JP6750978B2 - Novel baker's yeast, bread dough, method for producing breads, and method for screening baker's yeast - Google Patents

Description

The present invention is a novel baker's yeast having excellent bread-making properties and capable of imparting floor time stability to bread dough, bread dough containing the baker's yeast, a method for producing bread using the baker's yeast, and excellent bread-making properties and bread dough. The present invention relates to a method for screening baker's yeast capable of imparting stability to floor time.

Generally, breads are added to flours such as wheat flour and other raw materials for bread making, and kneaded, floor time (first fermentation), division, bench time, molding, proofing (secondary fermentation), baking・Manufactured through processes such as frying.
At the time of production, it does not easily occur in small-scale manufacturing facilities such as retail bakeries, but in relatively large-scale manufacturing facilities such as bread factories, since the amount of bread dough to handle is large, all of the bread dough will be consumed after the floor time ends. There will be a time lag before the division. Due to the extension of the floor time, the elasticity of the bread dough increases and the bread dough shrinks excessively, resulting in variations in the appearance and texture of the bread to be produced. There is a problem that it leads to loss of bread products.

In order to solve the above problems, enzyme preparations such as amylase and gluten, L-ascorbic acid and the like have been blended, but the present situation is still not sufficient.
Further, until now, it has not been attempted to impart floor time stability to bread dough with baker's yeast.

Further, in the past, in the development of baker's yeast, baker's yeast suitable for a frozen dough baking method, baker's yeast having a function of suppressing the softening of the dough and a fungus, and the like have been reported (see, for example, Patent Documents 1 and 2). ).
However, in these reports, leakage of extracellular components (particularly glutathione) to the outside of the cells (hereinafter sometimes referred to as “secretion” or “release”) causes softening of the dough, and In screening, it is used as an index for selecting strains with low leakage of glutathione.

Further, the present applicant has filed an application for baker's yeast having freezing resistance and low-temperature fermentation inhibiting ability for producing low-cost and stable-quality bread without adverse effects on bread dough due to freezing and/or refrigeration. (See Patent Document 3).
The above-mentioned application describes a basic method for breeding and screening baker's yeast, but does not describe baker's yeast that can impart floor time stability to bread dough.

On the other hand, by the present applicants, from baker's yeast and/or mutated baker's yeast, a cadmium-resistant strain is selected and obtained as a primary screening, and a cycloheximide-resistant strain is further selected and obtained as a secondary screening. , A method for producing baker's yeast with high production of glutathione has been proposed (see Patent Document 4).
However, it is considered that the baker's yeast obtained in the above proposal does not secrete glutathione to the outside of the cells, and that good breads cannot be obtained even if breads are produced using this baker's yeast. Conceivable.

Therefore, in the production of breads, baker's yeast having good bread-making properties, capable of suppressing changes in the physical properties of bread dough due to extension of floor time, and capable of reducing the difference in quality of the breads produced are still provided. It is not done, and prompt provision is required.

JP, 2014-83022, A International Publication No. 2013/161303 JP-A-8-332084 JP 2012-213361A

It is an object of the present invention to meet such a demand, break the present situation, solve the above-mentioned problems in the related art, and achieve the following objects. That is, the present invention has a good bread-making property in the production of breads, and suppresses the change in the physical properties of the bread dough due to the extension of the floor time, and can reduce the difference in the quality of the breads produced. It is an object of the present invention to provide a baker's yeast, a bread dough containing the baker's yeast, a method for producing breads using the baker's yeast, and a method for screening baker's yeast having excellent bread-making properties and capable of imparting floor time stability to the bread dough. ..

As a result of earnest studies to achieve the above-mentioned object, the present inventors have found that glutathione outside the cells (hereinafter, referred to as “GSH”) has been considered not to produce good breads. The main indicator is that the secretion amount of) is a certain amount or more, and by selecting and using baker's yeast having excellent bread-making properties, the bread dough is produced by extending the floor time in the production of bread with excellent bread-making properties. It was found that the changes in the physical properties of bread can be suppressed, the difference in the quality of breads produced can be reduced, and breads of excellent quality can be stably produced.

