Processing method for improving clarity of instant tea

Abstract

The invention discloses a processing method for improving clarity of instant tea, and belongs to the technical field of deep processing of tea leaves, the method mainly comprises the following steps: extracting and roughly filtering tea leaves to obtain primary tea soup; adding a compound enzyme into the primary tea soup, carrying out enzymolysis treatment, and then carrying out enzyme deactivation; sequentially performing ceramic membrane microfiltration, ultrafiltration membrane fine filtration and nanofiltration membrane concentration on the treated tea soup; quickly cooling the obtained concentrated solution, standing and aging at low temperature, and centrifuging at high speed to obtain supernatant liquid; and finally, drying to obtain the instant tea powder. According to the method, various substances causing turbidity in tea soup are systematically removed through the synergistic effect of exogenous enzymolysis, three-stage membrane integrated purification and low-temperature physical coagulation acceleration, and the method has the beneficial effects that the final clarity and cold water solubility of an instant tea product can be effectively improved, and the storage stability of the product is improved.

Description

Technical Field

[0001] This invention relates to the field of instant tea technology, and in particular to a processing method for improving the clarity of instant tea. Background Technology

[0002] Instant tea is a solid beverage that dissolves rapidly in water. It is made from finished tea, semi-finished tea, tea by-products, or fresh leaves through processes such as extraction, filtration, concentration, and drying. It is a new type of beverage that easily dissolves in water without tea residue, and can be in granular, powdered, or flake form. It has advantages such as convenient preparation and portability, and no pesticide residue. It is divided into two categories: pure tea and blended tea. Common pure teas include instant black tea, instant green tea, instant Tieguanyin, instant oolong tea, instant jasmine tea, and instant Pu-erh tea.

[0003] The process of instant tea generally includes extraction, filtration, refining, concentration, and drying. However, the instant tea products prepared by existing technologies are not clear and are relatively cloudy after dissolving, indicating that there are insoluble substances suspended in the tea soup. The existing production process cannot meet the product requirements. Summary of the Invention

[0004] The purpose of this invention is to provide a processing method to improve the clarity of instant tea, and to solve the technical problem that traditional instant tea processing technology is unable to remove various turbid substances of different properties from the tea soup, resulting in the product becoming cloudy when brewed with cold water and having poor storage stability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a processing method for improving the clarity of instant tea, comprising the following steps: S1. Raw material extraction and coarse filtration: The tea leaves are extracted and then coarsely filtered to obtain the primary tea infusion; S2. Exogenous enzymatic hydrolysis treatment: Add a compound enzyme to the primary tea infusion to carry out enzymatic hydrolysis reaction, and after the reaction is completed, perform enzyme inactivation treatment; S3. Three-stage membrane integrated purification: The tea soup after enzyme inactivation treatment is sequentially subjected to ceramic membrane microfiltration, ultrafiltration membrane fine filtration and nanofiltration membrane concentration to obtain high-purity tea concentrate. S4. Low-temperature physical coagulation: After the high-purity tea concentrate is rapidly cooled, it is allowed to stand at low temperature for aging, and then centrifuged at high speed to obtain the supernatant. S5. Drying and shaping: The upper clear liquid is dried to obtain high-clarity instant tea powder.

[0006] Furthermore, in step S2, the complex enzyme includes pectinase and β-glucanase, and the amount added is 0.03%-0.05% of the total weight of the primary tea infusion, wherein the mass ratio of pectinase to β-glucanase is 1.5%-2.5%:1; the enzymatic hydrolysis reaction temperature is 45-50℃, the pH is 4.5-5.5, and the time is 40-60 minutes.

[0007] Furthermore, in step S3, the ceramic membrane microfiltration uses a ceramic membrane with a pore size of 0.1-0.2 μm, an operating temperature of 45-50℃, a transmembrane pressure difference of 0.20-0.35 MPa, and uses a periodic reverse pulse method to maintain flux stability.

[0008] Furthermore, in step S3, the ultrafiltration membrane used for fine filtration has a molecular weight cutoff of 3000-5000 Da, an operating temperature of 40-45℃, and a transmembrane pressure difference of 0.8-1.2 MPa; the nanofiltration membrane used for concentration has a molecular weight cutoff of 200-400 Da, an operating temperature of 25-35℃, an operating pressure of 1.5-2.5 MPa, and the concentration endpoint is to concentrate the tea soup volume to 1 / 5 to 1 / 8 of the original volume.

