JPH07123975A - Bread yeast - Google Patents

Abstract

PURPOSE:To provide a new bread yeast such as Saccharomyces cerevisiae P-610, having excellent pH stability esp. at low temperatures, capable of giving bread dough not lowering its pH during refrigeration, thus capable of obtaining bread having mild flavor free from acid odor. CONSTITUTION:Each one platinum loop of normal bread yeast strain (NV59(a/a) ade<->) and a respiration-depleted strain (FP35rho<-> (a/alpha)) obtained by mutation with ethidium bromide of a bread yeast strain low in pH level at low temperatures (FP35(a/(alpha)) are inoculated on a medium and subjected to shaking culture at 30 deg.C for 24hr, respectively, and the resultant collective culture fluid is put to stationary culture at 30 deg.C for 24hr to conduct crossing to obtain a crossed strain (NV50(a/a)ade<->). Next, this strain is crossed with a mutant (FP36rho<->(a/alpha)) obtained by mutation with ethidium bromide of normal bread yeast (FP36(a/alpha)) to obtain the objective bread yeast such as Saccharomyces cerevisiae 610 (FERM P-13919) having the above-mentioned advantages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to baker's yeast, and more particularly to baker's yeast exhibiting pH stability in a low temperature range and a bread making system using the same.

[0002]

2. Description of the Related Art In recent years, in the bakery industry, the manufacture of bread using refrigerated dough has been attracting attention because of the great advantages of streamlining the bread making process and supplying freshly baked bread.

This refrigerated dough is a retard dough (ret
Also called ard dough), the partially fermented dough is put in a box called a refrigerator or a retarder and refrigerated and stored while suppressing the fermentation of the dough. This refrigerated dough is used not only for the production of ordinary bread such as a loaf of bread, but also for the production of bread that is rich in pastries, croissants and other ingredients.

[0004]

However, when the dough is stored in a refrigerator, its pH is lowered, and as a result,
A sour taste is generated, and the coloring of the bread is deteriorated, so that bread of excellent quality cannot be manufactured. The present invention was made for the purpose of solving the problem of structurally lowering the pH of refrigerated dough.

[0005]

Means for Solving the Problems The present invention has been made in order to achieve the above-mentioned object, and is a result of extensive studies from various aspects such as a refrigeration system, dough formulation, use of additives, and a baking process. , Came to pay attention to baker's yeast itself.

[0006] Therefore, there is a demand for baker's yeast which does not lower the pH even when refrigerated bread dough is refrigerated, that is, baker's yeast having a small change in pH in low-temperature dough, in other words, baker's yeast having excellent pH stability at low temperatures. We conducted a thorough screening, but did not succeed.

Then, the idea was changed, and the intended baker's yeast was created by breeding, and as a result of diligent efforts, the present invention finally succeeded in the preparation of the desired strain and completed the present invention.

That is, the present invention relates to Saccharomyces cerevisiae P-610 (Sacchar) which has an excellent bread-making function without lowering the pH even in refrigerated dough.
omyces cerevisiae P-610) strain. The present invention also relates to a new bread dough containing this useful new strain and a new bread making method using the same.

The present invention will be described in detail below.

[0010] In order to obtain the target strain most efficiently, as a result of examination from various directions, a method by crossing was adopted, and the target strain was produced by the crossing method.

First of all, a baker's yeast strain having a low pH change at a low temperature is selected, and if necessary, it is mutated and marker-treated as a respiratory deficient strain. Let's cross. Crossing may be performed according to a conventional method. After culturing each of these strains in a YPG medium or the like, mixing these, and then culturing the hybrid strain in a medium for detecting and detecting a hybrid strain such as YNB medium, the cell size and Select the target colony based on the complementarity of the marker.

After culturing the thus selected colonies, the fungus is separated, the resulting hybrid strain is sporulated, and then monospores are separated by a conventional method such as a micromanipulator to obtain the desired spore strain. To get If this is further cultured, a growing strain can be obtained. If necessary, this treatment may be repeated, or the crossing partner strain may be changed to carry out further crossing treatment to produce a further excellent crossing strain.

