Black tea with high gamma-aminobutyric acid content and preparation method thereof

Abstract

The invention discloses black tea with high gamma-aminobutyric acid content and a preparation method thereof, and relates to the technical field of tea processing. According to the method, tea waste is reduced, fresh tea leaves damaged by brown spot (white spot) are efficiently utilized, waste of tea resources is reduced, and economic loss is avoided; the process disclosed by the invention can be used for effectively removing bitter taste, which is harmed by brown spot, in the tea leaves, so that the final black tea product is mellower in mouth feel, and the lasting feeling of the bitter taste on tongue roots and throats is avoided; according to the process disclosed by the invention, the high content of gamma-aminobutyric acid is effectively reserved, so that the tea leaves not only have the functions of improving health, such as calming and reducing blood pressure, but also can meet the requirements of consumers on the quality of the tea leaves.

Description

Technical Field

[0001] This invention relates to the field of tea processing technology, specifically to a high-γ-aminobutyric acid (GABA) black tea and its preparation method. Background Technology

[0002] High-altitude mountainous areas are often shrouded in mist and fog, with abundant diffused light and little direct sunlight, which matches the warm and humid climate characteristics of tea trees, creating an excellent growing environment and fostering superior quality. However, at the same time, this low-temperature and high-humidity ecological environment in high-altitude tea regions also provides a favorable microclimate for the growth, reproduction, and spread of various pathogens.

[0003] Tea red spot disease (also known as white spot disease) is a fungal disease caused by low temperatures and high humidity. It mainly affects the tender leaves and new shoots of tea trees, but can also occur in mature leaves and petioles. It is a common foliar disease in high-altitude tea-growing areas. Tea leaves affected by red spot disease (white spot disease) show dark brown to purplish-brown spots with scattered black dots in the center. Finished tea made from these diseased leaves has a mottled color and an extremely strong, lingering bitter taste that adheres to the back of the tongue and throat. In practice, these diseased leaves must be discarded, or, after implementing disease control measures, unaffected leaves are harvested and processed into healthy tea leaves.

[0004] Therefore, the occurrence and prevalence of tea plantation red spot disease (white spot disease) seriously affects the quality and yield of tea, hindering the production and development of famous and high-quality teas in high-mountain tea-producing areas.

[0005] Analysis revealed that although black tea made from fresh tea leaves damaged by red star disease (white star disease) and processed through low-temperature, long-term withering has a more intense and lasting bitter taste than normal finished tea, this type of tea has a high content of γ-aminobutyric acid (GABA), exceeding the required GABA content.

[0006] Gamma-aminobutyric acid (GABA) has sedative, hypnotic, anticonvulsant, and blood pressure-lowering physiological effects.

[0007] However, under current technology, there is a lack of a method to debitter high-γ-aminobutyric acid black tea so that it can be consumed;

[0008] Therefore, finding a suitable method to remove bitterness can produce high-γ-aminobutyric acid (GABA) black tea, which can effectively improve the quality of black tea made from fresh tea leaves damaged by red spot disease (white spot disease) and promote a solution for the high-value utilization of fresh tea leaves damaged by red spot disease (white spot disease). Summary of the Invention

[0009] The purpose of this invention is to provide a high-γ-aminobutyric acid (GABA) black tea and its preparation method, so as to solve the technical problems mentioned in the background art.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a method for producing high-γ-aminobutyric acid (GABA) black tea, comprising at least the following steps:

[0011] S1: Collect fresh tea leaves infected with red spot disease (white spot disease) to prepare raw black tea;

[0012] S1.1: Collect fresh tea leaves that are susceptible to red spot disease (white spot disease);

[0013] S1.2: The collected fresh tea leaves are withered in an indoor withering trough to obtain withered leaves;

[0014] S1.3: The withered leaves are rolled using a tea rolling machine to obtain rolled leaves;

[0015] S1.4: Ferment the rolled leaves to obtain fermented leaves. The fermentation time is 2-4 hours, the temperature is 28℃-32℃, and the humidity is 90% or higher.

[0016] S1.5: Perform initial drying by quickly drying the fermented leaves in a dryer at 110~120℃ for 8 to 15 minutes. After initial drying, the moisture content should be around 35~45%.

[0017] S1.7: Cool down, let the semi-finished product that has just been dried cool to room temperature;

[0018] S1.8: The semi-finished product, which has been cooled to room temperature, is dried in a dryer at 80℃~90℃ until the moisture content is reduced to 6%, thus obtaining raw black tea.

