Aroma-producing yeast and its application in beer fermentation

Abstract

The present invention is applicable to the field of microbial technology and provides an aroma-producing yeast and its application in fermenting beer. The aroma-producing yeast is Maggi yeast with a deposit number of CGMCC NO.33897. The present invention isolates and purifies aroma-producing yeast strains from a natural environment, screens the purified strains, selects dominant aroma-producing yeasts with good tolerance for further experiments, measures the growth curve of the dominant aroma-producing yeasts, identifies the strains and observes their morphology, and evaluates their fermentation performance, thereby screening strains that meet the characteristics of beer brewing. The strains have good stress resistance and good growth ability. When used in beer fermentation using mixed fermentation, they have advantages over commercial beer fermented with single bacteria in multiple sensory dimensions such as foam, flavor coordination, various aromas, and mouthfeel, providing consumers with a better drinking experience.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and in particular relates to an aroma-producing yeast and an application thereof in fermenting beer. Background Art

[0002] Aroma-producing yeasts (also known as flavor-producing yeasts or ester-producing yeasts) are a group of functional microorganisms that can produce aromatic compounds (primarily esters) during metabolism. These yeasts are not defined based on taxonomic principles but rather as fungi classified according to their functional properties. Their metabolic mechanism uses sugars, aldehydes, and organic acids as substrates, catalyzing the synthesis of aromatic esters through esterases. Common aroma-producing yeasts include diverse taxa such as Hansenula, Candida, Pichia, Torulopsis, Brettanomyces, Geotrichum candidum, and Pseudomonas aeruginosa.

[0003] Aroma-producing yeasts are isolated from diverse sources, including koji (drinking yeast), fruit juice and wine, fermented dairy products, and traditional fermented foods (such as kimchi, fermented mash, and cured meats). Different species of aroma-producing yeasts, through specific metabolic pathways, can produce diverse aroma profiles, encompassing typical aromas such as fruity, floral, sauce-flavored, and burnt. These microorganisms have significant application value in the food industry, with widespread applications in liquor brewing, fruit wine fermentation, vinegar production, soy sauce production, and edible flavor development, effectively enhancing the content of the product's primary aroma components.

[0004] Therefore, screening new strains for fermentation is of great significance to actual production and life. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide an aroma-producing yeast, aiming to solve the problems raised in the above background technology.

[0006] The embodiment of the present invention is achieved by providing an aroma-producing yeast, wherein the aroma-producing yeast is Maggi yeast ( Metschnikowia pulcherrima ), the deposit number is CGMCC NO.33897, and it was deposited in the General Microbiology Center of China Culture Collection Administration on May 26, 2025.

[0007] Another object of an embodiment of the present invention is to provide an application of aroma-producing yeast in fermenting beer.

[0008] Preferably, the steps include:

[0009] The malt is mixed with water, and then the mixture is heated in stages after addition, and then filtered. The filtered wort is refluxed and boiled, hops are added, and the mixture is filtered again and sterilized to obtain a wort fermentation medium.

[0010] The aroma-producing yeast is activated and then centrifuged to obtain bacterial sludge, which is inoculated into a wort fermentation medium, and then inoculated with commercial yeast.

[0011] Preferably, the mass ratio of malt to water is 1:4-5.

[0012] Preferably, the specific operation of the staged insulation is: insulation at 46-50°C for 25-35 minutes, insulation at 62-55°C for 55-65 minutes, insulation at 70-74°C for 18-22 minutes, and insulation at 76-80°C for 8-12 minutes.

[0013] Preferably, the step of activating the aroma-producing yeast, centrifuging to obtain bacterial sludge, inoculating it into a wort fermentation medium, and then inoculating commercial yeast, specifically, inoculating commercial yeast after 70-74 hours.

[0014] Another object of an embodiment of the present invention is to provide a beer starter, wherein the starter includes the aroma-producing yeast.

