Brewing method capable of reducing content of ethyl carbamate in baijiu

Abstract

The invention belongs to the technical field of liquor quality control, and relates to a liquor making method capable of reducing the content of ethyl carbamate in Maotai-flavor liquor. The method comprises the following steps: (1) boiling ground pot water and tail wine, and putting into a steamer; and (2) opening steam pressure, collecting distilled wine liquid, and when the alcoholic strength of the distilled wine liquid reaches a set value, completing the collection of the round of wine. Wherein the use frequency of the ground boiler water is 1-2 times, and the distillation vapor pressure of the tail liquor is 0.08-0.10 MPa. The method is beneficial to reducing the content of ethyl carbamate in the Maotai-flavor liquor, and the liquor yield and the flavor substance content of the Maotai-flavor liquor are not influenced.

Description

Technical Field

[0001] This invention belongs to the field of liquor quality control technology, and relates to a brewing method for reducing the content of ethyl carbamate in liquor. Background Technology

[0002] Ethyl carbamate (EC) is an endogenous safety risk factor in alcoholic beverages. With increasing consumer awareness of safety, controlling ethyl carbamate has become a focus for industry researchers. Currently, control measures for ethyl carbamate mainly include enzymatic hydrolysis, genetic modification, chemical cleavage, physical adsorption, and double distillation. Although these methods are diverse and have some elimination effect, none have been widely adopted in the industry. This is because these measures have side effects during use, such as exogenous addition and damage to aroma and quality.

[0003] Solid-state distillation of baijiu differs from fermented beverages and Western liquid distillation. It involves directly feeding solid fermentation materials (fermentation mash) into the still, where steam generated by heating water in a still permeates the mash, creating a unique multi-layered concentration process. This is a crucial step in giving baijiu its distinctive flavor. Because solid-state distillation of baijiu involves the distillation of high-concentration ethanol and a large amount of water vapor, the mass transfer of the entire system is affected by the "solvent effect," making it complex and difficult to control. During baijiu production, ethyl carbamate and its precursors enter the new liquor through distillation. The non-volatile, highly water-soluble ethyl carbamate is mainly distilled off in the tail end of the distillation process. Therefore, taking measures during distillation to reduce the amount of ethyl carbamate entering the next batch is an effective way to control its concentration in baijiu. Summary of the Invention

[0004] In some embodiments, the present invention provides a method for brewing liquor, wherein the liquor is a sauce-flavored baijiu, the method comprising: (1) Boil water in a pot and steam the fermented mash. (2) Open the vapor pressure and collect the distilled liquor. When the alcohol content of the distilled liquor reaches the set value, the collection of the round liquor is completed; the method is a method to reduce the ethyl carbamate content in the round liquor. The round of wine includes the third round of wine; When the collected distillate is from the third distillation, the alcohol content of the distillate is set at 55% vol to 55.8% vol.

[0005] In some implementations, when the distillate is from the first distillation, the alcohol content of the distillate is set at 58.2% vol to 58.8% vol.

[0006] In some implementations, when the distillate is from the second distillation, the alcohol content of the distillate is set at 56.2% vol to 56.8% vol.

[0007] In some implementations, when the distillate is from the fourth distillation, the alcohol content of the distillate is set at 54.2% vol to 54.8% vol.

[0008] In some implementations, when the distillate is the fifth distillation, the alcohol content of the distillate is set at 54.2% vol to 54.8% vol.

[0009] In some implementations, when the distillate is the sixth distillation, the alcohol content of the distillate is set at 54% vol to 54.8% vol.

[0010] In some implementations, when the distillate is the seventh distillation, the alcohol content of the distillate is set at 53.2% vol to 53.8% vol.

[0011] In some implementations, the vapor pressure of the wine from the round is obtained as 0.07 MPa-0.10 MPa.

[0012] In some implementations, the vapor pressure of the wine from the round is obtained as 0.08 MPa-0.09 MPa.

[0013] In some implementations, in step (1), the water used in the earthen pot is reused water.

[0014] In some implementations, the water used in the earthen pot is water that has been used 1-4 times.

[0015] In some implementations, the water used in the earthen pot is water that has been used 1-3 times.

[0016] In some implementation schemes, the water used in the earthen pot is water that has been used 1-2 times.

[0017] In some implementations, when the distilled wine is the first distillation wine in step (2), the alcohol content of the distilled wine is set to 58.4%vol-58.6%vol.

[0018] In some implementations, when the distillate is from the second distillation, the alcohol content of the distillate is set at 56.4% vol to 56.6% vol.

[0019] In some implementations, when the distillate is from the third distillation, the alcohol content of the distillate is set at 55.1% vol to 55.4% vol.

[0020] In some implementations, when the distillate is from the fourth distillation, the alcohol content of the distillate is set at 54.4% vol to 54.6% vol.

[0021] In some implementations, when the distillate is the fifth distillation, the alcohol content of the distillate is set at 54.4% vol to 54.6% vol.

[0022] In some implementations, when the distillate is the sixth distillation, the alcohol content of the distillate is set at 54.1% vol to 54.4% vol.