[0009] Furthermore, in step S4, the rapid cooling involves reducing the temperature of the tea concentrate from 25-35°C to 2-5°C within 1-3 minutes; the low-temperature static aging involves standing at 0-4°C for 30-60 minutes; and the high-speed centrifugation involves a rotation speed of 15000-18000 rpm for 10-15 minutes.

[0010] Furthermore, in step S1, the extraction is carried out using a dynamic countercurrent extraction process, with an extraction temperature of 75-85℃, a material-to-liquid ratio of 1:(15-20), and a total extraction time of 15-25 minutes; the coarse filtration is carried out using a 100-200 mesh sieve or centrifugal separation to remove tea residue.

[0011] Furthermore, between steps S3 and S4, there is also a preparation step: adding 0.5%-1% of maltodextrin by weight to the high-purity tea concentrate and stirring evenly.

[0012] Furthermore, in step S5, the drying is spray drying, with an inlet air temperature of 140-155℃ and an outlet air temperature of 75-85℃; or, the drying is freeze drying.

[0013] Furthermore, an instant tea product, prepared by any of the above processing methods, wherein the instant tea product dissolves in cold water at 4°C for less than 30 seconds, and the turbidity of a 0.5% mass concentration tea infusion is less than 5.0 NTU.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention first uses exogenous enzymatic hydrolysis to effectively decompose large molecules such as pectin, which are the main components causing the tea soup to become viscous and cloudy. Then, a three-stage membrane integrated purification step uses membrane components of different precision to remove various impurities, ranging from micron-sized particles to nano-sized colloids and bitter small molecules. Finally, a low-temperature physical coagulation step specifically treats the unstable components that remain in the previous steps and are sensitive to temperature. These three processes work in a progressive and synergistic manner, so that the turbidity of the final product can be stably controlled at an extremely low level, solving the technical problem that traditional process products are prone to turbidity or precipitation when brewed with cold water or in low-temperature environments.

[0015] 2. This invention introduces rapid cooling and low-temperature static aging operations before drying. Through precise control of temperature and time, these trace, unstable, heat-sensitive components are pre-aggregated and form separable flocs, which are then completely removed by high-speed centrifugation. This step eliminates potential factors that could lead to quality deterioration of the product during its shelf life, ensuring that the instant tea powder remains consistently clear from production to the consumer. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic flowchart of a processing method for improving the clarity of instant tea according to the present invention; Figure 2 This is a schematic diagram of the core steps of a processing method for improving the clarity of instant tea according to the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The following specific embodiments may be combined or substituted with each other according to the actual situation, and the same or similar concepts or processes may not be described again in some embodiments.