[0015] In the embodiments of the present invention, aroma-producing yeast strains are isolated from a natural environment and purified, the purified strains are screened, the growth curves and tolerance of the dominant aroma-producing yeasts are measured, the strains are identified and their morphology is observed, and fermentation performance is evaluated, thereby screening out strains that meet the characteristics of beer brewing. The strains have good stress resistance and good growth ability. When used in beer fermentation, they have advantages over commercial beer in multiple sensory dimensions such as foam, flavor coordination, various aromas, and mouthfeel, and can provide consumers with a better drinking experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A classification chart for yeast aroma evaluation of multiple yeast strains provided in Example 1 of the present invention;

[0017] Figure 2 The gas production of three typical strains provided in Example 1 of the present invention;

[0018] Figure 3 The different color ester production characteristics of the three representative strains provided in Example 1 of the present invention;

[0019] Figure 4 The 100X microscopic morphology of the aroma-producing yeast YC111 provided in Example 1 of the present invention;

[0020] Figure 5 Morphological observation of the aroma-producing yeast YC111 provided in Example 1 of the present invention on a YPD plate;

[0021] Figure 6 This is the growth and development tree of the aroma-producing yeast YC111 provided in Example 1 of the present invention;

[0022] Figure 7 The ethanol tolerance test results of the aroma-producing yeast YC111 provided in Example 2 of the present invention;

[0023] Figure 8 The sugar tolerance test results of the aroma-producing yeast YC111 provided in Example 2 of the present invention;

[0024] Figure 9 This is the growth curve of the aroma-producing yeast YC111 provided in Example 2 of the present invention;

[0025] Figure 10 Comparison of CO2 weight loss curves of aroma-producing yeast YC111 provided in Example 2 of the present invention and commercial yeast;

[0026] Figure 11 This is a comparison of the sensory evaluation of beer fermented with mixed bacteria and single bacteria (commercial yeast) provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0029] Example 1: Screening and identification of an aroma-producing yeast:

[0030] (1) Isolation and purification of aroma-producing yeast: Local specialty fruits were collected to make natural fermentation wine, as shown in Table 1:

[0031] Table 1

[0032] Classification Fruit name Main production areas Features Berries wild blueberries Daxinganling Small fruit, high in anthocyanins, sweet and sour with a hint of forest aroma Blackcurrant Suihua, Heilongjiang Rich in vitamin C, sweet and sour with a slight astringency Red Raspberry Fushun, Liaoning Bright red, sweet and fragrant, easily broken Jiujiu Strawberry Dandong, Liaoning Sweet taste and high vitamin content Cold-region pears Pear Anshan, Liaoning The meat is firm and crisp, high in acidity, and becomes sweet after ripening. Frozen pears Heilongjiang tradition The juice after frozen saccharification is sweet and has a caramel flavor Small wild fruit mountain grape Changbai Mountain Area High acidity, rich tannins, and many seeds Actinidia arguta Tonghua, Jilin Hairless mini kiwi, high sweetness Rosehip Daxinganling Wild rose hips, high in vitamins, sour and astringent

[0033] (2) Collect the strain sample, wash and ferment it to make a sample solution, take 1mL of the sample solution and inoculate it into 9mL of YPD liquid culture medium, and let it stand at 28℃ for 24 hours for enrichment culture; perform a series of gradient dilutions on the bacterial suspension, and select 10 -3 , 10 -4 and 10 -5 Take 100 μL of each of the three gradient bacterial cultures and inoculate them onto Red Bengal solid medium using the spread plate method. Incubate the culture at 28°C for 48 hours. Select representative single colonies and transfer them to solid isolation medium for streak purification, incubating at 28°C for 48 hours. After microscopic confirmation, perform one or two purification cultures on the target single colonies and inoculate them into YPD liquid medium to obtain purified cultures. Mix the culture with equal volumes of 50% sterile glycerol, aliquot, and freeze.

[0034] (3) Screening of aroma-producing yeast: The yeasts stored at low temperature were inoculated onto YPD solid culture medium plates and cultured at 28°C for 2-3 days. The strains with typical aromas such as ester aroma, sweet aroma or wine aroma were screened based on the aroma of the colonies. The Dulbecco's tube fermentation method was used for primary screening. The yeasts stored at low temperature were inoculated onto YPD solid culture medium plates. After cultured at 28°C for 48 hours, a single colony was selected and inoculated into malt extract medium. The culture was cultured at 28°C for 48 hours. The gas production of the Dulbecco's tube was observed to evaluate the fermentation performance. The ester-producing solid culture medium was used for secondary screening. The yeasts were cultured at a constant temperature of 28°C for 3 days. A blank control and parallel experiment were set up. The commercial yeast was used as the control. The color change of the colonies was observed to evaluate the ester-producing ability.

