JP4195491B2 - Method for producing fermented foods such as beer - Google Patents

Description

The invention, prepared how fermented foods such as beer, and more specifically, primarily relates to how to produce a fermented food such as beer by using a yeast solution storage for stirring tank used in beer production process.

  In general, in a process for producing a fermented product such as beer, yeast recovered from a fermenter is stored in a storage agitation tank, returned to the fermenter as seed yeast, and reused.

  The yeast stored in the storage agitation tank settles down with time, and as a result, the yeast concentration and cooling temperature in the storage agitation tank become non-uniform, which is resolved. In order to do this, the yeast solution must be stirred.

  However, the yeast liquid is a non-Newtonian fluid, like butter and soap, and such a non-Newtonian fluid is different from a Newtonian fluid in which the stirring effect is improved in proportion to the stirring force. It is known that a stirring effect proportional to that cannot always be obtained.

  On the other hand, although stirring is necessary to make the yeast concentration and the temperature of the yeast liquid uniform as described above, it is also necessary not to damage the yeast by the stirring.

  In such a beer production process, conventionally, blades such as inclined paddle blades and propeller blades have been mainly used as the stirring blades provided in the stirring tank for storing the yeast liquid supplied to the fermenter.

  However, when the yeast liquid which is a non-Newtonian fluid is stirred using such a stirring blade, there is a problem that the whole cannot be mixed uniformly by low speed stirring.

  On the other hand, in order to eliminate this mixing failure and increase the uniformity of the yeast concentration and the temperature of the yeast solution, there is a problem that if high-speed strong stirring is performed, the yeast is damaged and destroyed, and its biological activity is reduced. .

  The present invention was made to solve such conflicting problems, and the entire tank can be uniformly stirred and mixed in a short time without causing poor mixing of the yeast liquid that is a non-Newtonian fluid. It is an object to prevent the yeast from being damaged and its biological activity from decreasing.

Yeast The present invention has been Do to solve such problems, as well as storing a part of yeast liquid discharged from the fermentor to ferment fermented foods such as bi Lumpur, which is stored In the method for producing fermented foods such as beer having a step of stirring the yeast liquid in the yeast liquid storage agitation tank for returning the liquid to the fermenter for reuse , the tank body of the yeast liquid storage agitation tank rotates with and is formed in a substantially cylindrical shape, around the tank body is provided with a jacket for flowing a refrigerant for cooling the yeast solution in the tank body, are constructed and a vertical surface without tilting, the teeth may A stirring blade configured such that the maximum diameter of the rotating body sometimes formed is 60 to 90% of the tank diameter and the height of the rotating body is 70% or more of the liquid depth at the time of standard storage of the yeast liquid. Provided in a liquid storage agitation tank, and the agitation blade is rotated at 1-30 rpm Rotation to, characterized in that stirring the yeast solution.

  The maximum diameter of the rotating body is 60 to 90% of the tank diameter, but is more preferably 70 to 90%.

  Here, the maximum diameter of the rotating body refers to the dimension (diameter) of the largest diameter portion in the rotating body formed when the stirring blade rotates.

  Moreover, although the height of a rotary body is 70% or more of the liquid depth at the time of standard storage of a yeast liquid, it is more desirable to set it as 90 to 120%.

  Here, at the time of standard storage of the yeast solution means a state in which the amount of yeast solution set in the design of the yeast solution storage agitation tank and the experience of operation management is stored, depending on the agitation tank. The standard storage amount of the yeast liquid is uniquely determined.

  Furthermore, although the rotation speed of a stirring blade is 1-30 rpm, it is more desirable to set it as 1-20 rpm.

  As described above, in the present invention, as the stirring blade of the stirring tank for storing yeast liquid, the maximum diameter of the rotating body that can be rotated by rotating the stirring blade is 60 to 90% of the tank diameter. Use a stirring blade that is 70% or more of the liquid depth at the time of standard storage of the yeast liquid, and the stirring blade is rotated at a rotation speed of 1 to 30 rpm, so that the entire inside of the tank is substantially uniform. The mixing and stirring effect can be remarkably improved compared to a yeast stirring tank equipped with a general inclined paddle blade or the like.