[0023] In some implementations, when the distillate is the seventh distillation, the alcohol content of the distillate is set at 53.4% ​​vol to 53.6% vol.

[0024] In some implementations, when the distilled wine is the first distillation wine in step (2), the alcohol content of the distilled wine is set to 58.5% vol - 58.6% vol.

[0025] In some implementations, when the distillate is from the second distillation, the alcohol content of the distillate is set at 56.5% vol to 56.6% vol.

[0026] In some implementations, when the distillate is from the third distillation, the alcohol content of the distillate is set at 55.1-55.2% vol.

[0027] In some implementations, when the distillate is from the fourth distillation, the alcohol content of the distillate is set at 54.5% vol to 54.6% vol.

[0028] In some implementations, when the distillate is the fifth distillation, the alcohol content of the distillate is set at 54.5% vol to 54.6% vol.

[0029] In some implementations, when the distillate is the sixth distillation, the alcohol content of the distillate is set at 54.1% vol - 54.2% vol.

[0030] In some implementations, when the distillate is the seventh distillation, the alcohol content of the distillate is set at 53.5% vol to 53.6% vol.

[0031] In some implementations, the boiler water includes water.

[0032] In some implementations, the boiler water includes drinking water.

[0033] In some implementations, the water from the earthen pot also includes tail wine.

[0034] In some implementations, the boiler water is a combination of drinking water and tail liquor.

[0035] In some implementations, the method for obtaining the tail liquor is as follows: (a) Boil water in a pot and steam the fermented grains; (b) Open the steam pressure to distill and collect the distillate; when the alcohol content of the distillate reaches the set value, after completing the collection of one round of wine, adjust the steam pressure to distill again and collect the distillate again to obtain the tail wine.

[0036] In some implementations, in step (b), when the distillate is from the first distillation, the alcohol content of the distillate is set to 58.5% vol - 58.6% vol.

[0037] In some implementations, in step (b), when the distillate is from the second distillation, the alcohol content of the distillate is set to 56.5% vol - 56.6% vol.

[0038] In some implementations, in step (b), when the distillate is from the third distillation, the alcohol content of the distillate is set to 55.1-55.2% vol.

[0039] In some implementations, in step (b), when the distillate is the fourth distillate, the alcohol content of the distillate is set to 54.5% vol - 54.6% vol.

[0040] In some implementations, in step (b), when the distillate is the fifth distillate, the alcohol content of the distillate is set to 54.5% vol - 54.6% vol.

[0041] In some implementations, in step (b), when the distillate is the sixth distillate, the alcohol content of the distillate is set to 54.1% vol - 54.2% vol.

[0042] In some implementations, in step (b), when the distillate is the seventh distillate, the alcohol content of the distillate is set to 53.5% vol - 53.6% vol.

[0043] In some implementations, in step (b), the vapor pressure is 0.06 MPa-0.12 MPa.

[0044] In some implementations, in step (b), the vapor pressure is 0.07 MPa-0.11 MPa.

[0045] In some implementations, in step (b), the vapor pressure is 0.08 MPa-0.10 MPa.

[0046] In some implementations, in step (b), the vapor pressure is 0.08 MPa-0.09 MPa.

[0047] In some implementations, step (2) further includes removing the foremilk, the foremilk comprising 0.1-0.5% of the mass of the mash.

[0048] In some implementations, the mass of the distillate from the first distillation stage accounts for 0.1-0.3% of the mass of the mash.

[0049] In some implementations, the temperature of the distilled liquor in step (2) is 35-45°C.

[0050] In some implementations, the temperature of the distilled liquor in step (2) is 40-45°C.

[0051] In some embodiments, the present invention provides the use of the method in brewing baijiu (Chinese liquor).

[0052] In some implementation schemes, the liquor is a sauce-flavored liquor.

[0053] In some embodiments, the present invention provides the use of the method in reducing the ethyl carbamate content in baijiu (Chinese liquor).

[0054] In some implementation schemes, the liquor is a sauce-flavored liquor.

[0055] In some implementation plans, the brewing processes of strong-aroma baijiu and sauce-aroma baijiu differ significantly. For example, during the distillation of strong-aroma baijiu, the distillation temperature is generally between 25 and 35°C. The distillation temperature is closely related to the vapor pressure, so the vapor pressure cannot be too high, otherwise the distillation temperature will be too high, which does not meet the requirements of the strong-aroma baijiu brewing process. On the other hand, during the distillation of sauce-aroma baijiu, the distillation temperature is generally between 40 and 45°C. If the vapor pressure is too low, the distillation temperature will not meet the requirements of the sauce-aroma baijiu brewing process, violating the requirement of "high-temperature distillation".