[0035] Analysis of the initial screening results: After enrichment, separation and purification, a total of 86 yeast strains with excellent quality and stable properties were obtained from the collected samples. The 86 yeast strains were screened based on the aroma results using the olfactory method. Among them, 17 strains showed ester aroma, 5 strains had strong ester aroma, 14 strains had wine aroma, 11 strains had sweet aroma, 15 strains had fruity and floral aroma, and the other 24 strains had no good aroma, such as Figure 1 As shown, 62 strains with good aroma were selected for subsequent screening;

[0036] Analysis of Dulbecco's tubule gas production results: Among the 62 aroma-producing yeast strains obtained in the initial screening, the fermentation capacity of the strains was evaluated by observing the gas production during the fermentation process using the Dulbecco's tubule fermentation method. The measurement was performed every 12 hours. The results are shown in Table 2:

[0037] Table 2

[0038] Fermentation time / h - + ++ +++ 12 58 3 1 \ 24 49 5 3 2 36 37 8 6 7 48 30 11 7 13 60 22 14 9 19 72 14 15 10 23

[0039] Note: "-" means that the fluid in the Dulbecco's tubules has not been drained; "+" means that 1 / 3 to 1 / 2 of the fluid in the Dulbecco's tubules has been drained; "++" means that about 4 / 5 of the fluid in the Dulbecco's tubules has been drained; "+++" means that the fluid in the Dulbecco's tubules has been drained.

[0040] As shown in Table 2, within 12 hours, no strains were able to empty the liquid in the samples, and only one strain discharged a relatively large amount of liquid (++). As time went on, the number of strains that could discharge all the liquid in the Dulbecco's tubules increased, reaching 23 strains at 72 hours. The number of strains that produced a relatively large amount of gas (++) was 3 strains, 7 strains, and 10 strains at 24 hours, 48 ​​hours, and 72 hours, respectively. During the experiment, a total of 48 yeast strains showed the ability to produce gas, among which the gas production of three typical strains (YC111, YP113, and YL11) was shown in the figure below. Figure 2 As shown in the figure, 33 aroma-producing yeast strains with high gas production (++) and liquid discharge (+++) within 72 hours were selected for secondary rescreening;

[0041] Analysis of ester production test results: By observing the color reaction of different yeast strains on the culture medium, their ester production ability can be evaluated. The color depth of the colony is positively correlated with the ester production ability, that is, the darker the color, the stronger the ester production ability. According to the degree of color development, they can be divided into three categories: white colonies (low ester production ability), light yellow colonies (medium ester production ability), and dark yellow colonies (strong ester production ability). The results are shown in Table 3 (ester production of each strain):

[0042] Table 3

[0043] Ester plate color development Number of strains / strain Ester production capacity White 6 Low ester production light yellow 15 Medium ester production dark yellow 12 High ester production

[0044] As shown in Table 3, in the ester production experiment, the ester production plates of 6 strains were white, indicating weak production capacity; the ester production plates of 15 strains were light yellow, indicating medium production capacity; the ester production plates of 12 strains were dark yellow, indicating strong ester production capacity. The color and ester production characteristics of the three representative strains (YC111, YP17, and YC16) are as follows: Figure 3 As shown, the YC16 strain showed white colonies, indicating that its ester production ability was weak, the YP17 strain showed light yellow colonies, with medium ester production ability, and the YC111 strain formed dark yellow colonies, showing excellent ester production performance;

[0045] Identification and morphological observation of aroma-producing yeast: Observation of strain morphological characteristics includes observation of cell morphology and colony morphology. For cell morphology observation, yeast was inoculated into YPD liquid culture medium and cultured in a constant temperature shaker at 28°C and 150 rpm for 24 hours to activate. Microscopic observation samples were prepared and observed under a 100X microscope. The results were as follows: Figure 4 As shown; colony morphology observation is to streak the yeast onto YPD solid agar medium, culture it at 28℃ for 72 hours, and observe the color, size, texture, protrusion, edge and surface characteristics of the colony, such as Figure 5 As shown;

[0046] Using DNA from strain YC111 as a template, the D1 / D2 region of the fungal 26S rDNA (also known as 28S rDNA) was amplified using the following primers:

[0047] NL1: 5'-GCATATCAATAAGCGGAGGAAAAG-3' (as shown in SEQ ID NO. 1);

[0048] NL4: 5'-GGTCCGTGTTTCAAGACGG-3' (as shown in SEQ ID NO. 2);

[0049] The PCR amplification system (25 μL) was as follows: 2×PCR Master Mix 12.5 μL, template DNA 1 μL, upstream and downstream primers 1 μL each, and ddH2O 9.5 μL.