  Moreover, since the maximum diameter of the rotating body formed by the rotation of the stirring blade is 60 to 90% of the tank diameter, the height of the rotating body is set to be 70% or more of the liquid depth at the time of standard storage of the yeast liquid. A good stirring effect can be obtained even at a relatively low number of revolutions of 1 to 30 rpm. As a result, there is an effect that there is no possibility of damaging and destroying the yeast and reducing its biological activity.

  In particular, when the maximum diameter of the rotating body formed by the rotation of the stirring blade is 70 to 90% of the tank diameter, it is possible to more reliably prevent the yeast liquid from staying in the vicinity of the inner wall of the tank and to stir more uniformly. It will be possible.

  In addition, when the height of the rotating body formed by the rotation of the stirring blades is 90 to 120% of the liquid depth at the time of standard storage of the yeast liquid, the yeast liquid can be stirred and mixed more uniformly and is generated at the time of charging. The effect is that the bubbling disappears quickly after stirring.

  Furthermore, when the rotation speed of the stirring blade is set to 1 to 20 rpm, there is an effect that the yeast damage due to the shearing force is more reliably prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic front view schematically showing a yeast liquid storage stirring tank as one embodiment.

  In FIG. 1, 1 is a tank main body, the trunk | drum 2 is formed in the substantially cylindrical shape, and the bottom part 3 is formed in the reverse cone shape.

  Reference numeral 4 denotes a rotary shaft suspended substantially at the center of the tank body 1. Paddle blades 5 a and 5 b are vertically attached to the rotary shaft 4 in two upper and lower stages.

  The upper and lower paddle blades 5a and 5b are arranged at an intersecting angle of 45 degrees as shown in FIG.

  The stirring blade 5 constituted by the paddle blades 5a and 5b is set so that the maximum diameter of the rotating body formed when the stirring blade 5 rotates is 60 to 90% of the tank diameter.

  In addition, the height of the rotating body is set to be 70% or more of the liquid depth when the yeast liquid is standardly stored.

  Furthermore, the lower surface side of the lower paddle blade 5 b is formed in a slope shape in accordance with the inverted conical bottom 3 of the tank body 1.

  The yeast solution storage agitation tank 6 having the above-described configuration is used by being arranged at the rear stage of the main fermentation tank 7 for producing beer as shown in FIG.

  That is, the production process of beer includes a malt saccharification process, a fermentation process using yeast, and the like. In the fermentation process using yeast, a part of the yeast discharged from the main fermentation tank 7 is the above-described stirred tank 6 for storing yeast liquid. And is returned to the main fermenter 7 as a seed yeast for reuse.

  And in the stirring tank 6 for yeast liquid storage, it is necessary for the yeast to be stirred uniformly.

  By using the yeast solution storage stirring tank as in the above embodiment, stirring can be performed at a low speed that does not damage the yeast, and the whole can be stirred and mixed uniformly.

  In this case, since the paddle blades 5a and 5b are arranged above and below, a discharge flow is generated from each paddle blade 5a and 5b, and the upper and lower discharge flows do not interfere with each other. The flow can be connected smoothly.

  In addition, since the maximum diameter of the rotating body formed by the rotation of the stirring blade 5 is set to be 60 to 90% of the tank diameter, the yeast liquid can also flow near the tank inner wall of the tank body 1. It does not cause yeast damage.

  That is, if the maximum diameter of the rotating body is 60% or less of the tank diameter, the yeast liquid in the vicinity of the inner wall of the tank does not flow, so the yeast liquid is not uniformly stirred, and the sliding surface between the non-flowing part and the flowing part, While the yeast is destroyed by shearing force, if it is 90% or more, the gap between the wing and the inner wall of the tank is reduced, and a high shearing force is generated between the wing and the inner wall of the tank, and the yeast may be damaged. This is because the mixing effect is reduced and uniform mixing cannot be performed.

  As described above, the maximum diameter of the rotating body is set to be 60 to 90% of the tank diameter, but is preferably 70 to 90%, more preferably 75 to 90% and 80 to 90%. It is more desirable.

  If it is 70% or more, the fluctuation of the yeast concentration is reduced and the yeast is stirred more uniformly. By setting it to 75% or more and 80% or more, the fluctuation of the yeast concentration is further reduced and the yeast concentration is reduced. A uniform stirring effect is further improved.