The present invention is based on the above findings of the present inventors, and means for solving the above problems are as follows. That is,
<1> A baker's yeast characterized by capable of imparting floor time stability to bread dough, which has a secretion amount of glutathione into the medium of 2 ppm or more when fermented at 30°C for 2 hours under the following fermentation conditions is there.
[Fermentation conditions]
Fermentation of 20 mL consisting of 5 mL of a yeast suspension having a yeast concentration of 10% w (weight)/v (volume), 3 mL of a sucrose solution having a sucrose concentration of 66.7% w/v, and 12 mL of ion-exchanged water The liquid is shake-fermented in a 100 cc Erlenmeyer flask by a horizontal reciprocating type, a shaking width of 6.0 cm, and a shaking frequency of 100 times/min.
<2> In the method for producing breads described below, the difference between the bread length obtained when the floor time is 20 minutes and the bread length obtained when the floor time is 40 minutes is within 3%. 1> is a baker's yeast.
[Method for manufacturing breads]
<Compound>
-Medium species-
・Flour for bread ・・・ 70 parts by mass ・Baker's yeast ・・・ 3 parts by mass ・ Yeast food ・・・ 0.1 parts by mass ・ Vitamin C ・・・ 10 ppm
・Glucose ・・・ 3 parts by mass ・Whole egg ・・・ 10 parts by mass ・Water ・・・ 32 parts by mass-main kneading-
・Bread flour ・・・ 30 parts by mass ・ Salt ・・・ 1 part by mass ・ Sugar ・・・ 22 parts by mass ・ Skim milk powder ・・・ 2 parts by mass ・ Margarine ・・・ 10 parts by mass ・ Water ・・・ 22 parts by mass Department <Process>
-Medium species-
・Mixing ・・・ Low speed 2 minutes Medium speed 2 minutes ・ Forging temperature ・・・ 26℃
・Fermentation conditions ・・・ 28℃, 2 hours-Main kneading-
・Mixing ・・・ Low speed 2 minutes Medium speed 6 minutes ↓ Medium speed 3 minutes High speed 1 minute ・Floor time ・・・ 20 minutes or 40 minutes ・Floor condition ・・・ 28℃, relative humidity 75%
・Divided weight ・・・ 70g
・Bench time ・・・ 20 minutes ・Bench condition ・・・ 28℃, relative humidity 75%
・Molding method・・・Molder roll molding (adjusting the moulder so that the bread dough length is 17±0.5 cm for 20 minutes floor time)
・Proofing time ・・・ 70 minutes ・Proofing condition ・・・ 35℃, relative humidity 85%
-Baking conditions: 200°C, 9 minutes "↓" in the mixing of the main kneading represents the time when margarine was added.
<3> Saccharomyces cerevisiae AD01 strain (NITE P-02251), AD02 strain (NITE P-02252), AD04 strain (NITE P-02253) or AD06 strain (NITE P-02254) <1. > Or <2>.
<4> A bread dough containing the baker's yeast according to any one of <1> to <3>.
<5> The bread dough according to <4> above, which is a frozen dough.
<6> A method for producing bread, comprising using the baker's yeast according to any one of <1> to <3>.
<7> A method for screening baker's yeast capable of imparting floor time stability to bread dough, comprising:
The method is characterized in that the amount of glutathione secreted into the medium when fermented at 30° C. for 2 hours is 2 ppm or more under the following fermentation conditions.
[Fermentation conditions]
20 mL of a fermented liquid consisting of 5 mL of a yeast suspension having a yeast concentration of 10% w/v, 3 mL of a sucrose solution having a sucrose concentration of 66.7% w/v, and 12 mL of deionized water was added to a 100 cc Erlenmeyer flask. Inside, a horizontal reciprocating type, a shaking width of 6.0 cm, and shaking fermentation at a shaking frequency of 100 times/min.
<8> Furthermore, in the following method for producing breads, the difference between the bread length obtained when the floor time is 20 minutes and the bread length obtained when the floor time is 40 minutes is within 3%. The method for screening baker's yeast according to <7>, wherein the above is used as an index.
[Method for manufacturing breads]
<Compound>
-Medium species-
・Flour for bread ・・・ 70 parts by mass ・Baker's yeast ・・・ 3 parts by mass ・ Yeast food ・・・ 0.1 parts by mass ・ Vitamin C ・・・ 10 ppm
・Glucose ・・・ 3 parts by mass ・Whole egg ・・・ 10 parts by mass ・Water ・・・ 32 parts by mass-main kneading-
・Bread flour ・・・ 30 parts by mass ・ Salt ・・・ 1 part by mass ・ Sugar ・・・ 22 parts by mass ・ Skim milk powder ・・・ 2 parts by mass ・ Margarine ・・・ 10 parts by mass ・ Water ・・・ 22 parts by mass Department <Process>
-Medium species-
・Mixing ・・・ Low speed 2 minutes Medium speed 2 minutes ・ Forging temperature ・・・ 26℃
・Fermentation conditions ・・・ 28℃, 2 hours-Main kneading-
・Mixing ・・・ Low speed 2 minutes Medium speed 6 minutes ↓ Medium speed 3 minutes High speed 1 minute ・Floor time ・・・ 20 minutes or 40 minutes ・Floor condition ・・・ 28℃, relative humidity 75%
・Divided weight ・・・ 70g
・Bench time ・・・ 20 minutes ・Bench condition ・・・ 28℃, relative humidity 75%
・Molding method・・・Molder roll molding (adjusting the moulder so that the bread dough length is 17±0.5 cm for 20 minutes floor time)
・Proofing time ・・・ 70 minutes ・Proofing condition ・・・ 35℃, relative humidity 85%
-Baking conditions: 200°C, 9 minutes "↓" in the mixing of the main kneading represents the timing of adding margarine.

ADVANTAGE OF THE INVENTION According to this invention, the said various problems in the past can be solved, it has a favorable bread-making property in manufacture of bread, and it suppresses the change of the physical property of the bread dough by extension of floor time, and is manufactured. Novel baker's yeast capable of reducing the difference in quality of breads, bread dough containing the baker's yeast, a method for producing breads using the baker's yeast, and bread having excellent bread-making properties and floor time stability to the bread dough A method for screening yeast can be provided.

FIG. 1 is a graph showing the results of measuring the length of the roll bread manufactured in Test Example 1. FIG. 2 is a graph showing the results of measuring the height of the roll bread manufactured in Test Example 1.

