in the ceiling of the pot main body (5), between which a sterilization filter (19) and an opening / closing valve (1) for washing air to prevent contamination of various bacteria are provided.
8) is provided. In addition, (15) is an open / close valve (1
It is a drain discharge pipe provided with 6). Also,
(6) is an entrance door. Reference numeral (8) is a rail formed in the shuttle body (5), and the rails (8) guide the carriages (9), (9) 'into the shuttle body (5).

Using such a retort sterilization / vacuum suction device, the retort sterilization according to the present invention is performed, for example, as follows. That is, a culture bag made of polypropylene or the like, which is filled with a raw material for culture medium such as sawdust and rice bran by a conventionally known method, and the opening of which is sealed is laminated on the trolley (9) in multiple stages. Next, this is stored in the shuttle body (5). In that state, the inlet door (6) is closed, the steam pipe (10) and the air intake pipe (17) are closed, and first, the vacuum suction pipe (1
The on-off valve (14) of 3) is opened, the vacuum pump (7) is operated, and the inside of the shuttle main body (5) is depressurized. The depressurized state at this time may be lower than atmospheric pressure. Next, close the vacuum suction pipe (13), open the on-off valve (11) of the steam pipe (10), and put it inside the pot body (5) at 100 ° C or higher.
0 kg / cm ² or less, that is, 1.03 to 10 kg / c at 100 to 180 ° C
Saturated steam is supplied at a pressure of m ² , preferably 1.5 to 2.7 kg / cm ² . Then, the inside of the kettle body (5) is kept at 100 ° C. or higher, preferably 110 to 130 ° C. for several minutes. Then again
The steam pipe (10) is closed, the opening / closing valve (14) of the vacuum suction pipe (13) is opened, the vacuum pump (7) is operated, and the inside of the pot body (5) is depressurized.

At this time, the proper depressurization condition in the kettle body (5) has a deep relationship with the medium product temperature, and it is important to set the saturated vapor pressure to the medium product temperature at the time of depressurization or a pressure slightly higher than that. When the pressure is reduced below the saturated vapor pressure with respect to the medium product temperature, the medium product temperature is cooled to either the boiling point of water under vacuum pressure or the lowest temperature part in vacuum, whichever is higher. This is cooling that occurs by removing latent heat from the medium when the medium moisture evaporates in a vacuum, and is called vacuum cooling.
When a reduced pressure condition that causes vacuum cooling is used, not only the water content of the medium changes and defects occur after the culturing step, but also the loss of heat energy required for heat sterilization increases and the processing time increases. Therefore, good results can be obtained when the pressure at this time is the same as the saturated vapor pressure with respect to the medium temperature at the time of depressurization or preferably within 1.3 times the saturated vapor pressure.

Next, the steam main body (5) is filled with steam again in the same manner as the previous time. The degassing of the air in the culture bag and the feeding of steam as described above are repeated several times as needed to perform retort sterilization.

It should be noted that the conditions such as the reduced pressure state, the pressure difference at each time, and the steam vary depending on the shape and weight of the culture medium, the temperature of the culture medium, the capacity of the apparatus, and the like. The above conditions may be controlled not only by pressure control but also by time control.

After performing the retort sterilization treatment as described above, the pressure in the kettle is returned to normal pressure, and the culture medium for mushroom cultivation is obtained by cooling according to a conventionally known method.

At the time of the above-mentioned retort sterilization, the culture bag filled with the medium raw material stored in the kettle body (5) behaves as shown in FIG. That is, when the vacuum pump is operated and the inside of the kettle body (5) is depressurized, the pressure inside the culture bag becomes higher than the pressure outside, so that as shown in FIG. As the air tries to come out, the whole inner surface of the culture bag is pushed. As a result, at the same time when the culture bag is inflated, the air inside the culture bag is deaerated through the vent hole such as the screw lid. Next, when steam is blown into the kettle body (5), the pressure outside the culture bag becomes higher than the pressure inside, so that the entire culture bag is compressed from outside the culture bag as shown in FIG. 2 (b). At the same time, a force acts in such a direction that outside steam enters the culture bag through a vent such as a screw lid. By repeating such depressurization and steam supply operations, the air inside the culture bag is gradually degassed and becomes leaner,
Steam penetrates and the temperature inside the culture bag rises rapidly and uniformly. At this time, especially when the culture medium container is a highly flexible container such as a polypropylene bag, as shown in FIG. 2, the container repeatedly expands and contracts and behaves as if an organism were breathing. The effect is remarkable.