[0019] Example 1, such as Figures 1 to 2 As shown, the present invention provides a processing method for improving the clarity of instant tea, comprising the following steps: S1. Raw material extraction and coarse filtration: Weigh 1.0 kg of medium-grade pan-fried green tea and crush it to 40-60 mesh using a crusher. The purpose of crushing the tea is to increase the contact area between the tea and water, accelerate the dissolution rate of effective components such as tea polyphenols and amino acids, and improve the extraction efficiency. A three-tank series dynamic countercurrent extraction device is used for extraction. The specific operation is as follows: In the first extraction tank, add the crushed tea and hot water at a temperature of (80±2)℃, with a solid-liquid mass ratio of 1:18. Turn on the stirring and extract for 10 minutes at a speed of 60 rpm. Then, pump all the first extraction liquid into the second extraction tank, which already contains new tea leaves, for a second extraction. The sample was subjected to a third extraction, with fresh hot water added to the first extraction tank. The total extraction time was controlled at 22 minutes. After extraction, a horizontal spiral sedimentation centrifuge with a 200-mesh screen was used to continuously centrifuge and coarsely filter the mixed tea liquor at 3000 rpm, separating visible tea residue and obtaining approximately 17.5 liters of primary green tea liquor. Refractometer analysis showed that its soluble solids content was 2.2 Brix. Dynamic countercurrent extraction is a solid-liquid extraction technology based on maximizing mass transfer efficiency. Its core principle lies in causing the solid raw material and the extraction solvent to move in opposite directions and continuously contact each other in a multi-stage series extraction unit. During this process, the fresh raw material is always in contact with the nearly saturated extract, while the fresh solvent is in contact with the almost exhausted raw material. This counter-flow and multi-stage series structure establishes and maintains the maximum solute concentration gradient at each contact surface, thereby continuously providing the driving force for efficient mass transfer. As a result, the process can achieve higher extraction rates of target components and obtain higher concentration extracts with relatively small solvent consumption and shorter extraction time, while reducing heat consumption and damage to heat-sensitive components. Refractometer Measurement Data Table - Table 1 ; S2. Exogenous Enzymatic Hydrolysis Treatment: The above-mentioned primary tea infusion is pumped into an enzymatic hydrolysis tank equipped with stirring and temperature control. It is rapidly cooled to 48°C using a plate heat exchanger. The pH of the tea infusion is adjusted to 5.0 using food-grade citric acid solution. Then, 7.0 g of pectinase (50,000 U / g activity) and 3.5 g of β-glucanase (20,000 U / g activity) are accurately weighed (the total amount added is 0.042% of the tea infusion weight, with a mass ratio of 2:1). After activation with a small amount of 40°C warm water, the mixture is added to the tea infusion. The mixture is continuously stirred at 70 rpm at 48°C for 50 minutes for enzymatic hydrolysis. After the reaction, steam is introduced into the jacket to raise the temperature of the tea infusion to 88°C within 5 minutes and maintain this temperature for 5 minutes to completely inactivate the enzymes. Cool to approximately 45°C; cooling the initial tea infusion ensures that it is in a state of maximum catalytic activity with the enzymes. The optimal temperature range for commonly used food enzymes such as pectinase and β-glucanase is usually 45-55°C. At the same time, lowering the temperature slows down the oxidation and loss of flavor substances in the tea infusion and stabilizes the pH at 5.0, which also creates the optimal acid-base environment for the compound enzymes used. Pectinase specifically hydrolyzes the pectin molecules, which are the most abundant in the tea infusion and contribute the most to viscosity, breaking down their long chains into short-chain oligosaccharides or galacturonic acid, thereby significantly reducing the viscosity of the tea infusion. β-glucanase specifically decomposes β-glucan and other colloidal polysaccharides released from the cell walls of tea leaves, forming a synergistic coating with pectinase to more comprehensively disintegrate the colloidal network. S3. This step uses a three-stage membrane system in series. S3a. Ceramic membrane microfiltration: The enzyme-inactivated tea liquor is used as the feed liquid and pumped into a microfiltration system equipped with a 0.2μm pore size zirconia ceramic membrane module. The operating temperature is set at 48℃, the inlet pressure is controlled at 0.28 MPa, and the outlet pressure is controlled at 0.20 MPa to maintain a stable transmembrane pressure difference. The system is set to automatically perform a 5-second reverse pulse flush every 25 minutes to maintain stable membrane flux. All microfiltration permeate is collected and is visually clear. This step can effectively filter out fine suspended particles, residual tea powder, and tiny fibers in the tea liquor. These substances are the main reasons for the tea liquor to appear dull and not clear.

