Method for inhibiting generation of ethyl carbamate in baijiu and application thereof

Abstract

The application discloses a method for inhibiting generation of ethyl carbamate in baijiu and application thereof, and relates to the following steps: adding tartary buckwheat extract into brewing materials before fermentation of the strong-flavor baijiu, and obtaining base liquor after fermentation, distillation and storage. It is found through a large number of comparison experiments that the tartary buckwheat extract has a significant inhibitory effect on the generation of ethyl carbamate in baijiu, and the inhibitory effect is closely related to the adding time: only when the tartary buckwheat extract is added before fermentation, can the active ingredients participate in the fermentation process, so that the generation path of EC is effectively blocked from the metabolic source.

Description

Technical Field

[0001] This invention belongs to the field of liquor brewing technology, specifically relating to a method and application for inhibiting the formation of ethyl carbamate during the brewing process of strong-aroma liquor. Background Technology

[0002] Ethyl carbamate (EC) is a Group 2A carcinogen found in fermented foods and alcoholic beverages. The International Agency for Research on Cancer has classified it as a potential carcinogen, and many countries and regions have set strict limits on the EC content in alcoholic beverages.

[0003] Currently, the main technical approaches to reducing EC content in baijiu (Chinese liquor) include: 1) optimizing raw materials and microbial strains to reduce the formation of urea precursors at the source; 2) using bioenzymes to degrade existing urea; and 3) improving distillation processes to separate some EC. However, these methods all have certain limitations: the selection and breeding cycle for microbial strains is long, directly adding exogenous enzymes may introduce exogenous proteins, and process improvement costs are high. Therefore, developing an efficient, low-cost EC inhibition method that can be easily integrated into existing processes has significant industrial value.

[0004] Buckwheat, a crop with both medicinal and edible uses, is rich in flavonoids and phenolic acids, and has been widely used in the development of buckwheat liquor. In existing technologies, buckwheat is mostly used in fermentation as a raw material or blended into finished liquor, primarily to impart a unique "buckwheat aroma" or increase the amount of flavonoids beneficial to health. For example, CN121182569A and CN118109258A disclose a brewing process for buckwheat liquor, and CN121182588A discloses a buckwheat herbal liquor and its preparation method, in which ultrafine buckwheat powder is directly added to the base liquor of sauce-flavored liquor. To date, no literature reports the use of buckwheat extract as a functional additive to actively intervene in and inhibit the formation of ethyl carbamate in liquor.

[0005] It is worth noting that while directly adding buckwheat extract to the finished liquor does result in a certain degree of reduction in EC content, the liquor also exhibits a distinct "buckwheat aroma." According to the "Terminology of Baijiu Industry" (GB / T15109-2021) and "Terminology and Classification of Alcoholic Beverages" (GB / T 17204-2021), adding exogenous extracts or edible flavorings to the finished liquor fundamentally changes the product classification—from "baijiu" to "blended liquor." This means that while simple post-production addition may achieve a partial reduction in EC, it comes at the cost of sacrificing the product's category attributes and traditional flavor characteristics, failing to meet the core requirements of strong-aroma baijiu producers to maintain product authenticity and category purity. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for efficiently inhibiting the formation of ethyl carbamate (EC) during the brewing process of strong-aroma baijiu. Specifically, the technical problem to be solved by this invention is to determine the optimal timing and method of adding buckwheat extract to the baijiu brewing process, so as to maximize the inhibition of EC formation without damaging the inherent microbial fermentation environment and main flavor characteristics of strong-aroma baijiu.

[0007] The first aspect of the present invention provides a method for inhibiting the formation of ethyl carbamate in strong-aroma baijiu, comprising adding buckwheat extract to the brewing materials before fermentation in the brewing process of strong-aroma baijiu, wherein the amount of buckwheat extract added is 0.1%-1.0% of the weight of the staple grain based on the dry matter of buckwheat.

[0008] Preferably, the amount of buckwheat extract added is 0.3%-0.8%.

[0009] Preferably, the buckwheat extract is prepared by the following method: pulverizing buckwheat bran to 40-60 mesh, extracting with an ethanol aqueous solution, filtering and concentrating to obtain a buckwheat extract concentrate or extract.

