Quick-flushing original leaf cold-brew tea and processing technology

Abstract

The present application relates to a kind of quick flush original leaf cold-brew tea and processing technology, the processing technology includes the following steps: tea gradient pressure puffing: raw material tea is placed in airtight container, gradient pressure puffing process is handled using puffing, and the puffing tea with interconnected pore network structure is obtained;And the moisture content of puffing tea is controlled to 8% or less to obtain dry tea;The pressure range of gradient pressure puffing process is 0.3-0.9MPa, and the temperature range is 85-110 DEG C;Laying: after laying dry tea, porous medium and fresh fruits and vegetables are mixed to lay and obtain mixture, and separation is obtained to lay tea;Packaging: laying tea is packaged to obtain quick flush original leaf cold-brew tea.The present application builds hierarchical interconnected pore network in tea, realizes the controllable adjustment of tea dissolution rate, and solves the problems of traditional cold-brew tea, such as insufficient aroma, poor stability, uncoordinated taste, and serious taste level.

Description

Technical Field

[0001] This invention relates to the field of tea reprocessing, specifically to a quick-brew cold-brew tea made from whole tea leaves and its processing technology. Background Technology

[0002] Instant whole-leaf tea is a product that prioritizes convenient brewing. The mainstream preparation technologies for instant whole-leaf tea in the industry can be divided into three categories, each with significant technical shortcomings, as detailed below: One method is physical crushing. This technique involves grinding and pulverizing tea leaves into ultrafine tea powder with a particle size of less than 100μm, thereby increasing the specific surface area of ​​the tea material and improving the dissolution rate during brewing. However, the finished product processed by this method has significant quality problems. After brewing, the tea soup is highly turbid, and a large amount of the bitter and astringent substances in the tea leaves are easily extracted, resulting in a strong bitter and astringent taste. At the same time, the original aroma of the tea leaves dissipates quickly, and the flavor retention is poor.

[0003] The second method is chemical extraction. This process uses organic solvent extraction or supercritical carbon dioxide extraction technology to extract the effective flavor and nutrients from tea leaves, which are then dried and granulated to produce instant tea products. The core drawback of this technology lies in the insufficient safety and authenticity of the product's flavor. Not only is there a safety hazard due to residual organic solvents, but it also damages the natural flavor system of tea leaves, ultimately leading to a distorted flavor and unpleasant taste in the finished tea.

[0004] Thirdly, there is the puffing and drying method. This method uses high-temperature and high-pressure puffing to disrupt the original cell structure of tea leaves, thereby improving the dissolution performance of the tea's effective components. However, at present, the parameter settings for this process are relatively crude, making it impossible to precisely control the pore structure of the tea leaves after puffing. This makes it difficult to balance the brewing dissolution rate with the flavor of the tea soup, resulting in poor product quality stability.

[0005] Based on current mainstream processing techniques, it can be seen that there are four major technological defects in the current quick-brew whole-leaf tea production, which restrict the upgrading of product quality: First, the pore structure of tea leaves is poorly controllable. Most existing puffing processes employ single-stage or simplified two-stage pressure regulation, resulting in insufficient precision in process control. This leads to uneven pore size distribution and poor pore connectivity in the processed tea leaves. An excessively high proportion of large pores in the finished product accelerates the loss of tea aroma, while an insufficient number of micropores significantly reduces the rate at which the effective components of the tea dissolve during brewing. Currently, there are no mature technologies for precisely controlling the pore size distribution.

[0006] Secondly, flavor retention and preservation are challenging. The characteristic aroma compounds in cold-brewed tea are highly volatile and easily lost during processing and storage. Current technologies only add aroma-retaining substances through simple material mixing and surface spraying, resulting in low aroma load and short aroma retention time. The final brewed tea soup has a thin aroma and lacks rich flavor layers.

[0007] Third, there is an inherent contradiction between dissolution efficiency and tea flavor. In order to increase the dissolution speed of quick-brew tea, the industry generally uses excessive crushing and expansion methods to damage the tea leaves. This processing method causes excessive dissolution of bitter and astringent core substances such as tea polyphenols and caffeine, while the proportion of dissolution of substances that determine the fresh and sweet taste of tea soup, such as amino acids, is unbalanced, ultimately resulting in a prominent bitterness and a disharmonious overall flavor.

[0008] Fourth, there is a lack of sequential flavor system design. When a high-quality tea beverage has a layered flavor change with top, middle, and base notes, its drinking experience is better. However, the flavor substances in existing instant whole-leaf tea products are basically released quickly in one go, without dynamic flavor changes, resulting in a serious lack of drinking fun and layered taste. Summary of the Invention

[0009] This invention provides a quick-brew whole-leaf cold-brew tea and its processing technology, enabling controllable adjustment of the tea leaf dissolution rate and solving the problems of insufficient aroma, poor stability, unharmonious flavor, and severe lack of flavor complexity in traditional cold-brew tea. The whole-leaf tea mentioned in this invention refers to tea products that retain the complete shape of the tea leaves.

