JP2019033696A - Bread yeast produced by hybridization between saccharomyces bayanus var. uvarum and saccharomyces cerevisiae - Google Patents

Abstract

To provide freeze tolerant yeast for bread making exhibiting a high dough fermenting ability not only in a normal temperature range but also in a low temperature range, and methods for bread making using the yeast.SOLUTION: By hybridizing Saccharomyces bayanus var. uvarum B35L1 and Saccharomyces cerevisiae H24U1M, freeze tolerant yeast for bread making exhibiting a high dough fermenting ability at a low temperature is obtained. Use of such a yeast enables efficient bread making from frozen dough.SELECTED DRAWING: Figure 1

Description

  The present invention relates to baker's yeast and the like. More specifically, a freeze-resistant bakery yeast having high fermentability even in low-temperature bread dough produced by crossing of a strain belonging to Saccharomyces bayanus bar Ubalum and a strain belonging to Saccharomyces cerevisiae, and breads using the yeast It relates to a manufacturing method of the above.

  In an oven fresh bakery that sells freshly baked bread, the products are manufactured in a variety of ways, which can be roughly divided into two. One is a scratch method that performs the process of baking the dough mixed with flour, water, sugar, salt, fats and yeasts, etc., and then baking it all at once. However, there is a drawback that it takes time and effort.

  The other is a bake-off method, which uses frozen bread dough delivered in a rapidly frozen form after mixing raw materials, dough preparation, primary fermentation, splitting and shaping in a factory. Even in a small-scale store, this frozen bread dough can be thawed and the breads can be produced simply by performing the subsequent fermentation and baking processes. Can be produced and is widely used in oven fresh bakery. In such a frozen dough baking method, bakery yeast having freezing resistance that is resistant to freezing damage in the dough is used.

  Moreover, there is a refrigerated dough baking method as an equivalent of the scratch method. In general, bread dough is fermented at 27 to 30 ° C. for several hours. In this method, the bread dough is stored and aged in a refrigerator at about 5 ° C. for 12 to 48 hours, then fermented and baked.

  In ordinary bread yeast, the fermentation progresses slowly even in the dough that has been stored for a long time at around 5 ° C, and the metabolic activity deteriorates, so that sufficient fermentation cannot be performed in the fermentation stage, and the ratio of baked bread The volume is reduced. Thus, in this refrigerated dough bread making method, bread yeast having low temperature sensitivity is used such that bread dough fermentation is suppressed at low temperatures and the dough fermentation power is restored when the temperature reaches a normal temperature range (Patent Documents 1 to 3). Such). Furthermore, bread-making yeasts having both characteristics of freezing tolerance and low-temperature sensitivity in bread dough have been developed (Patent Document 4, etc.).

  On the other hand, in stores that employ the bake-off method (frozen dough making method), the time from thawing to baking of frozen dough must be shortened to improve efficiency. Can be said to require a trait that quickly ferments the dough even in a low temperature dough during thawing. However, in the bakery industry, attention has been paid only to the characteristics of bread-making yeasts that suppress the fermentation of bread dough at low temperatures as described above. The current situation is missing.

  In such a technical background, it is considered that the development of freezing-resistant bread-making yeasts and the like that are useful in the frozen dough baking method is required in the industry, which has a high bread dough fermentation power not only at room temperature but also at low temperatures. It is done.

JP-A-7-246087 JP 2010-022322 A JP 2013-172739 A JP-A-9-220086

  An object of the present invention is to provide a freeze-resistant bread-making yeast having a high bread dough fermenting power not only in a normal temperature range but also in a low temperature range, a method for producing bread using the yeast, and the like.

  In order to achieve the above object, as a result of intensive studies, the present inventors have established that Saccharomyces bayanus var. Uvarum B35L1 strain and Saccharomyces cerevisiae strain 24 are combined with Saccharomyces cerevisiae strain H. The present inventors completed the present invention by finding that a freeze-resistant bakery yeast having high fermentative ability for low-temperature bread dough can be obtained.