[0010] Preferably, an aqueous ethanol solution with a volume fraction of 50%-70% is used, with a material-to-liquid ratio of 1:6-1:12 kg / L, and the extraction is carried out at 50-70°C for 1-3 hours.

[0011] Preferably, before adding the buckwheat extract, it is first diluted with a small amount of water or low-alcohol liquor with an alcohol content of 25%-40% vol to 2-5 times its original volume to facilitate even spraying.

[0012] A second aspect of this invention provides a brewing process for inhibiting the formation of ethyl carbamate in baijiu (Chinese liquor) from the source, comprising the following steps:

[0013] (1) Preparation of buckwheat extract: Buckwheat bran was crushed to 40-60 mesh, extracted with ethanol aqueous solution, filtered and concentrated to obtain buckwheat extract concentrate or extract. (2) Processing of brewing raw materials: The main grains of strong-aroma baijiu are moistened, steamed and cooled according to traditional processes; (3) After the grain mash has been spread out and mixed with Daqu, before it is put into the cellar for fermentation, the buckwheat extract prepared in step (1) is added evenly to the mash. The amount of buckwheat extract added is 0.1%-1.0% of the weight of the staple grain, based on the dry matter of buckwheat. (4) Fermentation: The mash with added buckwheat extract is put into the cellar and fermented in the cellar according to the traditional process of strong aroma baijiu; (5) Distillation and storage: After fermentation, the base wine is taken out of the cellar and distilled and graded according to conventional processes. The resulting base wine is then stored in the warehouse.

[0014] Preferably, the main grains for the strong-aroma baijiu include one or more of sorghum, rice, glutinous rice, wheat, and corn.

[0015] Preferably, in step (3), the buckwheat extract is added by diluting the extract and then uniformly mixing it in by atomizing and spraying it to ensure that the active ingredients are evenly distributed in the mash.

[0016] Preferably, after aging the base wine for 12 months, the inhibition rate of ethyl carbamate reaches more than 45%.

[0017] The third aspect of the present invention provides a strong-aroma baijiu brewed using the above method.

[0018] Compared with the prior art, the present invention has the following advantages: (1) This invention adds buckwheat extract before fermentation, allowing the active ingredients to participate in the entire fermentation process, effectively blocking the EC generation pathway at the source. Experimental data show that the EC content of strong-aroma baijiu produced using the method of this invention is reduced by more than 45% compared to the blank control group, which is significantly better than other additive steps.

[0019] (2) This invention adds buckwheat extract before fermentation, so that the active ingredients participate in biotransformation during the brewing process. The final product meets the national standards for baijiu and is still classified as "baijiu" rather than "blended liquor". This fundamentally solves the product classification dilemma faced by the traditional method of adding ingredients after fermentation and meets the core demand of production enterprises to maintain the authenticity of their products.

[0020] (3) This invention achieves EC inhibition without damaging the inherent microbial fermentation environment of strong-aroma baijiu. Experiments show that the baijiu brewed by the method of this invention has the same content and ratio of main aroma components such as ethyl hexanoate and ethyl acetate as traditional process, with a rich cellar aroma and harmonious taste.

[0021] (4) This invention allows the flavor components in the buckwheat extract to fully interact with the microorganisms in the mash during the fermentation process that lasts for several months. The special flavors it brings are integrated into the wine in a softer and more integrated way, forming a complex and harmonious aroma with the traditional cellar aroma, thus avoiding the "flavor stripping" or "aroma conflict" that may occur when directly adding to the finished wine.

[0022] (5) The present invention only requires adding a spraying and mixing step to the existing brewing process, without the need for additional equipment investment, and is easy to promote and apply in strong-aroma baijiu production enterprises. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of this invention is for describing specific implementation schemes and not for limiting the scope of protection of this invention.

[0024] When a range of values ​​is given, it should be understood that, unless otherwise stated in this invention, the two endpoints of each range and any value between the two endpoints may be selected.