[0010] In a first aspect, the present invention provides a processing method for quick-brew whole-leaf cold-brewed tea, comprising the following steps: Gradient pressure variable expansion of tea leaves: Raw tea leaves are placed in a sealed container and expanded using a gradient pressure variable expansion process to obtain expanded tea leaves with an interconnected pore network structure; the moisture content of the expanded tea leaves is controlled to below 8% to obtain dried tea leaves; the pressure range of the gradient pressure variable expansion process is 0.3-0.9MPa, and the temperature range is 85-110℃; Scenting: Dry tea leaves, porous media and fresh flowers and fruits are mixed and scented to obtain a mixture, and then the scented tea leaves are separated. Packaging: The scented tea leaves are packaged to obtain quick-brew whole-leaf cold-brew tea.

[0011] In one optional embodiment, during the gradient pressure variation puffing of tea leaves, the moisture content of the raw tea leaves is 30-60%. The gradient pressure variable expansion process involves gradually increasing pressure and temperature followed by pressure release; preferably, it is a three-stage pressure gradient pressure variable expansion process, including: Level 1: Maintain for 3-5 minutes under pressure of 0.3-0.5 MPa and temperature of 85-95℃; Second stage: Maintain for 2-4 minutes under pressure of 0.6-0.9 MPa and temperature of 100-110℃; Level 3: Within 3-10 seconds, the pressure is released to -0.095~-0.08MPa, and the temperature is reduced to 50-60℃.

[0012] 4. In an optional embodiment, the moisture content of puffed tea leaves is controlled to below 8% by freeze drying to obtain dried tea leaves. The specific process of freeze drying includes: adjusting the moisture content of puffed tea leaves to 25%-35% and freeze drying to obtain dried tea leaves with a moisture content controlled to below 8%. Preferably, in the freeze-drying process, the freezing conditions are: freezing treatment at -25℃ to -15℃ for 2-4 hours; the drying conditions are: sublimation under vacuum degree ≤10Pa and cold trap temperature ≤-50℃. The sublimation process includes: maintaining at -25~-15℃ for 3.5-4.5h, then maintaining at -15~-5℃ for 2.5-3.5h, and finally maintaining at -5~5℃ for 2h.

[0013] In one optional embodiment, during the scenting process, the mass ratio of the dried tea leaves, porous medium, and fresh flowers and fruits is (8-10):(1-2):(1-2). The fresh flowers and fruits include fresh flowers and / or fresh fruits.

[0014] In one optional embodiment, the scenting process includes: treating for 6-10 hours at a temperature of 35-45°C and a relative humidity of 55%-65%.

[0015] In one optional embodiment, the porous medium is porous ceramic particles; Preferably, the porous ceramic particles have a pore size of 50-200 μm and a specific surface area of ​​200-400 m². 2 / g; and / or, the porous ceramic particles are modified with a silane coupling agent.

[0016] In one alternative embodiment, the separation step is followed by a microcapsule loading step, which includes: mixing scented tea leaves with a microcapsule suspension under vacuum conditions and then subjecting the mixture to ultrasonic treatment to obtain microcapsule tea leaves; and encapsulating the microcapsule tea leaves to obtain quick-brew whole-leaf cold-brew tea.

[0017] In one optional embodiment, the ultrasonic treatment takes 15-25 minutes. The mass concentration of microcapsules in the microcapsule suspension is 5-10%; The microcapsules have a particle size of 5-20 μm.

[0018] Secondly, the present invention also provides a quick-brew whole-leaf cold-brew tea, which is prepared by the processing technology described above.

[0019] Thirdly, the present invention provides a brewing method for the above-mentioned quick-brew whole leaf cold-brew tea, which includes adding the above-mentioned quick-brew whole leaf cold-brew tea to room temperature water and letting it stand for 5-10 minutes.

[0020] The technical solution of this invention has the following advantages: 1. The present invention provides a processing technology for quick-brew whole-leaf cold-brew tea, comprising the following steps: gradient pressure expansion of tea leaves: placing raw tea leaves in a sealed container and using a gradient pressure expansion process to expand the tea leaves to obtain expanded tea leaves with a connected pore network structure; and controlling the moisture content of the expanded tea leaves to below 8% to obtain dried tea leaves; the pressure range of the gradient pressure expansion process is 0.3-0.9 MPa, and the temperature range is 85-110℃; scenting: mixing dried tea leaves, porous media, and fresh flowers and fruits and then scenting to obtain a mixture, and separating to obtain scented tea leaves; packaging: packaging the scented tea leaves to obtain quick-brew whole-leaf cold-brew tea.

[0021] This invention provides a processing technology for quick-brew whole-leaf cold-brewed tea. By constructing a graded and interconnected pore network inside the tea leaves and solidifying the pore structure, the dissolution rate of the tea leaves can be controlled and adjusted, solving the problems of insufficient aroma, poor stability, uncoordinated taste, and severe layering of flavor in traditional cold-brewed tea.

[0022] 2. The present invention provides a processing technology for quick-brew cold-brewed whole-leaf tea. Through the adsorption of porous media and microcapsule loading during the scenting process, the aroma stability is significantly improved. Furthermore, the processing technology of this application provides standardized process parameters, such as temperature, humidity, and time, to ensure that the aroma intensity of each batch of products is consistent.

