Yeast culture medium additive

Abstract

The present invention provides: a culture medium additive for yeast characterized by containing mango juice as an active ingredient; a method for proliferating yeast, the method being characterized by proliferating yeast in a culture medium containing said culture medium additive for yeast; and a method for fermenting yeast, the method being characterized by fermenting yeast in a culture medium containing said culture medium additive for yeast.

Description

Technical Field

[0001] The present invention relates to an additive for promoting yeast fermentation and growth, which uses plant-based materials as active ingredients, and a method for culturing, growing, or fermenting yeast in a medium containing the additive.

Background Art

[0002] Fermentation has long been widely used in food processing. For example, there are fermented foods that utilize yeast, lactic acid bacteria, etc., such as brewed beverages like beer and wine, fermented milk, natto, miso, etc. These fermented foods contain various components produced by microorganisms through fermentation. In recent years, the effects of these components on health have attracted attention. In addition, microorganisms themselves are also used as food materials. For example, there are yeast extracts and supplements that use lactic acid bacteria themselves with the expected intestinal regulating effect as active ingredients.

[0003] In the production of processed foods that utilize microorganisms themselves or fermentation by microorganisms, it is desired to promote the growth and fermentation of microorganisms from the perspective of improving production efficiency. Commonly used promoters for the growth and fermentation of microorganisms, especially yeast, mainly include peptone and yeast extract. However, due to recent health preferences, natural materials, especially plant-based materials, are preferably used for the growth and promotion of edible microorganisms.

[0004] As plant-based materials that promote the growth and fermentation of yeast, for example, Araliaceae ginseng saponin-containing substances (Patent Document 1) and malt root extracts (Patent Document 2) have been reported. In addition, as a growth promoter for lactic acid bacteria, for example, fruits of the pineapple genus or extracts thereof (Patent Document 3) are known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In making foods composed of natural materials, although there is a demand for an agent that promotes the growth and fermentation of yeast composed of plant-based materials, there is still no material that can sufficiently promote the fermentation or growth of yeast. An object of the present invention is to provide an additive for culturing yeast, which uses a plant-based material as an active ingredient and is used for promoting yeast fermentation and growth, and a method for culturing yeast in a medium containing the additive.

Means for Solving the Problems

[0007] The present inventors have found that the growth or fermentation of yeast is promoted by culturing yeast in the presence of mango juice, and have completed the present invention.

[0008] That is, the present invention is as follows. [1] A medium additive for yeast, characterized by using mango juice as an active ingredient. [2] The medium additive for yeast according to [1] above, wherein the mango juice is a concentrated and reduced juice. [3] The medium additive for yeast according to [1] or [2] above, wherein the mango juice is a clear juice. [4] The medium additive for yeast according to any one of [1] to [3] above, which is used for promoting yeast fermentation. [5] The medium additive for yeast according to any one of [1] to [3] above, which is used for promoting yeast growth. [6] The medium additive for yeast according to [4] or [5] above, wherein the yeast is a Saccharomyces genus bacterium. [7] The medium additive for yeast according to [6] above, wherein the Saccharomyces genus bacterium is Saccharomyces cerevisiae. [8] A method for culturing yeast, characterized by culturing yeast in a medium containing the medium additive for yeast according to any one of [1] to [7] above. [9] The method for culturing the yeast according to [8], wherein the medium contains fruit juice other than mango juice.

[10] The method for culturing yeast, which is characterized by culturing yeast in mango juice.

[11] The method for fermenting yeast, which is characterized by fermenting yeast in a medium containing any one of the yeast culture medium additives according to [1] to [7].

[12] The method for fermenting yeast according to

[11] , wherein the medium contains fruit juice other than mango juice.

[13] The method for fermenting yeast, which is characterized by fermenting yeast in mango juice.

[14] Fermented fruit juice obtained by fermenting fruit juice containing mango juice with yeast.

[15] The fermented fruit juice according to

[14] , wherein the fruit juice is concentrated reduced fruit juice.

[16] A beverage containing the fermented fruit juice according to

[14] or

[15] .