As the marker used for detecting the target strain, the one originally possessed by the parent strain can be used as it is, or the parent strain can be mutated to screen for lysine-requiring strains or respiratory deficient strains. May be screened or the target strain may be selected reliably and promptly. As the mutagenesis treatment, in addition to physical treatments such as γ-rays, ultraviolet rays, and temperature differences, conventional methods such as ethidium bromide, nitrogen mustard, diepoxybutane, colchicine, peroxide, purine derivatives and other mutagenesis agents can be widely used. .

The new strain thus obtained is Saccharomyces c.
erevisiae) P-610, and FERM P-13919 at the Institute of Biotechnology, Institute of Biotechnology, AIST.
Has been deposited as. The mycological properties are shown in Tables 1 and 2 below.

[0015]

[Table 1]

[0016]

[Table 2]

The strain of the present invention has the above-mentioned mycological properties and is characterized in that it is excellent in pH stability especially in a low temperature range. Such a strain was not found in previously known strains and was identified as a new strain. In the present invention, the present strain is not the only right, and includes all strains having excellent pH stability in the low temperature range, including all artificially produced strains and those isolated from the natural world. It is a thing. In the following, such strains will be referred to as LT
Sometimes called east.

To make bread according to the invention,
The bread-making step may be carried out using LT yeast such as P-610 strain and the like by a refrigerated dough manufacturing method or the like according to a conventional method.
At that time, according to the present invention, unlike the conventional method, the pH of the dough does not decrease during cold storage and no acid odor is generated, the coloring of the bread does not decrease, and the pH of the dough decreases. Therefore, bread having stable quality can be produced without causing the drawbacks of the conventional methods.

Therefore, the bread-making method according to the present invention can be used not only in the refrigerated dough-making method and the low-temperature long-time bread-making method, but also in the pastry-croissant making method and the like. Especially in the latter, since the large-divided dough is retarded at a low temperature before folding the fats and oils, a pH decrease occurs in normal baker's yeast, but in LT yeast, the pH decrease of the dough after retard is significantly suppressed, As a result, high quality pastries, croissants and the like can be manufactured.

As described above, since LT yeast does not lower the pH of the refrigerated bread dough, a large amount of the bread dough is prepared, stored in the refrigerated state, and the bread making process is carried out at the necessary place when necessary. Therefore, large-scale production and large-scale processing can significantly reduce costs, which is also excellent in terms of rationalization and industrial processing. On the other hand, since the refrigerated bread dough thus prepared can be stored in a refrigerator at home, various freshly made breads can be freely baked at home.

[0021]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited thereto.

[0022]

Example 1 Normal baker's yeast strain (NU59 (a / a) a
De-) and a baker's yeast strain (FP35 (a / α)) with little change in pH at low temperature were crossed according to Table 3 below.

[0023]

[Table 3]

First, BCP was selected as a pH stable strain.
Color change of (Bromcresol purple) (OD 59
The pH-stable strain (FP35 (a / α)) was selected from the situation of pH decrease by measuring 0 nm colorimetric). Next, this strain was subjected to mutation treatment with ethidium bromide (EtBr) to obtain its respiratory deficiency strain (FP35ρ- (a / α)). This respiratory deficiency strain and the ordinary baker's yeast strain are each
Take a platinum loop and inoculate it in YPG medium and incubate at 30 ℃
Shaking culture was performed for each time. 100 cultures each
After collecting 1 μl of each well and combining them, the mixture was added to YPG medium and statically cultured at 30 ° C. for 24 hours.

The YPG medium mentioned here is a medium consisting of 1 g of yeast extract, 2 g of polypeptone, 2 g of glucose and 100 ml of water, and the YPG agar medium is prepared by adding 2 g of agar to the above composition.

After stationary culture, centrifugation was performed (3000 rp).
m, 5 minutes) and after washing, the harvested strain is cultured in a medium for separating a hybrid (YNB medium free of amino acid: glycerol 2%, agar 2%) (10 ⁷ to 10 ⁸ , 30 ° C., 3 to 4 days). ), Picked out growing colonies.

Strains of the target hybrid strains are separated from the growing colonies, sporulated, and single spores are separated by a micromanipulator to obtain spore strains (NU50 (a / a) a
de-) was obtained.

