JPH08154666A - New yeast, bread dough containing the same and production of the dough - Google Patents

Abstract

PURPOSE: To provide bread dough containing a specific yeast, capable of well fermenting even in a highly saccharlc state and of obtaining excellent bread through the straight method as well as the batch method or the CHUDANE method(medium-leaven method). CONSTITUTION: This dough contains yeast such as Saccharomyces-cerevlsiae R-9152 (FERM-P-14675) or Saccharomyces-cerevlslae R-9155 (FERM-P-14676), which is highly suppressed in fermentation at low temperatures but can conduct enough fermentation in a highly saccharic medium. This yeast has a specific invertase activity of 10-150 unit, a fermenting ability in a highly saccharic medium at 30 deg.C for 115min. of >=350ml, resistance to refrigeration and/or freezing and also resistance to storage under refrigeration in a highly saccharic medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel yeast, bread dough containing the yeast and a method for producing the dough. More specifically, on bread making, in particular, pastries such as Danish and croissant including a retardation process, confectionery bread with high sugar concentration, and novel yeast useful for refrigerated dough or frozen dough in all types of bread and this yeast are contained. The present invention relates to bread dough and a method for producing the dough.

[0002]

2. Description of the Related Art Conventionally, there has been a demand for baker's yeast capable of producing good confectionery breads having high fermentation ability even in a confectionery bread dough having a sugar concentration of 25% or more. The invertase specific activity has been studied. However, the relationship between the latter invertase specific activity and the fermenting power in confectionery bread dough has not been sufficiently examined, and in particular, the invertase specific activity for the fermenting power after refrigeration and freezing in a high sugar dough such as confectionery bread dough. Currently, little research has been done on the involvement of. Therefore, the invention focusing on the invertase specific activity is disclosed in JP-A-61-231.
993, Japanese Patent Application Laid-Open No. 3-80073, discloses only baker's yeast having no or little invertase specific activity. However, these inventions relate to a fructooligosaccharide non-assimilating yeast that has been bred for use in bread containing fructooligosaccharide. Therefore, these yeasts do not have sufficient fermenting power in a high sugar dough such as sweet bread to which a large amount of sugar is added, and as yeasts for producing good sweet bread, they have a drawback that they are not sufficiently practical. .

Under these circumstances, yeasts have been developed up to now, which have an invertase specific activity more than a sufficient amount to decompose sugar in the dough, but the specific activity is considerably low and the fermentative power of high sugar dough is high. The current situation is that there are none.

In the recent bakery industry, the frozen dough method is popular in order to meet the needs of both the rationalization of the process by labor saving and the variety of varieties to meet various consumer needs. Has started to take place. Furthermore, a so-called refrigerated dough method has been actively studied, in which the dough is stored in a refrigerated state without being frozen, and at the same time, the dough is matured. However, in the case of conventional baker's yeast, even if the dough is cooled to a low temperature, the fermentation rate will be slower than that at room temperature, but since the fermentation proceeds, storage in refrigerated dough is at most about one day, and therefore Although it has been put to practical use, it has not yet been widely applied.

In the production of pastries such as Danish and croissant, a so-called "retard method" is adopted in which the dough is treated at a low temperature in order to fold the roll-in margarine into a neat layer. However, due to some fermentation of the dough in this retardation process, the roll-in margarine was not folded neatly, the bread layer formed was not clean, and the dough could not be stored refrigerated, so the utilization of the dough after molding was not possible. However, the yield of the bread making process is reduced.

In order to solve such a problem, Japanese Patent Laid-Open No. 5-76
348, JP-A-5-284896, and JP-A-5-336872 disclose yeasts that do not ferment during refrigeration but that ferment above a certain temperature (cold-sensitive yeasts). (Corresponding to the rewarming fermentation power in the present specification) is about 60% as compared with that before refrigeration. Therefore, when bread is made using refrigerated dough, there is a disadvantage that fermenting power is insufficient and bread with high quality cannot be produced.

[0007] Furthermore, the decrease in the reheat fermentation ability of the cold-sensitive yeast becomes more remarkable as the sugar concentration in the dough becomes higher, and it is as high as that of confectionary bread dough in which the added amount of sugar per flour is 25% or more. At present, a low-temperature-sensitive yeast having a fermenting power after refrigeration with sugar dough that is equivalent to that before refrigeration has not yet been developed.