Advantages of the Invention

[0009] The yeast culture medium additive according to the present invention uses mango juice, which is a plant-based material, as an active ingredient and has the effect of promoting the growth or fermentation of yeast. Therefore, the yeast culture medium additive according to the present invention is particularly useful for the preparation of processed foods and beverages or their raw materials.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0011] The culture medium additive for yeast according to the present invention is characterized by containing the fruit juice of mango (Mangifera indica) as an active ingredient. When yeast is cultured in the presence of mango fruit juice, although the reason for the yeast growth promotion effect and fermentation promotion effect is not clear, it is conceivable that mango fruit juice contains components that contribute to the growth and fermentation of yeast.

[0012] The mango fruit juice serving as the active ingredient of the culture medium additive for yeast according to the present invention is the fruit juice obtained by squeezing the pulp of mango. The variety, origin, etc. of the mango used as the raw material of the mango fruit juice to be used are not particularly limited, and any of various varieties generally served as raw food or processed foods may be used.

[0013] The mango fruit juice serving as the raw material of the culture medium additive for yeast according to the present invention may be the one obtained by crushing the pulp of mango, squeezing or filtering it, and removing the skin, seeds, etc. (mango juice), or the one obtained by concentrating the mango juice (concentrated fruit juice), or the one obtained by diluting the concentrated fruit juice (reduced fruit juice), or the one obtained by removing at least a part of the insoluble components from these.

[0014] The method for preparing mango fruit juice from the raw material mango is not particularly limited, and it can be obtained by the treatment methods usually performed when preparing fruit juice (a method in which various operations such as washing, sorting, crushing, squeezing, separating, heating, and cooling are appropriately combined). For example, the whole fruit (the entire fruit including the skin, etc.) is squeezed and separated into fruit juice and residue containing the fruit skin using an in-line juicer or the like, and the squeezed fruit juice is concentrated, sterilized, and cooled, or the whole fruit is separated into the fruit skin part and the pulp part, or after being halved, only the pulp part is squeezed, and concentrated, sterilized, and cooled. It can be produced by the methods generally used for producing fruit juice for raw materials of fruit beverages.

[0015] The mango juice that serves as a raw material for the medium additive for yeast according to the present invention is preferably a clear juice from which at least a part of insoluble solids such as pulp has been separated and removed. Specific methods for separating and removing insoluble solids include, for example, centrifugation, diatomaceous earth filtration, membrane separation, etc., but centrifugation is particularly preferred.

[0016] The obtained mango juice may be concentrated to a Brix of 20% by mass or more and 70% by mass or less using evaporation concentration, freeze concentration, reverse osmosis membrane concentration, etc., as necessary. This concentrated liquid can be used as it is, or diluted to an appropriate concentration with drinking water or the like and used as the main component of the medium additive for yeast according to the present invention. Also, if there is time before the mango juice is provided as a raw material for the medium additive for yeast, it can be sterilized, aseptically filled into a polyethylene bag or the like, and then stored refrigerated or frozen. Note that from the viewpoints of storage and handling workability, etc., it is preferably concentrated. The sterilization treatment can be appropriately selected from various methods used for sterilizing fruit juices and their processed products, such as heat sterilization and filter sterilization.

[0017] In the present invention and the present specification, the Brix value of mango juice can be measured by a conventional method using a measuring device such as a refractometer (RX-5000α, manufactured by ATAGO Co., Ltd.).

[0018] The medium additive for yeast according to the present invention may consist only of mango juice, or may contain various additives as long as they do not impair the yeast growth promoting action and fermentation promoting action in addition to mango juice. As such additives, antioxidants such as ascorbic acid and sodium ascorbate; pH adjusters such as inorganic acids, organic acids, and their salts; and various additives generally added to fruit juices and fruit juice processed products such as flavors can be appropriately selected and used.

[0019] The culture medium additive for yeast according to the present invention is added to a culture medium for culturing yeast. The culture medium for yeast to which the culture medium additive for yeast according to the present invention is added is not particularly limited, and those used in conventional methods can be used. For example, as the carbon source, one or more selected from the group consisting of glucose, sucrose, acetic acid, ethanol, molasses, and sulfite pulp waste liquor, which are used for culturing ordinary microorganisms, are used. As the nitrogen source, one or more selected from the group consisting of inorganic salts such as urea, ammonia, ammonium sulfate, ammonium chloride, or ammonium phosphate, and nitrogen-containing organic substances such as corn steep liquor (CSL), casein, yeast extract, or peptone are used. Furthermore, a phosphate component, a potassium component, and a magnesium component may be added to the culture medium, and as these, ordinary industrial raw materials such as superphosphate of lime, ammonium phosphate, potassium chloride, potassium hydroxide, magnesium sulfate, and magnesium chloride may be used. In addition, inorganic salts such as zinc, copper, manganese, and iron ions may be used. In addition, vitamins and the like may be added. Specifically, for example, media generally used for culturing yeast such as YPD liquid medium and SD medium can be used.

