Method for preparing low-alcohol-content baijiu through cooperation of gradient alcohol reduction and freezing filtration

Abstract

The invention relates to the technical field of white spirit brewing, and particularly provides a low-alcohol white spirit preparation method with synergism of gradient degree reduction and freezing filtration, which comprises the following steps: gradient degree reduction: carrying out gradient degree reduction treatment of at least three stages on low-alcohol white spirit base liquor with the alcoholic strength of 55-70% vol, so that the final alcoholic strength is reduced to 35-42% vol; and carrying out temperature synergistic freezing treatment: after each degree reduction stage is completed, cooling the wine body to a specified temperature interval of-3 DEG C to-10 DEG C, and carrying out low-temperature standing and filtering. According to the method, the degree reduction range is reduced by stages, the standing time is prolonged, esters are gradually migrated to a colloid phase, and irreversible precipitation is reduced. The freezing temperature is matched according to the ester solubility threshold value corresponding to the alcoholic strength in each stage, and flavor loss caused by excessive low temperature is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of liquor brewing, and in particular to a method for preparing low-alcohol liquor by synergistic gradient alcohol reduction and freeze filtration. Background Art

[0002] Traditional low-alcohol liquor production involves a single-step reduction in alcohol content (e.g., dilution from 65% vol directly to 38% vol). This results in a sudden drop in solubility and the precipitation of esters (such as ethyl acetate and ethyl hexanoate). These precipitates must be removed through activated carbon adsorption or cryogenic filtration, resulting in flavor loss. Furthermore, the low-alcohol environment accelerates the hydrolysis of esters, leading to a decline in aroma.

[0003] In the prior art, although single-temperature freeze filtration (such as -15°C) can remove some impurities, the low temperature causes flavor esters (such as ethyl lactate and ethyl acetate) to coprecipitate with impurities, which also causes irreversible flavor loss.

[0004] Therefore, providing a method for reducing the alcohol content to maximize the retention of flavor substances and inhibit hydrolysis has become one of the technical problems that need to be solved urgently. Summary of the Invention

[0005] In view of this, the present invention proposes a method for preparing low-alcohol liquor by synergistically combining gradient alcohol reduction and freeze filtration.

[0006] The technical solution of the present invention is achieved as follows: The present invention provides a method for preparing low-alcohol liquor by combining gradient alcohol reduction with freeze filtration, comprising the following steps:

[0007] (1) Gradient alcohol reduction: The base liquor with an alcohol content of 55-70% vol is subjected to at least three stages of gradient alcohol reduction treatment to reduce the final alcohol content to 35-42% vol;

[0008] (2) Temperature-coordinated freezing treatment: After each stage of temperature reduction, the wine is cooled to a specified temperature range of -3°C to -10°C for low-temperature standing and filtration.

[0009] By adopting a process that combines gradient alcohol reduction with freeze filtration, the reduction of alcohol content and temperature control are combined in stages to achieve dynamic coordinated processing. This ensures that only the impurities that are most easily precipitated at the current alcohol content and temperature are removed at each stage, maximizing the retention of flavor substances and inhibiting hydrolysis, effectively enhancing the flavor of low-alcohol liquor.

[0010] In some embodiments, the number of stages of the gradient reduction is 3-4 stages, and the reduction amplitude in each stage decreases step by step, wherein: the reduction amplitude in the first stage is 10-18% vol, and the standing time is 18-30h; the reduction amplitude in the last stage is ≤5% vol, and the standing time is 10-15h.

[0011] In some embodiments, the gradient reduction process is:

[0012] Stage 1: Reduce the alcohol content of the base wine to 50±2% vol, let it stand for 22-26 hours, then cool it to -6℃ to -4℃ and filter it;

[0013] Stage 2: Continue to reduce the concentration to 42±2% vol, let it stand for 16-20 hours, then cool to -9℃ to -7℃ and filter;

[0014] The third stage: continue to reduce the concentration to 38±2% vol, let it stand for 10-14 hours, then cool it to -11℃ to -9℃ and filter.

