A low-alcohol tea wine preparation method based on negative pressure low-temperature rotary evaporation

Abstract

The application discloses a kind of preparation methods of low-alcohol tea wine based on negative pressure low-temperature rotary evaporation, it is related to tea wine brewing technical field, specifically comprising the following steps: first, tea leaf or tea powder is mixed with water, and tea juice is obtained after leaching and filtering;Then active dry yeast and white granulated sugar are added to tea juice, and tea wine fermentation liquor is obtained after fermentation;Then tea wine fermentation liquor is mixed with base liquor, and the treated liquor is obtained after blending;The treated liquor is placed in rotary evaporation device for rotary evaporation, and low-alcohol concentrated liquor is obtained;Finally, low-alcohol concentrated liquor is filtered, cooled to room temperature, and then aseptically filled, to obtain low-alcohol tea wine;The method is evaporated by negative pressure low-temperature rotary evaporation, so that the boiling point of fermented tea wine is greatly reduced, and can be efficiently evaporated and removed, while water-soluble flavoring substances such as tea polyphenols, amino acids and tea polysaccharides, and heat-sensitive aroma components are retained in the concentrated liquor to the greatest extent due to their higher boiling points than the low-temperature fermentation temperature, avoiding flavor deterioration caused by high temperature in traditional distillation methods.

Description

Technical Field

[0001] This invention relates to the field of tea and wine brewing technology, specifically to a method for preparing low-alcohol tea and wine based on negative pressure low-temperature rotary evaporation. Background Technology

[0002] With increasing consumer awareness of health, the market demand for low-alcohol and low-sugar beverages is growing. Tea wine, as a unique beverage that blends the aroma of tea with the flavor of wine, possesses both the health benefits of tea and the mellow taste of wine, and has a promising market prospect. Traditional methods of preparing tea wine typically involve direct fermentation of tea extract or blending with base liquor. The former is difficult to precisely control the fermentation level, easily leading to high alcohol content or significant loss of tea aroma; the latter often masks the natural fragrance of tea due to the addition of high-proof base liquor, and ultimately makes it difficult to reduce the alcohol content to the ideal low-alcohol range.

[0003] Existing technologies for reducing alcohol content, such as vacuum distillation, membrane separation, and reverse osmosis, face numerous challenges when applied to tea and alcoholic beverages. While conventional vacuum distillation can remove alcohol, the operating temperature remains relatively high, easily leading to the significant volatilization and loss of heat-sensitive aroma components in tea, such as linalool and geraniol, thus disrupting the unique flavor profile of the tea and alcoholic beverage. Membrane separation and reverse osmosis technologies, although capable of operating at lower temperatures, suffer from problems such as membrane fouling, flux decline, limited selectivity, and high investment and operating costs. Furthermore, while low-temperature distillation techniques exist, they are primarily used in areas such as fruit juice and flavor extraction, and have not yet been effectively applied to the de-alcoholization and flavor preservation of tea and alcoholic beverages.

[0004] Therefore, there is an urgent need to propose a method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation, in order to solve the problems of high alcohol content and insufficient tea aroma and fermentation flavor in existing technologies caused by direct soaking or high-temperature distillation processes, and to achieve effective alcohol reduction. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation, so as to solve the problems of high alcohol content and insufficient tea aroma and fermentation flavor in tea wine caused by direct soaking or high-temperature distillation processes in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation, specifically including the following steps: S1. Tea extraction: Mix any one of the tea leaves or tea powder with water at a mass ratio of 1:8 to 15, extract at 50 to 65°C for 30 to 50 minutes, and then filter to obtain tea juice.

[0007] S2. Fermentation liquid preparation: Add 0.5%–1.5% active dry yeast and 5%–15% white sugar to the tea juice, and ferment at 22–26℃ for 6–8 days to obtain a tea wine fermentation liquid with an initial alcohol content of 8%–12% vol; the mass-volume ratio of active dry yeast to tea juice is 0.5%–1.5%; the mass-volume ratio of white sugar to tea juice is 5%–15%; among which, the active dry yeast for wine is a granular yeast product that has been industrially cultivated and dried. After rehydration and activation, it can quickly start and dominate the alcoholic fermentation process, and is often used in the brewing of fruit wine, tea wine, etc.