  Furthermore, since the height of the rotating body formed by the rotation of the stirring blade is set to be 70% or more of the liquid depth at the time of standard storage of the yeast liquid, mixing failure does not occur.

  That is, when the height of the rotating body is less than 70% of the liquid depth, a portion where the flow is difficult to be transmitted to the yeast liquid is generated and cannot be mixed, and the concentration and temperature of the yeast liquid in the tank vary.

  In particular, the height of the rotating body is preferably 90 to 120% of the liquid depth.

  If it is 90% or more, the top of the stirring blade is present near the liquid surface during standard storage of the yeast liquid, so that stirring and mixing can be carried out more uniformly from the time of standard storage to the discharge of the entire amount. There is also an effect of disappearing quickly after stirring.

  On the other hand, if the ratio is 120% or less, the top of the stirring blade is slightly above the liquid level during standard storage, so that more uniform stirring and mixing can be achieved, and foaming can be eliminated.

  Here, the height H1 of the rotating body means a distance between the upper end of the rotating body formed by the rotation of the stirring blade 5 and the lower end of the rotating body as shown in FIG.

  Moreover, the liquid depth H2 at the time of standard storage of the yeast liquid is as follows. As shown in FIG. 4, the liquid level of the yeast liquid when the yeast liquid is accommodated in the tank body 1 (at the time of storage) and the bottom 3 of the tank body 1. Of the standard liquid volume, that is, the amount set in the design of the tank for storing the yeast liquid and the experience of operation management. It means a state where the yeast solution is stored, and the standard storage amount of the yeast solution is uniquely determined according to the stirring tank. In addition, the space above the liquid level at the time of standard storage is a space prepared for expansion at the time of foaming. Therefore, the standard storage amount here represents a volume for only liquid and yeast.

  Furthermore, the distance H3 between the lower end of the rotating body and the lowermost part of the bottom 3 of the tank body 1 is provided to uniformly stir and mix the yeast liquid without damaging the yeast liquid. Yes. If this distance is too short, the yeast is damaged during stirring, and if the distance is too large, uniform stirring cannot be achieved.

  Furthermore, the stirring blade is rotated at a rotation speed of 1 to 30 rpm.

  This is because if it is less than 1 rpm, it is difficult to stir and mix the yeast solution, and if it exceeds 30 rpm, the torque increases rapidly and the yeast is damaged by shearing force.

  In particular, in the case of 1 to 20 rpm, yeast damage due to shearing force is more reliably prevented. When the completely settled and separated yeast liquid is uniformly dispersed, rapidly cooled, or restrained from foaming, stirring is carried out for a short time at 10 rpm or more, and when maintaining the temperature, an extremely low speed close to 1 rpm is used. When continuous operation is performed or intermittent operation is performed at a low speed of 1 to 10 rpm, damage to the yeast can be prevented. In particular, since it is possible to homogenize by stirring from a state in which the yeast has settled and separated, it is desirable that the cooling be maintained at the minimum necessary low-speed intermittent operation without fear of sedimentation and separation of the yeast.

  Furthermore, since the upper and lower paddle blades 5a and 5b are arranged at an intersecting angle of 45 degrees when viewed from the plane, this phase shift causes a smooth flow of the yeast liquid up and down.

  By the operation as described above, a uniform stirring and mixing effect in the stirring tank 6 for storing yeast liquid can be obtained.

(Other embodiments)
In the above embodiment, the paddle blades are arranged in two upper and lower stages, but it is also possible to arrange the paddle blades in three or more stages.

  Further, in this embodiment, the upper and lower paddle blades are disposed at an intersecting angle of 45 degrees when viewed from above, but this intersecting angle is not limited to this embodiment.

  However, in order to generate a smooth flow of the yeast solution up and down to some extent, it is preferably within a range of 30 to 90 degrees.

  Furthermore, the structure of the yeast liquid storage stirring tank 6 is not limited to the structure in which the upper and lower multi-stage paddle blades 5a, 5b,... It doesn't matter.