[0020] S3b. The microfiltration permeate is pumped into an ultrafiltration system equipped with spiral wound membrane elements. The membrane element is made of polyethersulfone with a nominal molecular weight cutoff of 3500 Daltons. The operating parameters are: temperature (40±2)℃, system pressure adjusted to inlet pressure 1.0 MPa, and reflux pressure 0.6 MPa. A full-flow filtration mode is used. Initially, all the concentrate and permeate are refluxed back to the feed tank. After running for 15 minutes until the permeate conductivity reading stabilizes, the permeate is separated. The concentrate reflux ratio is controlled to ensure the system operates at approximately 3 times the volumetric concentration ratio. The ultrafiltration permeate is clear and transparent, appearing watery. This step specifically removes large molecules such as proteins and pectin dissolved in the tea infusion. These substances tend to aggregate and form visible turbidity or sediment when the tea infusion temperature decreases or its concentration changes (e.g., when brewed with cold water or stored). Removing these substances allows instant tea to remain clear even when steeped in cold water. S3c, Nanofiltration Membrane Concentration and Modification: The ultrafiltration permeate is pumped into the nanofiltration system, using an aromatic polyamide composite nanofiltration membrane with a molecular weight cutoff of approximately 300 Da. Operation is carried out at 30°C and a pressure of 2.0 MPa. The tea infusion volume is concentrated to 1 / 6 of the original ultrafiltration permeate volume (i.e., 6 times concentrated), yielding approximately 2.9 liters of high-purity tea concentrate. The soluble solids content is measured to be approximately 20.5°Bx. The nanofiltration permeate water (containing some caffeine and minerals) is collected separately. This step, while efficiently removing water and significantly concentrating the tea, selectively removes some small molecules such as caffeine that contribute to bitterness, resulting in a smoother product taste and reduced bitterness. S4. Low-temperature physical coagulation: The nanofiltration concentrate is passed through a plate heat exchanger and cooled from 30°C to 4°C within 2 minutes using 2°C cooling water. This process significantly reduces the solubility of heat-sensitive colloidal substances, causing them to rapidly reach supersaturation from a "metastable dissolution state," thus forcing them to precipitate and form initial fine flocculent particles. The low-temperature concentrate is then transferred to a refrigerant-insulated tank and allowed to stand at 3°C ​​for 50 minutes, during which it is slowly stirred at 25 rpm. The mixture is then slowly stirred and maintained at a constant low temperature (0-4°C) for 30-60 minutes. This stage is the "maturation period," during which the fine particles collide and aggregate, growing into larger, denser, and more easily separated flocculent clumps. Finally, a high-speed tubular centrifuge is used to centrifuge at 16,000 rpm for 12 minutes to thoroughly and quickly separate the aggregated and grown flocculent clumps from the clear liquid. The upper clear liquid is then siphoned out, and a very small amount of dense flocculent material, accounting for about 3% of the total volume, is discarded at the bottom. S5. Drying and Shaping: Add 0.8% by weight of maltodextrin (DE value 15) to the supernatant obtained by centrifugation, stir in a 45℃ water bath until completely dissolved, standardize the formulation, and then perform spray drying: set the inlet air temperature to 152℃ and control the outlet air temperature at 80℃, use a centrifugal atomizer to collect the powder in the drying tower and cyclone separator to obtain about 215 grams of instant green tea powder, which solves the problem that high-purity tea concentrate is not easy to store and transport, and is prone to microbial spoilage or slow chemical changes; S6. Membrane Cleaning and Maintenance: After each batch of production is completed and the membrane system is shut down, immediately flush each membrane module with softened water at 50°C for 15 minutes. Then perform chemical cleaning: First, use a cleaning solution containing 1.0% NaOH and 0.2% Na-EDTA to clean the ceramic membrane and ultrafiltration membrane at 50°C for 45 minutes, and the nanofiltration membrane for 30 minutes; after rinsing with softened water until neutral, clean all membrane modules with a 0.5% nitric acid solution at 40°C for 30 minutes; finally, thoroughly rinse with softened water until the effluent pH is neutral. After cleaning, test the clean water flux; all fluxes have recovered to over 92% of the initial flux.

[0021] Comparative Example 1: S1. Raw material pretreatment: Weigh 1.00 kg of pan-fried green tea, which is exactly the same as in Example 1, and extract and coarsely filter it through a 200-mesh screen under the same conditions (80℃, 1:18, 22 minutes) to obtain a primary tea soup with the same initial properties. S2. Filtration: The initial tea infusion is pumped into a plate and frame diatomaceous earth filter. The total amount of pre-coated and added diatomaceous earth is 0.5% of the weight of the tea infusion. Filtration is carried out at a pressure of 0.4 MPa to obtain the filtrate. After filtration, the turbidity of the tea infusion decreased from 186 NTU to 65 NTU. S3. Vacuum thermal concentration: The above filtrate is transferred to a single-effect vacuum concentrator and concentrated by evaporation at 65°C and -0.085 MPa (absolute pressure) until the volume of the concentrate is similar to that of the nanofiltration concentrate in Example 1 (approximately 2.6 liters), and the soluble solids content is approximately 20.1°Bx. This process takes approximately 85 minutes. S4. The hot concentrated liquid is directly spray-dried with the same parameters as in Example 1 (inlet air 152°C, outlet air 80°C), and the powder is collected to obtain 203 grams of instant green tea powder.

[0022] Comparison Table 2 of Key Performance Indicators of Example 1 and Comparative Example 1 Based on the comparative data of Example 1 and Comparative Example 1 above, the following clear conclusions can be drawn: 1. In terms of product clarity, the process of this invention has significant advantages. Through the systematic treatment of "enzymatic hydrolysis-membrane integration-low temperature coagulation", the final tea soup turbidity (2.8 NTU) is much lower than that of the traditional diatomaceous earth filtration heating concentration process (15.6 NTU), proving that it removes various substances that cause turbidity more thoroughly.

[0023] 2. The process of this invention achieves a comprehensive improvement in the overall quality of the product. Compared with the traditional process, the product of this invention performs better in terms of cold water dissolution speed and state; it retains more heat-sensitive flavor substances (tea polyphenols, amino acids), which is related to the gentle membrane treatment process and avoidance of long-term heat concentration; in sensory evaluation, it has obtained higher scores in appearance, taste and resistance to "cold turbidity".