[0015] After each alcohol reduction, it enters the corresponding low-temperature filtration, using the dual effects of decreased alcohol content → decreased ester solubility and decreased temperature → triggered by the freezing point of impurities to accurately locate the window for precipitate formation.

[0016] The final freezing temperature is adjusted from the current conventional -15°C to around -10°C to prevent ultra-low temperatures from causing some flavor esters (such as ethyl lactate, with a freezing point of -20°C) to co-precipitate with impurities. At the same time, the freezing temperature is matched according to the ester solubility threshold corresponding to each stage of alcohol content. The freezing temperature for each stage is set near the freezing point of the main target impurities at the current alcohol content, preserving low-freezing-point flavor components and avoiding flavor loss caused by excessive low temperatures. The flavor ester retention rate is increased by 8%-12%.

[0017] By gradually reducing the alcohol reduction rate and extending the standing time, the esters gradually migrate to the colloidal phase, reducing irreversible precipitation. Traditional filtration methods involve cooling the wine to around -15°C and immediately performing diatomaceous earth filtration to intercept the precipitated precipitate without requiring a low-temperature standing time. This method, by extending the low-temperature standing time, allows the esters to gradually migrate to the colloidal phase, reducing irreversible precipitation.

[0018] In some embodiments, diatomaceous earth filtration is used for the first stage of filtration, and membrane filtration is used for subsequent stages of filtration after the first stage, with the accuracy of membrane filtration gradually increasing from 1 μm to 0.45 μm.

[0019] In some embodiments, the resting temperature is ≤ -5°C.

[0020] The entire post-alcohol reduction resting process is carried out at a low temperature (≤-5°C), reducing the hydrolysis reaction rate to less than 1 / 10 of that at room temperature (25°C) (k for ethyl hexanoate = 0.001 / day, k at 25°C = 0.01 / day). Furthermore, liquor blended using the gradient freezing process experiences less hydrolysis during later storage than conventional methods. This process can inhibit hydrolysis of low-alcohol liquor during its shelf life, improving the product's market acceptance.

[0021] In some embodiments, the specific process of the gradient reduction is:

[0022] In the first stage, the base wine (65% vol) is reduced to 50% vol, allowed to stand at -5°C for 24 hours, and then filtered through diatomaceous earth at -6°C to -4°C.

[0023] In the second stage, the alcohol content of the wine was reduced from 50% vol to 42% vol, allowed to stand at -5°C for 18 h, and then filtered through a 1 μm membrane at -9°C to -7°C.

[0024] In the third stage, the alcohol content of the wine was reduced from 42% vol to 38% vol, allowed to stand at -5°C for 18 h, and then filtered through a 0.45 μm membrane at -11°C to -9°C.

[0025] In some embodiments, the base liquor includes strong-flavor type, light-flavor type and sauce-flavor type.

[0026] The second aspect of the present invention also provides a low-alcohol liquor prepared based on the above preparation method.

[0027] In some embodiments, the final low-alcohol liquor prepared by the above method meets the following conditions:

[0028] Turbidity ≤ 0.1 NTU;

[0029] Total ester retention rate ≥90%;

[0030] After 12 months of storage, the total ester hydrolysis rate is ≤-6%.

[0031] The present invention has the following beneficial effects compared to the prior art:

[0032] The present invention reduces the alcohol reduction range in stages and prolongs the standing time, so that the esters gradually migrate to the colloidal phase and reduce irreversible precipitation. The freezing temperature is matched according to the ester solubility threshold corresponding to the alcohol content in each stage to avoid flavor loss due to excessive low temperature. The entire standing process after the alcohol reduction is carried out at low temperature (≤-5°C), so that the hydrolysis reaction rate drops to less than 1 / 10 of that at room temperature (ethyl hexanoate k = 0.001 / day, k = 0.01 / day at 25°C). Diatomaceous earth filtration is used in the first stage, and only membrane filtration is used in the second and third stages, which can avoid the loss of flavor substances in the current one-time reduction to 35 degrees, then cooling to -15°C and filtering through diatomaceous earth. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0035] Unless otherwise specified, the methods used in the following examples are conventional methods. The materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, unless otherwise specified, and can be obtained commercially by those skilled in the art.

