Composite microbial agent for enhancing production of β-phenylethyl alcohol in baijiu brewing process, and preparation method therefor and use thereof
By using a compound microbial agent consisting of Aspergillus niger, Pichia pastoris, Saccharomyces kazakhstanis, Saccharomyces cerevisiae, and Saccharomyces delbrueckii during the solid-state fermentation of baijiu, the problem of poor stability of single strains was solved, resulting in increased β-phenylethanol production and improved baijiu flavor.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- LUZHOU PINCHUANG TECH CO LTD
- Filing Date
- 2025-08-28
- Publication Date
- 2026-05-07
AI Technical Summary
The stability of single strains in enhancing β-phenylethanol production during baijiu fermentation is poor, making it difficult to maintain high-efficiency production.
A compound microbial agent composed of Aspergillus niger, Pichia pastoris, Saccharomyces kazakhstanis, Saccharomyces cerevisiae, and Saccharomyces delbrueckii was used in the solid-state fermentation of baijiu through artificial enhancement to regulate the eukaryotic microbial community structure and increase the yield of β-phenylethanol.
It significantly increased the yield of β-phenylethanol in baijiu, improved the flavor characteristics of baijiu, and promoted the quality of strong-aroma baijiu.
Smart Images
Figure CN2025117431_07052026_PF_FP_ABST
Abstract
Description
Compound microbial agents for enhancing β-phenylethanol production in Baijiu brewing process, their preparation methods and applications Technical Field
[0001] This invention belongs to the field of microbial technology, specifically relating to a compound microbial agent for enhancing the production of β-phenylethanol in the brewing process of baijiu (Chinese liquor), its preparation method, and its application. Background Technology
[0002] Baijiu (Chinese white liquor) occupies a vital position in China's food industry. Strong-aroma baijiu, one of the four basic aroma types, is favored by consumers for its pleasant flavor. The trace components in strong-aroma baijiu have a significant impact on its flavor profile. Among them, β-phenylethanol is a volatile aroma compound with a rose-like fragrance. Studies have shown that eukaryotic microorganisms such as brewer's yeast, Aspergillus niger, and Geotrichum can convert substrates into β-phenylethanol during baijiu fermentation. Therefore, β-phenylethanol is considered one of the important aroma backbone components of baijiu; a higher content of β-phenylethanol contributes to a mellow and sweet body and a full-bodied aroma.
[0003] Previous studies have mostly focused on aroma compounds such as esters in baijiu, with less attention paid to β-phenylethanol. Only a few studies have found that using single species of Pichia pastoris or Wickham's aberrant yeast can enhance the β-phenylethanol content in baijiu production.
[0004] CN111961599A discloses a yeast with a floral and fruity aroma that can be fermented in solid state and its application. By inoculating yeast with accession number CGMCC 19814 into mash for fermentation, the β-phenylethanol content in the mash increased from 0.009 g / kg to 0.456 g / kg.
[0005] CN107177520A discloses a high-yield β-phenylethanol-producing Saccharomyces cerevisiae strain and its application. By inoculating the Saccharomyces cerevisiae into a baijiu fermentation system, a β-phenylethanol content of 110 mg / L was obtained in distilled baijiu.
[0006] The methods mentioned above for increasing β-phenylethanol during the fermentation of baijiu are all accomplished by a single strain. However, the solid-state fermentation process of baijiu is usually accomplished by the cooperation of a complex microbial community. A single strain is difficult to maintain high efficiency and stability in actual production. Therefore, developing compound microbial agents from fermentation pits and specifically enhancing the yield of baijiu flavor substances has become a research hotspot and challenge in recent years. Summary of the Invention
[0007] The technical problem this invention aims to solve is the poor stability of methods for enhancing the production of β-phenylethanol during the fermentation of baijiu using a single strain. This invention aims to provide a compound microbial agent containing five eukaryotic core strains commonly found in the brewing process of strong-aroma baijiu. By artificially enhancing this compound agent and applying it to the solid-state fermentation of baijiu, the yield of the aroma component β-phenylethanol can be significantly increased, thus contributing to the improvement of the flavor characteristics of baijiu.