Also in the frozen dough method, after dough mixing, some fermentation (so-called pre-freeze fermentation) occurs in the freezing process, and ethyl alcohol is produced in the dough to reduce the freezing resistance of the yeast, or the freezer in the distribution process. Since the temperature rises due to poor storage conditions such as opening and closing, the quality of the dough, which has been frozen for a long time, is partially thawed due to the temperature rise and the quality is deteriorated. And in order to suppress pre-freezing fermentation, in the production of frozen dough, mixing is performed at a low temperature like a refrigerator in order to keep the mixing temperature extremely low, and a huge amount of energy is used such as using a spiral quick freezer for quick freezing. The reality is what is needed.

In order to solve such a problem, Japanese Unexamined Patent Publication No.
Although 234939 provides baker's yeast having low temperature sensitivity and freeze-tolerance, the baker's yeast originally has a considerably weaker fermenting power than general baker's yeast, which is problematic in practicality. .

[0010]

Therefore, there has been a demand for a baker's yeast that can be sufficiently fermented with a conventional dough of the middle seed type and the straight type confectionary bread dough.

In addition, the refrigerating dough method allows the dough to be distributed in a refrigerated state without freezing, and the dough expansion in the retarding process is less than that of conventional baker's yeast, and the product value is high, and the remaining dough can be utilized. It has been desired to provide a novel yeast that enables production of high pastry products, a bread dough containing the yeast, and a method for producing the dough.

Further, it has been desired to provide a yeast having a high fermenting power which is not deteriorated even after being refrigerated and which has a high reheat fermenting power even when the high sugar dough is refrigerated and stored.

Further, in the frozen dough method, fermentation is rapidly suppressed during the freezing process of the dough so that the freezing resistance is improved, and the frozen dough is resistant to temperature rise due to storage conditions in the frozen distribution process. A novel yeast and a frozen dough containing the same have been desired.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its object is to have a very high fermenting ability for high sugar dough, and to use the ordinary middle seed method, straight A good confectionery bread can be obtained by the method, and further, it has a resistance to refrigeration and / or freezing, a decrease in fermentation power after refrigeration and frozen storage is small, and a yeast that is resistant to refrigerated storage in high sugar dough is provided. Especially.

The present inventors extensively screened yeast using the strains obtained by screening from the natural world or from preserved strains or breeding operations such as mutation treatment, crossing and cell fusion. It was a yeast whose fermentation was extremely suppressed, and although the specific activity of invertase was sufficient to decompose sugar in the dough, its specific activity was rather low, and yeast with high sugar dough fermentation was isolated.
As a result of repeated screening and breeding from these yeasts, the target strain was successfully obtained, and the present invention was completed.

The present invention belongs to the genus Saccharomyces and has the following properties: (1) Invertase specific activity of 10 units or more, 15
0 units or less, and (2) High sugar dough has a fermenting power of 350 at 115 ° C for 115 minutes.
is more than ml.

In a preferred embodiment, the yeast of the present invention further has the following properties: (3) Fermentative power of 10 ml in a high sugar dough at 5 ° C. for 24 hours.
The following, and (4) reheat high sugar dough fermenting power of 30 ℃, 30 ℃, 115
90% or more of the high sugar dough fermenting power of minutes.

In a preferred embodiment, the yeast of the present invention further has the following properties: (5) -20 ° C, reheated high sugar dough fermenting power at 30 ° C after frozen storage for 1 week is 30 ° C, It has the property of being 90% or more of the high sugar dough fermenting power of 115 minutes.

As yeasts having the above-mentioned properties, the following yeasts: Saccharomyces cerevisiae R-9152 (FER
MP-14675), Saccharomyces cerevisiae R
-9155 (FERM P-14676), Saccharomyces cerevisiae R-9156 (FERM P-146)
77), Saccharomyces cerevisiae R-9160 (F
ERM P-14678) or Saccharomyces
Cerevisiae R-9194 (FERM P-14679)
Is mentioned.

The above yeast can be suitably used for ordinary pastry dough, refrigerated and / or frozen dough.

The present invention further relates to a bread dough containing at least one yeast described above, and in a preferred embodiment, the bread dough is an ordinary confectionery bread dough, refrigerated bread dough, or frozen dough.