[0036] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range. In the present specification and claims, range definitions may be combined and / or interchanged, and if not otherwise stated, such ranges include all subranges contained therein.

[0037] Example 1.

[0038] This embodiment provides a method for reducing the alcohol content of Luzhou-flavor liquor (65% vol base liquor)

[0039] 1. Raw materials: 65% vol Luzhou-flavor base wine (total esters 4.8 g / L, ethyl hexanoate 2.6 g / L).

[0040] 2. Gradient reduction and filtration process:

[0041] Stage 1: 65% vol → 50% vol (30 L water / 100 L base wine), cooled to -5°C and allowed to stand for 24 hours, then filtered through diatomaceous earth (10 μm) at -5°C;

[0042] Stage 2: Maintain at -5°C, 50% vol → 42% vol (add 19 L of water per 100 L of wine), keep at -5°C for 18 hours, cool to -8°C and filter with a membrane (1 μm);

[0043] The third stage: maintain -8℃, 42% vol→38% vol (add 10.5L water / 100L wine), maintain -8℃, let stand for 12h, then cool to -10℃, and filter with membrane (0.45μm).

[0044] Comparative Example 1

[0045] This comparative example provides a method for reducing the alcohol content of Luzhou-flavor liquor (65% vol base liquor) using a traditional process. Raw materials: 65% vol Luzhou-flavor base liquor (total esters 4.8 g / L, ethyl hexanoate 2.6 g / L)

[0046] Directly reduce the alcohol content to 38% vol (add 72.5 L water / 100 L base wine), let it stand at 25°C for 24 hours, then cool it to -15°C, keep it warm for 24 hours, filter it through diatomaceous earth (10 μm) once at -15°C, and can it after reheating.

[0047] Comparing the reduced-alcohol liquor obtained in Example 1 and Comparative Example 1, the results shown in the following table were obtained:

[0048]

[0049] In order to further verify the flavor changes during storage, samples were observed for one year and sensory evaluations were conducted regularly to observe the flavor changes, as shown in the following table:

[0050]

[0051] Note: The above comments are comprehensive comments from 8 national-level liquor judges and 4 national first-level sommeliers.

[0052] It can be seen that after one year of storage, the 38-proof Luzhou-flavor liquor prepared by the traditional method was slightly sour and had a slightly watery aftertaste according to professional evaluation. However, the 38-proof Luzhou-flavor liquor prepared by the method of the present invention had no obvious sour or watery after one year of storage, and had a smooth and sweet body. This shows that the 38-proof Luzhou-flavor liquor prepared by the method of the present invention has significantly better body quality than the traditional method after one year of storage.

[0053] The wine was tracked and monitored for one year to observe changes in its physical and chemical indicators such as total acid, total esters, and total chromatographic data. The results are shown in the following table:

[0054] Comparative example 1-0 months Comparative example 1-12 months Increase Example 1-0 month Example 1-12 months Increase Alcohol content 38.2 38.1 -0.3％ 38.2 38.1 -0.3％ Total acid (g / L) 0.97 1.15 18.6％ 1.12 1.23 9.8％ Total esters (g / L) 2.25 1.95 -13.3％ 2.41 2.33 -3.3％ Ethyl hexanoate 123.5 108.7 -12.0％ 129.7 123.8 -4.5％ Ethyl lactate 68.9 59.8 -13.2％ 71.2 67.9 -4.7％ Ethyl acetate 67.8 58.6 -13.6％ 71.2 67.8 -4.8％ Ethyl butyrate 18.6 15.9 -14.5％ 19.2 18.2 -5.4％ Methanol 11.2 12.1 8.0％ 11.9 12.1 1.3％ n-Propanol 25.3 26.4 4.3％ 26.3 26.1 -0.6％ sec-Butanol 3.3 4.0 21.2％ 3.9 3.3 -15.0％ Isobutanol 10.6 10.7 0.9％ 10.9 11.2 2.8％ Acetal 100.0 108.7 8.7％ 99.5 100.2 0.7％ n-Butanol 2.2 2.3 4.5％ 2.1 2.2 2.4％