[0056] In some embodiments, CN119506039A discloses a method for reducing the cyanide and ethyl carbamate content in solid-state distillation of baijiu. This method reduces the cyanide and ethyl carbamate content by adjusting the process parameters in the actual production of strong-aroma baijiu solid-state distillation without affecting the flavor of the baijiu. This prior art indicates that the height of the still affects the ethyl carbamate content of strong-aroma baijiu; however, in this invention, it has been confirmed that the height of the still does not affect the ethyl carbamate content of sauce-aroma baijiu. Therefore, it is clear that the method for reducing ethyl carbamate content cannot be simply extrapolated between strong-aroma and sauce-aroma baijiu.

[0057] In some implementations, this invention targets the brewing process of Maotai-flavor liquor. By adjusting the process parameters in actual production, it can reduce the content of ethyl carbamate without affecting the flavor and yield of the liquor, which is a significant improvement. Attached Figure Description

[0058] Figure 1 This describes the ethyl carbamate content and yield of wines from different distillation batches with varying alcohol strengths.

[0059] Figure 2 It describes the content of flavor compounds in wines from different distillation batches with varying alcohol content.

[0060] Figure 3 This is a comparison of the ethyl carbamate content in the wine obtained from different batches using traditional and optimized processes.

[0061] Figure 4 This is a comparison of the yield of wine obtained from different batches using traditional and optimized processes. Detailed Implementation

[0062] The following specific embodiments further illustrate the technical solution of the present invention. These specific embodiments do not represent a limitation on the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the concept of the present invention still fall within the scope of protection of the present invention.

[0063] Unless otherwise specified, all reagents, materials, and instruments used in the following description are conventional reagents, materials, and instruments, all of which are commercially available. The reagents involved can also be synthesized using conventional synthetic methods. Unless otherwise specified, the methods in the examples are conventional methods in the art.

[0064] This article does not mention other equipment, conditions, and process parameters used in distillation; it refers to the conventional distillation equipment, conditions, and process parameters for Maotai-flavor liquor.

[0065] In this article, the standard substances acetaldehyde, propionaldehyde, isobutyraldehyde, ethyl formate, ethyl acetate, acetal, methanol, isovaleraldehyde, 2-pentanone, sec-butanol, ethyl butyrate, propanol, ethyl isovalerate, isobutanol, isoamyl acetate, ethyl valerate, 2-pentanol, butanol, isovalerol, ethyl hexanoate, pentanol, 3-hydroxy-2-butanone, ethyl heptaate, ethyl lactate, hexanol, butyl hexanoate, ethyl octanoate, acetic acid, furfural, propionic acid, isobutyric acid, 2,3-butanediol, 1,2-propanediol, butyric acid, isovaleric acid, valerate, ethyl phenylacetate, hexanoic acid, β-phenylethanol, heptaate, octanoic acid, ethyl palmitate, ethyl oleate, and ethyl linoleate were purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0066] In this article, the technical terms used in this field are explained as follows: Distillation alcohol content (DOL): This refers to the alcohol content of the distillate collected after removing the heads during the distillation process. Once the alcohol content of the collected liquid reaches a certain set value, further distillation is stopped (the following distillate is called the tail liquor). In traditional processes, the DOL values ​​for Maotai-flavor baijiu are 57% vol for the first distillation, 55% vol for the second, 53.5% vol for the third, 53% vol for the fourth, 53% vol for the fifth, 52.5% vol for the sixth, and 52% vol for the seventh.

[0067] Heads: These are the first liquids distilled from the mash during the distillation process as the temperature rises. This portion contains many harmful aldehydes and alcohols and is typically "cut off" (discarded). Heads comprise 0.1-0.3% of the total mass of the mash.

[0068] Distilled liquor: refers to the liquor obtained in the production process of Maotai-flavor liquor by distilling different fermented mash, removing the heads, and then distilling according to the alcohol content of each distillation.

[0069] Tail liquor: refers to the remaining distillate collected after each distillation cycle's spirits have been collected according to their alcohol content during the distillation process. In the distillation of soy sauce-flavored baijiu, approximately 120 kg of tail liquor is typically collected for further extraction of residual alcohol or other purposes.

[0070] Bottom pot water: This refers to the liquid placed at the bottom of the still during distillation. Its function is to generate steam after high-temperature heating, carrying flavor compounds from the fermented mash into the liquor. Initially, the bottom pot water is usually drinking water. In traditional processes, after each still of mash is distilled, the collected tail liquor is used to replenish the bottom pot water before the next still is distilled. The bottom pot water needs to be replaced after four stills of mash have been distilled.

[0071] Example 1: Distillation of traditional sauce-flavored Baijiu in rounds In the traditional solid-state distillation process of Maotai-flavor baijiu, the water in the distillation vessel is replenished once, and the distillation is carried out four times. The first distillation uses 500 kg of drinking water as the distillation vessel water. After collecting the distillate from this round, 120 kg of tail liquor is obtained by distillation at 0.12 MPa. This is the first use of the distillation vessel water. The second distillation uses the remaining distillation vessel water, supplemented by the aforementioned 120 kg of tail liquor, and is repeated. After collecting the distillate from this round, 120 kg of tail liquor is obtained by distillation at 0.12 MPa. This is the second use of the distillation vessel water (already used once). The third distillation uses the remaining distillation vessel water from the second distillation, supplemented by the 120 kg of tail liquor obtained from the second distillation, and is repeated. After collecting the distillate from this round, 120 kg of tail liquor is obtained by distillation at 0.12 MPa. This is the third use of the distillation vessel water (already used twice). The fourth distillation uses the remaining water from the third distillation as a base, supplemented by 120 kg of tail liquor from the third distillation. After collecting all the distillate from this round, 120 kg of tail liquor is obtained by distillation at 0.12 MPa. This is the fourth time the base water has been used (it has already been used three times). Example 1 shows the fourth distillation, where the base water is used for the fourth time, and the tail liquor used as a supplement comes from the third distillation.