[0008] S3. Blending: Mix the tea wine fermentation liquid with the base wine at a volume ratio of 1 to 2:1 to obtain the wine liquid to be processed.

[0009] S4. Negative pressure low-temperature rotary evaporation treatment: The wine to be treated is placed in a rotary evaporator and rotary evaporation is carried out at 0.03-0.05 MPa and 32-42℃. Low-temperature heating is used to evaporate the alcohol and obtain low-alcohol concentrated wine. The endpoint of rotary evaporation is determined by real-time monitoring of the alcohol content in the condensate collector using a hydrometer or by monitoring the volume change of the remaining wine in the rotary evaporator flask; rotary evaporation is stopped when the alcohol content in the collected condensate drops below 2% vol or the volume of the wine to be processed decreases by 40% to 60%.

[0010] S5. Bottling: After filtering and cooling the low-alcohol concentrated liquor to room temperature, it is aseptically bottled to obtain a low-alcohol tea liquor with a final alcohol content of ≤10%vol.

[0011] Furthermore, in S1, the tea leaves are at least one of green tea, black tea, and oolong tea; the tea powder is at least one of green tea powder, black tea powder, white tea powder, and oolong tea powder. When using green tea, the extraction temperature is 55–60℃; when using black tea, the extraction temperature is 60–65℃; when using oolong tea, the extraction temperature is 50–55℃; when using green tea powder, the extraction temperature is 50–60℃; when using black tea powder, the extraction temperature is 60–70℃; when using oolong tea powder, the extraction temperature is 55–65℃; and when using white tea powder, the extraction temperature is 50–60℃.

[0012] Furthermore, in step S2, in addition to yeast and sugars, 0.05%–0.15% diammonium hydrogen phosphate and 0.1%–0.3% tartaric acid are added to regulate the fermentation environment. Diammonium hydrogen phosphate, as a yeast nutrient, provides crucial support for the fermentation process, directly supplementing the ammonium nitrogen and phosphorus elements most easily absorbed by yeast. This ensures rapid yeast population reproduction and maintains vigorous metabolic activity, effectively preventing slow fermentation initiation, incomplete fermentation, or the production of off-flavor substances such as hydrogen sulfide. This fundamentally guarantees fermentation efficiency and the final purity and alcohol conversion rate of the liquor. Tartaric acid regulates and stabilizes the fermentation environment, lowering the pH of the fermentation liquid to a slightly acidic range, thereby inhibiting the growth of unwanted microorganisms, optimizing yeast activity, and constructing a refreshing acidic framework for the tea liquor. Simultaneously, the addition of tartaric acid promotes the early crystallization of tartrate salts, improving the product's cold stability, preventing later precipitation, and ensuring comprehensive stability of the tea liquor in terms of flavor, microorganisms, and physical state.

[0013] Furthermore, the base liquor in S3 is a type of baijiu, rice wine, or sake with an alcohol content of 35% to 45% vol.

[0014] Furthermore, the rotary evaporation in S4 is carried out under segmented temperature control conditions, specifically including: the first stage is treated at 32-35°C for 30-60 minutes; the second stage is treated at 35-38°C for 30-60 minutes; the third stage is treated at 38-42°C for 20-40 minutes; and the pressure in each stage is kept constant at 0.03-0.05 MPa.

[0015] Furthermore, the rotational speed of the rotary evaporator in S4 is set to 80-120 rpm.

[0016] Furthermore, in step S5, a microporous membrane with a diameter of 0.22–0.45 μm is used for sterilization filtration.

[0017] Furthermore, the alcohol content of the low-alcohol tea wine ranges from 5% to 10% vol, and the tea polyphenol retention rate is ≥85%.

[0018] Furthermore, after step S4 and before step S5, step S4a is included: adding 0.5% to 2.0% by volume of tea volatile aroma compensation liquid to the low-alcohol concentrated wine, and stirring and mixing at a speed of 20 to 50 rpm for 5 to 15 minutes.