  For example, like a stirring blade disclosed in Japanese Patent Laid-Open No. 7-786, a large plate blade having a large number of holes, or Japanese Patent Laid-Open No. 61-200842 and Japanese Patent Laid-Open No. 8-281809. As in the stirring blade disclosed in the publication, a plurality of large vertical flat blades are provided with different angles, and as in the stirring blade disclosed in Japanese Utility Model Laid-Open No. 7-34928, a large trapezoidal large blade. It is also possible to use a plate having a plate-like auxiliary wing attached to the back surface of the vertical flat wing.

  However, the stirring blade of the present invention has a change in shape, size, and mounting method in the vertical direction as compared with a simple anchor blade, paddle blade, and lattice blade, and the stirring blade can move the liquid up and down by those changes. Is desirable.

  In addition, in a stirring tank that requires sanitary properties such as brewer's yeast, it is desirable that there is no blade inclination or hole that would be a blind spot in the cleaning operation when washing the tank, the blade is vertical, and there are openings such as holes. It is desirable to use no stirring blade.

  In other words, a stirring blade having a smooth curved surface without a horizontal surface and a vertical surface that does not have bolts and joints in the stirring tank and impairs cleaning properties is desirable.

  In addition, such a stirring blade can sufficiently mix the yeast solution even without a baffle plate, so that it is not necessary to attach a baffle plate to impair the washing performance of the tank.

  By using such a stirring blade, a sufficient cleaning effect is obtained, and accidents such as microbial contamination do not occur.

  Furthermore, although the said embodiment demonstrated the case where a yeast stirring tank was used for beer manufacture, the use is not limited to this, It is also possible to use it for yeast stirring other than beer.

  The concentration of the yeast solution is mainly 30 to 60%.

  Here, the concentration of the yeast liquid means the volume% of yeast with respect to the liquid.

(Example 1)
In this example, the correlation between the stirring time and the pH change of the yeast solution was tested.

  In this example, a stirring tank having a volume of 4 m 3, an inner diameter of 1900 mm, and a maximum stirring blade diameter of 60% of the tank diameter was used.

  Further, the height of the rotating body formed when the stirring blades were rotated was set to be 1490 mm. As a result, the height of the rotating body is 97% of the liquid depth at the time of standard storage, and the top of the stirring blade is at a position approximately 50 mm higher than the liquid surface at the time of standard storage of the yeast liquid.

  Further, the stirring blades have paddle blades 5a and 5b provided at the top and bottom so as to intersect each other at an angle of 45 degrees as in the above embodiment.

  Furthermore, in this example, stirring was performed at a low rotational speed of 20 rpm.

  On the other hand, an inclined paddle blade was used as a comparative example.

  The inclined paddle blade has a maximum diameter of 800 mm when rotated and an inner diameter of the tank of 2200 mm. Therefore, the maximum diameter of the rotating body formed when the rotating shaft is rotated is about 36% of the tank diameter. Become.

  In the comparative example, stirring was performed at a rotation speed of 58 rpm.

  The result is shown in FIG.

  As is clear from FIG. 5, in the comparative example, the pH of the yeast solution was significantly changed with the change in the stirring time, whereas in this example, the pH was less changed compared to the comparative example.

  From this result, it can be determined that the yeast of the present example was less damaged than the comparative example.

  In addition, when the state of the yeast after stirring was observed with an electron microscope, as shown in Reference Photo 1, when stirring was performed with the tilted paddle blade of the comparative example, it was apparent that the yeast was damaged. It could be confirmed.

  On the other hand, the yeast solution stirred using the stirring tank of this example was in a good state with no damage to the yeast as shown in Reference Photo 1.

(Example 2)
In this example, the fluctuation of the yeast concentration when the yeast liquid is dispensed is measured.

  In this example, a stirring tank having a volume of 5 m 3 and an inner diameter of 2200 mm was used.

  In addition, the maximum diameter of the rotating body formed by the stirring blades when the rotating shaft was rotated was set to be about 83% of the tank diameter.

  Further, the height of the rotating body formed when the stirring blades were rotated was set to be 1993 mm. As a result, the height of the rotating body is 93% of the liquid depth at the time of standard storage, and the top of the stirring blade is at a position approximately 50 mm higher than the liquid surface at the time of standard storage of the yeast liquid.