[0008] The technical solution adopted by this invention to solve its technical problem is:
[0009] In a first aspect, the present invention provides a compound microbial agent for enhancing the production of β-phenylethanol in the brewing process of baijiu (Chinese liquor). The compound microbial agent is composed of Aspergillus niger, Pichia membranifaciens, Kazachstania unispora, Saccharomyces cerevisiae, and Torulaspora delbrueckii.
[0010] In the above-mentioned compound microbial inoculant, the final concentration (OD) of Aspergillus niger was... 600 The final OD concentration of Pichia membranifaciens was 0.8–1.5. 600 The final OD concentration of Kazachstania unispora was 0.8–1.5. 600 The final OD concentration of Saccharomyces cerevisiae is 0.5–1. 600 The final OD concentration of *Torulaspora delbrueckii* was 0.8–1.5. 600 It ranges from 0.5 to 1.
[0011] Furthermore, the final concentration (OD) of Aspergillus niger in the aforementioned compound microbial agent was... 600 The final concentration OD of Pichia membranifaciens was 1. 600 The final concentration OD of Kazachstania unispora was 1. 600 The final concentration (OD) of Saccharomyces cerevisiae was 1. 600 The final concentration OD of *Torulaspora delbrueckii* was 1. 600 The value is 1.
[0012] Furthermore, Aspergillus niger, with accession number CGMCC 3.17612.
[0013] Furthermore, Pichia membranifaciens, with accession number CGMCC 2.5139.
[0014] Furthermore, the single-spore Kazakhstani yeast Kazachstania unispora, with accession number CGMCC 2.251.
[0015] Furthermore, the brewer's yeast Saccharomyces cerevisiae, with accession number CGMCC 2.3854.
[0016] Furthermore, Torulaspora delbrueckii, with accession number CGMCC 2.4064.
[0017] Secondly, the present invention provides a method for preparing the above-mentioned composite microbial agent: Aspergillus niger liquid, Pichia pastoris liquid, Kazakhstan yeast liquid, Saccharomyces cerevisiae liquid, and Delburophyll yeast liquid are cultured and prepared separately; the obtained microbial liquids are diluted according to the final concentration of each cell in the above-mentioned composite microbial agent; then they are mixed and thoroughly shaken to obtain a composite microbial agent for enhancing the production of β-phenylethanol in the brewing process of Baijiu.
[0018] Furthermore, the above-mentioned Aspergillus niger liquid preparation method is as follows: Aspergillus niger inoculates onto malt extract agar medium plates and activates at 30°C for 48-72 hours, scrapes Aspergillus niger spores into physiological saline to obtain Aspergillus niger liquid.
[0019] Furthermore, the preparation method of the above-mentioned Pichia pastoris culture is as follows: Pichia pastoris inoculum is inoculated onto YPD agar medium plates and activated at 30°C for 48 hours. The activated Pichia pastoris is then inoculated into YPD liquid medium and cultured at 30°C for 24 hours to obtain the Pichia pastoris culture.
[0020] Furthermore, the preparation method of the above-mentioned monosporous Kazakhstan yeast culture is as follows: monosporous Kazakhstan yeast is inoculated onto YPD agar medium plates and activated at 30°C for 48 hours. The activated monosporous Kazakhstan yeast is then inoculated into YPD liquid medium and cultured at 30°C for 24 hours to obtain monosporous Kazakhstan yeast culture.
[0021] Furthermore, the above-mentioned method for preparing the Saccharomyces cerevisiae liquid is as follows: Saccharomyces cerevisiae inoculum is inoculated onto YPD agar medium plates and activated at 30°C for 48 hours. The activated Saccharomyces cerevisiae is then inoculated into YPD liquid medium and cultured at 30°C for 24 hours to obtain the Saccharomyces cerevisiae liquid.
[0022] Furthermore, the preparation method of the above-mentioned Delbu spore yeast liquid is as follows: Delbu spore yeast strain is inoculated on YPD agar medium plate and activated at 30℃ for 48h, and the activated Delbu spore yeast is inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain Delbu spore yeast liquid.
[0023] Furthermore, the composition of the above-mentioned malt extract agar medium is as follows: 130.0 g / L malt extract powder, 15 g / L agar, pH value 6.0±0.2, autoclaved at 121℃ for 15 min.