[0019] Furthermore, the volatile aroma compensation liquid of the tea is extracted from the same batch of tea as S1 using supercritical CO2 extraction, with an extraction pressure of 20-30 MPa and an extraction temperature of 40-50℃.

[0020] Compared with existing technologies, the method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation provided by the present invention has the following beneficial effects: (1) The present invention uses negative pressure low temperature rotary evaporation to significantly reduce the boiling point of fermented tea wine alcohol, which can be efficiently evaporated and removed. Most of the water-soluble flavor substances such as tea polyphenols, amino acids, and tea polysaccharides, as well as heat-sensitive aroma components, are retained to the maximum extent in the concentrated wine because their boiling points are higher than the low temperature fermentation temperature, thus avoiding the flavor deterioration caused by high temperature in traditional distillation methods.

[0021] (2) By setting a clear rotary distillation endpoint and combining it with a segmented temperature control strategy, the present invention achieves low alcohol content in tea wine, which is highly controllable and conducive to obtaining a final product with stable alcohol content and consistent flavor.

[0022] (3) The preparation method provided by the present invention has good process compatibility and strong adaptability. It is suitable for combinations of different types of tea and different base wines. By adjusting the extraction temperature, fermentation conditions and rotary evaporation parameters, low-alcohol tea wine products with different styles can be prepared.

[0023] (4) The preparation method provided by the present invention is simple to operate, easy to industrialize, has a continuous process flow, and is easy to achieve automated control and large-scale production. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0025] Figure 1 The present invention provides a flowchart of a method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Low-alcohol tea wine: generally refers to alcoholic beverages with an alcohol content between 1% vol and 15% vol, brewed or blended with tea as one of the main raw materials.

[0028] Tea extraction: The process of extracting the effective components of tea leaves, such as tea polyphenols, amino acids, and aroma substances, using water as a solvent at specific temperatures and times.

[0029] Blending: The process of mixing different components or flavors of alcoholic beverages, such as fermented wines and distilled spirits, in a certain proportion to achieve a balance of alcohol content, taste, and flavor.

[0030] Sensory evaluation: A method of analyzing and evaluating the quality characteristics of a product, such as its color, aroma, taste, and texture, through human senses such as sight, smell, taste, and touch.

[0031] Negative pressure low-temperature rotary evaporation is a core process that integrates the principles of pressure reduction, low temperature, and high-efficiency evaporation. By creating an environment below atmospheric pressure in a closed system, the boiling point of the liquid is significantly reduced, allowing the liquor to evaporate rapidly at a temperature far below the normal boiling point. The core advantage of this method is that it can minimize the damage and loss of heat-sensitive flavor substances in the liquor, such as tea polyphenols and volatile aroma components, caused by high temperatures. It achieves the preservation of the original flavor and nutritional components of the product while effectively reducing the alcohol content, making it a key technology for producing high-quality low-alcohol tea liquor.

[0032] Rotary evaporator: A rotary evaporator is a specialized device for implementing a low-temperature, negative-pressure rotary evaporation process. It mainly consists of an evaporation flask, a condenser, a collector, a water bath, and a vacuum system. Its working principle is as follows: The evaporation flask containing the liquid rotates at a constant speed under the drive of a motor, causing the liquid inside the flask to form a uniform thin film, thereby greatly increasing the evaporation surface area. At the same time, the system maintains a stable negative pressure environment through a vacuum pump, which, together with the precise and gentle heat source provided by the water bath, promotes the efficient evaporation of alcohol and water into vapor at low temperatures. The vapor is then cooled and liquefied by the condenser and flows into the collector, ultimately achieving the separation and concentration of the target components.

[0033] Supercritical CO2 extraction is a separation technique that uses carbon dioxide in a supercritical state as a solvent. Under specific high pressure and temperature conditions, CO2 reaches a supercritical state, which combines the high permeability of a gas with the high solubility of a liquid. This allows for the efficient and selective dissolution of target components, such as the volatile aroma in tea. Subsequently, by reducing the pressure or changing the temperature, the solubility of supercritical CO2 is significantly reduced, thereby separating the extracted target components completely and gently. The entire process is controllable and at a low temperature, which maximizes the protection of the activity and original flavor of heat-sensitive natural components.