[0055] It can be seen that after one year of storage, the increase in total acid, the decrease in total esters, and the decrease in the four major esters (ethyl caproate, ethyl lactate, ethyl acetate, and ethyl butyrate) of the 38-degree Luzhou-flavor liquor prepared by the method of the present invention (Example 1) are smaller than those of the traditional method (Comparative Example 1), indicating that the method of the present invention can inhibit the hydrolysis of esters in low-alcohol Luzhou-flavor liquor during the shelf life.

[0056] Example 2

[0057] This embodiment provides a method for reducing the alcohol content of a light-flavor liquor (65% vol base liquor)

[0058] 1. Raw materials: 65% vol light-fragrance base wine (total ester 3.2 g / L, ethyl acetate 1.8 g / L, ethyl lactate 0.9 g / L).

[0059] 2. Gradient reduction and filtration process:

[0060] Stage 1: 65% vol → 50% vol (30 L water / 100 L base wine), cooled to -5°C and allowed to stand for 24 hours, then filtered through diatomaceous earth (10 μm) at -5°C;

[0061] Stage 2: Maintain at -5°C, 50% vol → 42% vol (add 19 L of water per 100 L of wine), keep at -5°C for 18 hours, cool to -7°C and filter with a membrane (1 μm);

[0062] The third stage: maintain at -7℃ 42% vol→38% vol (add 10.5L water / 100L wine), maintain at -8℃ for 15h, then cool to -10℃, and filter with membrane (0.45μm).

[0063] Comparative Example 2

[0064] In this comparative example, based on comparative example 1, the base wine is replaced with 65% vol light-fragrance base wine (total ester 3.2 g / L, ethyl acetate 1.8 g / L, ethyl lactate 0.9 g / L), and other conditions remain unchanged.

[0065] The above Example 2 and Comparative Example 2 were tested for indicators, and the results shown in the following table were obtained:

[0066]

[0067] In order to verify the flavor changes of the light-fragrance liquor produced by the invention process during storage, the samples of Example 2 and Comparative Example 2 were observed for one year, and sensory evaluation was carried out regularly to observe the flavor changes, as shown in the following table:

[0068]

[0069] Note: The above comments are comprehensive comments from 8 national-level liquor judges and 4 national first-level sommeliers.

[0070] It can be seen that the 38-degree fragrant liquor prepared by the traditional method is slightly sour and slightly watery after storage for one year in professional evaluation, while the 38-degree fragrant liquor prepared by the method of the present invention has no obvious sourness or watery taste after storage for one year, and the liquor is mellow and sweet. This shows that the 38-degree fragrant liquor prepared by the method of the present invention has significantly better liquor quality than the traditional method after storage for one year.

[0071] The wines of Example 2 and Comparative Example 2 were subjected to a one-year follow-up test to observe changes in their physical and chemical indicators such as total acid, total esters, and chromatographic data, as shown in the following table:

[0072] Conventional process-0 months Conventional process-12 months Increase This process - 0 months This process - December Increase Alcohol content 38.2 38.1 -0.3％ 38.2 38.1 -0.3％ Total acid (g / L) 0.67 0.80 19.4％ 0.78 0.86 10.3％ Total esters (g / L) 1.54 1.32 -14.3％ 1.84 1.75 -4.9％ Ethyl acetate 117.1 101.9 -13.0％ 121.5 114.3 -5.9％ Ethyl lactate 67.7 58.9 -13.0％ 78.5 74.4 -5.2％ Ethyl butyrate 0.7 0.6 -13.0％ 0.9 0.8 -11.1％ acetaldehyde 57.7 59.3 2.7％ 62.6 65.3 4.3％ Methanol 6.7 6.4 -4.8％ 7.0 6.8 -2.9％ n-Propanol 36.4 35.8 -1.7％ 39.9 38.9 -2.5％ sec-Butanol 9.3 9.1 -1.9％ 9.3 9.4 1.1％ Isobutanol 21.6 21.2 -2.0％ 21.3 21.1 -0.9％ Acetal 10.7 12.8 20.1％ 12.2 13.8 13.1％ n-Butanol 0.6 0.5 -20.8％ 0.8 0.9 12.5％ Isoamyl alcohol 60.9 61.1 0.3％ 60.7 59.6 -1.8％