[0025] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly used in the field to which this invention pertains. The terminology used to describe this invention is intended only to describe a particular implementation and is not intended to limit the scope of the teachings. This invention can be implemented using any prior art methods, apparatus, and materials similar to or equivalent to those described, used, or made in the embodiments of this invention.

[0026] Unless otherwise specified, "%" and "parts" as used in this document refer to "mass %" and "mass parts," respectively.

[0027] The term “and / or” as used herein should be understood to mean any one of the options or any combination of two or more of the options.

[0028] As used herein, the term "about" indicates a range of ±20% of the following value. In some embodiments, the term "about" indicates a range of ±10% of the following value. In some embodiments, the term "about" indicates a range of ±5% of the following value.

[0029] The following embodiments are provided to aid in understanding the present invention. However, it should be understood that these embodiments are for illustrative purposes only and do not constitute any limitation. The actual scope of protection of the present invention is set forth in the claims. It should be understood that any modifications and changes can be made without departing from the spirit of the present invention. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products in the art, their specifications are conventional specifications in the art, and the methods used are conventional methods in the art. The instruments and equipment used in the embodiments are conventional instruments and equipment in the art.

[0030] During the research and development process, the inventors unexpectedly discovered that buckwheat extract has a significant inhibitory effect on the formation of eclectic acid (EC) in baijiu (Chinese liquor). Further research revealed that this inhibitory effect is not a simple physical dilution or a late-stage reaction, but is closely related to the timing of addition: adding it before fermentation allows the active ingredients in the buckwheat extract to participate in the entire fermentation process, effectively blocking the EC formation pathway at its metabolic source. More importantly, this method achieves highly efficient EC inhibition without altering the product's category (still falling under the "baijiu" category) or compromising the traditional strong-aroma flavor characteristics. This discovery provides a novel approach for developing new safe baijiu production technologies and has significant industrial application value.

[0031] This specific embodiment relates to a brewing process that inhibits the formation of ethyl carbamate in strong-aroma baijiu from the source. It includes adding 0.1%-1.0% of the weight of buckwheat extract, which accounts for 0.1%-1.0% of the main grain, to the brewing materials in the form of a spray before fermentation in the strong-aroma baijiu brewing process. Specifically, after the grain mash has been spread out and mixed with koji, and before it is put into the fermentation pit, the buckwheat extract is evenly added to the mash.

[0032] The preparation method of buckwheat extract is as follows: buckwheat bran is pulverized to 40-60 mesh, and extracted with 50%-70% volume fraction ethanol aqueous solution at a material-liquid ratio of 1:6-1:12. The extraction is carried out at 50-70℃ for 1-3 hours, filtered, and concentrated to obtain buckwheat extract concentrate or extract.

[0033] The mash with added buckwheat extract is placed in a cellar and fermented according to the traditional process of strong-aroma baijiu. After fermentation, it is removed from the cellar and distilled and graded according to conventional processes. The resulting base liquor is then stored in a warehouse.

[0034] The present invention will be further described below with reference to specific embodiments and comparative examples, but the scope of protection of the present invention is not limited thereto. All embodiments and comparative examples used the same batch of raw materials and were carried out under the same environmental conditions.

[0035] Example 1 This embodiment provides a brewing process that inhibits the formation of ethyl carbamate in baijiu from the source, including the following steps: (1) Take 1 kg of buckwheat bran, crush it and pass it through a 50-mesh sieve. Add 8 L of 60% ethanol aqueous solution and extract it in a 60℃ water bath for 3 hours. Filter it and concentrate the filtrate to 1 L under reduced pressure at 50℃ to obtain buckwheat extract concentrate.

[0036] (2) Take 100 kg of sorghum and soak, steam, and cool to 18-22℃ according to the traditional process of strong aroma baijiu.

[0037] (3) Add the crushed high-temperature Daqu (a type of starter culture) and mix thoroughly.

[0038] (4) Dilute the above-mentioned buckwheat extract concentrate with 2L of water and spray it evenly on the surface of the mash with an atomizing sprayer. At the same time, stir the mash to ensure even mixing (equivalent to 0.5% of the amount of buckwheat dry matter added as the staple food).

[0039] (5) Put the mash into the cellar and seal it for fermentation.