The present invention also relates to a method for producing a bread dough containing at least one yeast described above, and in a preferred embodiment, a method for producing an ordinary confectionery bread dough, refrigerated bread dough or frozen bread dough.

By using the yeast of the present invention, which has a high fermenting power of high sugar dough and a high fermenting power even after refrigeration and freezing, a refrigerated dough which is an object of the present invention can be produced and can be stored for a long time, It enables the production of high quality, high yield pastry by the retard method and frozen dough with high freezing resistance. Further, it becomes possible to manufacture a sweet bun using a high sugar dough by the refrigerating dough method. Therefore, the object of the present invention is achieved. The present invention will be specifically described below.

The yeast of the present invention has at least the following properties: (1) Invertase specific activity of 10 units or more, 15
0 units or less, and (2) High sugar dough has a fermenting power of 350 at 115 ° C for 115 minutes.
It is more than ml.

If the invertase specific activity is lower than 10 units, sufficient fermentability cannot be obtained because the sugar in the dough cannot be sufficiently decomposed, and if it is higher than 150 units, the decomposition rate of sugar in the high sugar dough is high. It becomes faster and the osmotic pressure of the dough becomes higher. As a result, fermentation is inhibited, and sufficient high sugar dough fermenting power cannot be obtained. On the other hand, if it is higher than 150 units, the sugar is decomposed more quickly during refrigeration of the high-sugar dough, so that the osmotic pressure increases and the reheat fermentation power decreases.
From this point of view, the invertase specific activity is preferably 150 units or less.

[0026] The yeast of the present invention is further used in high sugar dough.
It has the property that the fermentation power at 0 ° C. for 115 minutes is 350 ml or more. The yeast having such properties is endowed with resistance to low temperatures and has a sufficient fermenting power during bread making, so that the object of the present invention can be achieved.

The yeast of the present invention further has the following properties: (3) Fermentation power of 10 ml in a high sugar dough at 5 ° C. for 24 hours
The following, and (4) reheat high sugar dough fermenting power of 30 ℃, 30 ℃, 115
90% or more of the high sugar dough fermenting power of minutes.

Fermentation power of high sugar dough for 24 hours at 5 ° C is 1
Since it is 0 ml or less, the dough hardly expands during refrigeration, and the dough can be easily formed by the retard method,
The remaining fabric can be reused. In addition, the re-warm high sugar dough fermenting power of 30 ° C is 30 ° C and the high sugar dough fermenting power of 115 minutes is 9
When it is 0% or more, a sufficient fermenting power is maintained even after refrigeration, and a voluminous good bread can be obtained by the refrigeration dough method.

The yeast of the present invention further has the following properties: (5) High-sugar dough fermenting ability for 15 minutes at 30 ° C for 15 minutes at re-warming high-sugar dough fermenting ability at -20 ° C and 30 ° C after frozen storage. It may have the property of being 90% or more of the force.

By imparting the property (5) to the property (3), the freezing resistance is particularly enhanced, and a good bread having a large volume can be obtained even in the frozen dough method.

Specific examples of the yeast having the above properties include the following yeast: Saccharomyces cerevisiae R-9152.
(FERM P-14675), Saccharomyces cerevisiae R-9155 (FERM P-14676), Saccharomyces cerevisiae R-9156 (FERM P
-14677), Saccharomyces cerevisiae R-91.
60 (FERM P-14678) or Saccharomyces cerevisiae R-9194 (FERM P-14
679).

The properties of the yeast of the present invention can be measured as follows.

The invertase specific activity is defined as the double amount (mg) of glucose produced from sucrose in 1 minute by dry weight of 1 g of cells.

Specifically, about 50 mg of yeast cells as a dry matter weight was added to 5 ml of 0.1 M acetate buffer (pH 5.
0), 0.2 ml thereof was added to 0.8 ml of 0.1 M acetate buffer pH 5.0, and another 1 ml of 15 ml was added.
30% by adding (W / V)% sucrose buffer solution
React at 10 ° C for 10 minutes. The reaction was stopped by adding 1 ml of 1N NaOH, neutralized by adding 1 ml of 1N HCl, centrifuged (3000 rpm, 5 minutes) to remove the cells, and the glucose concentration in the supernatant was determined by the glucostat method (trade name: Glucose B-Test Wako: manufactured by Wako Pure Chemical Industries, Ltd.). The concentration of the yeast to be measured is appropriately diluted depending on the level of invertase specific activity, and the measurement is performed within a range in which the absorbance is linear in the measurement by the glucostat method.