[0020] When the culture medium additive for yeast according to the present invention is used to promote the growth and fermentation of yeast used in the production of food and beverages or yeast that is a raw material for food and beverages, the culture medium for yeast to which the culture medium additive for yeast according to the present invention is added is preferably a medium in which the main carbon source, nitrogen source, etc. are composed of natural materials. Among them, those containing fruit juice or vegetable juice other than mango are preferred, and a medium using fruit juice or vegetable juice as the main carbon source and nitrogen source (hereinafter sometimes referred to as "fruit juice medium") is more preferred, and it may be fruit juice or vegetable juice itself, or mango juice itself. By growing and fermenting yeast in the fruit juice medium, fermented fruit juice, fermented vegetable juice, and brewed wines such as wine and cider can be produced. That is, by using the culture medium additive for yeast according to the present invention, in the production process of fermented fruit juice, fermented vegetable juice, and brewed wine, the time required for yeast growth and fermentation can be shortened and production can be carried out more efficiently.

[0021] The content of the medium additive for yeast according to the present invention to be contained in the yeast medium may be an amount sufficient to obtain the yeast growth promoting effect and the fermentation promoting effect, and is not particularly limited. The medium additive for yeast according to the present invention can be contained, for example, in a yeast culture medium such that the extract content (Brix derived from mango juice) derived from mango juice is preferably 0.1% by mass or more and 70% by mass or less, more preferably 0.5% by mass or more and 55% by mass or less, and even more preferably 1% by mass or more and 27% by mass or less. Note that yeast can be grown or fermented using only mango juice as a culture medium.

[0022] The fruit juice or vegetable juice to be contained in the yeast medium is not particularly limited, and various fruit and vegetable juices and their processed products can be used. Examples of fruit juices include soft fruits such as strawberry, peach, melon, grape, apple, pear, Japanese pear, and cherry; tropical fruits such as banana, pineapple, mango, and passion fruit; citrus fruits such as lemon, lime, yuzu, sudachi, kabosu, grapefruit, orange, iyo orange, satsuma mandarin, summer orange, hassaku, and hinoka; and the like. Examples of vegetable juices include juices of tomato, carrot, spinach, cabbage, Chinese cabbage, broccoli, cauliflower, celery, lettuce, parsley, cress, kale, soybean, beet, red pepper, pumpkin, and komatsuna. The fruit juice or vegetable juice to be contained in the yeast medium may be used as the juice of fruits or the like as it is, or may be concentrated fruit juice or concentrated vegetable juice, or may be reduced fruit juice or reduced vegetable juice, or may be a product obtained by removing at least a part of the insoluble solids therefrom. These fruit juices, vegetable juices, their concentrated juices, and reduced juices can be prepared, for example, by methods generally used in the production of juice and its raw materials.

[0023] The yeast culture conditions may follow general yeast culture conditions. For example, the temperature is 20 to 40°C, preferably 25 to 35°C, and the pH is 3.5 to 7.5, particularly preferably 4.0 to 6.0. The fermentation conditions of the yeast may follow the general fermentation conditions of yeast. For example, the temperature is preferably 0 to 35°C, and the pH is preferably 3.0 to 7.5, particularly 3.5 to 6.0. The growth and fermentation of the yeast may be carried out under aerobic conditions or anaerobic conditions. Also, it may be static culture or agitated culture.