[0024] 3. The process of this invention demonstrates excellent efficiency and yield. This invention achieves a higher product yield (215g vs. 203g), which may be attributed to the improved dissolution and retention of soluble components through enzymatic hydrolysis, and the efficient retention of target components by the membrane system. Simultaneously, the concentration process is significantly shortened (approximately 25 minutes vs. 85 minutes), indicating potential advantages in production efficiency and energy consumption.

[0025] In summary, compared with the traditional diatomaceous earth filtration combined with vacuum heat concentration process, the process provided by the present invention can not only significantly improve the clarity, cold-dissolving stability and flavor quality of instant tea products, but also show positive effects in terms of production efficiency and substance retention, fully demonstrating the beneficial effects and progressiveness of the technical solution described in the present invention.

[0026] Example 2; This example aims to illustrate that, within the overall technological framework of the processing method for improving the clarity of instant tea according to the present invention, black tea is selected as the processing object, demonstrating the feasibility of adjusting process parameters for different tea categories. The specific steps are as follows; S1. Raw material extraction and coarse filtration: Weigh 1.0 kg of broken black tea, grind it to about 40 mesh, and use hot water at 85℃ for countercurrent dynamic extraction. The material-to-liquid ratio is 1:16 (tea:water), and the total extraction time is 18 minutes. After extraction, it is coarsely filtered through a 200-mesh sieve to obtain primary black tea soup. S2. Exogenous enzymatic hydrolysis treatment: Adjust the tea infusion temperature to 45℃ and the pH value to 5.2. Add a compound enzyme at 0.035% of the total weight of the tea infusion, with a pectinase to β-glucanase mass ratio of 1.8:1. Carry out the enzymatic hydrolysis reaction at 45℃ for 55 minutes, then raise the temperature to 90℃ for 5 minutes to inactivate the enzyme, and then cool. S3. Three-stage membrane integrated purification: S3a. Ceramic membrane microfiltration: A 0.2μm ceramic membrane is used, the operating temperature is set to 50℃, and the transmembrane pressure difference is controlled at 0.25MPa; S3b. Ultrafiltration membrane fine filtration: Select a spiral wound ultrafiltration membrane with a molecular weight cutoff of 5000 Da, operating pressure of 1.2 MPa, and temperature of 40℃; S3c. Nanofiltration membrane concentration: The volume of tea infusion is concentrated to about 1 / 7 of the original volume of the ultrafiltration permeate, and the operating conditions are the same as in Example 1; S4. Low-temperature physical coagulation: The nanofiltration concentrate was rapidly cooled to 5°C, then transferred to a 2°C environment and allowed to stand for aging for 60 minutes. Finally, solid-liquid separation was performed using a high-speed centrifuge at 15,000 rpm, and the supernatant was collected. S5. Drying and Shaping: In order to preserve the flavor of black tea to the greatest extent, this embodiment adopts a freeze-drying process. After pre-freezing the supernatant, it is placed in a freeze dryer to dry and obtain instant black tea powder.

[0027] Results: The instant black tea powder produced by this process has a turbidity of 3.5 NTU in a 0.5% cold aqueous solution, a bright red color, good solubility, and a pure black tea flavor. This example demonstrates that by adjusting the extraction temperature, enzymatic hydrolysis parameters, and membrane operating conditions, the method is also applicable to black tea and can achieve the desired improvement in clarity. Example 3: This example further illustrates the implementation method of optimizing product characteristics by combining optional adjustment steps based on the overall process. The specific steps are as follows; The front-end process, from the extraction and coarse filtration of oolong tea raw materials to exogenous enzymatic hydrolysis, three-stage membrane integrated purification, and low-temperature physical coagulation, can be carried out with reference to Example 1 in terms of operation and parameter control. After low-temperature centrifugation, a highly clear oolong tea concentrate is obtained in the upper layer. Following this, the following mixing steps are introduced: Add 1.0% by weight of maltodextrin (DE value 15) to the clarified oolong tea concentrate and stir at 45°C until completely dissolved. This step aims to improve the physical properties of the subsequently dried material and enhance the flowability and solubility of the finished powder. Simultaneously, to enhance the characteristic aroma of oolong tea, 0.05% by weight of natural oolong tea essential oil can be selectively added, ensuring thorough mixing. After preparation, the liquid is spray-dried (inlet air temperature 150℃, outlet air temperature 80℃) to obtain instant oolong tea powder.