The dry weight of yeast is 105 yeast cells.
It is defined as the weight after drying at 5 ° C. for 5 hours.

The fermentative power of various high-sugar doughs was measured as follows in accordance with the high-sugar dough fermentative power set by the Yeast Industry Association.

(5 ° C. high sugar dough fermenting power) Blending of the following raw materials: flour 100 g yeast 3 g sucrose 30 g salt 0.5 g water 52 ml so that the dough has a kneading temperature of 20 ± 1 ° C. After mixing, put the dough in a cylinder and measure the amount of dough at the start in advance. The difference between the amount of dough after fermentation at 5 ° C for 24 hours and the amount of dough at the start is 5 ° C high sugar dough fermentation ability. And (30 ° C. high sugar dough fermenting power) By mixing the above raw materials, the dough is mixed so that the kneading temperature is 30 ± 1 ° C.,
The dough is put in a cylinder, the amount of dough at the start is measured in advance, and the difference between the amount of dough after fermentation at 30 ° C. for 115 minutes and the amount of dough at the start is defined as 30 ° C. high sugar dough fermenting power.

(30 ° C reheat high sugar dough fermenting power) The reheat fermenting power was 30 ° C after fermenting the high sugar dough prepared in the same manner as 5 ° C high sugar dough fermenting power measurement at 5 ° C for 24 hours. Reheat and measure. After rewarming, with fermenting power of 15 minutes at 30 ℃,
30 ℃ reheat and high sugar dough fermenting power.

(Re-warmed high-sugar dough fermenting power after 1 week of freezing) The re-warmed high-sugar dough fermenting power after freezing was obtained by fermenting a high-sugar dough prepared in the same manner as the 30 ° C. high-sugar dough fermenting power measurement at 30 ° C. for 1 hour. Pull out,
After freezing at -20 ° C for 1 week, the temperature is returned to 30 ° C and measurement is performed.
After rewarming, the fermenting power at 115 ° C for 30 minutes is used as the rewarming high sugar dough fermenting power after 1 week of freezing.

The bread dough of the present invention contains one or more yeasts having the above properties. The dough is preferably a high-sugar dough such as a confectionary dough, a refrigerated dough, or a frozen dough. The bread dough of the present invention includes pastry or confectionery bread dough, for example, Danish, croissant, bread, butter rolls, Chinese steamed buns, yeast donuts, and all using bread yeast as a swelling agent.

The present invention further relates to a method for producing the above dough. The ingredients of the bread dough may be blended according to the bread dough known to those skilled in the art.

By using the yeast of the present invention, the high sugar dough fermenting power is increased, and the high sugar dough fermenting power after refrigeration and freezing is increased because the invertase specific activity decomposes sugar in the dough. It is sufficient, but it is considered that the effect of screening and breeding yeast which is considerably low is large. Also,
Although the reason why fermentative power is suppressed at low temperature is not clear, yeast fermentation involves the use of extracellular sugars (glucose, fructose, sucrose, etc.) in the yeast cells by permease of sugars present in the cell membrane. It is said to proceed by classifying the transported saccharides into ethyl alcohol and carbon dioxide gas by a glycolytic enzyme, and in the case where the sugar permease present in this cell membrane is the yeast, especially at low temperature. In the case of the yeast, a part or all of the glycolytic enzymes existing in the cytoplasm decrease in activity at low temperature, and a protein specifically induced by temperature (heat shock protein) In the case of yeast, it is considered that fermentation is inhibited, and that fermentation is delayed by suppressing respiratory ability especially at low temperatures.

Generally, low temperature sensitivity (LOW TEMPERATURE
It is known that the gene (TURE SENSITIVE: LTS) exists in the genus Saccharomyces, but this is related to the phenomenon that "growth" at low temperature or high temperature is suppressed or killed, and "fermentation at low temperature""Is different from the phenomenon of being suppressed.

The method for obtaining the yeast of the present invention will be described below.

First, a method for obtaining a cold-sensitive yeast will be described.

The above-mentioned yeasts are screened from the natural world, nitrosoguanidine, ethyl methanesulfonate,
It can be obtained by mutation treatment such as ultraviolet irradiation, or breeding operation such as hybridization or cell fusion. Here, a method for obtaining the target yeast by mutation treatment is disclosed, but it goes without saying that the method for obtaining the yeast of the present invention is not limited to this method.