[0019] S2: Debittering black tea with supercritical CO2. The raw material for supercritical CO2 debittering can be either the raw black tea that has been fully processed in S1.7 or the semi-finished product that has been pre-dried in S1.5.

[0020] Furthermore, the degree of scab damage to the collected fresh tea leaves is level two or above;

[0021] The fresh tea leaves are one bud and one leaf to one bud and three leaves, with one bud and one leaf to one bud and two leaves being the best.

[0022] Furthermore, obtaining withered leaves includes at least the following steps: withering for more than 18 hours in an environment with a temperature of 15℃~25℃, preferably 18℃-22℃ and a humidity of 55%~75%;

[0023] During the withering period, blow air and turn the fresh leaves in a timely manner to ensure even water loss, until the moisture content reaches 58%–62%.

[0024] Furthermore, obtaining the twisted leaf includes at least the following steps:

[0025] First, pressurize with air for 20 minutes, then with light pressure for 10 minutes, then with medium pressure for 10 minutes, and finally with heavy pressure for 10 minutes.

[0026] Then pressurize under air for 10 minutes, under medium pressure for 10 minutes, and under heavy pressure for 10 minutes.

[0027] Finally, perform air compression for 10 minutes;

[0028] Total kneading time: 90 min.

[0029] Furthermore, S2 includes at least the following steps:

[0030] S2.1: Moisten the fully dried black tea leaves to achieve a moisture content of approximately 35%–45%, ideally 40%.

[0031] S2.2: Use fresh black tea leaves after moisture treatment or semi-finished products after initial drying as raw materials, and fill them into the extraction vessel of the supercritical CO2 extraction equipment for supercritical CO2 extraction.

[0032] S2.3: After 3 to 4 hours of extraction, the extracted tea leaves are taken out of the extraction vessel, which is the debittered black tea reprocessed product. The bitter components in the separation vessel are collected.

[0033] S2.4: Dry the debittered black tea product in a dryer with hot air at 90℃~100℃ until the moisture content is 6%, thus obtaining debittered high γ-aminobutyric acid black tea.

[0034] Furthermore, the amount of raw material loaded in the extraction vessel is 60% to 75% of the vessel capacity; the extraction temperature of the supercritical CO2 extraction is 40 to 50°C, preferably 45°C; the extraction pressure is 26 to 32 MPa, preferably 30 MPa; the pressure of the extraction vessel is about 4 MPa; and the extraction temperature is 30°C to 35°C.

[0035] A high-γ-aminobutyric acid (GABA) black tea is prepared using the above-mentioned method for producing high-γ-aminobutyric acid (GABA) black tea.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] 1. Reduce tea waste: By making efficient use of fresh tea leaves damaged by red spot disease (white spot disease), the waste of tea resources is reduced and economic losses are avoided.

[0038] 2. Improved quality: The process of this invention can effectively remove the bitterness in tea leaves damaged by red spot disease, making the final black tea product more mellow and avoiding the lingering bitterness on the back of the tongue and throat.

[0039] 3. Increased γ-aminobutyric acid (GABA) content: The process of this invention effectively retains a high GABA content, enabling tea to not only have health-improving functions, such as calming and lowering blood pressure, but also meet consumers' demands for tea quality. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart of the present invention;

[0042] Figure 2 This is a schematic diagram showing the γ-aminobutyric acid (GABA) content in raw black tea and high-γ-aminobutyric acid black tea after bitterness removal treatment in Example 2.

[0043] Figure 3 The content of γ-aminobutyric acid (GABA) in raw black tea and high-γ-aminobutyric acid black tea after debittering treatment in Example 3. Detailed Implementation

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0045] The purpose of this invention is to provide a green and pollution-free method to remove the bitterness of tea caused by red spot disease (white spot disease), thereby better processing black tea with high γ-aminobutyric acid content, ensuring the quality of finished tea and better meeting consumer needs.

[0046] This invention mainly includes steps such as black tea processing, supercritical CO2 debittering, and drying.

[0047] The method of this invention increases the utilization of tea leaves damaged by red spot disease (white spot disease), reduces the waste of tea raw materials and the resulting economic losses.