[0023] 3. The processing technology for quick-brew whole-leaf cold-brewed tea provided by this invention not only solves the problems of insufficient aroma and poor stability of traditional cold-brewed tea, but also endows the product with unique flavor characteristics and enhances its market competitiveness. By combining gradient pressure expansion with the scenting process, the amount of fresh flowers and fruits used in traditional scenting is also greatly reduced (the ratio of tea leaves to fresh flowers and fruits in traditional scenting is 3:1, while under the premise of stronger aroma and intensity, the amount of flowers is reduced to a ratio of tea leaves to fresh flowers and fruits of 6:1), thereby reducing processing costs. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 These are pore structure characterization diagrams of tea leaves before (a) and after (b) puffing in Embodiment 1 of the present invention. Detailed Implementation

[0026] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0027] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0028] Example 1 This embodiment provides a processing method for quick-brew whole-leaf cold-brewing jasmine tea, including the following steps: S1, Gradient Pressure Variable Expansion of Tea Leaves: Raw tea leaves, specifically whole-leaf green tea, are selected. The moisture content of the whole-leaf green tea is adjusted to 30%, and then placed in a variable temperature and pressure expansion tank. A three-stage gradient pressure expansion process is employed, including: In the first stage, under a pressure of 0.3 MPa and a temperature of 85℃, the tea leaves are kept at a high moisture content for 5 minutes. The fibrous macromolecules of the tea leaves fully swell, and some of the water vaporizes after heating and slowly permeates into the intercellular spaces, forming very small primary bubble nuclei. At this time, the size and shape of the tea leaves do not change, but dispersed and uniform primary micropores have been formed on the leaves. If a high pressure is suddenly applied at one time, the water vaporizes rapidly and overflows from the surface of the tea leaves without forming bubble nuclei. It may even cause the surface of the leaves to harden and prevent the formation of micropores. The dispersed and uniform micropores lay the foundation for the micropore interconnection in the second stage. In the second stage, under the conditions of 0.6 MPa pressure and 100℃ temperature, after 4 minutes of continuous pressurization and heating, the water enters a superheated state, and the vapor pressure also increases significantly. The high pressure causes the bubbles to shear and rupture at the weak points of the cell wall, and the primary pores are interconnected to form channels. Gradually, the dispersed micropores in the first stage expand and connect. The expansion and connection of micropores provides a "vapor release channel" for the instantaneous pressure relief in the third stage, so that the pore structure remains intact and is not destroyed. In the third stage, the pressure is released to -0.08MPa within 10 seconds, and the temperature is also simultaneously reduced to 60℃. The pore structure or interconnected pore structure formed in the first and second stages expands in volume by about 1600 times during the instantaneous vaporization of water. The interconnected pore network serves as a pressure release path to avoid local pressure concentration that could lead to structural collapse. While water flashes away, the pores solidify to form a hierarchical interconnected pore network structure. S2, freeze-drying: The expanded tea leaves were rehydrated by a second spray, controlling the moisture content to 25%. The tea leaves were then pre-frozen at -20℃ for 2 hours. During this time, the water absorbed into the pores and cells formed ice crystals, which filled and supported the expanded pores, further solidifying the pore network structure formed in the third stage of the pressure swing expansion process. Then, directional sublimation drying was carried out under vacuum ≤10Pa and cold trap temperature ≤-50℃. The drying temperature curve was: -20℃ for 4 hours → -10℃ for 3 hours → 0℃ for 2 hours. After the ice crystals sublimated, the pore network structure formed in the third stage was further solidified and shaped, resulting in dried tea leaves with a directional pore structure. At this point, the moisture content of the tea leaves was approximately 7%, and the volume expansion rate of the treated tea leaves was 150%. S3, Storage: Dried whole-leaf green tea, porous ceramic particles and fresh jasmine flowers are mixed in a mass ratio of 8:1:1 and scented for 10 hours at a temperature of 35℃ and a relative humidity of 65%. The porous ceramic particles have a pore size of 100 μm and a specific surface area of ​​300 m². 2 / g, porous ceramic particles modified with silane coupling agent; When fresh flowers are mixed with tea leaves that have a porous network structure, the moisture content of the tea leaves is about 7% and that of the fresh flowers is more than 75%. At this point, the tea leaves with a porous network structure have a strong water absorption capacity, and the aroma emitted by the fresh flowers can quickly diffuse into the porous network structure of the tea leaves along with the moisture and be absorbed. Meanwhile, the porous ceramic particles have micron and nano-sized pores inside. When aroma substances enter the ceramic pores, they are locked in by the intermolecular forces of the pore walls and then adsorbed. High-quality jasmine flowers typically release their fragrance most intensely and freshest during the 2-4 hour scenting process. At this time, the tea leaves don't have time to absorb the fragrance released by the flowers. Instead, the porous ceramic particles quickly absorb and store it. When the fragrance concentration of the flowers weakens, the porous ceramic particles can slowly release the fragrance to replenish the intensity. This allows the tea leaves to fully absorb the fragrance during the best time of release throughout the scenting process, maximizing the use of the aroma and improving the scenting quality.

[0029] S4. Fresh flower sorting: The scented fresh flowers are sifted out using a flower sifting machine, and the remaining mixture of tea leaves and porous ceramic particles enters the subsequent processing stage.