That is, the embodiment of the present invention is as follows.
(1) Carbon dioxide generation amount in bread dough comprising 5% by weight of sugar per 100% by weight of flour becomes 45 mL or more when measured at 30 ° C. for 2 hours (10 g of bread dough), and measured at 4 ° C. for 24 hours (10 g of bread dough) ), And the dough containing 5% by weight of sugar per 100% by weight of wheat flour is fermented at 30 ° C and 75% humidity for 1 hour, then quickly frozen at -30 ° C for 30 minutes, and after quick freezing The amount of carbon dioxide generated after frozen storage at −20 ° C. for 2 hours becomes 120 mL or more when measured at 30 ° C. for 5 hours (20 g bread dough), and carbon dioxide gas after freezing and stored at −20 ° C. for 21 days Baking yeast belonging to the genus Saccharomyces, whose generation amount is 75 mL or more when measured at 30 ° C. for 5 hours (bread dough 20 g).
(2) Baking yeast Saccharomyces sp., Which has freezing tolerance and low temperature and high fermentability. HB35 strain (NITE P-02469).
(3) A bread dough (especially refrigerated bread dough or frozen bread dough) containing the yeast for bread making according to (1) or (2).
(4) The bread dough described in (3) is fermented at 4 to 30 ° C. (for example, fermented in parallel with raising the temperature from a low temperature range of 4 to 10 ° C. to a fermentation temperature zone of 27 to 30 ° C. and fermentation temperature) A method for producing bread characterized by continuing fermentation after reaching the belt) and then baking (after completion of fermentation).
(5) Saccharomyces bayanus bar ubalum B35L1 strain (NITE P-02509) and Saccharomyces cerevisiae H24U1M strain (NITE P-02508) are crossed, and the freezing resistance and low temperature high belonging to the genus Saccharomyces A method for producing fermentable bread yeast.

  According to the present invention, it is possible to obtain a freeze-resistant bread-making yeast that quickly and well ferments bread dough not only in a normal fermentation temperature zone but also in low-temperature bread dough. By using the yeast, frozen dough can be obtained. In the bread-making method, the time from thawing to baking of frozen bread dough can be further shortened, and the efficiency of bread production can be further improved.

FIG. 3 is a diagram showing an outline of a process for obtaining a cross strain performed in Example 1.

  In the present invention, first, Saccharomyces bayanus bar ubalum NBRC10970, which is known as a wine-making yeast, is used to produce freeze-resistant bread-producing yeast having a high bread dough fermentation power in a low temperature range (about 4 to 10 ° C.). The B35L1 strain, which is a lysine-requiring mutant strain, is crossed with the H24U1M strain, which is a uracil-requiring mutant strain of Saccharomyces cerevisiae H24, which is known as a freeze-tolerant baker's yeast.

  The lysine-requiring mutant B35L1 and uracil-requiring mutant H24U1M may be obtained by a conventional method without any particular limitation. For example, UV or chemical substances (ethyl methanesulfonic acid (EMS), N-methyl) -N-nitrosoguanidine (NTG), nitrous acid, etc.) NBRC10970 and H24 strains are mutated, and then a predetermined selective medium (in the case of a lysine-requiring mutant, α-aminoadipic acid-containing medium, etc. are required for uracil. In the case of a mutant strain, a method of selecting with a 5-fluoroorotic acid-containing medium or the like is exemplified. And it is preferable to perform crossing by rare mating using these mutant strains, but the crossing method is not limited to this.

  And by crossing this B35L1 strain and the H24U1M strain, it is possible to easily obtain a yeast hybrid strain for bakery that has high freezing resistance and low-temperature bread dough fermenting ability, such as the HB35 strain. And this HB35 strain | stump | stock is a yeast for bread making very useful in the hybrid strain | stump | stock obtained by this crossing, and has the following mycological properties.

(A) Morphological properties When cultured at 30 ° C. for 1 day in a YPD liquid medium (dry yeast extract 1.0%, high polypeptone 2.0%, glucose 2.0%), the cells are spherical or elliptical, The size is 4-6 μm × 6-8 μm, and multipolar budding. Moreover, the colonies when cultivated on a YPD agar plate medium at 30 ° C. for 1 day are light brown and shiny. In addition, when cultured on an SPO agar medium (potassium acetate 1.0%, yeast extract 0.1%, glucose 0.05%, agar 2.0%) at 25 ° C. for 7 days, 2 to 4 spherical spores are obtained. Form.
(B) Physiological properties Grows at a temperature of 20 to 37 ° C.
(C) Fermentation of sugar Glucose: +
Galactose: +
Sucrose: +
Maltose: +
Lactose:-
Raffinose: +
Trehalose:-
Melibiose: +
(D) Utilization of carbon source Glucose: ++
Galactose: ++
L-sorbose:-
Sucrose: ++
Maltose: ++
Cellobiose:-
Trehalose: +
Lactose:-
Melibiose:-
Raffinose: +
Merezitose:-
Inulin:-
Soluble starch:-
D-xylose:-
L-arabinose:-
D-arabinose:-
D-ribose:-
L-rhamnose:-
Ribitol:-
D-mannitol: +
Glycerol: ++
Ethanol: ++
α-methylglucoside: ++
Salicin:-
Succinic acid:-
Citric acid:-
Myo-inositol:-
D-Glucosamine:-