[0040] (6) After fermentation, the wine is removed from the cellar and mixed distilled to extract the middle section of the wine as the base wine.

[0041] (7) After the base liquor is stored in earthenware jars for 12 months, samples are taken to test the EC content and flavor components.

[0042] Example 2 Except for adjusting the amount of buckwheat extract added to 0.3% of the staple food, the rest of the operation is the same as in Example 1.

[0043] Example 3 Except for adjusting the amount of buckwheat extract added to 0.8% of the staple food, the rest of the operation is the same as in Example 1.

[0044] Comparative Example 1 Except for the absence of any buckwheat extract, the raw materials and processing steps were exactly the same as in Example 1. The base spirit was distilled and stored for 12 months before testing.

[0045] Comparative Example 2 The base liquor was brewed using the same process as Comparative Example 1. The base liquor was then mixed with the same amount (equivalent to 0.5% of dry buckwheat matter) of the same batch of buckwheat extract as in Example 1, and the mixture was fully dissolved. After the base liquor was stored for 12 months, the EC content was tested.

[0046] Comparative Example 3 Fermentation was carried out using the exact same process as in Comparative Example 1. During the distillation process, an equal amount of buckwheat extract as in Example 1 was added to the bottom pot water of the still, and co-distilled with the steam. The base spirit was collected, stored for 12 months, and then tested.

[0047] Comparative Example 4 Fermentation was carried out using the exact same process as in Comparative Example 1. During the middle stage of fermentation, the fermentation pit was opened, and an equal amount of buckwheat extract (as in Example 1) diluted with a small amount of water was sprayed into the mash. After mixing thoroughly, the pit was resealed, and fermentation continued. Subsequent distillation and storage were the same as in Example 1.

[0048] Experimental detection methods and results 1. EC content detection Gas chromatography-mass spectrometry (GC-MS) was used for detection, referring to GB 5009.223-2014 "National Food Safety Standard - Determination of Ethyl Carbamate in Food". The results are shown in Table 1.

[0049] Table 1: EC content (μg / L) of base wines obtained from different examples and comparative examples

[0050] Results analysis: (1) The EC inhibition rate of the method of the present invention (Examples 1-3) reached more than 45%, which was significantly higher than that of all comparative examples.

[0051] (2) The EC inhibition rate of Comparative Example 2 (added to finished liquor) reached 44.90%, which is close to the inhibition rate (above 45%) of the embodiment of the present invention. However, this operation fundamentally changed the product attributes: according to the national beverage alcohol classification standard, after adding exogenous extracts to the finished liquor, the product no longer belongs to the category of "baijiu" but is classified as "blended liquor". At the same time, sensory evaluation showed that the liquor of Comparative Example 2 had a distinct buckwheat aroma, which differed from the traditional strong aroma style. This indicates that simply pursuing the EC inhibition rate without considering the product category attributes and flavor authenticity cannot meet the actual needs of strong aroma baijiu producers. In contrast, the embodiment of the present invention, while achieving the same or even higher inhibition rate, maintains the "baijiu" category attributes and traditional strong aroma style of the product, demonstrating the superiority of the technical solution.

[0052] (3) The inhibition rate of Comparative Example 3 (added during distillation) was about 11%. High-temperature distillation may cause some active ingredients to decompose, resulting in limited effect.

[0053] (4) The inhibition rate of Comparative Example 4 (added in the middle of fermentation) reached 33.56%, but it was significantly lower than that of the present invention. Furthermore, subsequent quality testing showed that its flavor was impaired (see Table 2), which further proves the criticality and non-obviousness of the timing of 'adding before fermentation' in the present invention.

[0054] 2. Detection of main flavor components The contents of the four major esters in the base wines obtained in each example and comparative example were determined by gas chromatography, and the results are shown in Table 2.

[0055] Table 2: Content of main flavor components (mg / L) in base wines obtained from different embodiments and comparative examples

[0056] Results analysis: The content and ratio of the four major esters in Examples 1-3 are basically the same as those in the blank control group (Comparative Example 1), indicating that the method of the present invention does not damage the main flavor of strong-aroma baijiu.