  In this example, stirring was performed at a rotation speed of 20 rpm (Example 2-1) and 5 rpm (Example 2-2).

  On the other hand, as Comparative Example 2-1, a stirring tank equipped with a propeller-shaped stirring blade was used.

  The inner diameter of the tank was 2800 mm, and the maximum diameter of the rotating body formed by rotating the propeller-shaped stirring blade was 1600 mm. Therefore, the maximum diameter of the rotating body is about 57% of the tank diameter. The rotation speed was 70 rpm.

  Further, as Comparative Example 2-2, an inverted trapezoidal frame-shaped wing was used.

  The inner diameter of the tank was 2500 mm, and the maximum diameter of the rotating body formed by rotating the inverted trapezoidal frame-shaped stirring blade was 1400 mm. Therefore, the maximum diameter of the rotating body is about 56% of the tank diameter. The rotation speed was 70 rpm.

  The test results are shown in FIG.

  As is clear from FIG. 6, in each comparative example, the yeast concentration varied within a range of 15%, whereas in this example, the variation in yeast concentration was within 5%.

  From this result, it can be judged that the yeast of this example was uniformly stirred compared to the comparative example.

(Example 3)
In this example, the correlation between the number of times of discharging yeast in the tank and pH is tested.

  After containing yeast in the stirring tank, a fixed amount was discharged every 3 hours, the discharge was performed 8 times, and the change in pH with the number of discharges was measured.

  More specifically, the mixture was stirred for 10 minutes at 10 rpm before discharging, and the pH of the discharged yeast liquid was measured.

  As the agitation tank, a tank in which the maximum diameter of the rotating body formed by the agitation blades when the rotating shaft is rotated is about 83% of the tank diameter was used.

  The height of the rotating body was set to be 93% of the standard storage time of the yeast solution in any case.

  The test results are shown in FIG. As is clear from FIG. 7, in both Example 3-1 and Example 3-2, the pH fluctuation was within 0.2 even though the discharging operation was performed 8 times for 24 hours.

  From this result, it was confirmed that almost no yeast damage was observed in both Example 3-1 and Example 3-2.

Example 4
In this example, the correlation between the number of times the yeast in the tank is discharged and the yeast concentration is tested.

  After storing the yeast in the stirring tank, a fixed amount was discharged every 3 hours in the same manner as in Example 3, the discharge was performed 8 times, and the change in the yeast concentration with the number of discharges was measured.

  The change in the yeast concentration was measured by the change in the viable cell sensor value.

  Yeast is positively charged in the living state, and negatively charged when it is killed.

  When the dielectric constant of the yeast liquid is measured, the viable cell sensor is one in which the viability of the yeast can be confirmed, and this can be detected by a sensor and converted into the yeast concentration.

  As an agitation tank, when the rotating shaft is rotated, the maximum diameter of the rotating body formed by the agitating blade is about 60% of the tank diameter (Example 4-1), and the maximum diameter of the rotating body is the tank diameter. 3 (Example 4-2), and the maximum diameter of the rotating body was about 83% of the tank diameter (Example 4-3).

  The height of the rotating body was set to be 93% of the standard storage time of the yeast solution in any case.

  The test results are shown in FIG.

  As is clear from FIG. 8, Example 4-1 and Example 4-2 were discharged 8 times, and Example 4-3 was discharged 4 times, but the fluctuation of the yeast concentration was within 8%. Met.

  In particular, in Example 4-2 in which the maximum diameter of the rotating body was about 75% of the tank diameter, the fluctuation of the yeast concentration was about 5%, and the maximum diameter of the rotating body was about 83% of the tank diameter. In the case of Example 4-3, the fluctuation of the yeast concentration was about 3%.

  From these results, it was confirmed that there was little yeast damage in each example, and in particular, in Example 4-2 and Example 4-3, almost no yeast damage was observed.

  Further, it was confirmed that a rotating body having a maximum diameter of about 60% or more, more than 80% or more than about 60%, was uniformly stirred.

(Example 5)
In this embodiment, the temperature change at each point in the tank is measured.

  In this example, the same stirring tank as in Example 1 was used.