[0030] S5. Drying and Separation: Drying and separation are carried out using a fluidized bed at a drying temperature of 70℃, an ambient humidity of 30%, and an internal circulating airflow velocity of 10m / s. The scented tea leaves and the porous ceramic particle mixture are placed in the fluidized bed. The high temperature and vibration cause the ceramic particles to continuously release the adsorbed aroma into the drying chamber, allowing the tea leaves to re-enrich the adsorbed aroma during the drying process and reducing aroma loss. Simultaneously, during the drying process, the tea leaves and ceramic particles are gradually separated by gravity and size due to vibration and airflow separation in the fluidized bed. The dried tea leaves and ceramic particles are discharged from different outlets, resulting in scented jasmine tea with a moisture content of less than 6%.

[0031] S6, Microcapsule loading: The dried jasmine tea was placed in a vacuum reactor and spread to a thickness of 3 cm. The reactor was evacuated to -0.09 MPa, and then a jasmine essential oil microcapsule suspension was injected. The mixture was treated with ultrasonic assistance for 20 minutes, so that the microcapsules were loaded into the pore structure of the tea leaves under negative pressure. The concentration of microcapsules in the microcapsule suspension was 5%, and the amount of microcapsule suspension added was 10% of the tea mass. The ultrasonic treatment frequency was 40kHz and the power was 200W. After ultrasonic treatment, the pressure should be slowly restored to normal within 10 minutes to avoid damaging the pore structure of the tea leaves. Post-processing: The tea leaves obtained after ultrasonic treatment are placed at a temperature of 40℃ and a humidity of 60% for 60 minutes to allow the surface pores to close appropriately. Then, they are dried with hot air at 50℃ for about 30 minutes until the moisture content of the tea leaves is below 6%. The loading of microcapsules was detected by thermogravimetric analysis, and the loading was above 10%. S7, Package: When the temperature is below 30℃ and the humidity is below 30%, nitrogen-filled packaging is used, and the oxygen content inside the packaging bag is below 2%.

[0032] Example 2 This embodiment provides a processing technology for quick-brew, cold-infusion gardenia oolong tea, including the following steps: S1, Gradient Pressure Variable Expansion of Tea Leaves: The original leaf oolong tea is adjusted to a moisture content of 50% and placed in a variable temperature and pressure puffing tank, employing a three-stage gradient pressure puffing process, including: In the first stage, under a pressure of 0.5 MPa and a temperature of 95℃, the tea leaves are kept at a high moisture content for 5 minutes. The fibrous macromolecules of the tea leaves fully swell in the high moisture state. Some of the water vaporizes after heating and slowly permeates into the intercellular spaces, forming very small primary bubble nuclei. At this time, the size and shape of the tea leaves do not change, but dispersed and uniform primary micropores have been formed on the leaves. If a high pressure is suddenly applied at one time, the water vaporizes rapidly and overflows from the surface of the tea leaves without forming bubble nuclei. It may even cause the surface of the leaves to harden and prevent the formation of micropores. The dispersed and uniform micropores lay the foundation for the micropore interconnection in the second stage. In the second stage, under the conditions of 0.9 MPa pressure and 110℃ temperature, after 4 minutes of continuous pressurization and heating, the water enters a superheated state, and the vapor pressure also increases significantly. The high pressure causes the bubbles to shear and rupture at the weak points of the cell wall, and the primary pores are interconnected to form channels. Gradually, the dispersed pores in the first stage expand and connect. The expansion and connection of pores provides a "vapor release channel" for the instantaneous pressure relief in the third stage, so that the pore structure remains intact and is not destroyed. In the third stage, the pressure is released to -0.095MPa within 10 seconds, and the temperature is also simultaneously reduced to 60℃. The pore structure or interconnected pore structure formed in the first and second stages expands in volume by about 1600 times during the instantaneous vaporization of water. The interconnected pore network serves as a pressure release path to avoid local pressure concentration that could lead to structural collapse. While water flashes away, the pores solidify to form a hierarchical interconnected pore network structure. S2, freeze-drying: The expanded oolong tea leaves were rehydrated by a second spray, controlling the moisture content to 35%. The tea leaves were then pre-frozen at -20℃ for 4 hours. During this time, the water absorbed into the pores and cells formed ice crystals, which filled and supported the expanded pores, thus solidifying the pore network structure formed in the third stage of the pressure swing expansion process. Then, directional sublimation drying was carried out under vacuum ≤10Pa and cold trap temperature ≤-50℃. The drying temperature curve was: -20℃ for 4 hours → -10℃ for 3 hours → 0℃ for 5 hours. After the ice crystals sublimated, the pore network structure formed in the third stage was further solidified and shaped, resulting in dried tea leaves with a directional pore structure. At this time, the moisture content of the tea leaves was about 7%. The volume expansion rate of the treated tea leaves was 150%.

[0033] S3, Storage: Dried oolong tea, porous ceramic particles and gardenia flowers are mixed in a mass ratio of 10:2:2 and scented for 10 hours at a temperature of 40℃ and a relative humidity of 65%. The porous ceramic particles have a pore size of 100 μm and a specific surface area of ​​300 m². 2 / g, porous ceramic particles modified with silane coupling agent; When gardenia flowers are mixed with tea leaves that have a porous network structure, the moisture content of the oolong tea is about 7%, while the moisture content of the gardenia flowers is over 75%. At this point, the oolong tea with a porous network structure has a very strong water absorption capacity, and the aroma emitted by the gardenia flowers can quickly diffuse into the porous network structure of the tea leaves along with the moisture and be absorbed. Meanwhile, the porous ceramic particles have micron and nano-sized pores inside. When aroma substances enter the ceramic pores, they are locked in by the intermolecular forces of the pore walls and then adsorbed. Gardenia flowers continuously release their aroma during the scenting process. After 6 hours of scenting, the tea leaves' ability to absorb aroma is greatly reduced, but the more robust gardenia flowers continue to release their aroma. At this time, the released aroma can be absorbed and stored by porous ceramic particles. During drying, the high temperature will release the aroma back into the tea leaves and the drying environment, thereby reducing the loss of aroma during the drying process.