Further, FIG. 4 is an explanatory view showing temperature change patterns of the central portion and the peripheral portion in the culture bag. FIG. 4 (a) shows the case of the conventionally known retort sterilization (vacuum sterilization) method, and FIG. 4 (b) shows the case of the sterilization method of the present invention.
The units of time and temperature in FIGS. 9A and 9B are the same. From the figure, the temperature in the culture bag in FIG.
It shows that the temperature rises more rapidly than in FIG. 4 (a), and that the temperature of the central portion also rises to the peripheral portion without delay.

Further, since the reduced pressure in the retort kettle is set to a saturated vapor pressure corresponding to the medium temperature at that time or a pressure slightly higher than that, there is no evaporation of water contained in the medium.

Further, in the present invention, as a device for reducing the pressure inside the pot main body, for example, a device in which a vacuum cooling device is integrally connected to a conventionally known retort sterilizer may be used in addition to the above-mentioned device. . Further, the method of reducing the pressure inside the retort kettle body is not limited to the vacuum pump, and for example, a suction device such as an ejector may be used.
Also, the vacuum capacity is greatly improved by installing a condenser in front of the vacuum device.

Further, the material of the culture container used in the present invention is not limited to polypropylene, but may be a bag of other material as long as it is a heat resistant material, and the effect using a glass bottle or a resin container is also not effective. can get. Further, the opening of the culture container is not limited to the culture container form in which the inside and outside of the culture container have a ventilation path by some means and is covered with a screw lid or the like. It may be in the form of a semi-hermetically sealed culture vessel that has been heat-sealed.

(Effect of the invention) As described above, in the method for producing a culture medium for mushroom cultivation of the present invention, the time required for the retort sterilization treatment is significantly shortened compared to the conventional 1 to 5 hours, and can be performed in about 0.5 hours. Becomes Further, the water content of the medium is retained after the retort sterilization treatment. That is, the retort sterilization treatment step, which has been the largest inhibiting factor when mass-producing the culture medium for mushroom cultivation in a production plant, etc. by carrying out the present invention,
The retort sterilization process time can be shortened without incurring a large cost such as the addition of a retort sterilizer, and the production efficiency is improved, and defects in the culture process due to changes in the water content of the medium do not occur.

Furthermore, the temperature inside the culture bag, which has the property of being difficult to raise the temperature, is raised without delaying to the peripheral portion, so that the inside of the culture bag is uniformly sterilized. As a result, in the subsequent culturing step, the contamination rate of miscellaneous bacteria due to insufficient sterilization is significantly reduced, and the quality of the step can be improved.

That is, according to the present invention, it is possible to dramatically improve the production efficiency and yield of products in a plant for producing a culture medium for mushroom cultivation.

Hereinafter, the present invention will be specifically described based on Examples.

<Example 1> 40 parts by weight of sawdust and 1 part by weight of rice bran were hydrated to a water content of 70
1 kg of the culture medium raw material adjusted to be 100% was filled in a polypropylene culture bag and formed into a cylindrical shape, and a commercially available shoulder cap having a vent hole was attached to the opening of the culture bag as shown in FIG.

Next, retort sterilization was performed using the retort sterilization / vacuum suction device described above. At this time, the first depressurized state in the pot body was 60 Torr, and the second was 160 T because the medium temperature was 61 ° C.
The vacuum suction device was operated at ortor for the third time at 260 Torr because the medium product temperature was 72 ° C. and for the fourth time at 360 Torr because the medium product temperature was 80 ° C. The steam supplied to the pot body is 2.5 kg / cm
The pressure was set to ² , the holding temperature was set to 121 ° C., and the holding time when the steam was filled was 2 minutes.

As a result, the retort sterilization treatment was completed in 35 minutes. In addition, no change in the water content of the medium was observed before and after the retort sterilization treatment.

<Example 2> Retort sterilization was performed using a culture bag filled with 0.5 kg of the medium raw material prepared in the same manner as in Example 1.

The first vacuum condition was 60 Torr, and the second time the medium product temperature was 80 ° C., so 360 Torr was set and the vacuum suction device was operated. The pressure of the supplied steam and the holding temperature were the same as those in Example 1, and the holding time when the steam was filled between the depressurized states was 0 minutes.

As a result, the retort sterilization treatment was completed in 30 minutes. In addition, no change in the water content of the medium was observed before and after the retort sterilization treatment.

<Example 3> As in Example 2, using a culture bag filled with 0.5 kg of medium raw material, the first depressurized state was 60 Torr, and the second time the medium temperature was 72 ° C.
Therefore, the vacuum suction device was operated at 260 Torr.
At this time, the time required to operate the vacuum suction device was 2 minutes and 3 minutes, respectively. In addition, the pressure of the steam and the holding temperature during this period were the same as those in Example 1, and the holding time was 3
Minutes.