[0072] In Example 1, solid-state distillation of Maotai-flavor liquor was carried out using three-stage fermented mash as the distillation object (parallel samples were taken from three fermentation pits). Add 380 kg of water (used three times) and 120 kg of tail liquor (tail liquor distillation pressure 0.12 MPa) to the earthen pot. Adjust the distillation pressure to 0.08 MPa. After the water boils, begin loading the still. The still contains 1500 kg of mash, with a loading height of 80 cm. Cover the still. The alcohol vapor is cooled by the cooling system and distilled from the receiving end (the distillate temperature is controlled at 40-45 ℃). Collect the first 3 kg of heads separately (cut off the heads). Collect the continuously distilling liquor in a barrel. When the alcohol content (i.e., the distillate alcohol content) in the barrel reaches 53.5% vol, transfer the continuously distilled liquor to the tail liquor barrel. At this point, adjust the distillation pressure (tail liquor distillation pressure) to 0.12 MPa, ensuring the tail liquor distillation temperature is >45 ℃. Continue collecting until 120 kg of tail liquor is full. The distillation process is complete after the tail liquor is distilled in the main still.

[0073] In this embodiment, the alcohol content of the collected wine is measured and recorded in real time before the distillation is completed. The alcohol content of the fraction is measured using a hydrometer (GB 5009.225-2023 National Food Safety Standard - Determination of Ethanol Concentration in Wine and Edible Alcohol, Method IV) and converted to alcohol content at 20 °C.

[0074] Comparative Example 1: Effects of alcohol content on yield per distillation, ethyl carbamate content, and flavor compound content in distillates. In Comparative Example 1, three rounds of fermented mash were used as the research object (parallel samples were taken from three fermentation pits). During the distillation process, based on Example 1, only the alcohol content of the distillate was adjusted, and the alcohol contents of the three rounds were set to 52.0% vol, 53.5% vol, 55.0% vol, and 56.5% vol, respectively. The effect of the distillate alcohol content on the ethyl carbamate content in the distillate was compared (the test results are averaged).

[0075] In Comparative Example 1, the remaining process parameters (such as distillation vapor pressure) for solid-state distillation of Maotai-flavor liquor were the same as in Example 1.

[0076] The content of ethyl carbamate in baijiu was determined using an Orbitrap Exploris 120 ultra-high performance liquid chromatography-high resolution mass spectrometry (Thermo Fisher Scientific (China) Co., Ltd.).

[0077] Sample pretreatment: Accurately pipette 1 mL of the sample into a centrifuge tube, place it in a 70 ℃ oven and dry it to 0.4 mL, then remove it, cool it and add water to make up to 1 mL, vortex to mix, filter through a 0.22 μm aqueous microporous membrane, and then test it.

[0078] Chromatographic analysis conditions: Mobile phase: Aqueous phase A was 0.1% (V:V) formic acid aqueous solution, and organic phase B was methanol; flow rate: 0.3 mL / min; Column: Hypersil GOLD Amino HPLC column (150 mm × 2.1 mm, 1.9 μm); Column temperature: 35℃; Injection volume: 10 μL; Gradient elution program: 0–1.0 min, 95% A, 5% B; 1.0–4.0 min, 95%–5% A, 5%–95% B; 4.0–5.5 min, 5% A, 95% B; 5.5–6.0 min, 5%–95% A, 95%–5% B; 6.0–11.0 min, 95% A, 5% B. Wherein, the percentage of A or B is the volume percentage of aqueous phase A or organic phase B in the mixture of aqueous phase A and organic phase B.

[0079] Mass spectrometry conditions: Ion source: Heated atmospheric piezoelectric ionization source, positive ion scanning mode; Scan type: Selected ion detection mode; Scan range: 55–95 m / z; Resolution: 70,000; Automatic gain control target ion number 1×10⁻⁶ 6Maximum injection time: 5 ms; sheath gas flow rate: 30 arb; auxiliary gas flow rate: 15 arb; spray voltage: 2.3 kV; ion transfer tube temperature: 350 ℃; S-lens RF evel: 80; auxiliary gas heating temperature: 200 ℃. Substances were qualitatively analyzed according to EC standard ion 62.02, and quantified using the external standard method combined with peak area.

[0080] The flavor compounds in the wine samples were detected using gas chromatography (Agilent 8890-GC).