  That is, the stirring tank of this example was a tank having a volume of 4 m 3 and an inner diameter of 1900 mm, and was installed so that the maximum diameter (blade diameter) of the rotating body was 1140 mm and the height of the rotating body was 1490 mm. As a result, the height of the rotating body is 97% of the liquid depth during standard storage.

  The temperature when the yeast liquid was stirred at 1 rpm and 20 rpm in such a stirring tank was measured over time.

  Specifically, the temperature change in the stirring vessel when the stirring blade in the stirring vessel is rotated at 1 rpm and 20 rpm at different rotation speeds is measured over time by a temperature sensor, and the effect of the stirring is measured. confirmed.

  The results are shown in FIGS.

  In addition, the temperature measurement site | part in a stirring tank is the point described in FIG.

  As shown in FIG. 9 to FIG. 11, it can be seen that there is little variation in temperature due to the difference in the measurement site in the tank, and that there is almost no variation when stirring at 20 rpm.

  From this, it can be seen that the temperature in the tank is uniformly stirred and maintained at a constant temperature even at a very low speed of 1 to 20 rpm.

(Example 6)
In this example, the temperature followability in the tank was tested.

  Also in the present example, similarly to the above-described Example 1, a container having a volume of 4 m 3 and an inner diameter of 1900 mm was used, and the rotating body had a maximum diameter of 1140 mm and the rotating body had a height of 1490 mm. The height of the rotating body is 97% of the liquid depth during standard storage.

  The stirring blade was stirred at 20 rpm. As a comparative example, a two-stage paddle blade as shown in FIG. 12 was used and stirred at 53 rpm. The result is shown in FIG.

  In general, the storage temperature of the yeast liquid is controlled according to the time chart, and until the temperature in the tank reaches the set temperature, a refrigerant is passed through the jacket around the stirring tank to cool the yeast liquid in the tank. is doing.

  Therefore, if the temperature followability in the tank is poor, the yeast liquid near the outer peripheral surface is rapidly cooled, but the yeast liquid in the center of the tank remains uncooled, resulting in a temperature difference within the tank. Will occur and the cooling efficiency of the tank will deteriorate.

  FIG. 13 shows the results of measuring the followability of the temperature in the tank when the yeast liquid was stirred using the stirring tank of the example and when the yeast liquid was stirred using the stirring tank of the comparative example.

  As shown in FIG. 13, even when the stirring speed is a low speed of 20 rpm, the temperature followability is better in this example than in the comparative example, and it can be seen that uniform stirring can be performed in a short time without performing high-speed stirring. Moreover, in order to follow a delicate temperature setting well, there exists an effect that the temperature control of yeast is performed appropriately.

(Example 7)
In this example, the viable cell rate of yeast is measured.

  Specifically, using three types of stirring tanks described later, the viable cell ratio before and after stirring when the yeast was stirred was determined.

  For the measurement of the viable cell rate, the yeast stained with methylene blue was observed with a microscope, and the viable cells were counted using a hematometer.

(Example 7-1)
The agitation tank of this example uses a tank having a volume of 5 m3 and an inner diameter of 2100 mm, and is installed so that the maximum diameter (blade diameter) of the rotating body is 1745 mm and the height of the rotating body is 1993 mm. The liquid depth during storage was set to 93%.

  The viable cell rate was measured when the yeast solution was stirred at 5 rpm for 36 hours in the stirring tank.

(Example 7-2)
The stirring tank of this example is a tank having a volume of 5 m3 and an inner diameter of 2100 mm, and is installed so that the maximum diameter (blade diameter) of the rotating body of the stirring blade is 1745 mm and the height of the rotating body is 1993 mm. The liquid depth at the time of standard storage of the liquid was set to 93%.

  The viable cell rate was measured when the yeast solution was stirred at 5 rpm with a residence time of 33 hours in the stirring tank.

(Example 7-3)
The stirring tank of this example is a tank having a volume of 5 m3 and an inner diameter of 2100 mm, and is installed so that the maximum diameter (blade diameter) of the rotating body of the stirring blade is 1745 mm and the height of the rotating body is 1993 mm. The liquid depth at the time of standard storage of the liquid was set to 93%.

  The viable cell rate was measured when the yeast solution was stirred at 5 rpm with a residence time in the stirring tank of 39 hours.