[0050] PCR amplification conditions were as follows: pre-denaturation at 94°C for 4 min; 35 cycles of denaturation at 94°C for 30 s, annealing at 55°C for 50 s, and extension at 72°C for 40 s; extension at 72°C for another 7 min, and storage at 4°C.

[0051] The amplified product (about 600 bp) was sent to Jilin Kumei Biotechnology Co., Ltd. for sequencing, and the 26S rDNA-NL sequence was obtained (shown as SEQ ID NO. 3). The sequencing results were uploaded to the NCBI database and homology comparison was performed using the BLAST tool. The phylogenetic tree was constructed by aligning the ITS sequences using ClustalW software and constructing the phylogenetic tree using MEGAX software. Figure 6 , and the species identification result was Metschnikowia pulcherrima;

[0052] It was deposited in the General Microbiology Center of China Culture Collection Administration on May 26, 2025, with the deposit address being No. 1 Beichen West Road, Chaoyang District, Beijing, with the deposit number being CGMCC NO.33897.

[0053] Example 2, Performance Analysis of Aroma-Producing Yeast YC111:

[0054] The aroma-producing yeast YC111 was subjected to tolerance analysis, which included ethanol tolerance and sugar tolerance experiments. In the ethanol tolerance experiment, YPD liquid medium with alcohol volume fractions of 0%, 6%, 12%, and 18% was prepared, and yeast culture liquid was inoculated at a 2% inoculation rate. The culture was kept at 28°C for 48 hours, and the OD was measured by a microplate reader. 600 The growth status is monitored and the results are as follows Figure 7 As shown in the figure, it can be seen that when the alcohol volume fraction changes from 0% to 18%, the OD of YC111 600 The values ​​always remain relatively stable and at a high level, indicating that it can maintain growth or metabolic activity in a wide range of alcohol concentrations and has strong adaptability; under most alcohol concentrations, the OD 600 The values ​​are higher than those of other groups (e.g., at concentrations of 0%, 6%, and 12%), meaning that under these conditions, the microorganisms (or substances) corresponding to YC111 proliferate and react better, and in competitive or experimental scenarios, they can more efficiently carry out relevant physiological activities, demonstrating good performance;

[0055] The sugar tolerance experiment used YPD medium with maltose instead of glucose. The medium with maltose concentration of 0g / L, 50g / L, 100g / L and 150g / L was prepared. After sterilization, yeast seed liquid was inoculated at 2% inoculum and the growth was monitored. The results were as follows: Figure 8 As shown in the figure, it can be seen that in the range of maltose concentration of 0-150g / L, the OD 600 The values ​​were always high (mostly 1.2 and above), much higher than those of other groups. This indicates that regardless of the changes in maltose concentration, the proliferation and reaction of substances in the system corresponding to YC111 (such as microbial culture) are good, and the growth or metabolic activity is stable and efficient. It can maintain good performance under different maltose concentrations and has strong adaptability. It can play a stable role in related applications using maltose (such as fermentation).

[0056] To perform growth curve determination, strain YC111 was activated and transferred to YPD medium at a 2% inoculum volume. The culture was cultured at 28°C for 48 hours. The OD600 value of the bacterial solution was measured every 4 hours using a microplate reader. The growth curve was drawn using the OD600 value of the blank medium at 0 hour inoculation as the control. The results were as follows: Figure 9 As shown, it can be seen that during the period of 0-10 hours, the OD600 value of the YC111 strain rose rapidly from a low level, indicating that this stage was in the logarithmic growth phase and the cells were rapidly dividing and proliferating; after 10 hours, the growth rate slowed down, but continued to rise, entering the stable growth phase, and the cell number was still slowly increasing, indicating that the strain could continue to grow and accumulate under the culture conditions; the YC111 strain has good growth ability and can quickly start growth and continue to proliferate under suitable conditions. The rapid growth in the logarithmic growth phase means that the strain has high efficiency in utilizing nutrients and active metabolism. The continued growth in the stable growth phase indicates that it has adapted to the culture environment, and the nutrition, space and other factors in the culture system can support its growth within a certain period of time. This growth characteristic provides the cell number basis for its aroma production. Only when a sufficient number of cells carry out metabolic activities can a large amount of aroma substances be produced.