[0048] Example 1:

[0049] Please see Figure 1 A method for producing high-γ-aminobutyric acid (GABA) black tea includes at least the following steps:

[0050] S1: Collect fresh tea leaves infected with red spot disease (white spot disease) to prepare raw black tea;

[0051] S1.1: Collect fresh tea leaves that are susceptible to red spot disease (white spot disease);

[0052] S1.2: The collected fresh tea leaves are withered in an indoor withering trough to obtain withered leaves;

[0053] S1.3: The withered leaves are rolled using a tea rolling machine to obtain rolled leaves;

[0054] S1.4: Ferment the rolled leaves to obtain fermented leaves. The fermentation time is 2-4 hours, the temperature is 28℃-32℃, and the humidity is 90% or higher.

[0055] S1.5: Perform initial drying. Dry the fermented leaves in a dryer at 120℃ for 10 to 15 minutes. After initial drying, the moisture content should be around 35% to 45%, preferably around 40%.

[0056] S1.6: Cool down, let the semi-finished product cool to room temperature;

[0057] S1.7: The semi-finished product, which has been cooled to room temperature, is dried in a dryer at 80℃~90℃ until the moisture content is reduced to 6%, thus obtaining raw black tea.

[0058] S2: Supercritical CO2 debittering of black tea. The raw materials for supercritical CO2 debittering can be either the raw black tea that has been fully processed in S1, or the semi-finished product that has been pre-dried in S1.5.

[0059] The degree of damage to fresh tea leaves infected with Acer arvensis is level II or above.

[0060] Fresh tea leaves range from one bud and one leaf to one bud and four leaves, with one bud and one leaf to one bud and two leaves being the best.

[0061] Obtaining withered leaves involves at least the following steps: withering for more than 18 hours in an environment with a temperature of 15℃~25℃, preferably 18℃-22℃ and a humidity of 55%~75%;

[0062] During the withering period, blow air and turn the fresh leaves in a timely manner to ensure even water loss, until the moisture content reaches 58%–62%.

[0063] Obtaining rolled leaves includes at least the following steps:

[0064] First, pressurize with air for 20 minutes, then with light pressure for 10 minutes, then with medium pressure for 10 minutes, and finally with heavy pressure for 10 minutes.

[0065] Then pressurize under air for 10 minutes, under medium pressure for 10 minutes, and under heavy pressure for 10 minutes.

[0066] Finally, perform air compression for 10 minutes;

[0067] Total kneading time: 90 min.

[0068] S2 includes at least the following steps:

[0069] S2.1: Moisten the fully dried black tea leaves to achieve a moisture content of approximately 35%–45%, ideally 40%.

[0070] S2.2: Use fresh black tea leaves after moisture treatment or semi-finished products after initial drying as raw materials, and fill them into the extraction vessel of the supercritical CO2 extraction equipment for supercritical CO2 extraction.

[0071] S2.3: After 3 to 4 hours of extraction, the extracted tea leaves are taken out of the extraction vessel, which is the debittered black tea reprocessed product. The bitter components in the separation vessel are collected.

[0072] S2.4: Dry the debittered black tea product in a dryer with hot air at 90℃~100℃ until the moisture content is 6%, thus obtaining debittered high γ-aminobutyric acid black tea.

[0073] The raw material filling amount in the extraction vessel is 60% to 75% of the vessel capacity. The extraction temperature of supercritical CO2 extraction is 40 to 50℃, preferably 45℃; the extraction pressure is 26 to 32 MPa, preferably 30 MPa; the pressure of the extraction vessel is about 4 MPa; and the extraction temperature is 30℃ to 35℃.

[0074] Example 2:

[0075] This embodiment proposes a specific process application based on the above embodiment one:

[0076] (1) The tea leaves damaged by red spot disease are classified as level 3, with one bud and two leaves.

[0077] (2) Withering: Fresh tea leaves are withered in an indoor withering trough at a temperature of 18-23℃ and a humidity of 75% for 19 hours. During withering, the leaves are blown and turned over as needed to ensure even water loss. The leaves are withered until the moisture content reaches 60%.

[0078] (3) Rolling: The withered leaves are rolled using a tea rolling machine. The specific pressing process is as follows: 20 min of air pressure → 10 min of light pressure → 10 min of medium pressure → 10 min of heavy pressure → 10 min of air pressure → 10 min of medium pressure → 10 min of heavy pressure → 10 min of air pressure, with a total rolling time of ~90 min.

[0079] (4) Fermentation: 4 hours, 30°C, and 92% or more humidity.

[0080] (5) Initial drying: Dry the fermented leaves in a 120℃ dryer for 10 minutes. After the initial drying, the moisture content is about 40%.

