JPS59159774A - Selection of grown seed of yeast - Google Patents

Abstract

PURPOSE:To obtain grown seed of yeast having given cohesiveness and dispersibility without carrying out fermentation test, by screening a yeast rapidly precipitating under agglomeration conditions and floating longer under dispersion conditions. CONSTITUTION:A yeast is suspended in a solution having pH and saccharide concentration adjusted to values suitable for agglomeration and dispersion, namely, a solution having fermentation period to carry out agglomeration and dispersion of yeast, or a solution made into the same conditions, the suspension is allowed to stand for a given time, the precipitated or floating yeast is collected, this yeast is suspended in a solution having pH and saccharide concentration adjusted to values suitable for agglomeration and dispersion, the suspension is allowed to stand for a given time, and the floating or precipitated yeast is collected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for breeding and selecting yeast, and more particularly to a method for breeding and selecting yeast having desired flocculation and dispersibility.

Yeast is used in a variety of fields, including the production of alcoholic beverages such as beer, sake, and wine. However, for example, in beer brewing, the settling ability of yeast may gradually change for some reason. Such a phenomenon is undesirable in terms of fermentation management. In addition, fermentation conditions 1
Yeast with different flocculating properties may be required due to changes in working conditions, etc.

A method of selecting yeast with specific properties is known for the purpose of freely controlling the flocculation and dispersibility of yeast. However, these conventional methods require confirmation by conducting fermentation tests, which are not only time-consuming, but also difficult to objectively judge, and the results vary depending on the test conditions, making them unreliable. There are many problems such as low

The present inventors believe that yeast flocculation and dispersion are phenomena that occur because the physicochemical properties of the cell surface change depending on the surrounding conditions, and that yeast sedimentation occurs quickly under flocculation conditions even without a fermentation test. However, we thought that if we screened for yeast that could float for a long time under dispersion conditions, we would be able to breed and select yeast with appropriate flocculation and dispersibility, and we conducted repeated studies. As a result, the present invention was completed.

The present invention is a yeast breeding and selection method including the following steps.

(b) A step of suspending yeast in a solution adjusted to the desired pH and sugar concentration for flocculating or dispersing yeast; (b) A step of collecting settled yeast or floating yeast after standing for a predetermined period of time; (c) a step of suspending yeast in a solution adjusted to the desired pH and sugar concentration for dispersion or flocculation, and (c) a step of recovering floating or settled yeast after standing for a predetermined period of time. Specifically, the solution used for the flocculation conditions in step (a) or (c) refers to a liquid at the fermentation period in which yeast flocculation is desired to be achieved, or a solution under conditions equivalent thereto. For example, in beer brewing, the beer composition used when fermentation is completed. In other words, it is a solution that has the conditions required to flocculate yeast. In this case, it is important to adjust the pH and sugar concentration, but also contain substances that are involved in yeast flocculation (e.g., yeast flocculating organic substances and inorganic salts present in barley, malt, or wort). It is also necessary to Note that when beer contains gas, yeast floats to the surface due to air bubbles, making accurate assay difficult. However, in such a case, a degassed solution should be used. In addition to degassed beer, fruit juice, fermented grain saccharified liquid, and non-fermentable oligosaccharides and their derivatives, which will be described later, can be used. When targeting brewer's yeast, pHA is 8 to 4.8. Preferably, the solution has a sugar concentration of 5% or less, usually about 0.1 to 3%.

This is the condition under which yeast would be expected to achieve flocculation. Therefore, if you want fermentation to proceed to the limit, 0
If you expect the residual sugar to be 5% after fermentation, choose 5%. When suspending yeast,
The yeast concentration should be α001 to α5fi'/IIL/, preferably α01 to α1 p/m7.

Further, as a container for storing the solution, a vertically long container such as a buret-type glass tube is preferable.

Next, there are no particular restrictions on the standing conditions in step (b), but it is desirable to stand at a low temperature, usually 0.
〜60℃1 Preferably 1 minute at a temperature of 0 to 20℃〜
Let stand for 48 hours, preferably 2 to 24 hours. After standing still for a predetermined period of time, settled yeast or floating yeast is collected. Yeast may be recovered by any appropriate means, such as using a burette-type glass tube,
The settled yeast may be gently removed from the bottom of the container. Further, floating yeast can be collected by collecting the suspension and performing centrifugation, filtration, etc.

The solution used for the dispersion conditions in step (c) or (a) refers to the liquid at the fermentation stage where yeast dispersion is desired to be achieved, as opposed to the aggregation conditions described above, or a solution under conditions equivalent thereto. In this case as well, it is necessary to appropriately adjust the pH and sugar concentration of the solution. Dispersion conditions are conditions that promote fermentation. At this time, a solution containing mainly non-fermentable sugars is used, specifically non-fermentable oligosaccharides and their derivatives, such as hexoses or their derivatives (such as sorbose, mannose, D-glucosamine, α- methyl-D-glucoside, α-methyl-D-galactoside, etc.), cellobiose, salicin,
These include arbutin, trehalose, lactose, sorbitol, and mannitol.

The concentration of non-fermentable saccharides in the solution is determined by considering the level of dispersibility or flocculation of the target yeast, and is usually between 2 and 3.
50%, preferably within the range of 4 to 20%. Furthermore, as a solvent for non-fermentable saccharides, various aqueous solutions other than water can be used, but buffers such as Q, 1M acetate buffer (TIH 5,0-60), etc. are usually used. As the eight vessels used here, the same burette type glass container as mentioned above is preferable. In addition, it is preferable to leave it at a low temperature.
The temperature is usually 0 to 60°d1, preferably 0 to 20°C.