[0057] The fermentation activity of strain YC111 was analyzed and compared with commercial yeast Fermentis US-05 ale yeast (produced by Fermentis Yeast Co., Ltd.). The CO2 weight loss value was measured daily during the fermentation process and the weight loss curve was plotted. The results are shown in the figure below. Figure 10As shown in the figure, commercial yeast exhibits a typical "slow at the beginning and fast at the end" fermentation pattern. The CO2 release rate increases sharply after the 4th day (weight loss of 1.12g on the 6th day and 1.38g on the 8th day), and the final weight loss is the highest, reaching 1.38g, indicating strong fermentation activity in the later stage. However, the initial adaptation period is long, with an average of only 0.13g in the first 3 days. The CO2 weight loss value of YC111 during the fermentation process is generally low. From 0 to 3 days, the weight loss value is basically stable with very little variation, indicating that the amount of CO2 produced by YC111 fermentation is very small during this stage, the fermentation process is relatively slow, and the microbial metabolic activity is not vigorous. From 3 to 6 days, the weight loss value increases slightly, indicating that the fermentation has begun to advance to a certain extent and the rate of CO2 production by microbial metabolism has increased, but the growth rate is still limited. From 6 to 7 days, the weight loss value reaches a relatively high point and then decreases from 7 to 8 days, indicating that the fermentation process fluctuates during this period, which may be affected by factors such as substrate concentration and environmental conditions.

[0058] Compared with commercial yeast, the CO2 weight loss value of YC111 during the entire process is much lower than that of commercial yeast, indicating that the rate of CO2 production during YC111 fermentation is slower and the fermentation intensity is weaker. The CO2 production rate is low and relatively stable, which is conducive to controlling the mildness of the fermentation process and avoiding some adverse effects caused by excessive fermentation, such as large temperature fluctuations in the fermentation system.

[0059] Example 3: Application of aroma-producing yeast YC111 in beer fermentation:

[0060] First, wort was saccharified, malt and water were mixed in a mass ratio of 1:4, and the mixture was fed at 45°C, kept at 48°C for 30 minutes, 63°C for 60 minutes, 72°C for 20 minutes, and 78°C for 10 minutes, and then filtered and washed. The filtered wort was refluxed and boiled, hopped, filtered again, and sterilized at 105°C for 10 minutes to prepare the wort fermentation medium. The activated strain YC111 suspension was added at a temperature of 1.0×10 6 CFU / mL inoculation was inoculated into the wort medium, and after 72 hours, the inoculum was adjusted to 1.0×10 6 CFU / mL inoculated with commercial yeast Femandis US-05 ale yeast;

[0061] In addition, a control group was set up for single-bacteria fermentation. Compared with the above, the strain YC111 was replaced with the commercial yeast Fermantis US-05 ale yeast, and the rest was the same as above.

[0062] The weight loss was measured every day during the fermentation process. Fermentation was stopped when the weight loss was less than 0.1 g / 150 mL. The alcohol content, total acidity, diacetyl, sugar content and fermentation degree of the fermented beer were measured according to the national standard GB / T4928-2008 "Beer Analysis Method". The results are shown in Table 4:

[0063] Table 4

[0064] Original wort concentration / °P Alcohol content / %vol <![CDATA[Total acid / (mL·100mL -1 > Sugar content / °P Actual fermentation degree / % pH Mixed fermentation 10.2 3.6 2.6 2.4 62.7% 4.65 Single bacteria fermentation 10.1 3.8 2.7 3 57.6% 4.52