As a result, the retort sterilization treatment time was 36 minutes. In addition, no change in the water content of the medium was observed before and after the retort sterilization treatment.

<Example 4> As in Example 2, using a culture bag filled with 0.5 kg of medium raw material, the pressure of steam to be supplied and the holding temperature were set in Example 3.
The operation of the vacuum pump, which was set to be the same as the above, to depressurize the inside of the kettle body, was controlled by time by installing a timer without using a pressure gauge. In other words, the vacuum pump is operated for 2 minutes in order to obtain the same reduced pressure condition as the condition of the third embodiment, the steam is kept in the pot body for the next 3 minutes, and the second vacuum pump is operated for 3 minutes.
Controlled by time, such as minutes.

As a result, the same result as in Example 3 was obtained by the time control.

<Comparative Example 1> As in the case of Example 2, a culture bag filled with 0.5 kg of a medium raw material was used, the pressure of steam to be supplied and the holding temperature were set to be the same, and the inside of the pot main body was set before the retort sterilization which is a conventionally known method. A method of reducing pressure was performed. That is, the same retort sterilization vacuum suction device as that used in the above example was used to store the culture bag filled with the medium raw material in the pot body in the same manner. Then, operate the vacuum pump to reduce the pressure inside the kettle body to 60
After setting to Torr, steam was supplied to perform retort sterilization.

As a result, the retort sterilization treatment time required 60 minutes.

<Comparative Example 2> As in Example 2, a culture bag filled with 0.5 kg of the culture medium raw material was used, and the pressure of the supplied steam and the holding temperature were set to be the same. The first depressurization in the retort kettle was 60 Torr, and the medium product temperature was 80 ° C. in the second time as well, but the pressure was reduced to 60 Torr. At this time, the medium temperature was 42 ° C. After that, steam was supplied again to perform retort sterilization treatment.

As a result, the treatment time was 42 minutes, and the water content after the retort sterilization treatment was 66.7%.

The retort sterilization treatment was carried out as in Examples 1 to 4 and Comparative Examples 1 to 2 described above, and 3,000 seeds of each of the culture media were inoculated with the inoculum of mushrooms and cultivated.

The results of these sterilization conditions and the contamination ratio of various bacteria are also shown in Table 1. In addition, the contamination ratio of various bacteria is due to insufficient sterilization.

As a result, none of the culture mediums of Examples 1 to 4 and Comparative Example 2 were contaminated with bacteria due to insufficient sterilization.
On the other hand, among the culture media of Comparative Example 1, the culture media contaminated with various bacteria due to insufficient sterilization was 18 out of 3000 (0.6%).

In addition, the number of culture media that failed culture was 60 to 90 out of 3000 (2 to 3%) in Examples 1 to 4 and Comparative Example 1, whereas
In Comparative Example 2, the number reached 720 (24%).

From the above results, the production method of the present invention can greatly improve the production efficiency and yield of products. Further, since the control of the vacuum pump and the like can be controlled not only by the pressure but also by the time, it is possible to manage the sterilization process by creating a time program in advance.

Therefore, the control method can be set according to the production scale of the production factory, the number of personnel, the device, etc., so that labor saving, labor saving, and speedup in the sterilization process can be achieved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a general culture medium for mushroom cultivation, FIG. 2 is an explanatory view showing the basic principle of the present invention, and FIG. 3 is an explanatory view showing an example of a retort sterilization / vacuum suction device used in the present invention,
FIG. 4 is an explanatory diagram showing a temperature change pattern in the central portion and the peripheral portion inside the culture bag. (1) ... medium material, (2) ... screw lid, (3) ... vent hole, (4) ... culture bag, (5) ... pot body, (7)
...... Vacuum pump, (12) …… Steam blowing pipe, (13)
…… Vacuum suction pipe, (17) …… Air intake pipe, (1
9) …… Sterilization filter.

Claims (1)

[Claims] 1. A step of depressurizing the inside of a container filled with the above medium by depressurizing the inside of the retort kettle when putting a container filled with a raw material for a medium for mushroom cultivation into a retort kettle to perform retort sterilization. And the step of supplying steam of 100 ° C. or higher at a pressure of 10 kg / cm ² or less into the retort kettle and sending the steam into the container are sequentially repeated to reduce the pressure in the retort kettle after the second time. A method for producing a culture medium for mushroom cultivation, characterized in that the pressure at that time is set to a saturated vapor pressure with respect to the medium temperature at that time or a pressure slightly higher than that.