(Baker's yeast, method for screening baker's yeast)
The baker's yeast of the present invention is a yeast capable of imparting floor time stability to bread dough in which the amount of glutathione secreted into the medium when fermented at 30° C. for 2 hours is 2 ppm or more under specific fermentation conditions.
The baker's yeast of the present invention can be preferably selected by the method for screening baker's yeast of the present invention.

<Floor time stability>
In the present invention, “capable of imparting floor time stability to bread dough” means suppressing changes in the physical properties of the bread dough due to extension of the floor time in the production of bread and reducing the difference in quality of the bread to be produced. It means what you can do.

The method for evaluating the floor time stability is not particularly limited and may be appropriately selected. For example, in the following method for manufacturing breads (hereinafter, sometimes referred to as “test baking method”), floor Examples include a method of evaluation by comparing bread obtained when the time is 20 minutes and bread obtained when the time is 40 minutes.
[Method for manufacturing breads]
-Compound-
--- Medium species ---
・Flour for bread ・・・ 70 parts by mass ・Baker's yeast ・・・ 3 parts by mass ・ Yeast food ・・・ 0.1 parts by mass ・ Vitamin C ・・・ 10 ppm
・Glucose ・・・ 3 parts by mass ・Whole egg ・・・ 10 parts by mass ・Water ・・・ 32 parts by mass
・Bread flour ・・・ 30 parts by mass ・ Salt ・・・ 1 part by mass ・ Sugar ・・・ 22 parts by mass ・ Skim milk powder ・・・ 2 parts by mass ・ Margarine ・・・ 10 parts by mass ・ Water ・・・ 22 parts by mass Department-Process-
--- Medium species ---
・Mixing ・・・ Low speed 2 minutes Medium speed 2 minutes ・ Forging temperature ・・・ 26℃
-Fermentation conditions: 28°C, 2 hours --- Main kneading ---
・Mixing ・・・ Low speed 2 minutes Medium speed 6 minutes ↓ Medium speed 3 minutes High speed 1 minute ・Floor time ・・・ 20 minutes or 40 minutes ・Floor condition ・・・ 28℃, relative humidity 75%
・Divided weight ・・・ 70g
・Bench time ・・・ 20 minutes ・Bench condition ・・・ 28℃, relative humidity 75%
・Molding method・・・Molder roll molding (adjusting the moulder so that the bread dough length is 17±0.5 cm for 20 minutes floor time)
・Proofing time ・・・ 70 minutes ・Proofing condition ・・・ 35℃, relative humidity 85%
-Baking conditions: 200°C, 9 minutes "↓" in the mixing of the main kneading represents the time when margarine was added.

The bread wheat flour used in the test bread making method is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include “Aishon” manufactured by Nisshin Seifun Co., Ltd.

The comparison item of the test bread making method is not particularly limited and can be appropriately selected, and examples thereof include bread length, height, width, specific volume and volume. If the difference in the comparison item between the bread obtained when the floor time is 20 minutes and the bread obtained when the floor time is 40 minutes is small, it is determined that the floor time stability is imparted. can do.

In the test baking method, the difference between the bread length obtained when the floor time is 20 minutes and the bread length obtained when the floor time is 40 minutes is not particularly limited and can be appropriately selected. Is preferably within 3%, more preferably within 2%.

Further, as breads obtained by the test bread making method, the difference between the bread length obtained when the floor time is 20 minutes and the bread length obtained when the floor time is 40 minutes is within 2%. It is preferable that the specific volume of breads is within the range of 6.5±0.5 mL/g. The specific volume in the test bread making method is an index indicating that the breads were produced without any abnormality, and the test bread making method is designed to fall within the above range.

In the test baking method, the difference between the height of bread obtained when the floor time is 20 minutes and the height of bread obtained when the floor time is 40 minutes is not particularly limited and may be appropriately selected. However, 2.5% or less is preferable, and 1.5% or less is more preferable.

<Selection of yeast>
The method for screening baker's yeast of the present invention is a method for screening baker's yeast capable of imparting floor dough stability to bread dough, and is a method for screening glutathione in a medium when fermented at 30° C. for 2 hours under specific fermentation conditions. The index is that the secreted amount is 2 ppm or more.

-Yeast-
The yeast used in the screening method (hereinafter, sometimes referred to as “parent strain”) is not particularly limited and can be appropriately selected. For example, Saccharomyces genus, Torulopsis genus, Mycotorula. ) Genus, Torula spora genus, Candida genus, Rhodotorula genus, Pichia genus, and the like, and specific strains include, for example, Saccharomyces cerevisiae, Saccharomyces cerevisiae, Saccharomyces, Saccharomyces Saccharomyces rouxii, Torulopsis utilis, Torulopsis candida, Mycotorula japonica, Mycotorula lipolytica, Torulaspora delbrueckii, Torulaspora fermentati, Candida sake, Candida tropicalis, Candida utilis, Hansenula anomala, Hansenula suaveolens, Saccharomycopsis fibligera, Saccharomyces lipolytica, Rhodotorula rubra, like Pichia farinosa is cited To be
As the yeast used in the screening method, naturally occurring baker's yeast may be used, commercially available baker's yeast may be used, mutated yeast may be used, or these are mixed and used. May be.
The method for the mutation treatment is not particularly limited, and a known method can be appropriately selected.