[0034] Hydrometer: An instrument that indirectly and quickly determines the alcohol content of a liquid by measuring its density.

[0035] Tea polyphenol retention rate: This is a key indicator for measuring the degree to which the process protects tea polyphenols, the core functional component of tea. Using the standardized Folin-Ciocalteu colorimetric method, the concentration of tea polyphenols in samples at two key points before and after the process is accurately measured, and the retention percentage is calculated by simple calculation. The calculation formula is: (tea polyphenol content in the treated wine / tea polyphenol content in the tea juice or fermentation liquid) × 100%. The higher the retention rate, the milder the process conditions and the less damage to the beneficial components.

[0036] Maillard reaction: refers to a non-enzymatic browning reaction that is widely present in food processing. It is a series of complex reactions that occur when amino acids and reducing sugars are heated. Under improper high-temperature processing, it can produce aromas such as caramel and toast, but it can also generate off-flavors or even bitter substances, which can ruin the fresh flavor of tea or wine.

[0037] Example 1: Please see Figure 1 A method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation specifically includes the following steps: S1. Tea juice extraction: Weigh 100g of West Lake Longjing green tea, add 1.2L of pure water, and extract in a 55℃ water bath for 40 minutes. Filter with a 200-mesh filter cloth to obtain green tea juice.

[0038] S2. Preparation of fermentation liquid: Add 1% active dry yeast for wine, 10% white sugar, 0.1% diammonium hydrogen phosphate and 0.2% tartaric acid to green tea juice, stir well and ferment at 24℃ for 7 days to obtain green tea wine fermentation liquid with an initial alcohol content of 10% vol.

[0039] S3. Blending: Mix the fermented green tea wine liquid with light-aroma baijiu with an alcohol content of 40% vol at a volume ratio of 1.5:1 to obtain the wine liquid to be processed.

[0040] S4. Low-temperature rotary evaporation under negative pressure: The wine to be treated is injected into the evaporation flask of the rotary evaporator. Rotary evaporation is carried out under the conditions of absolute pressure of 0.04MPa, constant water bath temperature of 38℃, and rotation speed of 100rpm. The alcohol content of the liquid in the condensate collector is measured by a densitometer. Rotary evaporation is stopped when the alcohol content in the condensate collector drops to 1.5% vol, and low-alcohol concentrated wine is obtained.

[0041] S5. Bottling: The low-alcohol concentrated liquor is filtered through a 0.45μm microporous membrane, cooled to room temperature, and then aseptically bottled into brown glass bottles to obtain the finished low-alcohol green tea liquor. The alcohol content of the finished product is measured to be 8.5% vol, with a tea polyphenol retention rate of 92%. Sensory evaluation shows a fresh and elegant tea aroma and a harmonious body.

[0042] Example 2: Please see Figure 1 This embodiment provides a technical solution based on Embodiment 1: a method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation, specifically including the following steps: S1. Tea juice extraction: Weigh 100g of Qimen black tea powder, add 1.0L of pure water, extract in a 62℃ water bath for 35 minutes, and filter with a 200-mesh filter cloth to obtain black tea juice.

[0043] S2. Preparation of fermentation liquid: Add 1% active dry yeast for wine, 10% white sugar, 0.1% diammonium hydrogen phosphate and 0.2% tartaric acid to black tea juice, stir well and ferment at 24℃ for 7 days to obtain black tea wine fermentation liquid with an initial alcohol content of 11% vol.

[0044] S3. Blending: Mix the fermented black tea wine liquid with rice wine with an alcohol content of 38% vol at a volume ratio of 1:1 to obtain the wine liquid to be processed.