When the one-step mutation treatment is insufficient, it is also possible to use a combination of a method of repeating the mutation treatment, a method of obtaining spores and backcrossing, a method of cell fusion, and the like. Details will be described later.

(A) Method for Mutating Yeast Here, ethyl methane sulfonate (hereinafter referred to as EMS) is used.
Will be described). The medium used is as follows.

YPD Medium YPD Agar Plate Glucose 20 g Glucose 20 g Polypeptone 20 g Polypeptone 20 g Yeast Extract 10 g Yeast Extract 10 g Water 1000 ml Agar 20 g Water 1000 ml First, from the parent slant, 1 platinum loop, YPD medium 5
The cells are inoculated in ml and cultured with shaking at 30 ° C. for 16 hours. After completion of the culture, the cells were collected by centrifugation at 3000 rpm for 10 minutes, 0.1 M, pH 7.
Wash once with 0 phosphate buffer. The cells were suspended in 5 ml of the same phosphate buffer, 0.15 ml of EMS was added, and the mixture was treated at 30 ° C. for 2 hours with occasional stirring.
The cells are collected by centrifugation at 00 rpm for 10 minutes, washed with a phosphate buffer, 5 ml of 20% Na ₂ S ₂ O ₃ is added, and the mixture is allowed to stand at 30 ° C. for 10 minutes to decompose EMS. 20% Na ₂ S ₂ O ₃ treatment was performed twice, washed with 5 ml of physiological saline 3 times, and 5 ml of physiological saline was added.
Then, the cells are suspended in, and appropriately diluted on a YPD agar plate having the above composition, and the bacteria are applied.

(B) Screening for cold-sensitive yeast B-1. Primary screening: Microplate method By using bromcresol purple (BCP), the properties of BCP that becomes bluish purple at high pH and yellow at low pH are used. This is a method of screening the fermentative power.

The strain grown on the YPD agar plate is inoculated into a microplate containing 1 platinum loop and 200 μl of YPD medium and statically cultured at 30 ° C. for 16 hours. YCP medium containing BCP in each well of the microplate (bromcresol purple (BCP) 30 mg added to the above YPD medium) 200
20 μl of this culture broth was transplanted to each of 2 microplates, 10 ° C,
And incubate at 30 ° C. for 5 hours. In the 30 ° C culture group, the growth is good and the amount of bacteria is large, and the pH of the broth is yellow because the pH of the broth is low because the fermentation is good. Select a strain whose color has not turned yellow.

B-2. Secondary screening: Meissel method: 2
The subsequent screening is a method of selecting a strain having a large weight difference before and after Mycel fermentation. The medium used is as follows.

Molasses medium Meissel liquid Molasses (as sugar) 30 g Glucose 80 g Ammonium sulfate 5 g (NH ₄ ) ₂ HPO ₄ 5 g Phosphorus ammonium 3 g KH ₂ PO ₄ 5 g Urea 2 g Water 1000 ml Water 1000 ml The molasses medium was used as a molasses medium. 1 to 5 ml
Platinum loops are inoculated and cultured with shaking at 30 ° C. for 24 hours. Transfer 5 ml of this culture to 50 ml of molasses medium and
Culture with shaking at 24 ° C for 24 hours. After culturing, 80 ml of the culture solution was collected from the two flasks together, 3000 rpm, 1
The cells are collected by centrifugation for 0 minute and washed once with sterile water. 100m
Suspend in 50 ml each of Mycel solution,
C. for 15 hours and at 30.degree. C. for 5 hours. The weight difference before and after Mycel fermentation is defined as the Mycel fermenting power, 30
A strain that is well fermented at 0 ° C and has low fermentative power at 10 ° C is selected.

From the viewpoint of obtaining the yeast of which fermentative power is suppressed at low temperature, which is the object of the present invention, the mutagenized yeast is inoculated into a YPD medium containing a drug that kills the growing yeast. It is more effective to add a step of culturing in an anaerobic state at low temperature. This is because the bacterial cells that proliferate at low temperature are killed and the screening efficiency is further improved. Examples of agents that kill proliferating yeast include nystatin, amphotericin B, cycloheximide, and the like, but any agent can be used as long as it has an effect of killing proliferating cells at a relatively low concentration. The concentration of the drug in the medium is 10 μg / ml for nystatin.
50 μg / ml, 100 μg for amphotericin B
/ Ml to 500 μg / ml, in the case of cycloheximide,
1000 μg / ml to 5000 μg / ml is suitable.