[0081] Sample pretreatment: Take an appropriate amount of wine sample to be tested and filter it through a 0.22 μm organic filter membrane. Take 990 μL of the filtered wine sample into a 2 mL gas chromatograph vial, add 10 μL of mixed internal standard solution (final concentrations are: tert-amyl alcohol 285.15 mg / L, n-amyl acetate 300.72 mg / L, 2-ethylbutyric acid 296.68 mg / L, solvent is 53% vol ethanol aqueous solution), cap and seal, place on a vortex mixer and shake for 1 min to mix, let stand, and wait for instrumental analysis.

[0082] Gas chromatography conditions: DB-WAX UI column (30 m × 0.25 mm × 0.25 μm); column temperature program: initial temperature 35 ℃, hold for 3 min, increase to 100 ℃ at 3.5 ℃ / min, increase to 200 ℃ at 7 ℃ / min, hold for 15 min; injector temperature 250 ℃; detector temperature 250 ℃; injection volume 1.0 μL; split ratio 30:1; column flow rate 0.8 mL / min; hydrogen (H2):air:makeup gas (N2) = 300:30:35. Detection of substances was performed qualitatively based on the peak order and retention time of standards, and quantification was performed using the internal standard method combined with peak area.

[0083] The flavor compounds detected include: esters such as ethyl formate, ethyl acetate, ethyl butyrate, ethyl isovalerate, isoamyl acetate, ethyl valerate, ethyl hexanoate, ethyl heptaate, ethyl lactate, butyl hexanoate, ethyl octanoate, ethyl phenylacetate, ethyl palmitate, ethyl oleate, and ethyl linoleate; ketones such as 2-pentanone and 3-hydroxy-2-butanone; aldehydes such as acetaldehyde, propionaldehyde, isobutyraldehyde, acetal, isovaleraldehyde, and furfural; acids such as acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, valerate, hexanoic acid, heptaate, and octanoic acid; and alcohols such as methanol, sec-butanol, propanol, isobutanol, 2-pentanol, butanol, isopentanol, pentanol, hexanol, 2,3-butanediol, 1,2-propanediol, and β-phenylethanol. Yield refers to the mass of the collected distillations.

[0084] In Comparative Example 1, the detection and analysis results are as follows: Figure 1As shown, with the increase of alcohol content at the distillation batch, the content of ethyl carbamate in the distillation batch first decreases and then stabilizes. Furthermore, appropriately increasing the alcohol content at the distillation batch has no significant impact on the yield.

[0085] Further data analysis revealed that adjusting the alcohol content of the three distillations from 53.5% vol to 55.0% vol resulted in a 21.8% decrease in the ethyl carbamate content of the subsequent distillations compared to the initial 56.52 µg / L (53.5% vol), reaching 44.2 µg / L. This demonstrates that adjusting the distillation alcohol content can effectively reduce the ethyl carbamate content in the distillations.

[0086] Figure 2 Flavor radar charts of different distillation alcohol concentrations were plotted based on the flavor compound content of distillates obtained at a distillation alcohol concentration of 53.5% vol. Figure 2 It is evident that appropriately increasing the alcohol content of the distillate from each batch does not significantly affect the content of flavor compounds in the distillate. However, when the alcohol content reaches 56.5% vol, the content of alcohols and acids shows a more significant shift compared to 53.5% vol.

[0087] Using the adjustment range of the alcohol content in the three rounds of distillation as a reference, the alcohol content of distillations from round one to round seven was further increased by 1.5% vol (only the alcohol content differed before and after the adjustment within the same round; other process conditions and parameters remained consistent). The changes in ethyl carbamate (EC) content in the distillates from each round were compared, and the statistical results are shown in Table 1. After increasing the alcohol content, the EC content decreased in all rounds, with a reduction rate ranging from 19.8% to 21.6%. This indicates that the measure of appropriately increasing the alcohol content to reduce the EC content in the distillate from each round can be applied to other rounds.

[0088] Table 1. Statistical results before and after adjusting the alcohol content of the distilled spirits.

[0089] Comparative Example 2: Effect of Distilled Tail Wine Vapor Pressure on Ethyl Carbamate Content in Tail Wine Based on Example 1, only the vapor pressure of the distilled tail liquor was adjusted. The vapor pressure was set to 0.14 MPa, 0.12 MPa, 0.10 MPa, 0.08 MPa, and 0.06 MPa. At each of these five pressures, 120 kg of tail liquor was collected, and the ethyl carbamate content in the tail liquor was compared under different pressures (parallel samples were taken from three fermentation pits, and the results are averaged). The method for detecting the ethyl carbamate content in the tail liquor was the same as in Comparative Example 1.