[0073] It can be seen that after one year of storage, the increase in total acid, the decrease in total ester, and the decrease in skeleton flavor components (ethyl acetate, ethyl lactate) of the 38-degree light-fragrance liquor prepared by the method of the present invention are smaller than those prepared by the traditional method, indicating that the method of the present invention can inhibit the hydrolysis of esters in low-alcohol light-fragrance liquor during the shelf life.

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

Claims

1. A method for preparing low-alcohol liquor by combining gradient alcohol reduction with freeze filtration, characterized in that: The steps include: (1) Gradient alcohol reduction: The base liquor with an alcohol content of 55-70% vol is subjected to at least three stages of gradient alcohol reduction treatment to reduce the final alcohol content to 35-42% vol; (2) Temperature-coordinated freezing treatment: After each stage of temperature reduction, the wine is cooled to a specified temperature range of -3°C to -10°C for low-temperature standing and filtration.

2. The method for preparing low-alcohol liquor by combining gradient alcohol reduction with freeze filtration according to claim 1, characterized in that: The number of stages of the gradient reduction is 3-4 stages, and the reduction amplitude in each stage decreases step by step, wherein: the reduction amplitude in the first stage is 10-18% vol, and the standing time is 18-30h; the reduction amplitude in the last stage is ≤5% vol, and the standing time is 10-15h.

3. The method for preparing low-alcohol liquor by combining gradient alcohol reduction with freeze filtration according to claim 1, wherein: The process of gradient reduction is as follows: Stage 1: Reduce the alcohol content of the base wine to 50±2% vol, let it stand for 22-26 hours, then cool it to -6℃ to -4℃ and filter it; Stage 2: Continue to reduce the concentration to 42±2% vol, let it stand for 16-20 hours, then cool to -9℃ to -7℃ and filter; The third stage: continue to reduce the concentration to 38±2% vol, let it stand for 10-14 hours, then cool it to -11℃ to -9℃ and filter.

4. The method for preparing low-alcohol liquor by combining gradient alcohol reduction with freeze filtration according to claim 1, wherein: The first stage of filtration uses diatomaceous earth filtration, and subsequent stages of filtration after the first stage use membrane filtration. The accuracy of membrane filtration is gradually improved from 1μm to 0.45μm.

5. The method for preparing low-alcohol liquor by combining gradient alcohol reduction with freeze filtration according to claim 1, wherein: Standing temperature ≤-5℃.

6. The method for preparing low-alcohol liquor by combining gradient alcohol reduction with freeze filtration according to claim 1, wherein: The process of gradient reduction is as follows: In the first stage, the base wine (65% vol) is reduced to 50% vol, allowed to stand at -5°C for 24 hours, and then filtered through diatomaceous earth at -6°C to -4°C. In the second stage, the alcohol content of the wine was reduced from 50% vol to 42% vol, allowed to stand at -5°C for 18 h, and then filtered through a 1 μm membrane at -9°C to -7°C. In the third stage, the alcohol content of the wine was reduced from 42% vol to 38% vol, allowed to stand at -5°C for 18 h, and then filtered through a 0.45 μm membrane at -11°C to -9°C.

7. The method for preparing low-alcohol liquor by combining gradient alcohol reduction with freeze filtration according to claim 1, wherein: The base liquor includes strong-flavor type, light-flavor type and sauce-flavor type.

8. A low-alcohol liquor, characterized in that: The compound is prepared by the preparation method described in any one of claims 1 to 7.

Images