[0024] The yeast cultured in the presence of the medium additive for yeast according to the present invention may be any unicellular fungus. Specifically, it includes bacteria belonging to the genus Saccharomyces, Shizosaccharomyces, Pichia, Candida, Kluyveromyces, Williopsis, Debaryomyces, Galactomyces, Torulaspora, Rhodotorula, Yarrowia, Zygosaccharomyces, Hanseniaspora, Cyberlindnera, Brettanomyces (Dekkera), etc. Among these, because they are edible, Saccharomyces cerevisiae, Saccharomyces pastorianus, Pichia anomala, Pichia (Komagataella) pastoris, Candida tropicalis, Candida lypolitica, Candida sake, Kluyveromyces lactis, Kluyveromyces marxianus, Debaryomyces hansenii, Hanseniaspora uvarum, Cyberlindnera jadinii, Brettanomyces (Dekkera) bruxellensis, etc. are preferred, and more preferably Saccharomyces cerevisiae which is widely used.

[0025] The yeast cells obtained by culturing edible yeast in the presence of the yeast culture medium additive according to the present invention can be used as raw materials for various beverages and foods, just like other edible yeasts. In addition, the fermented product obtained by fermenting edible yeast in an edible medium added with the yeast culture medium additive according to the present invention can also be used as raw materials for various beverages and foods. For example, the brewing wines such as wine and cider obtained by fermentation in the presence of the yeast culture medium additive according to the present invention can be used directly as beverages or as raw materials for mixed wines. Also, the fermented fruit juice and fermented vegetable juice obtained by fermentation in the presence of the yeast culture medium additive according to the present invention can be used directly as beverages or as raw materials for beverages and foods.

Examples

[0026] Next, examples are shown to explain the present invention in more detail, but the present invention is not limited to the following examples.

[0027] <Preparation of fruit juice> The fruit juice used in the following experiments was a concentrated and reduced clear fruit juice unless otherwise specified. Specifically, a commercially available concentrated and reduced fruit juice was adjusted to the target Brix value and filter-sterilized for use.

[0028] <Preparation of starter> In the following experiments, the preculture of the yeast used was carried out as follows unless otherwise specified. First, the yeast was inoculated into a YPD liquid medium and cultured with shaking at 25°C for 48 hours. Then, the yeast cells were collected by centrifugation (7000×g, 5 minutes), washed with sterile water, and then adjusted to a cell concentration of 1.0×10 8 cells / mL with sterile water and used as a starter.

[0029] <Measurement of yeast fermentation degree> In the subsequent experiments, unless otherwise specified, the fermentation degree by yeast was determined using the alcohol production amount as an index. The alcohol amount in the sample was measured using a multifunctional biosensor (BF-5D, manufactured by Oji Scientific Instruments Co., Ltd.) for a solution diluted with distilled water so that the alcohol concentration was 0.0 to 2.0% by volume. The multifunctional biosensor is a device that electrochemically detects hydrogen peroxide (H2O2) generated by oxidation with alcohol oxidase. The value obtained by multiplying the measured value by the dilution factor was taken as the alcohol concentration (% by volume) in the sample.

[0030] <Measurement of Yeast Growth Degree> In the subsequent experiments, unless otherwise specified, the growth degree of yeast was determined using turbidity (OD660: absorbance at 660 nm) as an index. OD660 was measured using a turbidimeter (UV-1800, manufactured by Shimadzu Corporation).

[0031] [Example 1] To extract fruit juices in which yeast fermentation proceeds well, the fermentation degrees in fruit juice media were compared. As the fruit juice media, nine types of fruit juices were used: Mango Juice 1 (frozen concentrated clear mango juice <MEXIFRUTAS>, manufactured by Mexifrutas S.A. de C.V., Tommy Atkins variety), Mango Juice 2 (clear concentrated mango juice, manufactured by KLT Fruits, Inc., Carabao variety), Pineapple Juice (Golden Pine 5-fold concentrated clear juice, manufactured by Koka Shokai), Apple Juice (frozen concentrated clear apple juice, manufactured by Dalian Haisheng Fresh Fruit Juice CO, Ltd.), Red Grape Juice (68° grape clear high polyphenol, manufactured by Welch Foods Inc.), White Grape Juice (68° white grape clear juice, manufactured by ENAV S.A.), La France Juice (Yamagata-produced La France 5-fold concentrated clear juice, manufactured by Koka Shokai), Kiwi Juice (frozen concentrated kiwifruit clear juice, manufactured by ProFruit 2006 Limited), and Muscat Juice (Z10 Muscat clear concentrated juice, manufactured by AUSTRALIAN VINTAGE LIMITED). All the fruit juices used were adjusted to 10% by mass in terms of Brix according to the <Preparation of Fruit Juice> described above.