  Moreover, the B35L1 strain and the H24U1M strain, which are hybrid parent strains, have the following mycological properties.

<B35L1 stock>
(A) Morphological properties When cultured at 30 ° C. for 1 day in a YPD liquid medium (dry yeast extract 1.0%, high polypeptone 2.0%, glucose 2.0%), the cells are spherical or elliptical, The size is 5-9 μm × 4-8 μm, and multipolar budding. Moreover, the colonies when cultivated on a YPD agar plate medium at 30 ° C. for 1 day are light brown and shiny. In addition, when cultured on an SPO agar medium (potassium acetate 1.0%, yeast extract 0.1%, glucose 0.05%, agar 2.0%) at 25 ° C. for 7 days, 3 to 4 spherical spores are obtained. Form.
(B) Physiological properties Grows at a temperature of 20 to 33 ° C.
(C) Fermentation of sugar Glucose: +
Galactose: +
Sucrose: +
Maltose: +
Lactose:-
Raffinose: +
Trehalose:-
Melibiose: +
(D) Utilization of carbon source Glucose: ++
Galactose: ++
L-sorbose:-
Sucrose: ++
Maltose: ++
Cellobiose:-
Trehalose: +
Lactose:-
Melibiose:-
Raffinose: ++
Merezitose:-
Inulin:-
Soluble starch:-
D-xylose:-
L-arabinose:-
D-arabinose:-
D-ribose:-
L-rhamnose:-
Ribitol:-
D-mannitol: +
Glycerol: ++
Ethanol: ++
α-methylglucoside: +
Salicin:-
Succinic acid:-
Citric acid:-
Myo-inositol:-
D-Glucosamine:-

<H24U1M stock>
(A) Morphological properties When cultured at 30 ° C. for 1 day in a YPD liquid medium (dry yeast extract 1.0%, high polypeptone 2.0%, glucose 2.0%), the cells are spherical or elliptical, The size is 4-6 μm × 3-5 μm, and multipolar budding. Moreover, the colonies when cultivated on a YPD agar plate medium at 30 ° C. for 1 day are light brown and shiny. Further, no spore formation was observed even when cultured on an SPO agar medium (potassium acetate 1.0%, yeast extract 0.1%, glucose 0.05%, agar 2.0%) at 25 ° C. for 7 days. .
(B) Physiological properties Grows at a temperature of 20 to 35 ° C.
(C) Fermentation of sugar Glucose: +
Galactose: +
Sucrose: +
Maltose: +
Lactose:-
Raffinose: +
Trehalose:-
Melibiose:-
(D) Utilization of carbon source Glucose: ++
Galactose: ++
L-sorbose:-
Sucrose: ++
Maltose: ++
Cellobiose:-
Trehalose: +
Lactose:-
Melibiose:-
Raffinose: +
Merezitose: +
Inulin:-
Soluble starch:-
D-xylose:-
L-arabinose:-
D-arabinose:-
D-ribose:-
L-rhamnose:-
Ribitol:-
D-mannitol:-
Glycerol:-
Ethanol: ++
α-methylglucoside: −
Salicin:-
Succinic acid:-
Citric acid:-
Myo-inositol:-
D-Glucosamine:-

  These HB35, B35L1 and H24U1M strains are all incorporated in the National Institute of Technology and Evaluation Microorganism Depositary Center (2-5-8 Kazusa Kamashi, Kisarazu City, Chiba Prefecture 292-0818). Was deposited on May 11, 2017, and the B35L1 and H24U1M strains were deposited on July 14, 2017. The deposit numbers are NITE P-02469 and NITE, respectively. P-02509 and NITE P-02508.