[0090] The test results are shown in Table 2. When the steam pressure of the distilled tail liquor was 0.14 MPa, 0.12 MPa, 0.10 MPa, 0.08 MPa, and 0.06 MPa, the corresponding ethyl carbamate (EC) contents in the tail liquor were 160.69 µg / L, 138.53 µg / L, 117.38 µg / L, 96.54 µg / L, and 91.43 µg / L, respectively. Calculations showed that increasing the steam pressure of the distilled tail liquor to 0.14 MPa, compared to 0.12 MPa used in Example 1, resulted in a 16% increase in the EC content of the tail liquor. Furthermore, decreasing the steam pressure of the distilled tail liquor from 0.12 MPa to 0.10 MPa, 0.08 MPa, and 0.06 MPa resulted in EC reduction rates of 15.27%, 30.31%, and 34%, respectively; and the distillation time to obtain 120 kg of tail liquor increased by 2 min, 6 min, and 14 min, respectively. This indicates that when the vapor pressure of the tail liquor is 0.08 MPa, the EC content in the tail liquor remains at a low level and the distillation time is relatively short. Therefore, 0.08 MPa can be selected as the vapor pressure for distilling the tail liquor.

[0091] Table 2. Statistics on ethyl carbamate content and distillation time in tail liquor under different vapor pressures.

[0092] Comparative Example 3: Effect of the number of times the water from the earthen pot is used on the content of ethyl carbamate in each batch of liquor and the tail liquor. In the traditional solid-state distillation process of Maotai-flavor baijiu, the water in the distillation vessel is replenished once, and the distillation is carried out four times. The first distillation uses 500 kg of drinking water as the distillation vessel water. After collecting the distillate from this round, 120 kg of tail liquor is obtained by distillation at 0.12 MPa. This is the first use of the distillation vessel water. The second distillation uses the remaining distillation vessel water, supplemented by the aforementioned 120 kg of tail liquor, and is repeated. After collecting the distillate from this round, 120 kg of tail liquor is obtained by distillation at 0.12 MPa. This is the second use of the distillation vessel water (already used once). The third distillation uses the remaining distillation vessel water from the second distillation, supplemented by the 120 kg of tail liquor obtained from the second distillation, and is repeated. After collecting the distillate from this round, 120 kg of tail liquor is obtained by distillation at 0.12 MPa. This is the third use of the distillation vessel water (already used twice). The fourth distillation uses the remaining water from the third distillation as a base, supplemented by 120 kg of tail liquor from the third distillation. After collecting all the distillate from this round, 120 kg of tail liquor is obtained by distillation at 0.12 MPa. This is the fourth time the base water has been used (it has already been used three times). Example 1 shows the fourth distillation, where the base water is used for the fourth time, and the tail liquor used as a supplement comes from the third distillation.

[0093] Based on Example 1, only the number of times the boiler water was used was adjusted. Boiler water that had been used 3 times, 2 times, and 1 time, as well as unused standard domestic water, were used. The replenished tail liquor corresponded to the tail liquor obtained from the previous distillation. The corresponding batch liquor and tail liquor were collected and the changes in carbamic acid content were compared and analyzed (parallel samples were taken from three fermentation pits, and the test results are averaged). This is equivalent to comparing the batch liquor and tail liquor obtained from the first distillation (boiler water used 0 times), second distillation (boiler water used 1 time), third distillation (boiler water used 2 times), and fourth distillation (boiler water used 3 times) in the above traditional process.

[0094] In Comparative Example 3, the method for detecting ethyl carbamate content was the same as in Comparative Example 1. The distillation cycles, distillation environment, and conditions were kept consistent for each reuse of the boiler water.

[0095] The analysis results are shown in Table 3. The ethyl carbamate (CFC) content in the distillate after using water that had been used 3 times, 2 times, 1 time, and never used was 56.27 µg / L, 49.67 µg / L, 45.32 µg / L, and 44.52 µg / L, respectively. The CFC content in the tail liquor was 114.52 µg / L, 97.66 µg / L, 89.32 µg / L, and 86.21 µg / L, respectively. This indicates that reducing the number of times the CFC water is reused is beneficial for reducing the CFC content in both the distillate and the tail liquor. However, considering the changes in CFC content, the difference between using water that has been used once and using unused standard drinking water is not significant. Therefore, the CFC water should not be reused more than twice.

[0096] Table 3. Effect of the number of times the water used in the earthen pot has been used on the content of ethyl carbamate in each batch of liquor and the tail liquor.

[0097] Comparative Example 4: Effect of still height on ethyl carbamate content in distilled and tail liquors In the comparative examples, the loading height of the still is determined by the amount of mash loaded, which affects the change in the space inside the still. Based on Example 1, only the loading height was adjusted, with loading heights of 75 cm, 80 cm, 85 cm, and 90 cm set respectively. Other process parameters in the distillation process remained unchanged, and the method for detecting ethyl carbamate content was the same as in Example 1. The effect of loading height on the ethyl carbamate content in the distillate and tail liquor was compared (parallel samples were taken from three fermentation pits, and the test results are averaged). The results are shown in Table 4.