-Specific fermentation conditions-
The specific fermentation (hereinafter sometimes referred to as "main fermentation" or "glutathione secretory fermentation") conditions are "5 mL of yeast suspension having a yeast concentration of 10% w/v and a sucrose concentration of 66. 20 mL of a fermented solution consisting of 3 mL of 7% w/v sucrose solution and 12 mL of ion-exchanged water was placed in a 100 cc Erlenmeyer flask at 30° C. for 2 hours, horizontal reciprocating type, shaking width 6.0 cm, and shaking frequency 100. Shaking and fermenting at a rate of once per minute (hereinafter sometimes referred to as "test fermentation method"). The test fermentation method was in accordance with the (1) liquid fermentation method on page 5 of the yeast yeast test method (Japan Yeast Industry Association, August 1996).

The method for preparing the yeast suspension (hereinafter sometimes referred to as “pre-culture”) is not particularly limited and can be appropriately selected. For example, it can be prepared as follows.
The strain was inoculated into a test tube containing 5 mL of YPD medium and shake-cultured at 30° C. for 24 hours to obtain 100 mL of YMPD medium (yeast extract 0.3%, malt extract 0.3%, peptone 0.5%, glucose (3%) is inoculated into a flask, and cultured at 30° C. for 48 hours with shaking.
The above culture solution is washed twice with a standard method to obtain a cultured cell. This is cultivated under the following [culture conditions for pre-culture]. The sugar used is diluted with molasses so that the sugar concentration is always 35%. Molasses is fed and cultured using a syringe pump PHD2000 (manufactured by Harvard Apparatus) with a multi-holder.
100 mL of this culture solution is collected, and the cells are washed twice by a conventional method (centrifugation method), and then sterilized water is added so that the yeast concentration becomes 10% w/v to obtain a yeast suspension.
[Culture conditions for pre-culture]
Culture vessel: 200 mL graduated cylinder Volume of culture solution: 100 mL
Species: Cultured cells Species amount: 3g
Culture temperature: 32℃
Cultivation time: 14 hours Aeration: 0.4 L/min Sugar content: 7.8 g
Nitrogen (N) source: Urea N/Carbon (C): 4.0
Phosphorus (P) source: monosodium phosphate P/C: 0.4

-Measurement of glutathione amount-
The method of measuring the amount of glutathione secreted out of the cells by fermentation in the test fermentation method is not particularly limited and can be appropriately selected. For example, it can be measured as follows.
2.5 mL of phosphate buffer is dispensed into a spectrophotometer glass cell with 5 mL of Pipetman. Next, 100 μL of nicotinamide adenine dinucleotide phosphate (NADPH) and 30 μL of a 5-5′-dithiobis[2-nitrobenzoic acid] (DTNB) solution are added with a Pipetman. Add 200 μL of the sample using a calibrated Pipetman and pipette in the cell to mix well. After incubation for 1 minute, 100 μL of glutathione reductase (GR) is added, and then the absorbance at an absorption wavelength of 412 nm is measured every 10 seconds for 90 seconds. The reaction rate is calculated from the absorbances 20 seconds and 80 seconds after the start of the reaction.
As a standard, glutathione solutions of 0 ppm, 5 ppm, 10 ppm, and 15 ppm are prepared, and a calibration curve is obtained.
The amount of glutathione is calculated by correcting with a factor to correct the amount of cells.

As described above, in the test fermentation method, baker's yeast having a secreted amount of glutathione into the medium of 2 ppm or more when fermented at 30° C. for 2 hours can be selected.
As shown in Test Example 1 described later, the baker's yeast of the present invention in which the amount of glutathione secreted is 2 ppm or more can impart floor time stability to bread dough.

The amount of glutathione secreted by the baker's yeast is not particularly limited as long as it is 2 ppm or more and can be appropriately selected, but it is 2 to 30 ppm in terms of more excellent floor time stability imparted to the bread dough. A range is preferred.

The screening method may further use, as the index, an index other than the glutathione secretion amount (hereinafter, also referred to as “other index”).
The other indexes are not particularly limited and may be appropriately selected. For example, a comparison item in the method for evaluating floor time stability described in <Floor time stability>, fermentability, and dough. Feeling and workability (extendability of dough, presence/absence of stickiness), yield, bread-making properties other than the above-mentioned floor time stability, quality of breads obtained (internal phase, texture, flavor) and the like can be mentioned.

The baker's yeast of the present invention is not particularly limited as long as it is a baker's yeast having a secretion amount of glutathione in the medium of 2 ppm or more when fermented at 30° C. for 2 hours in the test fermentation method, and may be appropriately selected. However, in the comparison item in the method for evaluating the floor time stability described in the item <Floor time stability>, the bread length obtained when the floor time was 20 minutes and the bread time was 40 minutes. A baker's yeast having a difference of 3% or less from the length of bread sometimes obtained is preferable, and Saccharomyces cerevisiae AD01 strain, AD02 strain, AD04 strain, or AD06 strain is more preferable.
The preferable baker's yeast not only imparts the floor time stability, but also has versatility such as excellent freezing resistance and use in low sugar region to high sugar region as shown in Test Examples 2 and 3 described later. Therefore, it is advantageous.