[0032] To 10 mL of each fruit juice, Saccharomyces cerevisiae NCYC917 strain prepared according to the above <Preparation of Starter> was inoculated so that the inoculum concentration was 1% (1.0×10 6 cells / mL), and static culture was carried out at 25°C for 24 hours. The culture after cultivation was filter sterilized, and the amount of alcohol produced was measured.

[0033] The measurement results of the amount of alcohol produced in the obtained fermented fruit juice are shown in Table 1. As a result, it was shown that the amount of alcohol produced was the largest and the fermentation was good in the mango juice 1 medium and the mango juice 2 medium.

[0034]

Table 1

[0035] [Example 2] It was confirmed that the effect of promoting fermentation by mango juice can be obtained without depending on the strain in the case of Saccharomyces cerevisiae. As Saccharomyces cerevisiae, in addition to the NCYC917 strain (a strain held by the National Collection of Yeast Culture) used in Example 1, a total of 7 strains including Maurivin SW strain (a strain held by Mauri Co., Ltd.), NBRC0848 strain, NBRC0849 strain, NBRC0850 strain, NBRC0853 strain, and NBRC0965 strain (all strains held by the Biotechnology Center of the National Institute of Technology and Evaluation) were used. These strains were selected from the strains available from strain preservation institutions and suppliers, and are strains that are used for fermentation as wine yeast, or strains that can be used for fermentation using grapes or sake as a source of isolation.

[0036] Using the mango juice 1, pineapple juice, and apple juice used in Example 1 as fruit juice media, each strain was inoculated into each fruit juice and fermented in the same manner as in Example 1, and the amount of alcohol produced was measured. The measurement results are shown in Table 2. As a result, in all strains, the amount of alcohol produced was the largest in the mango juice medium and the fermentation was good.

[0037]

Table 2

[0038] [Example 3] The growth degree and fermentation degree of Saccharomyces cerevisiae in mango juice, pineapple juice, and apple juice were measured and compared over time.

[0039] Specifically, the NCYC917 strain used in Example 1 was inoculated into the mango juice, pineapple juice, or apple juice used in Example 2 in the same manner as in Example 1, sampled at 0, 12, 24, 48, 72, and 96 hours after the start of cultivation, and the alcohol production amount (volume %) and turbidity (OD660) were measured. The measurement results of the alcohol production amount are shown in Fig. 1, and the measurement results of the turbidity are shown in Fig. 2, respectively.

[0040] As shown in Figs. 1 and 2, when mango juice was used as the medium, the turbidity was the highest and the alcohol production amount was also higher from 12 hours after the start of cultivation to at least 96 hours after the start of cultivation than when pineapple juice or apple juice was used as the medium. From these results, it was shown that in mango juice, both the growth and fermentation of yeast were promoted more than in other juices.

[0041] [Example 4] The effects of inoculation conditions and temperature conditions on the cultivation of yeast in the presence of mango juice were examined. Specifically, except that the amount of yeast inoculated into the juice was 1.0×10 5 or 1.0×10 6 cells / mL and the cultivation temperature was 25°C or 30°C, the NCYC917 strain was inoculated into mango juice, pineapple juice, or apple juice and cultivated in the same manner as in Example 2, and the alcohol production amount and turbidity (OD660) after cultivation were measured.

[0042]

Table 3

[0043] The measurement results are shown in Table 3. As a result, in any culture condition, the amount of alcohol production was the highest in the mango juice medium, and fermentation was progressing. Similarly, in any culture condition, the turbidity was the highest in the mango juice medium, and yeast was growing.

[0044] [Example 5] The fermentation promoting effect obtained by adding mango juice to the yeast medium was examined. As the raw fruit juices for the fruit juice medium, the apple juice, white grape juice, and red grape juice used in Example 1 were used. As the fruit juices (additive juices) added as additives to the fruit juice medium, the mango juice 1, pineapple juice, and apple juice used in Example 1 were used.

[0045] Specifically, first, the raw fruit juice used as the fruit juice medium was prepared so that the final Brix became 10% by mass according to the <Preparation of Fruit Juice>. On the other hand, the mango juice, pineapple juice, and apple juice, which are additive juices, were adjusted so that the final Brix derived from the additive in the fruit juice medium became 0.5% by mass or 1% by mass and added to the raw fruit juice. Also, as a control, ultrapure water equal in amount to the added additive juice was added.