[0098] With the still heights set to 75 cm, 80 cm, 85 cm, and 90 cm, the corresponding ethyl carbamate (CFC) contents in the distillation batches were 44.66 µg / L, 45.64 µg / L, 45.32 µg / L, and 45.38 µg / L, respectively, while the CFC contents in the tail liquor were 95.85 µg / L, 97.66 µg / L, 96.87 µg / L, and 97.21 µg / L, respectively. Overall, there was a slight increasing trend, but the increase was not significant. This indicates that adjusting the still height had no significant effect on controlling the CFC content in either the distillation batches or the tail liquor.

[0099] Table 4. Effect of still height on ethyl carbamate content in distilled and tail liquor.

[0100] Example 3: Effects of process optimization on ethyl carbamate content, yield, and flavor compound content in batches of wine. Example 1 is a traditional solid-state distillation process for Maotai-flavor liquor (parallel samples were taken from five fermentation pits).

[0101] The optimized process in this embodiment is as follows: Compared with Example 1, the differences are: (1) During distillation, the alcohol content of the distillate is set to 55.0% vol. (2) During distillation, the boiler water is 380 kg of newly added domestic drinking water and 120 kg of tail liquor (the tail liquor is collected at a vapor pressure of 0.08 MPa). Other distillation environments and conditions remain the same, and the parallel samples are taken from five fermentation pits.

[0102] The ethyl carbamate content and yield in three rounds of liquor from five fermentation pits using either traditional or optimized processes were analyzed. The results are as follows: Figure 3 , Figure 4 As shown, the ethyl carbamate content in the three rounds of wine produced by the optimized process can be reduced by 26% compared to 56.76 µg / L in the traditional process, reaching 42 µg / L. Furthermore, the optimized process has no significant impact on the wine yield.

[0103] Acetic acid, lactic acid, hexanoic acid, butyric acid, ethyl acetate, ethyl lactate, ethyl butyrate, and ethyl hexanoate are key flavor compounds in baijiu. The detection methods for acetic acid, hexanoic acid, butyric acid, ethyl acetate, ethyl lactate, ethyl butyrate, and ethyl hexanoate are the same as those in Comparative Example 1. The detection method for lactic acid was optimized by referring to the literature of Yi Zongwei (Yi Zongwei, Cai Wenchao, Yu Peirong, Chen Wei, Shan Chunhui, Wang Yurong, Qu Dingwu. Determination of four organic acids in sauce-flavored baijiu by high performance liquid chromatography [J]. China Brewing, 2025, 44(6):281-286 https: / / doi.org / 10.11882 / j.issn.0254-5071.2025.06.040) and combined with laboratory conditions. That is, 1 mL of the baijiu sample to be tested was passed through a 0.22 μm organic filter membrane with an injection needle and then detected by the instrument (Agilent HPLC-1260). The HPLC chromatographic conditions were as follows: ZORBAX SB-C18 column (4.6 mm × 150 mm 5 μm); mobile phase: 0.02 mol / L KH2PO4, pH 2.3; detection wavelength: 208 nm; column temperature: 30 ℃; mobile phase flow rate: 0.8 mL / min; injection volume: 1 μL.

[0104] Further comparison was made between the key flavor compounds obtained from the optimized process and those obtained from the traditional process. The results are shown in Table 5. There were no significant differences in the contents of acetic acid, lactic acid, hexanoic acid, butyric acid, ethyl acetate, ethyl lactate, ethyl butyrate, and ethyl hexanoate in the wine obtained from the optimized process compared to the wine obtained from the traditional process.

[0105] Table 5. Comparison of key flavor compounds obtained from distillation batches using integrated methods versus traditional methods.

[0106] The above embodiments are only for further elaboration and explanation of the technical solutions of the present invention, so that those skilled in the art can more accurately understand the inventive concept and operation scheme of the present invention, and are not intended to further limit the present invention. Any non-prominent substantive features and non-significant improvements made by those skilled in the art on this basis shall fall within the protection scope of the present invention.

Claims

1. A method for brewing wine, characterized in that, The liquor is a sauce-flavored baijiu, and the method includes: (1) Boil water in a pot and steam the fermented mash. (2) Open the vapor pressure and collect the distilled liquor. When the alcohol content of the distilled liquor reaches the set value, the collection of the round liquor is completed; the method is a method to reduce the ethyl carbamate content in the round liquor. The round of wine includes the third round of wine; When the collected distillate is from the third distillation, the alcohol content of the distillate is set at 55% vol to 55.8% vol.

2. The method as described in claim 1, characterized in that, When the distillate is from the first distillation, the alcohol content of the distillate is set at 58.2% vol - 58.8% vol. Preferably, when the distillate is from the second distillation, the alcohol content of the distillate is set to 56.2% vol - 56.8% vol. Preferably, when the distillate is from the fourth distillation, the alcohol content of the distillate is set to 54.2% vol - 54.8% vol. Preferably, when the distillate is from the fifth distillation, the alcohol content of the distillate is set to 54.2% vol - 54.8% vol. Preferably, when the distillate is from the sixth distillation, the alcohol content of the distillate is set to 54% vol - 54.8% vol. Preferably, when the distillate is from the seventh distillation, the alcohol content of the distillate is set to 53.2% vol - 53.8% vol. Preferably, the vapor pressure of the wine obtained in the round is 0.07 MPa-0.10 MPa; Preferably, the vapor pressure of the wine obtained in the round is 0.08 MPa-0.09 MPa; Preferably, in step (1), the water used in the earthen stove is reused earthen stove water; Preferably, the water used in the earthen stove is water that has been used 1-4 times; Preferably, the water used in the earthen stove is water that has been used 1-3 times; Preferably, the water used in the earthen pot is water that has been used 1-2 times.