  And bread | pane is manufactured by the frozen dough bread-making method using the yeast hybrid strain for bread making which has such a low temperature bread dough fermenting power which has such freezing tolerance. It is not limited to this, but after mixing bread yeast and other ingredients such as flour to knead to make dough, freeze it to make frozen dough. Thaw and heat the dough up to 27-30 ° C (simultaneously in parallel), ferment the dough, continue to fermentation if necessary even after reaching 27-30 ° C, baked after the end of fermentation The process of performing etc. is illustrated. In the present invention, even if the temperature of the bread dough is 4 to 27 ° C., the fermentation has proceeded to a certain degree or more, and after that, even if the bread dough reaches the normal fermentation temperature of 27 to 30 ° C., the fermentation is sufficiently performed. It is characterized by advancing.

  In the present invention, the criterion that the low-temperature bread dough fermenting power of bread yeast is high is that the amount of carbon dioxide generated in bread dough comprising 5% by weight of sugar per 100% by weight of flour is 4 ° C. as the representative temperature in the low temperature region. When measured for 24 hours (10 g of bread dough), it is 15 mL or more, preferably 20 mL or more. Furthermore, as a typical temperature in a normal yeast fermentation temperature range for breadmaking, 45 mL or more when measured at 30 ° C. for 2 hours (10 g of dough) It means that the ratio of the bread dough fermentation power at 4 ° C. to the bread dough fermentation power at 30 ° C. is 40% or more.

  In addition, in the present invention, the standard for freezing tolerance of bakers' yeast is that a bread dough comprising 5% by weight of sugar per 100% by weight of wheat flour is rapidly fermented at −30 ° C. for 30 minutes after fermentation for 1 hour at 30 ° C. and 75% humidity The amount of carbon dioxide generated after freezing and freezing at −20 ° C. for 2 hours after freezing is 120 mL or more, preferably 130 mL or more when measured at 30 ° C. for 5 hours (bread dough 20 g). It means that the amount of carbon dioxide generated after being stored frozen at −20 ° C. for 21 days is 75 mL or more, preferably 80 mL or more when measured at 30 ° C. for 5 hours (bread dough 20 g).

  In this way, the B35L1 strain, which is a lysine-requiring mutant of the strain belonging to Saccharomyces bayanus bar ubalum, a wine brewing yeast with excellent low-temperature growth ability, and a high bread dough fermentation ability and freezing tolerance By crossing with Saccharomyces cerevisiae H24 strain, a uracil-requiring mutant strain, H24U1M, a yeast for bread, a yeast strain for bakery that combines high low-temperature bread dough fermentation power and freezing resistance in bread dough can be produced. By using the strain, it is possible to further increase the efficiency of bread production by the frozen dough baking method.

  Examples of the present invention will be described below, but the present invention is not limited to these examples, and various modifications can be made within the technical idea of the present invention.

(Acquisition of hybrid strain)
The hybrid strain of the present invention was obtained by the following method.

  Saccharomyces bayanus bar ubalum NBRC10970 strain obtained from the Incorporated Administrative Agency National Institute of Technology and Evaluation Microbial Collection from the NBRC 10970 strain by the method of Kitamoto (Japan Brewing Association, 84 [1], 34-37, 1989) B35L1 strain was isolated. On the other hand, from haploid strain H24 strain derived from baker's yeast strain Saccharomyces cerevisiae for frozen dough and showing mating type a, uracil by Kitamoto's method (Japan Brewing Association, 84 [12], 849-853, 1989). The auxotrophic strain H24U1M was isolated.

  Next, this B35L1 strain and the H24U1M strain were used for crossing by rare mating. Specifically, for both strains, the cells of one platinum loop were placed in a YPD medium (dry yeast extract: 1.0%, high polypeptone in a test tube (diameter 1.8 cm × length 10.5 cm): 2.0 ml, glucose: 2.0%, agar: 2.0%) was inoculated into 3 ml, and cultured with shaking (150 rpm) at 30 ° C. After 24 hours, 1 ml of the culture solution was aseptically centrifuged and the cells collected were washed twice with sterile water. The cells were suspended in 3 ml of a liquid MM medium (Yeast nitrogen base without amino acids: 0.67%, glucose: 2.0%), and cultured with shaking (150 rpm) at 30 ° C. for 24 hours. When 0.03 ml of this culture solution was inoculated into another new liquid MM medium (minimum liquid medium) and similarly cultured with shaking for 48 hours, the culture solution that was transparent immediately after inoculation became cloudy due to the growth of the cells. The hybrid yeast strain HB35 was purely isolated by streaking the grown yeast cells in this culture on a MM agar plate medium. The outline of the process for obtaining this cross strain is shown in FIG.