On the other hand, ordinary baker's yeast (FP36 (a /
α)) is subjected to mutation treatment with ethidium bromide,
A mutant strain (FP36ρ-) was created. Then, this mutant strain and the spore strain (NU50 (a / a) ade obtained as described above)
-) And are treated in the same manner as in the above method to carry out crossing and spore separation, and to obtain the desired hybrid strain Saccharomy
ces cerevisiae P-610 (FERM
P-13919) was obtained.

[0029]

Example 2 P-610 obtained in Example 1 as yeast
A strain (FERM P-13919) was used to produce a Danish pastry according to the pastry method (large split refrigerated dough manufacturing method) according to the formulation and process shown in Table 4 below. As a control, a commercially available yeast (manufactured by Oriental Yeast Co., Ltd.) was used and treated in the same manner as above to produce a Danish pastry.

[0030]

[Table 4]

The taste of the Danish pastry thus obtained was examined. As a result, the pastry using LT yeast had a very low acid odor and fermentation odor, but had a strong buttery aroma and exhibited a light flavor overall. . On the other hand, the pastry using ordinary commercial yeast had a very strong acid odor and also a strong fermentation odor, ester odor and wax odor, and exhibited a heavy flavor overall.

These findings were in good agreement with the results of actually measured pH, organic acid content (FIG. 1) and higher alcohol content (FIG. 2).

The behavior of pH in the retard was measured for these doughs, and the results shown in FIG. 3 were obtained. As is clear from this result, LT yeast had a pH during storage under refrigeration.
It can be seen that the deterioration of sourness and the coloring of bread are both suppressed as a result.

[0034]

Example 3 P-610 obtained in Example 1 as yeast
Using the strain (FERM P-13919), a croissant was produced according to the large-division refrigerated dough production method according to the formulation and process shown in Table 5 below. The obtained croissants were able to bring out the characteristics of the flavor of the auxiliary raw material, and the butter flavor was emphasized more than ever before.

[0035]

[Table 5]

[0036]

Example 4 P-610 obtained in Example 1 as yeast
A butter roll was produced using the strain (FERM P-13919) according to the formulation and process shown in Table 6 below.

[0037]

[Table 6]

[0038]

Example 5 P-610 obtained in Example 1 as yeast
Using the strain (FERM P-13919), confectionery bread (anpan bread) was produced according to the formulation and process shown in Table 7 below.

[0039]

[Table 7]

[0040]

INDUSTRIAL APPLICABILITY In the present invention, since a novel baker's yeast (LT yeast) having excellent pH stability is used especially in a low temperature range, there is no decrease in pH even when the refrigerated bread dough is stored at a low temperature, A remarkable effect that bread of excellent quality can be produced without producing an acid odor and no deterioration in coloring of bread is exhibited.

As described above, the bread produced according to the present invention can suppress the sour odor and pungent odor, and can produce a stable bread having a light flavor as a whole.
The following effects are also achieved.

1. In pastry and croissant manufacturing method: (1) It is possible to raise the set temperature during refrigeration (5-10
℃), running costs can be reduced. (2) Overflow of the dough in the box and irregularity during sheeting can be prevented, and there is almost no difference in volume before and after molding. (3) Stable product can be obtained throughout the year by suppressing the fluctuation of the dough fermentation caused by high and low outside air temperature during molding. (4) The dough can be refrigerated and stored after a large division, which is useful for labor measures such as holidays. (5) The amount of yeast used, the blending, and the manufacturing process are performed in the same manner as in the past, so that bread of consistent quality can always be obtained.

2. In the refrigerating dough manufacturing method (1) The same characteristics as above can be obtained in the dough ball and the molding refrigerating manufacturing method. (2) In particular, the storage stability of refrigerated dough is good, so that weakening of physical properties of the dough is suppressed.

[Brief description of drawings]

1 shows the pH of bread and the amount of organic acids.

FIG. 2 shows the higher alcohol content in bread.

FIG. 3 shows the pH behavior of dough during retardation (major dough ball).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C12R 1: 865)

Claims (4)

[Claims] 1. A baker's yeast having pH stability. 2. The baker's yeast is Saccharomyces.
cerevisiae P-610 (FERM P-
13919), The baker's yeast according to claim 1. 3. A dough containing the baker's yeast according to claim 1 or 2. 4. A refrigerated dough / pastry bread-making method, which comprises using the baker's yeast according to claim 1 or 2.