JPS5841833B2 - How to treat liquid medium after fermentation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [I] Background of the Invention The present invention relates to a method for separating and recovering microorganisms from a liquid medium that has undergone fermentation.

Viewed from another perspective, the present invention relates to a method for separating and recovering a liquid fermentation product from a liquid medium that has undergone fermentation.

More specifically, the present invention relates to a method for recovering concentrated yeast from residual yeast, for example during the brewing of beer.

Yeast used in beer production in Japan (bottom-fermenting beer yeast) settles at the bottom of the fermentation tank and separates into semi-finished beer when the main fermentation and post-fermentation are nearing completion.

The yeast thus separated, i.e. residual yeast, is present in a considerable amount (e.g. approximately 2 V/V% of the total semi-finished product in the fermenter).
reach.

The residual yeast separated from the fermentation liquid by decantation etc. has a solid content of about 15 to 20% by weight,
Contains about 80-85% by weight of semi-finished beer.

In the past, this residual yeast was only used to recover the yeast, and the semi-finished beer contained therein was discarded without being separated and recovered.

In other words, if residual yeast with a high concentration of yeast is left to stand under atmospheric pressure, most of the yeast will settle, but some will rise to the surface of the liquid in the form of a scum due to the carbon dioxide gas generated by fermentation of the residual sugar. It forms a thick layer and is divided into three layers: yeast, semi-finished beer, and yeast, and it is difficult to efficiently recover only the semi-finished beer, so it is washed together with the yeast to obtain the recovered yeast.

In that case, the beer in the middle layer is discarded without being recovered, and the yeast in the bottom layer is recovered, and the Q yeast in the upper layer is discarded because it is difficult to recover, so the yield of the process is poor. At the same time, the COD load of wastewater becomes significantly large, requiring large amounts of capital investment and operating costs.

From this point of view, and with the support of recent advances in brewing technology, recovery of semi-finished beer and yeast from residual yeast that has been discarded is being considered overseas as well.

However, these methods all use filtration machines and centrifuges to separate and recover yeast and beer, so they require a large amount of capital investment, labor, and power. However, it is difficult to put it into practical use because the labor burden is relatively large.

Such problems occur not only in beer production, but also in general when trying to separate and recover microorganisms and liquid fermentation products from a liquid medium after fermentation.

(1) Summary of the Invention The present invention aims to provide a solution to the above-mentioned problems, and attempts to achieve this purpose by allowing the liquid medium after fermentation to stand still under pressure.

Therefore, the method for treating a liquid medium after fermentation according to the present invention is to treat a liquid medium containing a solid component and a liquid component after fermentation.
The method is characterized in that after a part of the liquid component is removed, it is allowed to stand still under pressure to promote sedimentation of the solid component.

As described above, the present invention provides a solution to the liquid component (
By performing sedimentation separation of solid components (hereinafter referred to as beer) and solid components (hereinafter referred to as yeast) under pressure, virtually the entire amount of yeast can be removed without the levitation of a part of the yeast that conventionally occurs. We succeeded in improving the recovery rate of beer and yeast by sedimentation.

In the present invention, pressurization depends on the conditions of the beer and yeast, but for example, a pressure of about 0.5 kg/crtt (gauge) or higher is sufficient, so a conventional closed container can be used as it is with N or It can be used simply by making it somewhat pressure resistant, and since the pressurizing means is typically the injection of air or other gas, the increase in equipment investment is small and labor can be saved.

Additionally, removing a portion of the liquid component is also normally carried out in order to recover the fermentation products contained in the liquid component.

Therefore, for example, by simply placing yeast in a separation sedimentation tank, leaving it under pressure for a certain period of time (for example, day and night), and expelling the settled yeast out of the tank by the applied pressure,
Approximately 50-60% of the recoverable beer (40% of the total residual yeast)
~50%) can be collected almost unattended.

Furthermore, yeast can be reused in the same way as before.

In addition, in the past, yeast recovery and cleaning work was concentrated for a period of time after the completion of fermentation, creating difficulties in terms of equipment and work, but with the method of the present invention, time constraints on yeast processing work are greatly alleviated. will be done.

0 Detailed Description of the Invention 1. Liquid medium after fermentation A liquid medium after fermentation comprising a solid component and a liquid component is generally the subject of the present invention.

Specifically, there are, for example, beer fermentation liquid, Japanese sake fermentation liquid, and the like.

The liquid medium targeted by the present invention is obtained by removing a part of the liquid components from this liquid medium, and specifically, for example, a solid component concentrate that has been sedimented and separated (for example, during beer brewing) residual yeast).

One representative example of the fermented liquor after completion of fermentation is beer fermented liquor.

And, more specifically, it is the residual yeast recovered from the fermenter, especially the main fermenter.

This is recovered from the main fermentation liquid by decantation or the like, and has a solid content of about 15 to 20% by weight.

In the following explanation, the present invention will be explained with respect to the residual yeast after the completion of the main fermentation.

2. Pressurization Pressurization can be performed not only by pressurization by a rigid surface such as pressurization by a piston in a cylinder, but also by pressurizing gas into a closed tank.

The most preferable method is pressurization by injecting gas.

Any pressurizing gas may be used as long as it does not have an adverse effect on the semi-finished beer or yeast to be recovered.

From an economic point of view, air and carbon dioxide are suitable.

After completion of the main fermentation, residual yeast recovered from the fermentation tank is collected in a closed sedimentation tank, air is forced into the tank, and the tank is preferably allowed to stand still while keeping the internal pressure constant.

The flotation and scum formation of yeast observed when no pressure is applied is suppressed, and the yeast continues to settle naturally.

As a result, the yeast settles to the bottom of the settling tank, and a beer tank forms at the top of the tank.

If the outlet at the bottom of the tank is opened, the precipitated yeast will be discharged by the pressure inside the tank.

Solid-liquid separation progresses over time, and its effect appears in a logarithmic curve.

3-An example of the solid-liquid separation effect of the main fermentation residue yeast when a sedimentation tank is used and left under an air pressure of 1.8 kg/ca (gauge) is as shown in the table below.

The effect of national isolation seems to vary depending on how the physiological state of the yeast is managed.

It also depends on various process control factors such as the following.

(1) Product temperature The separation effect is better when the product temperature is appropriately high.

This is especially true when the settling time is short (the solid-liquid separation effect depends on the product temperature).

Specifically, for example, 0 to 20°C, preferably 3 to 8°C
It is normal that it is about a certain degree.

An example of the solid-liquid separation effect when using a 50J sedimentation tank and standing under an air pressure of 1.8 kg/crA (gauge) at product temperatures of 5°C and 15°C is as shown in the table below. be.

(2) Pressure It is desirable that the pressure be low from the standpoint of equipment, work, safety, etc., and also from the viewpoint of yeast physiology, but if the pressure is too low, the yeast layer often floats in the form of a scum.

The specific pressure can be determined by a simple experiment taking into account other conditions (for example, product temperature), but for example, if the product temperature is around 5°C, the
Gauge) can provide sufficient effect.

(3) Sedimentation Tank Volume and Yeast Amount The separation situation seems to vary depending on the sedimentation tank volume and the amount of yeast in the tank.

Generally, in a small-scale case, the separation speed and separation effect are lower than in a field-scale case.

Claims (1)

[Claims] 1. Termination of fermentation, which is characterized by removing part of the liquid medium from a liquid medium containing solid components and liquid components after completion of fermentation, and then leaving the medium under pressure to promote sedimentation of the solid components. How to process the liquid medium afterwards.