[0046] To 10 mL of the fruit juice medium prepared by adding the fruit juice as an additive, the Saccharomyces cerevisiae NCYC917 strain prepared according to the <Preparation of Starter> was inoculated so as to be 1% (1.0×10 6 cells / mL), and statically cultured at 25°C for 24 hours. The cultured product after culture was filter sterilized, and the amount of alcohol production was measured.

[0047]

Table 4

[0048] The measurement results are shown in Table 4. As a result, in the fruit juice medium to which the additive fruit juice was added to a Brix of 1% by mass, in any of the raw fruit juices, the mango fruit juice-added fruit juice medium had the highest alcohol production, indicating that fermentation was promoted by the addition of mango fruit juice. Also, in the fruit juice medium to which the additive fruit juice was added to a Brix of 0.5% by mass, fermentation was most promoted in the fruit juice medium to which mango fruit juice was added.

[0049] [Example 6] The growth promotion effect obtained by adding mango fruit juice to the yeast medium was examined. As the yeast culture medium, a glucose-free SD medium (0.67% Yeast Nitrogen Base w / o Amino Acids, manufactured by Difico), which is a minimum nutrient medium, was used. As the fruit juice (additive fruit juice) added as an additive to the culture medium, in addition to the mango fruit juice 1, pineapple fruit juice, and apple fruit juice used in Example 5, molasses (derived from sugar beet) and glucose were also used.

[0050] Specifically, first, a medium was prepared by adjusting the additive mango fruit juice, pineapple fruit juice, apple fruit juice, molasses, and glucose so that the final Brix from the additive was 1% by mass and adding it to the glucose-free SD medium. Also, as a control, a medium was prepared by adding an equal amount of ultrapure water to the added additive fruit juice.

[0051] To 10 mL of each prepared culture medium, the Saccharomyces cerevisiae NCYC917 strain prepared according to the <Preparation of Starter> was inoculated to a concentration of 1% (1.0×10 6 cells / mL) and statically cultured at 25°C for 24 hours. The turbidity (OD660) of the culture after culture was measured.

[0052]

Table 5

[0053] The measurement results are shown in Table 5. As a result, it was shown that the culture in the medium added with mango juice had the highest turbidity, indicating that the addition of mango juice promoted the growth of yeast.

Claims

1. A medium additive for yeast, characterized in that it contains mango juice as an active ingredient and is contained in a yeast culture medium so that the extract content derived from mango juice is 1% by mass or more and 27% by mass or less.

2. The yeast medium additive according to claim 1, wherein the mango juice is a concentrated and reconstituted juice.

3. The yeast medium additive according to claim 1 or 2, wherein the mango juice is a clear juice.

4. The yeast medium additive according to any one of claims 1 to 3, which is used for promoting yeast fermentation.

5. The yeast medium additive according to any one of claims 1 to 3, which is used for promoting yeast growth.

6. The yeast medium additive according to claim 4 or 5, wherein the yeast is a Saccharomyces bacterium.

7. The yeast medium additive according to claim 6, wherein the Saccharomyces bacterium is Saccharomyces cerevisiae.

8. A method for culturing yeast, characterized in that the yeast is cultured in a medium containing the yeast medium additive according to any one of claims 1 to 7 and having an extract content derived from mango juice of 1% by mass or more and 27% by mass or less.

9. The method for culturing yeast according to claim 8, wherein the medium contains fruit juice other than mango juice.

10. The method for culturing yeast according to claim 8 or 9, wherein the yeast is a Saccharomyces bacterium.

11. The method for culturing yeast according to claim 10, wherein the Saccharomyces bacterium is Saccharomyces cerevisiae.

12. A method for fermenting yeast, characterized in that the yeast is fermented in a medium containing the yeast medium additive according to any one of claims 1 to 7 and having an extract content derived from mango juice of 1% by mass or more and 27% by mass or less.

13. The method for fermenting yeast according to claim 12, wherein the medium contains fruit juice other than mango juice.

14. The method for fermenting yeast according to claim 12 or 13, wherein the yeast is a Saccharomyces bacterium.

15. The method for fermenting yeast according to claim 14, wherein the Saccharomyces bacterium is Saccharomyces cerevisiae.

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