[0045] S4. Negative Pressure Low-Temperature Rotary Evaporation Treatment: The wine to be treated is injected into the evaporation flask of the rotary evaporator, and segmented temperature control is adopted: In the first stage, rotary evaporation is carried out for 50 minutes under the conditions of absolute pressure of 0.035MPa, constant water bath temperature of 34℃, and rotation speed of 100rpm; In the second stage, while keeping the pressure constant, the water bath temperature is raised to 37℃, and rotary evaporation is carried out for 40 minutes at a rotation speed of 100rpm; In the third stage, while keeping the pressure constant, the water bath temperature is raised to 40℃, and rotary evaporation is carried out for 30 minutes at a rotation speed of 100rpm; By monitoring the scale of the rotary evaporation flask in real time, rotary evaporation is stopped when the volume of the remaining wine is reduced to 50% of the initial volume, and low-alcohol concentrated wine is obtained.

[0046] S5. Bottling: The low-alcohol concentrated liquor is filtered through a 0.45μm microporous membrane, cooled to room temperature, and then aseptically bottled into brown glass bottles to obtain the finished low-alcohol black tea liquor. The resulting low-alcohol black tea liquor has an alcohol content of 9.2% vol, a tea polyphenol retention rate of 89%, and exhibits a distinct sweet aroma of black tea and a mellow aroma of rice wine, with a smooth and rounded taste.

[0047] Example 3: This embodiment provides a technical solution based on Embodiment 1: adding an aroma compensation step, specifically including the following steps: S1. Tea juice extraction: Weigh 100g of West Lake Longjing green tea, add 1.2L of pure water, and extract in a 55℃ water bath for 40 minutes. Filter with a 200-mesh filter cloth to obtain green tea juice.

[0048] S2. Preparation of fermentation liquid: Add 1% active dry yeast for wine, 10% white sugar, 0.1% diammonium hydrogen phosphate and 0.2% tartaric acid to green tea juice, stir well and ferment at 24℃ for 7 days to obtain green tea wine fermentation liquid with an initial alcohol content of 10% vol.

[0049] S3. Blending: Mix the fermented green tea wine liquid with light-aroma baijiu with an alcohol content of 40% vol at a volume ratio of 1.5:1 to obtain the wine liquid to be processed.

[0050] S4. Low-temperature rotary evaporation under negative pressure: The wine to be treated is injected into the evaporation flask of the rotary evaporator. Rotary evaporation is carried out under the conditions of absolute pressure of 0.04MPa, constant water bath temperature of 38℃, and rotation speed of 100rpm. The alcohol content of the liquid in the condensate collector is measured by a densitometer. Rotary evaporation is stopped when the alcohol content in the condensate collector drops to 1.5% vol, and low-alcohol concentrated wine is obtained.

[0051] Aroma components were extracted from West Lake Longjing green tea from the same batch as the extraction using a supercritical CO2 extraction device: the extraction pressure was set at 25 MPa, the extraction temperature at 45℃, the separation pressure at 6 MPa, and the separation temperature at 35℃, to obtain a tea volatile aroma compensation liquid; under stirring conditions at 30 rpm, the tea volatile aroma compensation liquid was slowly added to the above low-alcohol concentrated liquor, the amount of aroma compensation liquid added was 1.2% (vol / vol) of the total volume of the low-alcohol concentrated liquor, and the mixture was stirred and mixed for 10 minutes to allow the aroma to be evenly integrated.

[0052] S5. Bottling: The low-alcohol concentrated liquor is filtered through a 0.45μm microporous membrane, cooled to room temperature, and then aseptically bottled into brown glass bottles to obtain the finished low-alcohol green tea liquor. The alcohol content of the finished product is 8.5% vol, with a tea polyphenol retention rate of 95%. Sensory evaluation shows that its green tea aroma intensity, freshness, and persistence are significantly better than the control sample without aroma compensation liquid, with an overall flavor score increase of 25%. The tea aroma is fresh and elegant, and the liquor body is harmonious.

[0053] This embodiment addresses the unavoidable slight aroma loss during rotary distillation by introducing a supercritical CO2 extraction solution to compensate for the volatile aroma loss of tea. This extraction condition is mild and highly enriches the natural top notes of the tea. Adding this solution back to the low-alcohol concentrated liquor precisely compensates for aroma loss, enhancing the complexity and fullness of the tea aroma.