3. The method as described in claim 1, characterized in that, In step (2), when the distilled wine is the first distillation, the alcohol content of the distilled wine is set to 58.4%vol-58.6%vol. Preferably, when the distillate is from the second distillation, the alcohol content of the distillate is set to 56.4% vol - 56.6% vol. Preferably, when the distillate is from the third distillation, the alcohol content of the distillate is set to 55.1% vol - 55.4% vol. Preferably, when the distillate is from the fourth distillation, the alcohol content of the distillate is set to 54.4% vol - 54.6% vol. Preferably, when the distillate is from the fifth distillation, the alcohol content of the distillate is set to 54.4% vol - 54.6% vol. Preferably, when the distillate is from the sixth distillation, the alcohol content of the distillate is set to 54.1% vol - 54.4% vol. Preferably, when the distillation is the seventh distillation, the alcohol content of the distillate is set to 53.4% ​​vol - 53.6% vol.

4. The method as described in claim 1, characterized in that, In step (2), when the distilled wine is the first round of distillation, the alcohol content of the distilled wine is set to 58.5% vol - 58.6% vol. Preferably, when the distillate is from the second distillation, the alcohol content of the distillate is set to 56.5% vol - 56.6% vol. Preferably, when the distillate is from the third distillation, the alcohol content of the distillate is set to 55.1-55.2% vol. Preferably, when the distillate is from the fourth distillation, the alcohol content of the distillate is set to 54.5% vol - 54.6% vol. Preferably, when the distillate is from the fifth distillation, the alcohol content of the distillate is set to 54.5% vol - 54.6% vol. Preferably, when the distillate is from the sixth distillation, the alcohol content of the distillate is set to 54.1% vol - 54.2% vol. Preferably, when the distillation is the seventh distillation, the alcohol content of the distillate is set to 53.5% vol - 53.6% vol.

5. The method as described in claim 2, characterized in that, The water in the earthen pot includes water; Preferably, the water in the boiler includes domestic drinking water; Preferably, the water from the earthen pot also includes the tail wine; Preferably, the water used in the boiler is a combination of drinking water and tail liquor.

6. The method as described in claim 5, characterized in that, The method for obtaining the tail wine is as follows: (a) Boil water in a pot and steam the fermented grains; (b) Open the steam pressure to distill and collect the distillate; when the alcohol content of the distillate reaches the set value, after completing the collection of one round of wine, adjust the steam pressure to distill again and collect the distillate again to obtain the tail wine. Preferably, in step (b), when the distillate is from the first distillation, the alcohol content of the distillate is set to 58.5% vol - 58.6% vol. Preferably, in step (b), when the distillate is from the second round, the alcohol content of the distillate is set to 56.5% vol - 56.6% vol. Preferably, in step (b), when the distillate is from the third distillation, the alcohol content of the distillate is set to 55.1-55.2% vol. Preferably, in step (b), when the distillate is from the fourth distillation, the alcohol content of the distillate is set to 54.5% vol - 54.6% vol. Preferably, in step (b), when the distillate is from the fifth distillation, the alcohol content of the distillate is set to 54.5% vol - 54.6% vol. Preferably, in step (b), when the distillate is the sixth distillate, the alcohol content of the distillate is set to 54.1% vol - 54.2% vol. Preferably, in step (b), when the distillate is the seventh distillate, the alcohol content of the distillate is set to 53.5% vol - 53.6% vol.

7. The method as described in claim 6, characterized in that, In step (b), the vapor pressure is 0.06 MPa - 0.12 MPa; Preferably, in step (b), the vapor pressure is 0.07 MPa-0.11 MPa; Preferably, in step (b), the vapor pressure is 0.08 MPa-0.10 MPa; Preferably, in step (b), the vapor pressure is 0.08 MPa-0.09 MPa.

8. The method as described in claim 1, characterized in that, Step (2) further includes removing the distillate from the first stage, wherein the mass of the distillate from the first stage accounts for 0.1-0.5% of the mass of the mash. Preferably, the mass of the distillate from the first stage accounts for 0.1-0.3% of the mass of the mash. Preferably, in step (2), the temperature of the distilled liquor is 35-45°C; Preferably, in step (2), the temperature of the distilled liquor is 40-45°C.

9. The use of the method according to any one of claims 1-8 in the brewing of baijiu (Chinese liquor); Preferably, the liquor is a sauce-flavored liquor.

10. Use of the method according to any one of claims 1-8 in reducing the ethyl carbamate content of baijiu (Chinese liquor); Preferably, the liquor is a sauce-flavored liquor.

Images