[0028] Implementation Results: The product obtained in this embodiment firstly inherits the high clarity advantage brought by the core process. Secondly, the physical properties of the powder are improved by adding maltodextrin. The selective addition of natural essential oils helps to form or enhance the pleasant characteristic flavor. This embodiment shows that the core clarification process can be effectively combined with subsequent compliant blending steps, providing a specific solution for developing customized high clarity instant tea products that meet different market demands.

[0029] In addition to the preferred embodiments described above, the present invention has other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection claimed by the present invention.

Claims

1. A processing method for improving the clarity of instant tea, characterized in that, Includes the following steps: S1. Raw material extraction and coarse filtration: The tea leaves are extracted and then coarsely filtered to obtain the primary tea infusion; S2. Exogenous enzymatic hydrolysis treatment: Add a compound enzyme to the primary tea infusion to carry out enzymatic hydrolysis reaction, and after the reaction is completed, perform enzyme inactivation treatment; S3. Three-stage membrane integrated purification: The tea soup after enzyme inactivation treatment is sequentially subjected to ceramic membrane microfiltration, ultrafiltration membrane fine filtration and nanofiltration membrane concentration to obtain high-purity tea concentrate. S4. Low-temperature physical coagulation: After the high-purity tea concentrate is rapidly cooled, it is allowed to stand at low temperature for aging, and then centrifuged at high speed to obtain the supernatant. S5. Drying and shaping: The upper clear liquid is dried to obtain high-clarity instant tea powder.

2. The processing method for improving the clarity of instant tea according to claim 1, characterized in that, In step S2, the complex enzyme includes pectinase and β-glucanase, and the amount added is 0.03%-0.05% of the total weight of the primary tea infusion, wherein the mass ratio of pectinase to β-glucanase is 1.5%-2.5%:1; the enzymatic hydrolysis reaction temperature is 45-50℃, the pH is 4.5-5.5, and the time is 40-60 minutes.

3. The processing method for improving the clarity of instant tea according to claim 1, characterized in that, In step S3, the ceramic membrane microfiltration uses a ceramic membrane with a pore size of 0.1-0.2 μm, an operating temperature of 45-50℃, a transmembrane pressure difference of 0.20-0.35 MPa, and uses a periodic reverse pulse method to maintain flux stability.

4. The processing method for improving the clarity of instant tea according to claim 1, characterized in that, In step S3, the ultrafiltration membrane used for fine filtration has a molecular weight cutoff of 3000-5000 Da, an operating temperature of 40-45℃, and a transmembrane pressure difference of 0.8-1.2 MPa; the nanofiltration membrane used for concentration has a molecular weight cutoff of 200-400 Da, an operating temperature of 25-35℃, an operating pressure of 1.5-2.5 MPa, and the concentration endpoint is to concentrate the tea soup volume to 1 / 5 to 1 / 8 of the original volume.

5. The processing method for improving the clarity of instant tea according to claim 1, characterized in that, In step S4, the rapid cooling is to reduce the tea concentrate from 25-35℃ to 2-5℃ within 1-3 minutes; the low-temperature static aging is to stand at 0-4℃ for 30-60 minutes; the high-speed centrifugation is carried out at a speed of 15000-18000 rpm for 10-15 minutes.

6. The processing method for improving the clarity of instant tea according to claim 1, characterized in that, In step S1, the extraction is carried out using a dynamic countercurrent extraction process, with an extraction temperature of 75-85℃, a material-to-liquid ratio of 1:15-1:20, and a total extraction time of 15-25 minutes; the coarse filtration is carried out using a 100-200 mesh sieve or centrifugal separation to remove tea residue.

7. The processing method for improving the clarity of instant tea according to claim 1, characterized in that, Between steps S3 and S4, there is also a preparation step: adding 0.5%-1% of maltodextrin by weight to the high-purity tea concentrate and stirring evenly.

8. The processing method for improving the clarity of instant tea according to claim 1, characterized in that, In step S5, the drying is spray drying, with an inlet air temperature of 140-155℃ and an outlet air temperature of 75-85℃; or, the drying is freeze drying.

9. An instant tea product, characterized in that, The instant tea product, prepared by the processing method according to any one of claims 1 to 8, has a dissolution time of less than 30 seconds in cold water at 4°C and a turbidity of less than 5.0 NTU in a 0.5% mass concentration tea infusion.

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