The four strains have been applied for deposit to the Patent Microbial Depositary Center (2-5-8 Kazusa Kamasa, Kisarazu City, Chiba Prefecture, 292-0818, Japan 292-0818, Japan Institute for Product Evaluation Technology), and the AD01 strain is NITE P-02251. The AD02 strain is NITE P-02252, the AD04 strain is NITE P-02253, and the AD06 strain is NITE P-02254, which were entrusted on May 11, 2016.

Further, according to the baker's yeast of the present invention, breads having good appearance (volume, specific volume, height and length), texture and flavor can be obtained while imparting floor time stability to bread dough. ..

(Method for manufacturing bread dough and bread)
The bread dough of the present invention is not particularly limited as long as it contains the bread yeast of the present invention, and a known bread dough can be appropriately selected. Since the baker's yeast of the present invention also has freezing resistance as shown in Test Example 2 described later, it can be used for frozen dough.
As the method for producing breads of the present invention, as long as the baker's yeast of the present invention is used, there is no particular limitation, and a known method can be appropriately selected, for example, a cereal flour mainly composed of wheat flour as a main raw material, Water, baker's yeast of the present invention, milk, eggs, fats and oils, salts, knead by adding other materials such as sugars, the obtained dough, fermentation, molding, a method of baking, etc. Can be mentioned.
The type of bread-making method is not particularly limited and can be appropriately selected, and examples thereof include a medium-type production method, a straight-type production method, a hot-water production method, and a refrigerated or frozen dough production method.

<Flour mainly composed of wheat flour>
The wheat flour-based flours mean wheat flour-containing flours, starches and modified starches thereof. The wheat flour-based flours may be wheat flour alone, or wheat flour may be used in combination with other flours or starches.

The cereal flour is not particularly limited and may be appropriately selected, and examples thereof include wheat flour, rye flour, buckwheat flour, rice flour, barley flour, soybean flour and corn flour. The flour may be used alone or in combination of two or more.

The starches are appropriately selected depending on the intended purpose without any limitation, and examples thereof include wheat starch, rice starch, potato starch, tapioca starch, corn starch, and sweet potato starch. The starches may be used alone or in combination of two or more.

The modified starch is appropriately selected depending on the intended purpose without any limitation, and examples thereof include heat-treated starch, pregelatinized starch, acid-treated starch, crosslinked starch, etherified starch, and esterified starch. The modified starch may be used alone or in combination of two or more. In addition, a plurality of processing treatments (crosslinking and etherification, acid treatment and crosslinking, etc.) may be performed.

The amount of the baker's yeast to be used is not particularly limited and may be appropriately selected according to a conventional method, and examples thereof include 2 to 5 parts by mass with respect to 100 parts by mass of cereal flour mainly composed of wheat flour.

<Breads>
The breads are not particularly limited and can be appropriately selected, for example, bread, rolls, confectionery bread, prepared bread, croissant, Danish, brioche, French bread, German bread (Kaiser Semmel, rye bread, etc.), focaccia. , Panettone and the like.

Since the bread dough or the method for producing bread of the present invention uses the baker's yeast of the present invention, in the production of bread, the change in the physical properties of the bread dough due to the extension of the floor time is suppressed, and the difference in the quality of the bread to be produced. Can be reduced.
Therefore, the present invention also relates to a method for suppressing changes in the physical properties of bread dough due to extension of floor time, and a method for reducing the difference in quality of breads produced, which is characterized by using the baker's yeast of the present invention.

Hereinafter, the present invention will be described with reference to test examples, but the present invention is not limited to these test examples.

(Test Example 1: Screening test for baker's yeast)
About 3,000 strains of Saccharomyces cerevisiae strain (diploid) library and baker's yeast product possessed by the applicant were constructed according to the method described in JP-A-2014-117212.

<Measurement of glutathione secretion>
(1) Pre-cultivation The strain was inoculated into a test tube containing 5 mL of YPD medium and shake-cultured at 30° C. for 24 hours to obtain 100 mL of YMPD medium (yeast extract 0.3%, malt extract 0.3%, peptone). The whole amount was inoculated into a flask containing 0.5% and glucose 3%), and cultured by shaking at 30° C. for 48 hours.
The above culture solution was washed twice with a standard method to obtain a cultured cell. This was cultivated under the following [culture conditions for pre-culture]. The sugar used was diluted with molasses so that the sugar concentration was always 35%. Molasses was fed and cultured using a syringe pump PHD2000 (manufactured by Harvard Apparatus) with a multi-holder.
100 mL of this culture solution was collected, and the cells were washed twice by a standard method (centrifugation method), and then sterilized water was added to adjust the yeast concentration to 10% w/v.
[Culture conditions for pre-culture]
Culture vessel: 200 mL graduated cylinder Volume of culture solution: 100 mL
Species: Cultured cells Species amount: 3g
Culture temperature: 32℃
Cultivation time: 14 hours Aeration: 0.4 L/min Sugar content: 7.8 g
Nitrogen (N) source: Urea N/Carbon (C): 4.0
Phosphorus (P) source: monosodium phosphate P/C: 0.4