  FIG. 14 shows the result of measuring the viable cell rate of the yeast before and after stirring when stirring is performed under the above conditions.

  As is apparent from FIG. 14, the viable cell rate in this example was almost the same before and after stirring. This shows that the yeast cells were not damaged by stirring.

(Example 8)
In this example, the correlation between the rotational speed of the stirring blade and the shaft torque was tested using the stirring tank of Example 7. The liquid depth at the time of standard storage of the yeast liquid was also tested in the same state as in Example 7.

  The correlation is shown in FIG. 15 for yeast immediately after collection, yeast after 24 hours of collection, and known Newtonian fluid.

  As shown in FIG. 15, the axial torque required for the yeast immediately after recovery is larger than the axial torque required for the yeast after 24 hours of recovery.

  In FIG. 15, the intersection of the line indicating the yeast data and each line indicating the Newtonian fluid data indicates that the apparent viscosity of the yeast liquid at that rotational speed is equal to the viscosity of the Newtonian fluid.

  It can be understood that the apparent viscosity of the yeast liquid changes from 30000 cp to 1000 cp with respect to the rotation speed from 2 rpm to 20 rpm, and is a non-Newtonian fluid.

  Furthermore, it is recognized that the stirring torque of the yeast slurry tends to be almost constant regardless of the rotation speed at 10 rpm or less. This trend is a characteristic observed in Bingham fluid, and the data in FIG. 15 indicates that the yeast fluid is Bingham fluid. Bingham fluid is a fluid having a yield stress, and the fluid does not move even if a force below the yield stress is applied.

  From this, it is estimated that the yeast fluid is not a general fluid that can be mixed relatively easily, but a special fluid that requires special consideration for fluidizing the whole and mixing it uniformly. The

The schematic front view which shows typically the yeast stirring tank as one Embodiment. The schematic plan view which shows the arrangement | positioning state of the paddle blade of a yeast stirring tank. The schematic block diagram which shows the positional relationship of a yeast stirring tank and a main fermentation tank. The schematic front view for showing the height of a rotary body, and the liquid depth at the time of the standard storage of a yeast liquid. The graph which shows correlation with stirring time and pH of a yeast liquid. The graph which shows the fluctuation | variation of yeast concentration. The graph which shows correlation with the frequency | count of discharging | emitting the yeast in a tank, and pH. The graph which shows the correlation with the frequency | count of discharging | emitting the yeast in a tank, and a yeast concentration. The graph which shows the correlation with the temperature in a tank, and stirring time. The graph which shows the correlation with the temperature in a tank, and stirring time. Explanatory drawing which shows the temperature measurement position in a stirring tank. Explanatory drawing which shows the stirring blade of a comparative example. The graph which shows the correlation with the temperature in a tank, and elapsed time. The graph which shows the viable cell rate of yeast. The graph which shows correlation with a rotation speed and shaft torque.

Explanation of symbols

    1 ... tank body 5 ... stirring blade

Claims (3)

While reserving a portion of the yeast liquid discharged from the fermentor to ferment fermented foods such as bi Lumpur (7), return to for reuse stored yeast solution the fermenter to (7) In the method for producing fermented foods such as beer having a step of stirring the yeast solution in the yeast solution storage stirring tank, the tank body (1) of the yeast solution storage stirring tank is formed in a substantially cylindrical shape, Around the tank body (1), there is provided a jacket for flowing a refrigerant for cooling the yeast liquid in the tank body (1), and is constituted by a non-tilted vertical plane, A stirring blade (5) configured such that the maximum diameter is 60 to 90% of the tank diameter and the height of the rotating body is 70% or more of the liquid depth at the time of standard storage of the yeast liquid, Provided in a stirring tank, rotate the stirring blade (5) at a rotation speed of 1 to 30 rpm, Manufacturing method of fermented foods such as beer, characterized in that the 拌. Method for producing a stirring blade (5) fermented foods such as beer according to claim 1, wherein the maximum diameter of the rotation body formed during the rotation is 70 to 90% of the So径of. Producing how fermented foods such as beer according to claim 1 or 2, wherein rotating at 1~20rpm a stirring blade (5).

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