[0081] (6) Cooling: Spread the semi-finished product that has been initially dried to room temperature.

[0082] (7) Drying: The pre-dried product, which has been cooled to room temperature, is dried in a dryer at 100°C until the moisture content is about 6%, thus obtaining raw black tea.

[0083] (8) Debittering treatment: The fully dried black tea leaves are moistened to a moisture content of about 40% and then packed into the extraction vessel of a supercritical CO2 extraction device, filling the vessel to 65% of its capacity. Supercritical CO2 extraction is then performed. The extraction temperature is 40℃, the extraction pressure is 30 MPa, and the extraction time is 3 hours. Separation vessel I has a pressure of 7 MPa and a temperature of 50℃; separation vessel II has a pressure of 4 MPa and a temperature of 36℃. After extraction, the extracted tea leaves are removed from the extraction vessel, which is the debittered black tea product.

[0084] (9) Drying: Dry the debittered black tea product in a dryer at 95°C with hot air until the moisture content is about 6%, and thus obtain debittered high γ-aminobutyric acid black tea.

[0085] Table 1 Sensory quality of raw black tea and debittered high-γ-aminobutyric acid black tea

[0086] As shown in Table 1, the raw black tea made from tea leaves damaged by red spot disease has a sweet and mellow taste, but a distinct bitter taste that lingers on the tongue and throat. However, after the raw black tea is treated with supercritical CO2 to remove bitterness, the bitterness in the tea soup is reduced to almost imperceptible, and the tea soup is sweeter and mellower, with a significant improvement in taste and quality.

[0087] Depend on Figure 2 It can be seen that the content of γ-aminobutyric acid (GABA) in the raw tea made from fresh tea leaves affected by red spot disease is 2.31±0.26 mg / g, while the content of GABA after supercritical CO2 treatment is 2.12±0.13 mg / g. There is no significant difference in the GABA content between the two samples, and both are greater than 1.5 mg / g, which indicates that they belong to Gabaron tea.

[0088] Example 3:

[0089] This embodiment proposes a specific process application based on the above embodiment one:

[0090] (1) Fresh tea leaves with one bud and two leaves when the red spot disease is level 4.

[0091] (2) Withering: Fresh tea leaves are withered in an indoor withering trough at a temperature of 18-23℃ and a humidity of 65%-78% for 20 hours. During withering, the leaves are blown and turned over as needed to ensure even water loss. The leaves are withered until the moisture content reaches 58%.

[0092] (3) Rolling: The withered leaves are rolled using a tea rolling machine. The specific pressing process is as follows: 20 min of air pressure → 10 min of light pressure → 10 min of medium pressure → 10 min of heavy pressure → 10 min of air pressure → 10 min of medium pressure → 10 min of heavy pressure → 10 min of air pressure, with a total rolling time of 90 min.

[0093] (4) Fermentation: 3 hours, 30 ℃, and 90% or more humidity.

[0094] (6) Initial drying: Dry the fermented leaves in a 120℃ dryer for 10 minutes. After the initial drying, the moisture content is about 30%.

[0095] (7) Cooling: Cool the semi-finished product from the initial drying process to room temperature.

[0096] (8) Debittering treatment: The pre-dried tea with a moisture content of 30% is loaded into the extraction vessel of a supercritical CO2 extraction device, filling the vessel to 65% of its capacity, and then subjected to supercritical CO2 extraction. The extraction temperature is 50℃; the extraction pressure is 28 MPa; and the extraction time is 4 hours. The pressure of separation vessel I is 7 MPa and the temperature is 50℃; the pressure of separation vessel II is 4 MPa and the temperature is 36℃. After extraction, the extracted tea leaves are taken out of the extraction vessel, which is the debittered black tea product.

[0097] (9) Drying: Dry the debittered black tea product in a dryer at 100°C with hot air until the moisture content is about 6%, and thus obtain debittered high γ-aminobutyric acid black tea.

[0098] Table 2 Sensory quality of raw black tea and debittered high-γ-aminobutyric acid black tea

[0099] As shown in Table 2, the black tea made from fresh tea leaves damaged by red spot disease using traditional processing techniques has a strong and persistent bitter taste, making it difficult to swallow. However, by adding supercritical CO2 debittering treatment to the traditional process, the bitterness of the resulting high-γ-aminobutyric acid black tea is significantly reduced, and the sweet and mellow taste of the tea soup is highlighted, resulting in a significant improvement in flavor quality.