Next, screening and breeding of strains having a low invertase specific activity will be described.

As a method for obtaining a strain having a low invertase specific activity, one is to measure the invertase activity of more strains before selecting a parent strain for obtaining a cold-sensitive strain, and to select a strain having a specific activity within a desired range. Examples of the method include mutation screening of cold-sensitive strains using.
Further, a spore strain having a low invertase specific activity is isolated, a spore strain of a cold-sensitive strain obtained by the above method and a hybrid strain are formed, the spore strain is isolated, and the yeast is in the range of the desired invertase specific activity. There may be mentioned any method such as screening, mutation, crossing, cell fusion and the like without particular limitation.

The yeasts obtained by the above method are evaluated for various fermentative powers, cold storage resistance, freezing resistance, bread-making properties and the like. The bacterial cells used for evaluation can be prepared by the following method.

[0058] Dispense 100 ml of medium into a 500 ml Sakaguchi flask, sterilize, and transplant 1 platinum loop from fresh slant at 30 ° C, 2
Incubate with shaking for 4 hours.

Second seed mother: 5 L of the same medium 1 L as the first seed mother
After dispensing into a conical Erlenmeyer flask and sterilizing, the first seed mother is inoculated in the total amount and shake-cultured at 30 ° C. for 24 hours.

Seed culture: Medium composition: Molasses (as sugar) 300 g Ammonium sulfate 4 g Phosphorus 0.7 g Urea 2.5 g 10 L volume added as a fed-batch method 1 L of medium was added to a mini jar fermenter to sterilize , And the total amount of the second seed mother to make 2L. 30-35
℃, pH 4-5 (control with ammonium hydroxide), 300 rpm
Aeration is carried out at 2 NL / min while stirring for 12 hours, and the cells are cultured for 12 hours.

Main culture: Medium composition: molasses (as sugar) 350 g Added by fed-batch system.

Ammonium sulphate 4 g Phosphorus ammonium 1 g Urea 2.5 g 10 L Miniger fermenter was sterilized by adding 1.3 L of medium to 700 L of seed culture to make 2 L.
30-35 ° C., pH 4-5 (control with ammonium hydroxide), 3
Aeration is carried out at 2 NL / min while stirring at 00 rpm, and the cells are cultured for 10 hours.

The above culture broth is separated, washed with water, filtered,
Obtain live cells.

Although the yeast screening, breeding method and the like of the present invention have been described above, in the process of obtaining a cold-sensitive strain, fermentation at 30 ° C. is possible even if the fermenting ability at low temperature is suppressed by only one-step mutation treatment. Power is also declining. Further, in obtaining a low invertase specific activity strain, it may not be possible to obtain a strain having a desired activity sufficiently by a single operation of isolating a spore strain from a hybrid with the low invertase specific activity strain.
In such a case, the following method can also be implemented.

That is, in the case of obtaining a cold-sensitive strain, a method in which the mutation treatment is repeated one or more times, a spore strain of a cold-sensitive mutant strain and a wild-type obtained by at least one mutation treatment which suppress fermentation under low temperature And a method in which this cold-sensitive mutant strain and a wild diploid yeast are fused back at least once.

When a low invertase specific activity strain is to be obtained, a cross between a spore strain of the hybrid strain obtained by one cross and a low invertase specific activity strain and isolation of the spores are performed once or more. Is the way.

Backcrossing means that spore strains of a mutant strain and a wild strain are separated, spore strains having different sexes are crossed to obtain a crossbred strain, and a spore strain is taken from the crossbred strain to obtain a wild strain. The operation of crossing with the spore strain of the strain is performed once or more. By carrying out this, it is possible to obtain a strain having a gene of low temperature sensitivity (related to fermentation) and a gene of excellent fermentability of a wild strain.

If a spore strain can be obtained in this way, the above-mentioned backcrossing method is possible. However, if the obtained mutant strain or wild strain has an extremely low sporulation ability or an extremely low spore germination rate. If it is difficult to obtain a spore strain, the cell fusion method may be used. A marker may be attached according to a conventional method, or fusion can be performed without a marker if the fusion frequency is high. Examples of the marker include a combination of a lysine-requiring strain and a respiratory-deficient strain described in JP-A-63-294778.