There are no particular restrictions on the standing conditions (especially the time) in (next trap, step), and after leaving it standing for 1 minute or more for about 7 days, usually 50 minutes to 24 hours, the floating yeast or settled yeast is removed. to recover. The standing time is determined by considering the shape of the container, the standing temperature, etc. Yeast can be recovered by collecting the suspension excluding precipitated matter and performing operations such as centrifugation and filtration. Further, the settled yeast may be recovered by gently pulling it out from the bottom of the container.

Alternatively, instead of the non-fermentable oligosaccharides in step (c) above, a solution containing fermentable sugars (such as wort) can be used. In this case, if the yeast is suspended and left for a long time, fermentation will occur and the yeast will float, making accurate assay impossible. It should be a short period of time, about 5 hours. Furthermore, when using such a fermentable solution, conditions such as conditions that do not allow yeast to ferment (but preferably within a range that does not reduce the activity of yeast), such as low temperature, pressure, addition of a fermentation inhibitor, etc. It needs to be done below. Specifically, at a low temperature of -2 to 0°C,
α5~skg/c++ at 0~10°C within 2 hours! For 24 to 48 hours under pressure, or by adding a fermentation inhibitor such as an antibiotic (such as actidione) or monoiodoacetic acid (α005 to about 0.01%), and these methods can be used alone or in combination as appropriate. Note that addition of salts is not preferable because it affects cohesiveness.

The above steps (a) and γ) can be carried out in any order, and it is preferable to repeat steps (c) and 2) multiple times, usually 4 to 6 times.

As described above, according to the present invention, agglomeration and
It is possible to select yeast that will settle and disperse and float at the desired time of dispersion. By appropriately changing the conditions, the method of the present invention can be applied to brewer's yeast, sake yeast, wine yeast, etc.
whiskey yeast.

It can be applied to various yeasts such as alcoholic yeast.

Next, the present invention will be explained using examples.

Example 1 2 t of brewer's yeast (Saccharomyces ubarum AE AM 4206), which had been statically cultured in wort, was suspended in 2 (1 m/ml) of degassed Kiheel (pH 4.1, sugar content 1.8%),
It was placed in a 0 m capacity burette and left standing. After 2 hours, the yeast that had settled to the bottom of the container was removed.

Next, the entire amount of this sampled yeast was mixed with 5% α-methyl-D-
The suspension was suspended in 201 glucoside 01M acetic acid-grade buffer solution (pH 5.5), placed in a 2Qml buret, and left to stand. After standing for a day and night, the yeast suspension from which the settled yeast had been removed was collected and centrifuged to recover the yeast.

Thereafter, a 5% α-methyl-D-glucoside solution (p
The operations of suspending yeast in H5-5), standing still, and recovering yeast by centrifugation were repeated four times.

The yeast thus obtained was placed on a wort agar medium at 25'C, 4
Plated for 8 hours. From this culture 4 large colonies
The strains were harvested and each strain was cultured in wort at 20'C for 48 hours until 7 days old. A flocculation test was conducted on the obtained yeast. That is, 0.61 of each yeast was mixed with acetic acid (pH 4.2).
) The yeast was suspended in 1'Oif and taken into a blood sedimentation tube, and the flatness of the sedimented yeast was compared after 60 minutes.

Next, the one strain that showed the greatest flocculation-sedimentation property among the four strains was cultured again in wort at 20° C. for 48 hours. After repeating the flocculation/dispersion selection method described above twice for the yeast obtained by this culture, the yeast was cultured again on a wort agar medium at 25°C.

Plated for 48 hours. Ten strains were picked from this culture, and each strain was cultured again on a wort agar medium. The obtained yeast was subjected to an agglutination test in the same manner as above.

In this case, as a control, the parent strain was tested under the same conditions for comparison. The results are shown in Figure 1.

As is clear from the figure, all of the 10 selected strains had strong aggregation properties, both as well as the parent strain. This yeast has a pH of 4,
2. It has the property of aggregating at a sugar concentration of 0% and dispersing at a pH of 5.5 and a sugar concentration of 5%.

Example 2 Degassed diet beer (pH 4.8, extract (13%) was used as a substitute for the degassed beer of Example 1, and
Yeast for diet beer was selected in the same manner as in Example 1, except that a 4% lactose solution was used instead of the 1% α-methyl-p-glucoside solution. This yeast aggregates at pH 4.3 and sugar concentration 11.3%, and at pH 6.0,
It has the property of dispersing at a sugar concentration of 5%.

Example 3 When the yeast was treated in the same manner as in Example 1 except that the dispersion conditions were first set and then the flocculation conditions were set, yeast having the same dispersibility and flocculation properties as in Actual IFi Example 1 was obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the results of an agglutination test conducted on yeast selected by the method of the present invention. Patent applicant: Sapporo Breweries Ltd., patent attorney: Kubota Fujibe f.J.

Claims (1)

[Claims] 1. A yeast breeding and selection method comprising the following steps. (b) A step of suspending yeast in a solution adjusted to the desired pH and sugar concentration for flocculating or dispersing yeast; (b) A step of collecting settled yeast or floating yeast after standing for a predetermined period of time; (c) a step of suspending yeast in a solution adjusted to the desired pH and sugar concentration for dispersion or flocculation, and (c) a step of collecting floating or settled yeast after standing for a predetermined period of time.