[0034] S4. Fresh flower sorting: The scented fresh flowers are sifted out using a flower sifting machine, and the remaining mixture of tea leaves and porous ceramic particles enters the subsequent processing stage.

[0035] S5. Drying and Separation: Drying and separation are carried out using a fluidized bed at a drying temperature of 90℃, an ambient humidity of 30%, and an internal circulating airflow velocity of 10m / s. The scented tea leaves and the porous ceramic particle mixture are placed in the fluidized bed. The high temperature and vibration cause the ceramic particles to continuously release the adsorbed aroma into the drying chamber, allowing the tea leaves to re-enrich the adsorbed aroma during the drying process and reducing aroma loss. Simultaneously, during the drying process, the tea leaves and ceramic particles are gradually separated by gravity and size due to vibration and airflow separation in the fluidized bed. The dried tea leaves and ceramic particles are discharged from different outlets, resulting in scented gardenia oolong tea with a moisture content of less than 6%.

[0036] S6, Microcapsule loading: The dried gardenia oolong tea was placed in a vacuum reactor and spread to a thickness of 3cm. The reactor was evacuated to -0.09MPa, and then gardenia essential oil microcapsule suspension was injected. The mixture was treated for 15 minutes under ultrasonic assistance so that the microcapsules could be loaded into the pore structure of the tea leaves under negative pressure. The concentration of microcapsules in the microcapsule suspension was 10%, and the amount of microcapsule suspension added was 12% of the tea mass. The ultrasonic treatment frequency was 40kHz and the power was 200W. After ultrasonic treatment, the pressure should be slowly restored to normal within 15 minutes to avoid damaging the pore structure of the tea leaves. Post-processing: The tea leaves obtained after ultrasonic treatment are placed at a temperature of 50℃ and a humidity of 60% for 60 minutes to allow the surface pores to close appropriately. Then, they are dried with hot air at 45℃ for 30 minutes until the moisture content of the tea leaves is below 6%. The loading of microcapsules was detected by thermogravimetric analysis, and the loading was above 10%. S7, Package: When the temperature is below 30℃ and the humidity is below 30%, nitrogen-filled packaging is used, and the oxygen content inside the packaging bag is below 2%.

[0037] Example 3 This embodiment provides a processing method for cold-brewed jasmine tea made from whole leaves. The difference from Embodiment 1 is that it does not include a freeze-drying process, and includes the following steps: S1, Gradient Pressure Variable Expansion of Tea Leaves: The raw green tea leaves are adjusted to a moisture content of 30% and placed in a temperature- and pressure-switching expansion tank. A three-stage gradient pressure-switching expansion process is then employed, including: In the first stage, under a pressure of 0.3 MPa and a temperature of 85℃, the tea leaves are kept at a high moisture content for 5 minutes. The fibrous macromolecules of the tea leaves fully swell, and some of the water vaporizes after heating and slowly permeates into the intercellular spaces, forming very small primary bubble nuclei. At this time, the size and shape of the tea leaves do not change, but dispersed and uniform primary micropores have been formed on the leaves. If a high pressure is suddenly applied at one time, the water vaporizes rapidly and overflows from the surface of the tea leaves without forming bubble nuclei. It may even cause the surface of the leaves to harden and prevent the formation of micropores. The dispersed and uniform micropores lay the foundation for the micropore interconnection in the second stage. In the second stage, under the conditions of 0.6 MPa pressure and 100℃ temperature, after 4 minutes of continuous pressurization and heating, the water enters a superheated state, and the vapor pressure also increases significantly. The high pressure causes the bubbles to shear and rupture at the weak points of the cell wall, and the primary pores are interconnected to form channels. Gradually, the dispersed micropores in the first stage expand and connect. The expansion and connection of micropores provides a "vapor release channel" for the instantaneous pressure relief in the third stage, so that the pore structure remains intact and is not destroyed. In the third stage, the pressure is released to -0.08MPa within 10 seconds, and the temperature is also simultaneously reduced to 60℃. The pore structure or interconnected pore structure formed in the first and second stages expands in volume by about 1600 times during the instantaneous vaporization of water. The interconnected pore network serves as a pressure release path to avoid local pressure concentration that could lead to structural collapse. While water flashes away, the pores solidify to form a hierarchical interconnected pore network structure. S2, Hot air drying: The expanded whole-leaf green tea was placed in a hot air dryer for drying. The hot air drying temperature was 70℃ and the ambient humidity was 30%. After drying, the moisture content of the tea leaves was about 7%. The volume expansion rate of the tea leaves after treatment was 130%.