(2) Main fermentation (Glutathione secretory fermentation)
Baker's yeast was fermented in accordance with the (1) liquid fermentation method on page 5 of the yeast yeast test method (Japan Yeast Industry Association, August 1996). Specifically, the yeast suspension obtained in the above (1) pre-culture was shake-fermented (horizontal reciprocation) in a 100 cc Erlenmeyer flask in the amount of [fermentation liquid] shown below in a warm water tank at 30°C for 2 hours. Formula, shaking width 6.0 cm, shaking frequency 100 times/min). The obtained bacterial cell fermentation liquid was separated into bacterial cells and a supernatant by centrifugation, and the supernatant was used as a glutathione measurement sample.
[Fermentation liquid]
Yeast suspension (10% w/v): 5 mL
Sucrose solution (66.7% w/v): 3 mL
Ion-exchanged water: 12 mL
Total volume 20 mL

(3) Measurement of Glutathione (GSH) Amount 2.5 mL of phosphate buffer was dispensed into a glass cell for a spectrophotometer with 5 mL of Pipetman. Next, 100 μL of nicotinamide adenine dinucleotide phosphate (NADPH) and 30 μL of a 5-5′-dithiobis[2-nitrobenzoic acid] (DTNB) solution were added using a Pipetman. 200 μL of the sample was added using a calibrated Pipetman, and pipetting was performed in the cell to mix well. After incubating for 1 minute, 100 μL of glutathione reductase (GR) was added, and then the absorbance at an absorption wavelength of 412 nm was measured every 10 seconds for 90 seconds. The reaction rate was calculated from the absorbances 20 seconds and 80 seconds after the reaction started.
As a standard, 0 ppm, 5 ppm, 10 ppm, and 15 ppm GSH solutions were prepared and a calibration curve was obtained.
The amount of glutathione was calculated by correcting with a factor to correct the amount of bacterial cells.
The composition of the reagents used for the measurement is shown below.
-Phosphate buffer: 50 mM, pH 7.0, 2 mM EDTA
· GR: 5U / mL GR in phosphate buffer · DNTB _{solution: 19.8mg DNTB, 7.5mg NaHCO 3 /} 5mL phosphate buffer · β-NADPH: 4mg / mL NADPH in 10mM Tris solution

By measuring the amount of glutathione secreted, a plurality of baker's yeasts having a secreted amount of glutathione of 2 ppm or more were obtained.

<Floor time stability>
A bread roll was produced by the seeding method using each of the baker's yeast having a secreted amount of glutathione of 2 ppm or more and the commercially available baker's yeasts 1 to 3. The formulation and process are as follows.

[Compound]
-Medium species-
・Flour for bread ^※・・・ 70 parts by mass ・Baker's yeast ・・・ 3 parts by mass ・ Yeast food ・・・ 0.1 parts by mass ・ Vitamin C ・・・ 10 ppm
・Glucose ・・・ 3 parts by mass ・Whole egg ・・・ 10 parts by mass ・Water ・・・ 32 parts by mass-main kneading-
・Flour for bread ^※・・・ 30 parts by mass ・Salt ・・・1 part by mass ・Sugar ・・・22 parts by mass ・Skim milk powder ・・・2 parts by mass ・Margarine ・・・10 parts by mass ・Water ・・・22 Mass part *: "Aushon" manufactured by Nisshin Seifun Co.

[Process]
-Medium species-
・Mixing ・・・ Low speed 2 minutes Medium speed 2 minutes ・ Forging temperature ・・・ 26℃
・Fermentation conditions ・・・ 28℃, 2 hours-Main kneading-
・Mixing ・・・ Low speed 2 minutes Medium speed 6 minutes ↓ Medium speed 3 minutes High speed 1 minute ・Floor time ・・・ 20 minutes or 40 minutes ・Floor condition ・・・ 28℃, relative humidity 75%
・Divided weight ・・・ 70g
・Bench conditions ・・・ 28℃, relative humidity 75%
・Molding method・・・Molder roll molding (adjusting the moulder so that the bread dough length is 17±0.5 cm for 20 minutes floor time)
・Proofing time ・・・ 70 minutes ・Proofing condition ・・・ 35℃, relative humidity 85%
-Baking conditions: 200°C, 9 minutes "↓" in the mixing of the main kneading represents the time when margarine was added.

[Evaluation]
The results of measuring the length, height and specific volume of the manufactured rolls are shown in Tables 1-1 to 1-3. The specific volume is calculated by the volume (ml) of bread obtained/mass of dough (g).
Regarding the length and height, the measurement results are shown in FIGS. 1 and 2, and the results evaluated by the following evaluation criteria are also shown in Tables 1-1 and 1-2.
Regarding the baker's yeast in which the amount of glutathione secreted was 2 ppm or more, the results of the AD01 strain, the AD02 strain, the AD04 strain, and the AD06 strain are shown as representative examples.
-Evaluation criteria for roll length-
◯: The difference between the bread length when the floor time was 20 minutes and the bread length when the floor time was 40 minutes was within 2%.
Δ: The difference between the bread length when the floor time was 20 minutes and the bread length when the floor time was 40 minutes was more than 2% and within 3%.
X: The difference between the bread length when the floor time is 20 minutes and the bread length when the floor time is 40 minutes is more than 3%.
-Evaluation criteria for roll bread height-
◯: The difference between the height of the bread when the floor time was 20 minutes and the height of the bread when the floor time was 40 minutes was within 1.5%.
Δ: The difference between the height of the bread when the floor time was 20 minutes and the height of the bread when the floor time was 40 minutes was more than 1.5% and within 2.5%.
X: The difference between the height of the bread when the floor time was 20 minutes and the height of the bread when the floor time was 40 minutes was more than 2.5%.