[0024] Furthermore, the composition of the above-mentioned malt extract liquid culture medium is as follows: 130.0 g / L malt extract powder, pH value 6.0±0.2, autoclaved at 121℃ for 15 min.
[0025] Furthermore, the composition of the YPD agar medium is as follows: yeast extract 10g / L, peptone 20g / L, glucose 10g / L, agar 15g / L, pH 7.0±0.2, autoclaved at 121℃ for 15min.
[0026] Furthermore, the composition of the aforementioned YPD liquid culture medium is as follows: yeast extract 10g / L, peptone 20g / L, glucose 10g / L, pH 7.0±0.2, autoclaved at 121℃ for 15min.
[0027] Thirdly, the present invention provides the application of the above-mentioned compound microbial agent or the compound microbial agent prepared by the above-mentioned preparation method: adding 1% (v / v) of the compound microbial agent per kilogram of mash for mixed fermentation to enhance the production of β-phenylethanol in the solid-state fermentation process of strong-aroma baijiu.
[0028] The beneficial effects of this invention are: when the compound microbial agent provided by this invention is applied to the solid-state fermentation system of strong-aroma baijiu, it can significantly increase the yield of the aroma substance β-phenylethanol by adjusting the eukaryotic microbial community structure of the fermentation system, which is beneficial to improving the flavor characteristics of baijiu. The compound microbial agent of this invention has a promoting effect and is of great significance in improving the quality of strong-aroma baijiu. Attached Figure Description
[0029] Figure 1 shows the changes in the relative content of β-phenylethanol during the solid-state fermentation of Baijiu (CK: control group; T: enhanced group);
[0030] Figure 2 shows a comparison of eukaryotic microbial community diversity (Shannon index);
[0031] Figure 3 shows the species composition of the eukaryotic microbial community. Detailed Implementation
[0032] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with the embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Unless otherwise defined, all technical terms used herein have the same meaning as understood by those skilled in the art.
[0033] A compound microbial agent for enhancing the production of β-phenylethanol in the brewing process of Baijiu (Chinese liquor), the compound microbial agent being composed of Aspergillus niger, Pichia membranifaciens, Kazachstania unispora, Saccharomyces cerevisiae, and Torulaspora delbrueckii.
[0034] In this example, strains deposited by the China General Microbiological Culture Collection Center (CGMCC) were preferred for the experimental results. The specific strain numbers and sources are as follows:
[0035] Aspergillus niger, accession number CGMCC 3.17612; Pichia membranifaciens, accession number CGMCC 2.5139; Kazachstania unispora, accession number CGMCC 2.251; Saccharomyces cerevisiae, accession number CGMCC 2.3854; Torulaspora delbrueckii, accession number CGMCC 2.4064.
[0036] All of the above strains were purchased from the China General Microbiological Culture Collection Center (CGMCC).
[0037] The culture media and their components involved in the examples are as follows:
[0038] Malt extract agar medium: 130.0 g / L malt extract powder, 15 g / L agar, pH 6.0 ± 0.2, autoclaved at 121℃ for 15 min.
[0039] Malt extract liquid culture medium: 130.0 g / L malt extract powder, pH 6.0 ± 0.2, autoclaved at 121℃ for 15 min.
[0040] YPD agar medium: yeast extract 10g / L, peptone 20g / L, glucose 10g / L, agar 15g / L, pH 7.0±0.2, autoclaved at 121℃ for 15min.
[0041] YPD liquid culture medium: yeast extract 10g / L, peptone 20g / L, glucose 10g / L, pH 7.0±0.2, autoclaved at 121℃ for 15min.
[0042] The specific method for analyzing volatile components in distiller's grains using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) is as follows:
[0043] Using 10 μL of 2-octanol (8.29 mg / mL) as an internal standard, 2 g of fermented mash was placed in a 20 mL vial and sealed. The sample was then extracted using an automated headspace sampling system (CTC-pal RSI 85 autosampler with SPME adapter, CTC Analytics, Zwingen, Switzerland) and a 50 / 30 μm DVB / CAR / PDMS coated optical fiber (2 cm, Supelco INc., Bellefonte, PA, USA). Extraction was performed at 4 °C for 45 min. Volatile components in the fermented mash were detected using an Agilent Intuvo 9000 gas chromatograph connected to a 5977BMSD (Agilent Technologies, Palo Alto, CA, USA) equipped with an Agilent DBWAX UI column (30 m, 0.25 mm, 0.25 μm). The column temperature was maintained at 50 °C for 2 min, then increased to 230 °C at a rate of 6 °C / min. The MS electron impact energy was 70 eV, the ion source temperature was 230 °C, and the MS scan range was 30–350 amu. Compound search results were matched and identified with the NIST standard spectral library, and their concentrations were expressed as the GC peak area correlated with the GC peak area of the internal standard (μg / g).