[0038] S3, Storage: Dried whole-leaf green tea, porous ceramic particles and fresh jasmine flowers are mixed in a mass ratio of 8:1:1 and scented for 10 hours at a temperature of 35℃ and a relative humidity of 65%. The porous ceramic particles have a pore size of 100 μm and a specific surface area of ​​300 m². 2 / g, porous ceramic particles modified with silane coupling agent; When fresh flowers are mixed with tea leaves that have a porous network structure, the moisture content of the tea leaves is about 7% and that of the fresh flowers is more than 75%. At this point, the tea leaves with a porous network structure have a strong water absorption capacity, and the aroma emitted by the fresh flowers can quickly diffuse into the porous network structure of the tea leaves along with the moisture and be absorbed. Meanwhile, the porous ceramic particles have micron and nano-sized pores inside. When aroma substances enter the ceramic pores, they are locked in by the intermolecular forces of the pore walls and then adsorbed. High-quality jasmine flowers typically release their fragrance most intensely and freshest during the 2-4 hour scenting process. At this time, the tea leaves don't have time to absorb the fragrance released by the flowers. Instead, the porous ceramic particles quickly absorb and store it. When the fragrance concentration of the flowers weakens, the porous ceramic particles can slowly release the fragrance to replenish the intensity. This allows the tea leaves to fully absorb the fragrance during the best time of release throughout the scenting process, maximizing the use of the aroma and improving the scenting quality.

[0039] S4. Fresh flower sorting: The scented fresh flowers are sifted out using a flower sifting machine, and the remaining mixture of tea leaves and porous ceramic particles enters the subsequent processing stage.

[0040] S5. Drying and Separation: Drying and separation are carried out using a fluidized bed at a drying temperature of 70℃, an ambient humidity of 30%, and an internal circulating airflow velocity of 10m / s. The scented tea leaves and the porous ceramic particle mixture are placed in the fluidized bed. The high temperature and vibration cause the ceramic particles to continuously release the adsorbed aroma into the drying chamber, allowing the tea leaves to re-enrich the adsorbed aroma during the drying process and reducing aroma loss. Simultaneously, during the drying process, the tea leaves and ceramic particles are gradually separated by gravity and size due to vibration and airflow separation in the fluidized bed. The dried tea leaves and ceramic particles are discharged from different outlets, resulting in scented jasmine tea with a moisture content of less than 6%.

[0041] S6, Microcapsule loading: The dried jasmine tea was placed in a vacuum reactor and spread to a thickness of 3 cm. The reactor was evacuated to -0.09 MPa, and then a jasmine essential oil microcapsule suspension was injected. The mixture was treated with ultrasonic assistance for 20 minutes, so that the microcapsules were loaded into the pore structure of the tea leaves under negative pressure. The concentration of microcapsules in the microcapsule suspension was 5%, and the amount of microcapsule suspension added was 10% of the tea mass. The ultrasonic treatment frequency was 40kHz and the power was 200W. After ultrasonic treatment, the pressure should be slowly restored to normal within 10 minutes to avoid damaging the pore structure of the tea leaves. Post-processing: The tea leaves obtained after ultrasonic treatment are placed at a temperature of 40℃ and a humidity of 60% for 60 minutes to allow the surface pores to close appropriately. Then, they are dried with hot air at 50℃ for about 30 minutes until the moisture content of the tea leaves is below 6%. The loading of the microcapsules was determined by thermogravimetric analysis, and the loading was approximately 7%. S7, Package: When the temperature is below 30℃ and the humidity is below 30%, nitrogen-filled packaging is used, and the oxygen content inside the packaging bag is below 2%.

[0042] Comparative Example 1 This comparative example provides a processing technology for quick-brew cold-infusion jasmine tea made from whole leaves. The difference from Example 1 is that the puffing process is a single-stage high-pressure puffing process, which includes the following steps: S1, Single-stage high-pressure expansion: The original green tea leaves were adjusted to a moisture content of 30% and placed in a high-pressure expansion tank. Using a single-stage expansion process, the temperature of the expansion tank was first raised to 100℃. The rehydrated tea leaves were then placed in the expansion tank and pressurized at a pressure of 0.6MPa. After continuous pressurization, the moisture entered a superheated state, and the vapor pressure also increased significantly. The high pressure caused the bubbles to shear and rupture at the weak points of the cell walls. When the pressure reached the set value, it was instantly depressurized to -0.08MPa, and the temperature dropped to 70℃ at the same time. At this time, the pore structure of the tea leaves expanded by about 1600 times in volume during the instantaneous vaporization of moisture, causing the tea tissue to partially disintegrate and break or become loose and porous.