The amounts of glutathione secreted by the AD01 strain, AD02 strain, AD04 strain, and AD06 strain and commercially available baker's yeasts 1 to 3 are as follows.
-Glutathione secretion-
・AD01 strain・・・4.0ppm
・AD02 strain ・・・8.8ppm
・AD04 strain ・・・ 8.0ppm
・AD06 strain ・・・ 6.3ppm
・Commercial baker's yeast 1・・・0.6ppm
・Commercial baker's yeast 2・・・1.2ppm
・Commercial baker's yeast 3・・・0.9ppm

From the results of Tables 1-1 to 1-3 and FIGS. 1 and 2, in the case of using a commercially available baker's yeast having a secretion amount of glutathione of less than 2 ppm, the bread length and height were different due to the difference in floor time. It was confirmed that there was a difference in at least one of them, and that there was a difference in bread quality. Specifically, in the commercial baker's yeast 1, shrinkage of the bread dough occurred due to the difference in floor time, and in the commercial baker's yeasts 2 and 3, the shrinkage of the bread dough was remarkable, and as a result, the difference in bread height also became large. On the other hand, when the baker's yeast of the present invention in which the amount of glutathione secreted was 2 ppm or more, differences in bread quality (appearance such as length and height) due to differences in floor time were suppressed. Therefore, it was confirmed that by using the baker's yeast of the present invention, floor time stability can be imparted to bread dough.
Further, as a result of the floor time stability being imparted to the bread dough, the bread using the baker's yeast of the present invention has a fine internal phase of the bread at both floor times of 20 minutes and 40 minutes, and has a light texture. Was there. On the other hand, in the bread using the commercially available baker's yeast, the bread having a floor time of 40 minutes had a slightly rough internal phase and the texture was slightly repulsive as compared with the bread having a floor time of 20 minutes. ..
1 is a diagram showing the result of measuring the bread length, and FIG. 2 is a diagram showing the result of measuring the bread height. 1 and 2, the graphs on the left side of each item on the horizontal axis show the results when the floor time is 20 minutes, and the graphs on the right side show the results when the floor time is 40 minutes.

The Saccharomyces cerevisiae AD01 strain, AD02 strain, AD04 strain, and AD06 strain are used as a patent microorganism deposit center (2-5-8 Kazusa Kamasa, Kisarazu City, Chiba Prefecture, 292-0818, Japan). ), the AD01 strain is NITE P-02251, the AD02 strain is NITE P-02252, the AD04 strain is NITE P-02253, and the AD06 strain is NITE P-02254 on May 11, 2016. Was entrusted.

(Test Example 2: Freezing resistance)
Frozen bread dough was produced using the AD01 strain, the AD02 strain, the AD04 strain, and the AD06 strain obtained in Test Example 1, and the commercially available baker's yeast 4 and the commercially available baker's yeast 5. The formulation and process are as follows.

<Compound>
・Flour for bread ^※・・・ 100 parts by mass ・Baker's yeast ・・・5 parts by mass ・Improver ・・・1 part by mass ・Salt ・・・1.5 parts by mass ・Sugar ・・・15 parts by mass ・Skim milk powder・・・ 3 parts by mass ・ Shortening ・・・ 5 parts by mass ・ Water ・・・ 55 parts by mass *: "Aushon" manufactured by Nisshin Seifun Co., Ltd.

<Process>
・Mixing ・・・ 4 minutes ・Upper temperature ・・・ 20℃
・Floor time ・・・ 60 minutes ・Floor condition ・・・ 25℃, relative humidity 80%
・Divided weight ・・・ 25g
・Bench time ・・・ 20 minutes ・Bench conditions ・・・ 25℃, relative humidity 85%
-Molding method-Rounding-Freezing condition-Freezing at -40°C freezer for 1 hour, then freezing at -20°C freezer-Thawing time...45 minutes-Thawing condition...25°C, relative 80% humidity

<Evaluation>
With a -20[deg.] C. freezer, the amount of generated huero carbon dioxide at 35[deg.] C. was measured for the dough after storage for 7 days to 90 days. In addition, the amount of proof carbon dioxide generated was also measured for unfrozen bread dough. The results are shown in Table 2 together with the residual rate when the gas generation amount of the bread dough after storage for 7 days was set to 100%.

From the results in Table 2, it was confirmed that the AD01 strain, the AD02 strain, the AD04 strain, and the AD06 strain had sufficient gas generation amounts even when the dough was frozen. Therefore, it was confirmed that the AD01 strain, the AD02 strain, the AD04 strain, and the AD06 strain have freezing resistance in addition to the floor time stability, and it was found that they can also be used for frozen dough.

(Test Example 3: Versatility at various sugar concentrations)
Using the AD01 strain, the AD02 strain, the AD04 strain, and the AD06 strain obtained in Test Example 1 and the commercially available baker's yeast 6, bread dough with a sugar concentration of 5% or 35% was produced. The formulation and process are as follows. The commercially available baker's yeast 6 is "regular" (product name) manufactured by Oriental Yeast Co., Ltd., which has been confirmed to have versatility.