[0044] Example 1: Preparation of Compound Microbial Agent
[0045] (1) Preparation of seed culture for each strain
[0046] The method for preparing the seed culture of Aspergillus niger CGMCC 3.17612 is as follows: the inoculum is inoculated onto malt extract agar plates for activation (30℃, 48h), and Aspergillus niger spores are scraped into physiological saline to prepare a spore suspension as the seed culture. The concentration of the mycelium in the suspension is OD0.05. 600=24, continue to dilute the Aspergillus niger seed culture with physiological saline to the final concentration OD. 600 =1, reserved.
[0047] The method for preparing the seed culture of *Pichia pastoris* CGMCC 2.5139 is as follows: The inoculum was inoculated onto YPD agar plates and activated (30℃, 48h). The activated *Pichia pastoris* was then inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain the seed culture. The cell concentration was OD0.05. 600 =13.61, continue to dilute the final concentration (OD) of the Pichia pastoris seed culture with physiological saline. 600 =1, reserved.
[0048] The method for preparing the seed culture of *Saccharomyces kazakhstanense* CGMCC 2.251 is as follows: The inoculum was inoculated onto YPD agar plates and activated (30℃, 48h). The activated *Saccharomyces kazakhstanense* was then inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain the seed culture. The cell concentration was OD0.05. 600 =7.28, continue to dilute the final concentration (OD) of the *Saccharomyces kazakhstanense* seed culture with physiological saline. 600 =1, reserved.
[0049] The method for preparing the seed culture of Saccharomyces cerevisiae CGMCC 2.3854 is as follows: The inoculum was inoculated onto YPD agar plates and activated (30℃, 48h). The activated Saccharomyces cerevisiae was then inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain the seed culture; the cell concentration was OD0.05. 600 =12.1, continue to dilute the final concentration (OD) of the Saccharomyces cerevisiae seed culture with physiological saline. 600 =1, reserved.
[0050] The preparation method of *Saccharomyces cerevisiae* CGMCC 2.4064 seed culture is as follows: The inoculum was inoculated onto YPD agar plates and activated (30℃, 48h). The activated *Saccharomyces cerevisiae* was then inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain the seed culture; the cell concentration was OD0.05. 600 =20.84, continue to dilute the Delbrio spore-forming yeast seed culture to the final concentration OD using physiological saline. 600 =1, reserved.
[0051] (2) Preparation of microbial agents
[0052] Take the Aspergillus niger seed liquid, Pichia pastoris seed liquid, Saccharomyces kazakhstan seed liquid, Saccharomyces cerevisiae seed liquid and Saccharomyces delbrueckii seed liquid prepared in step (1) respectively, mix them thoroughly by shaking to obtain a total volume of 100 ml and the final OD concentration of each cell is 100 ml.600 =1 compound microbial inoculant.
[0053] Example 2: Enhancement of β-phenylethanol production during solid-state fermentation of Baijiu
[0054] The compound microbial agent prepared in Example 1 was applied in liquid form to enhance the solid-state fermentation process of strong-aroma baijiu. The differences in β-phenylethanol production and fungal community structure between the enhanced group and the control group were tracked and compared to comprehensively evaluate the enhancement effect of the compound microbial agent.
[0055] Twenty-four 1L sterile ground-glass stoppered bottles were used. 550g of fermented mash (containing yeast) from a strong-aroma baijiu distillery and 3% (v / v) yellow brine (yellow brine from the 60th day of fermentation) were added to each bottle. The enhanced group was inoculated with 1% (v / v) compound microbial inoculant, while the control group received the same volume of sterile water. All were mixed thoroughly. There were 12 bottles in the control group and 12 bottles in the enhanced group. The sealed bottles were placed in a biochemical incubator and fermented at 30℃ for 28 days. Samples were taken on days 0, 7, 14, and 28 of fermentation, with three bottles from each group. The mash in each bottle was thoroughly mixed separately before sampling for β-phenylethanol yield and fungal community structure analysis.