(Bread dough fermentation test)
The bread dough fermentation power at 30 ° C. and 4 ° C. of the hybrid strain HB35 obtained in Example 1 was measured using the NBRC 10970 strain, the H24 strain, the cross-parent B35L1 strain and the H24U1M strain, and the commercial baker's yeast isolate Saccharomyces In order to confirm the comparison with S. cerevisiae HP467 and HP216 strains, the following test was performed.

Each strain of HB35 strain, NBRC10970 strain, H24 strain, B35L1 strain, H24U1M strain, HP467 strain, HP216 strain was added to a YPD medium (dry yeast extract: 1.0%, high polypeptone: 2.0%, glucose, in a test tube. : 2.0%) YPS medium (bacterial yeast extract: 2.0%, bactopeptone: 4) in an Erlenmeyer flask with 300 ml baffle, reciprocally shaking culture (150 rpm) at 30 ° C. for 24 hours at 3 ml. 0.0%, KH ₂ PO ₄ : 0.2%, MgSO ₄ · 7H ₂ O: 0.1%, NaCl: 2.0%, Adecanol LG-294: 0.05%, sucrose: 2.0%) 60 ml was inoculated and cultured at 30 ° C. for 24 hours with shaking shaking (150 rpm). The cultured cells were collected by centrifugation, washed twice with distilled water, and then placed on a dried absorbent plate for several minutes to obtain cultured cells. Although the solid content of the cultured cells is about 30%, an accurate numerical value is calculated by drying a part thereof. In the following experiments, the cultured cells were used for preparing the dough as a weight converted to a solid content of 33%.

  For each yeast, 10 ml of flour (strong), 5.5 ml of distilled water containing 0.5 g of sucrose and 0.2 g of NaCl and 1.0 ml of a suspension containing 0.2 g of yeast cells were mixed for 1 minute. The prepared low-sugar bread dough (containing 5% sucrose and 2% NaCl with respect to the weight of flour) is put in a 2.4 cm × 20 cm test tube, and the amount of generated carbon dioxide gas is introduced into a graduated cylinder in saturated saline solution at 30 ° C. Then, the amount of carbon dioxide generated per 24 hours at 4 ° C. for 2 hours was measured as the bread dough fermentation power. All these operations were performed at 30 ° C. or 4 ° C.

  The results are shown in Table 1 below. The crossed strain HB35 is 48.1ml / 2h / 10g flour with bread dough fermentation power at 30 ° C and 22.1ml / 24h / 10g flour with bread dough fermentation at 4 ° C. The ratio of the bread dough fermenting power at 4 ° C. was calculated to be 45.9%. The H24 strain, H24U1M strain and HP467 strain had a bread dough fermentation power at 30 ° C. of 44 ml / 2h / 10g flour or higher, but the bread dough fermentation power at 4 ° C. was higher than the bread dough fermentation power at 30 ° C. The ratio was less than 25%. The ratio of bread dough fermentation power at 4 ° C to bread dough fermentation power at 30 ° C of NBRC10970 and B35L1 was high, but this was because bread dough fermentation power at 30 ° C was only about half that of other strains. It was unsuitable for use as a yeast strain. Therefore, it was revealed that the hybrid strain HB35 has a high bread dough fermentation power at both 30 ° C. and 4 ° C., unlike other strains.

(Freezing tolerance confirmation test)
The freezing tolerance of the hybrid strain HB35 obtained in Example 1 was determined in the process of fermenting frozen dough from a low temperature state with Saccharomyces cerevisiae HP467 strain and HP758 strain (strain with freezing tolerance), which are commercial baker's yeast isolates. The following tests were carried out to compare and confirm the change in the amount of carbon dioxide gas generated.