<Sugar concentration 5%>
-Compound-
・Flour for bread ^※・・・ 100 parts by mass ・Baker's yeast ・・・2 parts by mass ・Sugar ・・・5 parts by mass ・Salt ・・・2 parts by mass ・Water ・・・68 parts by mass *: Nisshin Flour Milling Co., Ltd. Company-made "Aution"

-Process-
・Mixing ・・・ 3 minutes ・Upper temperature ・・・ 28℃
・Divided weight ・・・ 30g

<Sugar concentration 35%>
-Compound-
・Bread flour ^※・・・ 100 parts by mass ・Baker's yeast ・・・ 4 parts by mass ・ Sugar ・・・ 35 parts by mass ・ Salt ・・・ 0.5 parts by mass ・ Water ・・・ 56 parts by mass *: Nissin Milling Co., Ltd. "Aution"

-Process-
・Mixing ・・・ 3 minutes ・Upper temperature ・・・ 28℃
・Divided weight ・・・ 30g

<Evaluation>
In the above step, after dividing into 30 g, the gas generation amount at 28° C. for 2 hours was measured by a thermograph (manufactured by Ato Co., Ltd.). The results are shown in Table 3.

From the results in Table 3, it was confirmed that the AD01 strain, the AD02 strain, the AD04 strain and the AD06 strain show a sufficient gas generation amount from the low sugar region to the high sugar region. Therefore, it was confirmed that the AD01 strain, the AD02 strain, the AD04 strain, and the AD06 strain have versatility in that they can be used in a low sugar region to a high sugar region in addition to floor time stability and freeze resistance.

NITE P-02251
NITE P-02252
NITE P-02253
NITE P-02254

Claims (6)

A baker's yeast capable of imparting floor time stability to bread dough, wherein the amount of glutathione secreted into the medium when fermented at 30° C. for 2 hours under the following fermentation conditions is 2 ppm or more.
[Fermentation conditions]
Fermentation solution of 20 mL consisting of 5 mL of yeast suspension having a yeast concentration of 10% w/v, 3 mL of sucrose solution having a sucrose concentration of 66.7% w/v, and 12 mL of deionized water was added to a 100 cc Erlenmeyer flask. Inside, a horizontal reciprocating type, a shaking width of 6.0 cm, and shaking fermentation at a shaking frequency of 100 times/min. In the method for manufacturing breads described below, the difference between the bread length obtained when the floor time is 20 minutes and the bread length obtained when the floor time is 40 minutes is within 3%. Baker's yeast.
[Method for manufacturing breads]
<Compound>
-Medium species-
・Flour for bread ・・・ 70 parts by mass ・Baker's yeast ・・・ 3 parts by mass ・ Yeast food ・・・ 0.1 parts by mass ・ Vitamin C ・・・ 10 ppm
・Glucose ・・・ 3 parts by mass ・Whole egg ・・・ 10 parts by mass ・Water ・・・ 32 parts by mass-main kneading-
・Bread flour ・・・30 parts by mass ・Salt ・・・1 part by mass ・Sugar ・・・22 parts by mass ・Skim milk powder ・・・2 parts by mass ・Margarine ・・・10 parts by mass ・Water ・・・22 parts by mass Department <Process>
-Medium species-
・Mixing ・・・ Low speed 2 minutes Medium speed 2 minutes ・ Forging temperature ・・・ 26℃
・Fermentation conditions ・・・ 28℃, 2 hours-Main kneading-
・Mixing ・・・ Low speed 2 minutes Medium speed 6 minutes ↓ Medium speed 3 minutes High speed 1 minute ・Floor time ・・・ 20 minutes or 40 minutes ・Floor condition ・・・ 28℃, relative humidity 75%
・Divided weight ・・・ 70g
・Bench time ・・・ 20 minutes ・Bench condition ・・・ 28℃, relative humidity 75%
・Molding method・・・Molder roll molding (adjusting the moulder so that the bread dough length is 17±0.5 cm for 20 minutes floor time)
・Proofing time ・・・ 70 minutes ・Proofing condition ・・・ 35℃, relative humidity 85%
-Baking conditions: 200°C, 9 minutes "↓" in the mixing of the main kneading represents the time when margarine was added. Claim 1 or 2 which is Saccharomyces cerevisiae (Saccharomyces cerevisiae) AD01 strain (NITE P-02251), AD02 strain (NITE P-02252), AD04 strain (NITE P-02253) or AD06 strain (NITE P-02254). The described baker's yeast. A bread dough containing the baker's yeast according to claim 1. A method for producing breads, which comprises using the baker's yeast according to any one of claims 1 to 3. A method for screening baker's yeast which can impart floor time stability to bread dough,
Under the following fermentation conditions, the method is characterized in that the amount of glutathione secreted into the medium when fermented at 30° C. for 2 hours is 2 ppm or more as an index.
[Fermentation conditions]
20 mL of a fermented liquid consisting of 5 mL of a yeast suspension having a yeast concentration of 10% w/v, 3 mL of a sucrose solution having a sucrose concentration of 66.7% w/v, and 12 mL of deionized water was added to a 100 cc Erlenmeyer flask. Inside, a horizontal reciprocating type, a shaking width of 6.0 cm, and shaking fermentation at a shaking frequency of 100 times/min.