[0043] S2, freeze-drying: The expanded tea leaves were rehydrated twice to control the moisture content at 25%. The tea leaves were then pre-frozen at -20℃ for 4 hours. During this time, the water absorbed into the pores and cells formed ice crystals, which filled and supported the expanded pores, thus solidifying the pore structure formed by the single high-pressure expansion. Then, directional sublimation drying was carried out under vacuum ≤10Pa and cold trap temperature ≤-50℃. The drying temperature curve was: -20℃ for 4 hours → -10℃ for 3 hours → 0℃ for 2 hours. After the ice crystals sublimated, the pore structure was further shaped, resulting in dried tea leaves with a shaped pore structure. The moisture content of the dried tea leaves was approximately 7%, and the volume expansion rate of the treated tea leaves was 115%. S3, Storage: Dried whole-leaf green tea, porous ceramic particles and fresh jasmine flowers are mixed in a mass ratio of 8:1:1 and scented for 10 hours at a temperature of 35℃ and a relative humidity of 65%. The porous ceramic particles have a pore size of 100 μm and a specific surface area of ​​300 m². 2 / g, porous ceramic particles modified with silane coupling agent; When fresh jasmine flowers are mixed with tea leaves that have a porous structure, the moisture content of the tea leaves is about 7%, while the moisture content of the fresh flowers is over 75%. At this point, the tea leaves with a porous structure have a strong water absorption capacity, and the aroma emitted by the fresh flowers can quickly diffuse into the porous structure of the tea leaves along with the moisture and be absorbed. Meanwhile, the porous ceramic particles have micron and nano-sized pores inside. When aroma substances enter the ceramic pores, they are locked in by the intermolecular forces of the pore walls and then adsorbed. High-quality jasmine flowers typically release their fragrance most intensely and freshest during the 2-4 hour scenting process. At this time, the tea leaves don't have time to absorb the fragrance released by the flowers, so the porous ceramic particles quickly absorb it first. When the fragrance concentration of the flowers weakens, the porous ceramic particles can slowly release the fragrance to replenish the intensity, allowing the tea leaves to fully absorb the fragrance during the best time of release throughout the entire scenting process, maximizing the use of the fragrance and improving the scenting quality. S4. Fresh flower sorting: The scented fresh flowers are sifted out using a flower sifting machine, and the remaining mixture of tea leaves and porous ceramic particles enters the subsequent processing stage.

[0044] S5. Drying and Separation: Drying and separation are carried out using a fluidized bed at a drying temperature of 70℃, an ambient humidity of 30%, and an internal circulating airflow velocity of 10m / s. The scented tea leaves and the porous ceramic particle mixture are placed in the fluidized bed. The high temperature and vibration cause the ceramic particles to continuously release the adsorbed aroma into the drying chamber, allowing the tea leaves to re-enrich the adsorbed aroma during the drying process and reducing aroma loss. Simultaneously, during the drying process, the tea leaves and ceramic particles are gradually separated by gravity and size due to vibration and airflow separation in the fluidized bed. The dried tea leaves and ceramic particles are discharged from different outlets, resulting in scented jasmine tea with a moisture content of less than 6%.

[0045] S6, Microcapsule loading: The dried jasmine tea was placed in a vacuum reactor and spread to a thickness of 3 cm. The reactor was evacuated to -0.09 MPa, and then a jasmine essential oil microcapsule suspension was injected. The mixture was treated with ultrasonic assistance for 20 minutes, so that the microcapsules were loaded into the pore structure of the tea leaves under negative pressure. The concentration of microcapsules in the microcapsule suspension was 5%, and the amount of microcapsule suspension added was 10% of the tea mass. The ultrasonic treatment frequency was 40kHz and the power was 200W. After ultrasonic treatment, the pressure should be slowly restored to normal within 10 minutes to avoid damaging the pore structure of the tea leaves. Post-processing: The tea leaves obtained after ultrasonic treatment are placed at a temperature of 40℃ and a humidity of 60% for 60 minutes to allow the surface pores to close appropriately. Then, they are dried with hot air at 50℃ for about 30 minutes until the moisture content of the tea leaves is below 6%. The loading of the microcapsules was determined by thermogravimetric analysis, and the loading was approximately 5%. S6, Package: When the temperature is below 30℃ and the humidity is below 30%, nitrogen-filled packaging is used, and the oxygen content inside the packaging bag is below 2%.

[0046] Experimental Example 1 1. The pore structure of tea leaves before and after gradient pressure puffing in Example 1 of the present invention was characterized, and the characterization results are as follows: Figure 1 As shown (an electron microscope image of green tea used for scenting jasmine tea). Figure 1 Image a shows the structure of green tea before puffing, exhibiting a dense and complete original structure. Figure 1 Table b shows the expanded chloroplasts, exhibiting a loose, porous, honeycomb-like reconstructed structure, as detailed in Table 1: Table 1:

[0047] 2. The tea leaves prepared in Examples 1-3 and Comparative Example 1 of this invention were tested, and the test results are shown in Table 2: Table 2:

[0048] The greater the volume expansion rate, the higher the total porosity.

[0049] Connecting porosity is indirectly represented by the loading of aroma microcapsules; the higher the loading, the higher the connecting porosity.

[0050] The water extract content was tested according to the national standard method GB / T 8305-2013. 5g of tea leaves were weighed, added to 250ml of room temperature water, brewed, and then tested.

[0051] Compared with Comparative Example 1, Examples 1-2 showed that the interconnected porosity (aroma loading) was increased by 1 time, the cold soaking time to reach 80% extract was shortened by more than 40 minutes, the extract was increased by more than 45% after 5 minutes of cold soaking, and the leaf integrity rate was significantly improved.

[0052] Compared with Example 3 (without freeze-drying), Examples 1-2 show that: the interconnected porosity (aroma loading) is increased by 42%, the cold soaking time to reach 80% extract is shortened by more than 25 minutes, and the extract yield is increased by more than 8% after 5 minutes of cold soaking.

[0053] The data above show that Examples 1-3 have a significant advantage in cold-soaking effect compared with Comparative Example 1.