[0054] Comparative Example 1: Compared with Example 1, this comparative example uses conventional atmospheric distillation to reduce alcohol content. The preparation method specifically includes the following steps: S1. Tea juice extraction: Weigh 100g of West Lake Longjing green tea, add 1.2L of pure water, and extract in a 55℃ water bath for 40 minutes. Filter with a 200-mesh filter cloth to obtain green tea juice.

[0055] S2. Preparation of fermentation liquid: Add 1% active dry yeast for wine, 10% white sugar, 0.1% diammonium hydrogen phosphate and 0.2% tartaric acid to green tea juice, stir well and ferment at 24℃ for 7 days to obtain green tea wine fermentation liquid with an initial alcohol content of 10% vol.

[0056] S3. Blending: Mix the fermented green tea wine liquid with light-aroma baijiu with an alcohol content of 40% vol at a volume ratio of 1.5:1 to obtain the wine liquid to be processed.

[0057] S4. Conventional distillation: The wine to be treated is poured into a distillation flask and distilled at normal pressure and a constant water bath temperature of 85°C. The distillate is collected until the volume of the residual liquid in the distillation flask is reduced by 50%. Distillation is then stopped, and the concentrated wine is obtained after the residual liquid is cooled.

[0058] S5. Bottling: The concentrated liquor is filtered through a 0.45μm microporous membrane, cooled to room temperature, and then aseptically bottled into brown glass bottles to obtain the low-alcohol green tea liquor. The alcohol content of the finished product was measured to be 8% vol, but sensory evaluation showed an extremely weak tea aroma, with a distinct "cooked" and burnt taste. The tea polyphenol retention rate was only 65%, indicating a severely degraded flavor.

[0059] Comparative Example 2: Compared with Example 1, this comparative example does not involve rotary evaporation to reduce alcohol content; instead, it achieves low alcohol content solely through dilution. The preparation method specifically includes the following steps: S1. Tea juice extraction: Weigh 100g of West Lake Longjing green tea, add 1.2L of pure water, and extract in a 55℃ water bath for 40 minutes. Filter with a 200-mesh filter cloth to obtain green tea juice.

[0060] S2. Preparation of fermentation liquid: Add 1% active dry yeast for wine, 10% white sugar, 0.1% diammonium hydrogen phosphate and 0.2% tartaric acid to green tea juice, stir well and ferment at 24℃ for 7 days to obtain green tea wine fermentation liquid with an initial alcohol content of 10% vol.

[0061] S3. Blending: The fermented green tea liquor was directly mixed with purified water to adjust the alcohol content to 8.5% vol. The liquor was then filtered through a 0.45μm microporous membrane and bottled in brown glass bottles under aseptic conditions to obtain low-alcohol green tea liquor. The alcohol content of the finished product was measured to be 8.5% vol, and the tea polyphenol retention rate was 75%. However, the liquor was thin, and both the tea aroma and the liquor flavor were significantly diluted. The taste was watery and the coordination was poor. Compared with the product of Example 1, the flavor intensity was insufficient.

[0062] Comparative Example 3: Compared with Example 1, the rotary evaporation conditions in this comparative example are outside the range (rotary evaporation temperature 32-42℃, pressure 0.03-0.05MPa), and the preparation method specifically includes the following steps: S1. Tea juice extraction: Weigh 100g of West Lake Longjing green tea, add 1.2L of pure water, and extract in a 55℃ water bath for 40 minutes. Filter with a 200-mesh filter cloth to obtain green tea juice.

[0063] S2. Preparation of fermentation liquid: Add 1% active dry yeast for wine, 10% white sugar, 0.1% diammonium hydrogen phosphate and 0.2% tartaric acid to green tea juice, stir well and ferment at 24℃ for 7 days to obtain green tea wine fermentation liquid with an initial alcohol content of 10% vol.

[0064] S3. Blending: Mix the fermented green tea wine liquid with light-aroma baijiu with an alcohol content of 40% vol at a volume ratio of 1.5:1 to obtain the wine liquid to be processed.