[0056] (1) Comparison of β-phenylethanol yield
[0057] The volatile components in the distiller's grains were analyzed by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), and the results are shown in Table 1 and Figure 1.
[0058] Table 1. Changes in the relative content of β-phenylethanol during solid-state fermentation of Baijiu.
[0059] In Table 1, CK represents the control group and T represents the enhanced group; 0, 7, 14, 28 represent the fermentation days, and 1, 2, 3 represent the replicates; taking CK-7-1 as an example, it represents the first replicate of the control group treated with 7 days of fermentation, and so on.
[0060] As shown in Table 1 and Figure 1, as fermentation progressed, the cumulative relative content of β-phenylethanol in the enhanced mash group with added compound microbial agent was consistently higher than that in the control group, increasing by 13.1%, 19.8%, and 98.1% at 7, 14, and 28 days, respectively. This indicates that the compound microbial agent of the present invention can effectively enhance the production of β-phenylethanol during the solid-state fermentation process of Baijiu.
[0061] (2) Comparison of fungal community structure
[0062] Metagenomic DNA was extracted from the fermented grains using the CTAB method. Using the quality-tested metagenomic DNA as a template, PCR amplification of the ITS1-5F region of eukaryotic microorganisms was performed using universal primer pairs, as detailed below:
[0063] SEQ ID NO:1:5'-GGAAGTAAAAGTCGTAACAAGG-3'
[0064] SEQ ID NO:2:5'-GCTGCGTCTTCATCGATGC-3'
[0065] Small fragment libraries were constructed from the amplified products, and paired-end sequencing was performed on these libraries using the Illumina NovaSeq sequencing platform. Sequencing results were processed through read splicing filtering, species annotation, and α-diversity analysis to compare species differences between the enhanced and control groups. Eukaryotic microbial community diversity (Shannon index) is shown in Table 2 and Figure 2, and relative species abundance is shown in Table 3 and Figure 3.
[0066] Table 2 Comparison of Shannon index in eukaryotic microbial communities
[0067] In Table 2, CK represents the control group and T represents the enhanced group; 0, 7, 14, and 28 represent the fermentation days; for example, CK-7 represents the control group fermented for 7 days, and so on.
[0068] As shown in Table 2 and Figure 2, the eukaryotic microbial community diversity (Shannon index) of the control group continuously decreased as fermentation progressed, while the eukaryotic diversity of the enhanced group showed a trend of first decreasing and then increasing. This result indicates that the addition of the compound microbial agent significantly altered the eukaryotic diversity of the enhanced group on days 14 and 28, especially at the end of fermentation, where the Shannon value of the enhanced group was significantly higher than that of the control group.
[0069] Table 3. Relative abundance of species
[0070] In Table 3, CK represents the control group and T represents the enhanced group; 0, 7, 14, and 28 represent the fermentation days; CK-7 is an example of the control group fermenting for 7 days, and so on.
[0071] Table 3 and Figure 3 show that the species composition of eukaryotic microorganisms in the control group underwent succession as fermentation progressed. The species composition of the enhanced group was similar to that of the control group at each fermentation time, but the relative abundance of each species differed significantly from the control group on days 14 and 28. For example, on day 28, the relative proportion of *Monascus purpureus* increased from 3.98% in the control group to 10.07% in the enhanced group. Therefore, the compound microbial agent can improve the yield of β-phenylethanol in the solid-state fermentation of strong-aroma baijiu by regulating the eukaryotic microbial community structure.
Claims
1. A compound microbial agent for enhancing the production of β-phenylethanol during the brewing process of Baijiu (Chinese liquor), characterized in that: The compound microbial agent consists of Aspergillus niger, Pichia membranifaciens, Kazachstania unispora, Saccharomyces cerevisiae, and Torulaspora delbrueckii. The final concentration (OD) of Aspergillus niger in the compound microbial agent was... 600 The final OD concentration of Pichia membranifaciens was 0.8–1.