  4.0 g of yeast cells of HB35 strain, HP467 strain, and HP758 strain cultured by the method of Example 2 (converted to solid content of 33%), 200 g of flour (camellia), 10.0 g of sugar, 4.0 g of salt, shortening 10 0.0 g, 1.0 ml (0.1 mg / ml) of ascorbic acid solution and 133 ml of distilled water are mixed with a pin mixer for 3 minutes, and the dough is adjusted to 21.0 ± 1.0 ° C. Prepared. This was immediately divided into 20 g, rounded, fermented for 1 hour at 30 ° C. and 75% humidity, and then quickly frozen in a freezer at −30 ° C. for 30 minutes. The frozen dough was transferred to a −20 ° C. freezer and stored appropriately. After 7, 14 and 21 days of frozen dough, 3 pieces were taken out for each strain, and the amount of carbon dioxide generated was measured for 5 hours with a pharmagraph (Ato Co., Ltd.). In addition, the thing thawed | decompressed after -20 degreeC storage for 2 hours was measured as the 0th day of freezing.

  The results are shown in Table 2 below. The bread dough fermenting power of the hybrid strain HB35 on freezing day 0 and day 21 is 136.6 ml / 5h / 20 g bread dough and 80.9 ml / 5h / 20 g bread dough, respectively. The fermenting power ratio was calculated to be 59.2%. Although this value was lower than 71.1% of HP758 strain which is a strain having freezing tolerance, it was sufficiently higher than 38.3% of HP467 strain having no freezing tolerance. Therefore, it was revealed that the hybrid strain HB35 has high freezing resistance in bread dough.

  From the above, by crossing Saccharomyces bayanus bar ubalum B35L1 strain with Saccharomyces cerevisiae H24U1M strain, it is possible to produce an excellent bakery yeast strain that combines high low-temperature bread dough fermentation ability and freezing tolerance in bread dough It was shown that the production of breads using frozen dough can be greatly improved by applying the strain.

  The present invention is summarized as follows.

  An object of the present invention is to provide a freeze-resistant bread-making yeast having a high bread dough fermenting power not only in a normal temperature range but also in a low temperature range, a method for producing bread using the yeast, and the like.

  Then, by crossing Saccharomyces bayanus bar ubalum B35L1 strain with Saccharomyces cerevisiae H24U1M strain, it is possible to obtain a freeze-resistant bakery yeast having a high low-temperature bread dough fermenting ability, and using the yeast from the frozen dough Bread can be produced efficiently.

The accession numbers of the microorganisms deposited in the present invention are shown below.
(1) Saccharomyces sp. HB35 strain (NITE P-02469).
(2) Saccharomyces bayanus var. Uvarum B35L1 strain (NITE P-02509).
(3) Saccharomyces cerevisiae H24U1M strain (NITE P-02508).

In order to achieve the above object, as a result of intensive studies, the present inventors have established that Saccharomyces bayanus var. Uvarum B35L1 strain and Saccharomyces cerevisiae rare strain 24 are combined with Saccharomyces cerevisiae strain 24. As a result, it was found that freeze-resistant bread-making yeast having a high low-temperature bread dough fermentation ability could be obtained, and the present invention was completed.

That is, the embodiment of the present invention is as follows.
(1) Carbon dioxide generation amount in bread dough comprising 5% by weight of sugar per 100% by weight of flour becomes 45 mL or more when measured at 30 ° C. for 2 hours (10 g of bread dough), and measured at 4 ° C. for 24 hours (10 g of bread dough) ), And the dough containing 5% by weight of sugar per 100% by weight of wheat flour is fermented at 30 ° C and 75% humidity for 1 hour, then quickly frozen at -30 ° C for 30 minutes, and after quick freezing The amount of carbon dioxide generated after frozen storage at −20 ° C. for 2 hours becomes 120 mL or more when measured at 30 ° C. for 5 hours (20 g bread dough), and carbon dioxide gas after freezing and stored at −20 ° C. for 21 days Baking yeast belonging to the genus Saccharomyces, whose generation amount is 75 mL or more when measured at 30 ° C. for 5 hours (bread dough 20 g).
(2) Baking yeast Saccharomyces sp., Which has freezing tolerance and low temperature and high fermentability. HB35 strain (NITE P-02469).
(3) A bread dough (especially refrigerated bread dough or frozen bread dough) containing the yeast for bread making according to (1) or (2).
(4) The bread dough described in (3) is fermented at 4 to 30 ° C. (for example, fermented in parallel with raising the temperature from a low temperature range of 4 to 10 ° C. to a fermentation temperature zone of 27 to 30 ° C. and fermentation temperature) A method for producing bread characterized by continuing fermentation after reaching the belt) and then baking (after completion of fermentation).
(5) Freezing tolerance belonging to the genus Saccharomyces, characterized by crossing Saccharomyces bayanus bar Ubalum B35L1 strain (NITE P-02509) with Saccharomyces cerevisiae H24U1M strain (NITE P-02508) by rare mating And a method for producing low-temperature highly fermentable bread yeast.