[0065] S4. Rotary evaporation: The wine to be treated is injected into the evaporation flask of the rotary evaporator. Rotary evaporation is carried out under the conditions of absolute pressure of 0.08MPa, constant water bath temperature of 48℃, and rotation speed of 100rpm. The alcohol content of the liquid in the condensate collector is measured by a densitometer. Rotary evaporation is stopped when the alcohol content in the condensate collector drops to 1.5% vol, and low-alcohol concentrated wine is obtained.

[0066] S5. Bottling: The low-alcohol concentrated liquor was filtered through a 0.45μm microporous membrane, cooled to room temperature, and then aseptically bottled into brown glass bottles to obtain the finished low-alcohol green tea liquor. The alcohol content of the finished product was measured to be 8.3% vol, but the tea aroma was significantly lost, the tea polyphenol retention rate was 80%, and trace amounts of off-flavor substances produced by the Maillard reaction were detected. The taste was not as pure as in Example 1.

[0067] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation, characterized in that, Specifically, the following steps are included: S1. Tea juice extraction: Mix any one of the tea leaves or tea powder with water at a mass ratio of 1:8 to 15, extract at 50 to 65°C for 30 to 50 minutes, and filter to obtain tea juice; S2. Preparation of fermentation liquid: Add 0.5% to 1.5% active dry yeast and 5% to 15% white sugar to the tea juice, and ferment at 22 to 26℃ for 6 to 8 days to obtain tea wine fermentation liquid; S3. Blending: Mix the tea wine fermentation liquid with the base wine at a volume ratio of 1 to 2:1 to obtain the wine liquid to be processed. S4. Negative pressure low-temperature rotary evaporation treatment: The wine to be treated is placed in a rotary evaporator and rotary evaporated at 0.03-0.05 MPa and 32-42℃ to obtain low-alcohol concentrated wine. S5. Bottling: After filtering and cooling the low-alcohol concentrated liquor to room temperature, it is aseptically bottled to obtain a low-alcohol tea liquor with a final alcohol content of ≤10% vol.

2. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 1, characterized in that, The tea leaves in S1 are at least one of green tea, black tea, and oolong tea; the tea powder is at least one of green tea powder, black tea powder, white tea powder, and oolong tea powder.

3. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 1, characterized in that, In S2, in addition to yeast and sugars, 0.05% to 0.15% diammonium hydrogen phosphate and 0.1% to 0.3% tartaric acid are also added to regulate the fermentation environment.

4. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 1, characterized in that, The base liquor in S3 is a type of baijiu, rice wine, or sake with an alcohol content of 35% to 45% vol.

5. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 1, characterized in that, The rotary evaporation in S4 is carried out under segmented temperature control, specifically including: the first stage is treated at 32-35℃ for 30-60 minutes; the second stage is treated at 35-38℃ for 30-60 minutes; the third stage is treated at 38-42℃ for 20-40 minutes; the pressure in each stage is kept constant at 0.03-0.05MPa.

6. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 1, characterized in that, The rotational speed of the rotary evaporator in S4 is set to 80-120 rpm.

7. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 1, characterized in that, In the S5 filtration process, a microporous membrane with a diameter of 0.22–0.45 μm is used for sterilization filtration.

8. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 1, characterized in that, The alcohol content of the low-alcohol tea wine ranges from 5% to 10% vol, and the tea polyphenol retention rate is ≥85%.

9. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 1, characterized in that, After step S4 and before step S5, step S4a is also included: adding 0.5% to 2.0% by volume of tea volatile aroma compensation liquid to the low-alcohol concentrated wine, and stirring and mixing at a speed of 20 to 50 rpm for 5 to 15 minutes.

10. The method for preparing low-alcohol tea wine based on negative pressure low-temperature rotary evaporation according to claim 9, characterized in that, The volatile aroma compensation liquid for tea was extracted from the same batch of tea as S1 using supercritical CO2 extraction at an extraction pressure of 20–30 MPa and an extraction temperature of 40–50 °C.

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