[0057] In Comparative Example 4 (added mid-fermentation), the contents of ethyl hexanoate and ethyl acetate decreased significantly, while the content of ethyl lactate increased, indicating that the mid-fermentation addition did indeed interfere with normal microbial metabolism, leading to flavor imbalance. Sensory evaluation results were consistent with this.

[0058] in conclusion Based on the above experimental results, the following conclusions can be drawn: (1) Buckwheat extract has the effect of inhibiting EC formation during the brewing process of strong-aroma baijiu. This inhibitory effect is closely related to the timing of addition: only by adding it before fermentation can the best inhibitory effect be achieved (inhibition rate >45%), and the fermentation environment and main flavor of strong-aroma baijiu be preserved.

[0059] (2) Although the addition of finished wine can achieve a certain EC inhibition (44.90%), it causes the product to fall into the category of "blended wine" and changes the flavor, which cannot meet the needs of strong-aroma baijiu producers to maintain the authenticity of their products.

[0060] (3) Adding during distillation and adding during the middle of fermentation either has limited effect (inhibition rate of 11.27% and 33.56%, respectively) or causes significant damage to flavor (adding during the middle of fermentation leads to a 66% decrease in ethyl hexanoate), further proving the non-obviousness of the "adding before fermentation" technical solution of this invention.

[0061] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims

1. A method for inhibiting the formation of ethyl carbamate in strong-aroma baijiu, characterized in that, Before fermentation in the brewing process of strong-aroma baijiu, buckwheat extract is added to the brewing materials. The amount of buckwheat extract added is 0.1%-1.0% of the weight of the staple grain, based on the dry matter of buckwheat.

2. The method according to claim 1, characterized in that, The amount of buckwheat extract added is 0.3%-0.8%.

3. The method according to claim 1, characterized in that, The buckwheat extract is prepared by the following method: buckwheat bran is pulverized to 40-60 mesh, extracted with an aqueous ethanol solution, filtered and concentrated to obtain a concentrated buckwheat extract or paste.

4. The method according to claim 3, characterized in that, Use a 50%-70% volume fraction of ethanol aqueous solution, with a material-to-liquid ratio of 1:6-1:12 kg / L, and extract at 50-70℃ for 1-3 hours.

5. The method according to claim 1, characterized in that, Before adding the buckwheat extract, dilute it with a small amount of water or low-alcohol liquor with an alcohol content of 25%-40% vol to 2-5 times its original volume to facilitate even spraying.

6. A brewing process for inhibiting the formation of ethyl carbamate in baijiu (Chinese liquor) from the source, characterized in that, Includes the following steps: (1) Preparation of buckwheat extract: Buckwheat bran was crushed to 40-60 mesh, extracted with ethanol aqueous solution, filtered and concentrated to obtain buckwheat extract concentrate or extract. (2) Processing of brewing raw materials: The main grains of strong-aroma baijiu are moistened, steamed and cooled according to traditional processes; (3) After the grain mash has been spread out and mixed with Daqu, before it is put into the cellar for fermentation, the buckwheat extract prepared in step (1) is added evenly to the mash. The amount of buckwheat extract added is 0.1%-1.0% of the weight of the staple grain, based on the dry matter of buckwheat. (4) Fermentation: The mash with added buckwheat extract is put into the cellar and fermented in the cellar according to the traditional process of strong aroma baijiu; (5) Distillation and storage: After fermentation, the base wine is taken out of the cellar and distilled and graded according to conventional processes. The resulting base wine is then stored in the warehouse.

7. The process according to claim 6, characterized in that, The main grains for strong-aroma baijiu include one or more of sorghum, rice, glutinous rice, wheat, and corn.

8. The process according to claim 6, characterized in that, In step (3), the buckwheat extract is added by diluting the extract and then mixing it evenly in the form of atomized spray to ensure that the active ingredients are evenly distributed in the mash.

9. The process according to claim 6, characterized in that, After aging for 12 months, the base liquor obtained showed an inhibition rate of over 45% against ethyl carbamate.

10. A strong-aroma type of baijiu, characterized in that, It is brewed using the process described in any one of claims 6-9.

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