The lysine-requiring mutant B35L1 and uracil-requiring mutant H24U1M may be obtained by a conventional method without any particular limitation. For example, UV or chemical substances (ethyl methanesulfonic acid (EMS), N-methyl) -N-nitrosoguanidine (NTG), nitrous acid, etc.) NBRC10970 and H24 strains are mutated, and then a predetermined selective medium (in the case of a lysine-requiring mutant, α-aminoadipic acid-containing medium, etc. are required for uracil. In the case of a mutant strain, a method of selecting with a 5-fluoroorotic acid-containing medium or the like) is exemplified. Then, the crossing by rare junction (rare mating) using these mutant strains.

And by crossing by rare joining of this B35L1 strain and the H24U1M strain, a yeast hybrid strain for bread making having high freezing tolerance such as HB35 strain and high fermenting ability for low temperature bread dough can be easily obtained. And this HB35 strain | stump | stock is a yeast for bread making very useful in the hybrid strain | stump | stock obtained by this crossing, and has the following mycological properties.

In this way, the B35L1 strain, which is a lysine-requiring mutant of the strain belonging to Saccharomyces bayanus bar ubalum, a wine brewing yeast with excellent low-temperature growth ability, and a high bread dough fermentation ability and freezing tolerance Saccharomyces cerevisiae, a bread yeast, can be produced by crossing rarely with the H24U1M strain, a uracil-requiring mutant of the H24 strain, to produce a yeast strain for bakery that combines high low-temperature bread dough fermentation power and freezing tolerance in bread dough. By using the yeast strain, it is possible to further improve the efficiency of bread production by the frozen dough bread method.

As mentioned above, the Saccharomyces bayanus bar Ubalum B35L1 strain and the Saccharomyces cerevisiae H24U1M strain are crossed by rare mating, thereby providing an excellent bakery yeast strain having high low-temperature bread dough fermentation ability and freezing tolerance in bread dough. It has been shown that the production of bread using frozen dough can be greatly improved by applying the strain.

And by crossing Saccharomyces bayanus bar ubalum B35L1 strain and Saccharomyces cerevisiae H24U1M strain by rare conjugation , it is possible to obtain a freeze-resistant bakery yeast with high low temperature bread dough fermenting ability, and by using the yeast Bread can be produced efficiently from frozen dough.

Claims (5)

  The amount of carbon dioxide generated in bread dough containing 5% by weight of sugar per 100% by weight of wheat flour is 45 mL or more when measured at 30 ° C. for 2 hours (10 g of dough), and when measured at 4 ° C. for 24 hours (10 g of dough) 15 ml or more, and the bread dough containing 5% by weight of sugar per 100% by weight of flour is fermented at 30 ° C./humidity 75% for 1 hour, rapidly frozen at −30 ° C. for 30 minutes, and after quick freezing at −20 ° C. The amount of carbon dioxide generated after freezing and storage for 2 hours is 120 mL or more when measured at 30 ° C. for 5 hours (bread dough 20 g), and the amount of carbon dioxide generated after rapid freezing and stored at −20 ° C. for 21 days is The yeast for bakery belonging to the genus Saccharomyces which becomes 75 mL or more when measured at 30 ° C. for 5 hours (bread dough 20 g).   Baking yeast Saccharomyces sp. HB35 strain (NITE P-02469).   Bread dough containing the yeast for breadmaking according to claim 1 or 2.   A method for producing bread, wherein the bread dough according to claim 3 is fermented at 4 to 30 ° C and then baked.   Saccharomyces bayanus var. Uvarum B35L1 strain (NITE P-02509) and Saccharomyces cerevisiae H24TE-M02 A method for producing freezing-resistant and low-temperature and high-fermentability bread yeast belonging to the genus (Saccharomyces).

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