[0069]

The present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

(Example 1) A strain of Kaneka Red Yeast (produced by Kaneka Kagaku Kogyo Co., Ltd.) was applied to a Fowell plate (sodium acetate 0.4%, agar 2%, pH 6.7) at 28 ° C and 2 ° C.
Spore strain R-6R obtained by culturing for a day to form spores
As a parent strain, mutation was carried out by the EMS method of the above (A), and the screening of the above (B) was carried out. As a result, Saccharomyces cerevisiae R-6180-1 having low temperature sensitivity was obtained.

Next, this strain was crossed with a strain of Saccharomyces cerevisiae R-13R having a very low invertase specific activity screened from a large number of spore strains isolated from Kaneka Red Yeast to form spores,
Spore strain Saccharomyces cerevisiae R-9152 (FERM P-1467), which has a low invertase specific activity and is cold-sensitive, has been deposited at the Institute of Biotechnology.
5), Saccharomyces cerevisiae R-9155 (FE
RM P-14676) and Saccharomyces cerevisiae R-9156 (FERM P-14677).

Jar culture of these strains was carried out to measure invertase specific activity, 5 ° C. high sugar dough fermenting power, 30 ° C. high sugar dough fermenting power, 30 ° C. reheat high sugar dough fermenting power, and the method shown below was used. In the above, a conventional sweetened medium seed method sweet bread and a straight method sweet bread were prepared by two methods, an ordinary method and a method of undergoing a refrigeration step, and the specific volume by the rapeseed substitution method, the appearance of the bread, and the internal phase were evaluated. The stock was evaluated.

In the usual straight bread making without refrigerating storage, the bread making was performed under the same conditions except that the refrigerating storage step was not included in the following steps.

Formulation and Steps of Sweetened Medium Method Sweet Bread: The numbers in the formulation represent parts by weight.

Medium seeds Main kneading blend: Strong flour 63 27 Thin flour 7 3 Sugar 525 Salt -1 Oil / fat 8 Yeast 4-Degrinization-2 Egg-10 Yeast food 0.1-Water 4010 Process conditions: Medium seed mixing: Low speed 2 minutes, medium speed 2 minutes Kneading temperature: 27 ° C Medium seed fermentation: 30 ° C, 2.5 hours Main kneading mixing: Low speed 2 minutes, medium speed 4 minutes, high speed 2 minutes Floor time: 30 ° C, 30 minutes division Weight: 400 g Bench time: 30 ° C, 15 minutes Molding: Molding with moulding Proof: 38 ° C, 80% humidity (1.5 cm on mold)
Baking is started at the time when it is expanded.) Baking: 200 ° C., 15 minutes Blending of sweet bread by the straight method and process: Numbers in blending represent parts by weight. Formulation: Strong flour 90 Light flour 10 Sugar 30 Salt 1 Oil and fat 8 Yeast 4 Desalting 2 Whole egg 10 Yeast food 0.1 Water 50 Process conditions: Mixing: Low speed 3 minutes, Medium speed 6 minutes, High speed 2 minutes Forging temperature: 27 ° C Fermentation time: 30 ° C, 1.5 hours Divided weight: 400g Bench time: 30 ° C, 15 minutes Refrigerated storage: 5 ° C for 1,4,7 days Molding: Molding with molder Roh: 38 ° C, 80% humidity (on mold) Firing starts at the time of expansion to 1.5 cm) Firing: 200 ° C., 15 minutes The results are shown in Tables 1, 2, 3 and 4.

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

[Table 3]

[0079]

[Table 4]

As shown in the table, the yeast of the present invention can obtain good bread even in the ordinary middle seed method and straight method confectionery bread as compared with the ordinary yeast, and the dough does not expand during refrigeration. It can be seen that there is little deterioration in the specific volume, appearance, and internal phase due to refrigerated storage, and even in confectionary bread dough, good bread can be obtained for a long time by the refrigerated dough method.

Example 2 In the same manner as in Example 1, Saccharomyces cerevisiae R-9156 which has a low invertase specific activity, is cold-sensitive, and is freeze-tolerant.
(FERM P-14677), Saccharomyces cerevisiae R-9160 (FERM P-14678), and Saccharomyces cerevisiae R-9194 (FER
MP-14679).