5. 600 The final OD concentration of Kazachstania unispora was 0.8–1.
5. 600 The final OD concentration of Saccharomyces cerevisiae is 0.5–1. 600 The final OD concentration of *Torulaspora delbrueckii* was 0.8–1.
5. 600 It ranges from 0.5 to 1.
2. The compound microbial agent for enhancing the production of β-phenylethanol in the liquor brewing process according to claim 1, characterized in that, At least one of the following conditions must be met: Aspergillus niger, accession number CGMCC 3.17612; Pichia membranifaciens, accession number CGMCC 2.5139; Kazakhstan yeast Kazachstania unispora, accession number CGMCC 2.251; Saccharomyces cerevisiae, preservation number CGMCC 2.3854; Torulaspora delbrueckii, accession number CGMCC 2.4064.
3. The method for preparing the composite microbial agent according to any one of claims 1 to 2, characterized in that: Aspergillus niger, Pichia pastoris, Saccharomyces cerevisiae, Saccharomyces kazakhstanensis, Saccharomyces cerevisiae, and Saccharomyces delbrueckii were cultured and prepared separately. The bacterial solutions were diluted according to the final concentration of each cell in the compound microbial agent described in claim 1, and then mixed and thoroughly shaken to obtain a compound microbial agent for enhancing the production of β-phenylethanol in the baijiu brewing process.
4. The method for preparing the composite microbial agent according to claim 3, characterized in that: The preparation method of Aspergillus niger liquid is as follows: Aspergillus niger inoculates on malt extract agar medium plates and activates at 30℃ for 48-72h. Scrape Aspergillus niger spores into physiological saline to obtain Aspergillus niger liquid. The composition of malt extract agar medium is: 130.0 g / L malt extract powder, 15 g / L agar, pH 6.0 ± 0.2, autoclaved at 121℃ for 15 min; The composition of the malt extract liquid culture medium is: 130.0 g / L malt extract powder, pH 6.0 ± 0.2, autoclaved at 121℃ for 15 min.
5. The method for preparing the composite microbial agent according to claim 3, characterized in that: The preparation method of Pichia pastoris culture medium is as follows: Pichia pastoris inoculum is inoculated onto YPD agar medium plates and activated at 30℃ for 48h. The activated Pichia pastoris is then inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain Pichia pastoris culture medium.
6. The method for preparing the composite microbial agent according to claim 3, characterized in that: The preparation method of single-spore Kazakhstan yeast culture is as follows: single-spore Kazakhstan yeast strain is inoculated onto YPD agar medium plates and activated at 30℃ for 48h. The activated single-spore Kazakhstan yeast is then inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain single-spore Kazakhstan yeast culture.
7. The method for preparing the composite microbial agent according to claim 3, characterized in that: The method for preparing Saccharomyces cerevisiae liquid is as follows: Saccharomyces cerevisiae inoculum is inoculated onto YPD agar medium plates and activated at 30℃ for 48h. The activated Saccharomyces cerevisiae is then inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain Saccharomyces cerevisiae liquid.
8. The method for preparing the composite microbial agent according to claim 3, characterized in that: The preparation method of Delbu spore yeast culture is as follows: Delbu spore yeast strain is inoculated on YPD agar medium plate and activated at 30℃ for 48h. The activated Delbu spore yeast is then inoculated into YPD liquid medium and cultured at 30℃ for 24h to obtain Delbu spore yeast culture.
9. The method for preparing the composite microbial agent according to any one of claims 5 to 8, characterized in that: The YPD agar medium consists of: yeast extract 10 g / L, peptone 20 g / L, glucose 10 g / L, agar 15 g / L, pH 7.0 ± 0.2, and is autoclaved at 121°C for 15 min. The YPD liquid culture medium consists of: yeast extract 10 g / L, peptone 20 g / L, glucose 10 g / L, pH 7.0 ± 0.2, and is autoclaved at 121°C for 15 min.
10. The application of the composite microbial agent according to any one of claims 1 to 2 or the composite microbial agent prepared by the preparation method according to any one of claims 3 to 9, characterized in that: Add 1% (v / v) of compound microbial inoculant per kilogram of mash and mix with fermentation to enhance the production of β-phenylethanol in the solid-state fermentation process of strong-aroma baijiu.