[0065] As shown in Table 4, compared with single-strain fermentation (using only commercial yeast), mixed fermentation (using aroma-producing yeast YC111 mixed with commercial yeast) improved fermentation efficiency—actual fermentation reached 62.7% (57.6% for the single-strain group) and sugar conversion efficiency increased by 5.1 percentage points. Residual sugar control was optimized, with the final sugar content reduced to 2.4°P (3.0°P for the single-strain group), giving the beer a drier mouthfeel. Flavor balance was enhanced, with total acidity slightly reduced to 2.6 mL / 100 mL (2.7 mL / 100 mL for the single-strain group) and pH increased to 4.65 (4.52 for the single-strain group), alleviating sourness and astringency. Based on the characteristic signatures of yeast YC111, combined with the high fermentation degree and low residual sugar environment, it is speculated that their synergistic effect facilitates the release of aroma compounds such as esters.

[0066] After the beer fermentation process was completed, 10 personnel with professional food research capabilities were organized to conduct a sensory evaluation of each beer sample. A comprehensive evaluation was conducted based on the four elements of sensory analysis of appearance, foam, aroma and taste characteristics in accordance with the national standard GB / T4928-2008 "Beer Analysis Method". The scores were scored in a standard sensory laboratory and the weighted average score was calculated to evaluate the sensory quality. The sensory scoring standard table for beer samples is shown in Table 5:

[0067] Table 5

[0068]

[0069] The result is as follows Figure 11 As shown, it can be seen that mixed bacteria fermentation brewing beer has the following advantages:

[0070] In terms of foam: the score corresponding to mixed-bacteria fermentation beer (4.4) is higher than that of single-bacteria fermentation beer (4.3), indicating that the foam performance of mixed-bacteria fermentation beer is better, and the foam may be richer, delicate, and long-lasting, which can bring better visual and taste experience to drinkers.

[0071] In terms of flavor coordination: mixed-bacteria fermentation beer scored higher than single-bacteria fermentation beer, which means that beer brewed with YC111 performs better in the integration and balance of various flavors. No one flavor is too abrupt, the overall flavor is more harmonious, and the taste is more comfortable when drinking.

[0072] In terms of ester aroma, mellow aroma, and mouthfeel, mixed-bacteria fermented beer scored higher than commercial beer in these dimensions, indicating that YC111-brewed beer has a stronger ester aroma, bringing richer fruity and other pleasant aromas; a more mellow aroma, reflecting the complex aroma characteristics produced by beer fermentation; and a stronger mouthfeel, with a more pronounced carbon dioxide stimulation, which can enhance the refreshing and stimulating feeling when drinking.

[0073] In summary, the mixed fermentation of YC111 and commercial yeast for brewing beer has more advantages than brewing beer with commercial yeast alone in terms of multiple sensory dimensions such as foam, flavor coordination, various aromas, and mouthfeel, and can provide consumers with a better drinking experience.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An aroma-producing yeast, characterized in that The aroma-producing yeast is Maggi yeast ( Metschnikowia pulcherrima ), the deposit number is CGMCC NO.33897, and it was deposited in the General Microbiology Center of China Culture Collection Administration on May 26, 2025.

2. A use of the aroma-producing yeast according to claim 1 in fermenting beer, characterized in that: The following steps are involved: The malt is mixed with water, and then the mixture is heated in stages after addition, and then filtered. The filtered wort is refluxed and boiled, hops are added, and the mixture is filtered again and sterilized to obtain a wort fermentation medium. The aroma-producing yeast is activated and then centrifuged to obtain bacterial sludge, which is inoculated into a wort fermentation medium, and then inoculated with commercial yeast, which is Femandis US-05 ale yeast.

3. The use according to claim 2, characterized in that The average mass ratio of the malt to water is 1:4-5.

4. The use according to claim 2, characterized in that The specific operation of the staged insulation is: insulation at 46-50°C for 25-35 minutes, insulation at 62-55°C for 55-65 minutes, insulation at 70-74°C for 18-22 minutes, and insulation at 76-80°C for 8-12 minutes.

5. The use according to claim 2, characterized in that The step of activating the aroma-producing yeast and then centrifuging to obtain bacterial sludge, inoculating it into a wort fermentation medium, and then inoculating commercial yeast, specifically, inoculating the commercial yeast after 70-74 hours.

6. A beer fermentation agent, characterized in that The fermentation agent includes the aroma-producing yeast according to claim 1.

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