[0054] 3. Sensory evaluation was conducted on the teas prepared in Examples 1-3 and Comparative Example 1 of this invention using the national standard GB / T 23776-2018 and the industry-standard cold-brew tea brewing method. The results are shown in Table 3. Table 3:

[0055] Physicochemical index testing: Weigh 5g of tea leaves, add 250ml of room temperature water and steep for 15 minutes, then pour out the tea soup for testing of solids and tea polyphenols.

[0056] Sensory evaluation: Weigh 5g of tea leaves, add 250ml of room temperature water, steep for 15 minutes, and then pour out the tea for evaluation.

[0057] Based on the above sensory and basic physicochemical results, it can be seen that: Examples 1-2 achieved a comprehensive score of over 90 points, exhibiting intact and fluffy leaves with fully expanded infusions, a bright yellow-green liquor, a fresh and rich aroma, and a mellow, refreshing taste with a pronounced floral fragrance; the solid content (0.32-0.33 brix) and tea polyphenols (0.42%-0.45%) were significantly higher than those of Comparative Example 1. The processes in Examples 1-3 have good universality and are applicable to various tea types such as jasmine tea and gardenia oolong tea. They can effectively maintain the integrity of the tea leaf structure, promote the coordinated dissolution of internal components, and achieve a comprehensive improvement in color, aroma, and flavor quality.

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A processing method for quick-brew whole-leaf cold-brewing tea, characterized in that, Includes the following steps: Gradient pressure variable expansion of tea leaves: Raw tea leaves are placed in a sealed container and expanded using a gradient pressure variable expansion process to obtain expanded tea leaves with an interconnected pore network structure; the moisture content of the expanded tea leaves is controlled to below 8% to obtain dried tea leaves; the pressure range of the gradient pressure variable expansion process is 0.3-0.9MPa, and the temperature range is 85-110℃; Scenting: Dry tea leaves, porous media and fresh flowers and fruits are mixed and scented to obtain a mixture, and then the scented tea leaves are separated. Packaging: The scented tea leaves are packaged to obtain quick-brew whole-leaf cold-brew tea.

2. The processing technology according to claim 1, characterized in that, In the gradient pressure variation puffing of tea leaves, the moisture content of the raw tea leaves is 30-60%. And / or, the gradient pressure variation expansion process is a method of gradually increasing pressure and temperature followed by pressure release; preferably, it is a three-stage pressure gradient pressure variation expansion process, including: Level 1: Maintain for 3-5 minutes under pressure of 0.3-0.5 MPa and temperature of 85-95℃; Second stage: Maintain for 2-4 minutes under pressure of 0.6-0.9 MPa and temperature of 100-110℃; Level 3: Within 3-10 seconds, the pressure is released to -0.095~-0.08MPa, and the temperature is reduced to 50-60℃.

3. The processing technology according to claim 1, characterized in that, The moisture content of puffed tea leaves is controlled to below 8% by freeze-drying to obtain dried tea leaves. The specific process of freeze-drying includes: adjusting the moisture content of puffed tea leaves to 25%-35% and then freeze-drying them to obtain dried tea leaves with a moisture content controlled to below 8%. Preferably, in the freeze-drying process, the freezing conditions are: freezing treatment at -25℃ to -15℃ for 2-4 hours; the drying conditions are: sublimation under vacuum degree ≤10Pa and cold trap temperature ≤-50℃. The sublimation process includes: maintaining at -25~-15℃ for 3.5-4.5h, then maintaining at -15~-5℃ for 2.5-3.5h, and finally maintaining at -5~5℃ for 2h.

4. The processing technology according to claim 1, characterized in that, During the scenting process, the mass ratio of the dried tea leaves, porous medium, and fresh flowers and fruits is (8-10):(1-2):(1-2). The fresh flowers and fruits include fresh flowers and / or fresh fruits.

5. The processing technology according to claim 4, characterized in that, The scenting process includes: treating for 6-10 hours at a temperature of 35-45℃ and a relative humidity of 55%-65%.

6. The processing technology according to claim 4, characterized in that, The porous medium is porous ceramic particles; Preferably, the porous ceramic particles have a pore size of 50-200 μm and a specific surface area of ​​200-400 m². 2 / g; and / or, the porous ceramic particles are modified with a silane coupling agent.

7. The processing technology according to claim 1, characterized in that, The separation step is followed by a microcapsule loading step, which includes: mixing scented tea leaves with microcapsule suspension under vacuum conditions and then subjecting the mixture to ultrasonic treatment to obtain microcapsule tea leaves; and encapsulating the microcapsule tea leaves to obtain quick-brew whole-leaf cold-brew tea.

8. The processing technology according to claim 7, characterized in that, The ultrasonic treatment time is 15-25 minutes; And / or, the mass concentration of microcapsules in the microcapsule suspension is 5-10%; And / or, the microcapsules have a particle size of 5-20 μm.

9. A quick-brew whole-leaf cold-brew tea, characterized in that, It is prepared by the processing technology described in any one of claims 1-8.

10. A method for brewing quick-infusion cold-brewed whole-leaf tea, characterized in that, The steps include: adding the quick-brew whole-leaf cold-brew tea as described in claim 9 to room temperature water and letting it stand for 5-10 minutes.

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