[0100] Depend on Figure 3 It can be seen that the content of γ-aminobutyric acid (GABA) in the raw tea made from fresh tea leaves processed by traditional techniques is 2.71±0.08 mg / g. However, after supercritical CO2 debittering treatment, the content of GABA in the raw tea is 2.89±0.10 mg / g. There is no significant difference in the GABA content between the two samples, and both are greater than 1.5 mg / g, which indicates that they belong to Gabaron tea.

[0101] Example 4:

[0102] A high-γ-aminobutyric acid (GABA) black tea was prepared using the method described in Examples 1, 2, and 3 above.

[0103] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for producing high-γ-aminobutyric acid (GABA) black tea, characterized in that: At least the following steps are included: S1: Collect fresh tea leaves with red spot disease to prepare raw black tea; S1.1: Collect fresh tea leaves that are susceptible to red spot disease; S1.2: The collected fresh tea leaves are withered in an indoor withering trough to obtain withered leaves; S1.3: The withered leaves are rolled using a tea rolling machine to obtain rolled leaves; S1.4: Ferment the rolled leaves to obtain fermented leaves. The fermentation time is 2-4 hours, the temperature is 28℃-32℃, and the humidity is 90% or higher. S1.5: Perform initial drying by quickly drying the fermented leaves in a dryer at 110~120℃ for 8 to 15 minutes. After initial drying, the moisture content should be 35~45%. S1.6: Cool down, let the semi-finished product cool to room temperature; S1.7: Fully dried. The semi-finished product, which has been cooled to room temperature, is dried in a dryer at 80℃~90℃ until the moisture content is reduced to 6%, thus obtaining raw black tea. S2: Supercritical CO2 debittering of black tea. The raw material for supercritical CO2 debittering can be either fully dried black tea from S1.7 or semi-finished product from S1.

5.

2. The method for producing high-γ-aminobutyric acid (GABA) black tea according to claim 1, characterized in that: The degree of Acer spp. damage to the collected fresh tea leaves is level two or above. The fresh tea leaves are one bud and one leaf to one bud and three leaves.

3. The method for producing high-γ-aminobutyric acid (GABA) black tea according to claim 1, characterized in that: The process of obtaining withered leaves includes at least the following steps: In an environment with a temperature of 15℃~25℃ and a humidity of 55%~75%, the withering time should be maintained for more than 18 hours; During the withering period, blow air and turn the fresh leaves in a timely manner to ensure even water loss, until the moisture content reaches 58%–62%.

4. The method for producing high-γ-aminobutyric acid (GABA) black tea according to claim 1, characterized in that: The process of obtaining the twisted leaves includes at least the following steps: First, pressurize with air for 20 minutes, then with light pressure for 10 minutes, then with medium pressure for 10 minutes, and finally with heavy pressure for 10 minutes. Then pressurize under air for 10 minutes, under medium pressure for 10 minutes, and under heavy pressure for 10 minutes. Finally, perform air compression for 10 minutes; Total kneading time: 90 min.

5. The method for producing high-γ-aminobutyric acid (GABA) black tea according to claim 1, characterized in that: S2 includes at least the following steps: S2.1: The fully dried black tea leaves are moistened to achieve a moisture content of 35% to 45%. S2.2: Use fresh black tea leaves after moisture treatment or semi-finished products after initial drying as raw materials, and fill them into the extraction vessel of the supercritical CO2 extraction equipment for supercritical CO2 extraction. S2.3: After 3 to 4 hours of extraction, the extracted tea leaves are taken out of the extraction vessel, which is the debittered black tea reprocessed product. The bitter components in the separation vessel are collected. S2.4: Dry the debittered black tea product in a dryer with hot air at 90℃~100℃ until the moisture content is 6%, thus obtaining debittered high γ-aminobutyric acid black tea.

6. The method for producing high-γ-aminobutyric acid (GABA) black tea according to claim 1, characterized in that: The raw material filling amount in the extraction vessel is 60% to 75% of the vessel capacity. The supercritical CO2 extraction temperature is 40 to 50°C, the extraction pressure is 26 to 32 MPa, the pressure of the extraction vessel is 4 MPa, and the extraction temperature is 30°C to 35°C.

7. A high-γ-aminobutyric acid (GABA) black tea, characterized in that: The high-γ-aminobutyric acid black tea was prepared using the method described in any one of claims 1-6.

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