Jar culture was performed on these strains in the same manner as in Example 1, and the invertase specific activity, high sugar dough fermenting power at 5 ° C.,
30 ℃ high sugar dough fermenting power, 30 ℃ reheat high sugar dough fermenting power,-
Measure the reheated high sugar dough fermenting power after freezing at 20 ℃ for 1 week,
Furthermore, a frozen dough confectionery bread is prepared by the following method,
The above strains were evaluated for freeze resistance.

Formulation: Formulation numbers represent parts by weight.

Strong flour 90 Thin flour 10 Sugar 30 Salt 1 Oil and fat 8 Yeast 4 Desalting 2 Whole egg 10 Yeast food 0.1 Water 50 Process conditions: Mixing: low speed 3 minutes, medium speed 6 minutes, high speed 2 minutes Forging temperature: 27 C. Fermentation time: 30.degree. C., 1 hour Divided weight: 400 g Bench time: 30.degree. C., 15 minutes Molding: Molding with moulder Freezing conditions: -20.degree. C., 1, 2 and 4 weeks Thawing: 30.degree. C., 1 hour Proofer: 38.degree. , Humidity 80%, (Baking starts when it expands to 1.5 cm on the mold) Baking: 200 ° C., 15 minutes When not frozen, the above steps are the same without the freezing and thawing steps. Bread was made under the conditions.

The results are shown in Tables 5, 6 and 7.

[0086]

[Table 5]

[0087]

[Table 6]

[0088]

[Table 7]

As shown in the table, the yeast of the present invention shows less decrease in specific volume, appearance and internal phase deterioration due to frozen storage than ordinary yeast. It can be seen that good bread can be obtained in the long term.

[0090]

INDUSTRIAL APPLICABILITY By using the yeast of the present invention, in a rich bread such as sweet bread having a high sugar concentration, the intermediate seed method,
In both straight methods, better bread can be obtained as compared with conventional yeast. Furthermore, by introducing this good property into the low temperature sensitive strain, in the refrigerated dough method, the retard method and the frozen dough method, fermentation is suppressed, the dough expansion is small, and the fermenting power does not decrease even after refrigeration and freezing. , You can get good bread. In particular, even in a rich bread production method having a high sugar concentration, excellent bread can be provided in the long-term stable refrigeration and frozen dough method, which has been impossible in the past.

Claims (10)

[Claims] 1. The following properties belonging to the genus Saccharomyces: (1) Invertase specific activity of 10 units or more, 15
0 units or less, and (2) High sugar dough has a fermenting power of 350 at 115 ° C for 115 minutes.
Yeast having a volume of at least ml. 2. The following properties are further provided: (3) Fermentation power of high sugar dough at 5 ° C. for 24 hours is 10 ml.
The following, and (4) reheat high sugar dough fermenting power of 30 ℃, 30 ℃, 115
The yeast according to claim 1, which has a high sugar dough fermenting power of 90% or more. 3. The following properties are further provided: (3) Fermentation power of high sugar dough for 10 hours at 5 ° C. for 24 hours
Below, (4) reheat high sugar dough fermenting power of 30 ℃, 30 ℃, 115
90% or more of the high sugar dough fermenting power of 5 minutes, and (5) -20 ℃, re-warmed high sugar dough fermenting power at 30 ℃ after frozen storage for 1 week, 30 ℃, 115 minutes high sugar dough fermentation The yeast according to claim 1, having 90% or more of the force. 4. The yeast is Saccharomyces cerevisiae R-9152 (FERM P-14675), Saccharomyces cerevisiae R-9155 (FERM P-1).
4676), Saccharomyces cerevisiae R-9156.
(FERM P-14677), Saccharomyces cerevisiae R-9160 (FERM P-14678), or Saccharomyces cerevisiae R-9194 (FE
RM P-14679).
The yeast according to. 5. A dough containing at least one yeast according to any one of claims 1 to 4. 6. The dough according to claim 5, wherein the dough is a refrigerated dough. 7. The dough according to claim 5, wherein the dough is a frozen dough. 8. A method for producing a dough containing at least one yeast according to any one of claims 1 to 4. 9. The method for producing bread dough according to claim 8, wherein the bread dough is a refrigerated dough. 10. The method for producing a dough according to claim 8, wherein the dough is a frozen dough.