Preparation method of golden flower Pu'er tea

Abstract

The invention relates to the technical field of tea drink preparation, in particular to a golden flower Pu'er tea preparation method, which takes Pu'er raw tea containing natural strains as a preparation raw material, and further comprises the steps of raw material pretreatment, pressing process treatment, fermentation treatment and post-treatment. According to the preparation method of the golden flower Pu'er tea, staged gradient steaming is combined with microwave treatment, so that the activity of eurotium cristatum can be retained while infectious microbes can be accurately killed, the sterilization efficiency is effectively improved, and the problem that tea leaves and strains are damaged by traditional high-temperature treatment is solved; honeycomb-shaped micropores preset on the surface form a three-dimensional oxygen introduction network, it is ensured that oxygen permeation of the interior of the mold to a tea body is uniform, the density of golden flowers in the mold is improved, then a dynamic three-stage fermentation technology and a composite flora fermentation intervention technology are combined, and temperature and humidity regulation and control and an ultrasonic and infrared synergistic technology are utilized, so that the fermentation period is effectively shortened, and the production efficiency is improved. And the number of eurotium cristatum florae is increased.

Description

Technical Field

[0001] The invention relates to the technical field of tea preparation, in particular to a method for preparing Jinhua Pu'er tea. Background Art

[0002] Golden Flower Pu'er Tea is a special type of Pu'er tea. Its name comes from the golden granular substance that grows naturally on the surface or inside the tea leaves, namely "golden flowers". These golden flowers are actually a beneficial fungus "Cornus cristatus", which can grow under specific temperature and humidity conditions, giving Pu'er tea a unique flavor and health value. It has the effects of regulating intestinal flora, promoting digestion and improving cardiovascular function. It is especially suitable for daily drinking by middle-aged and elderly people.

[0003] After searching, it was found that a process for making Golden Flower Pu'er tea was disclosed in the invention patent with the Chinese patent publication number CN114631574A. The process for making Golden Flower Pu'er tea in the invention patent is to carry out pile fermentation according to the respective characteristics of sun-dried green raw tea and Pu'er cooked loose tea. On the one hand, the color of the tea leaves after pile fermentation can be made as close as possible to Pu'er cooked loose tea, and on the other hand, the coarse green smell can be eliminated, the bitter taste can be reduced, and the aging can be accelerated. By utilizing the characteristic of luxuriant flowering of sun-dried green raw tea, an appropriate proportion of the tea leaves is blended with Pu'er cooked loose tea. As a result, the Golden Flower Pu'er tea processed from this mixed raw material not only has luxuriant "golden flowers" and rich fungus aroma, but also has a mellow and sweet taste, a bright red soup color, and a distinct aged aroma. This solves the problem of less flowering of Pu'er cooked loose tea, and improves the mellowness and sweetness of sun-dried green raw tea after flowering.

[0004] However, the process of preparing Jinhua Pu'er tea relies on competition among natural bacterial species and cannot regulate the bacterial population in a targeted manner. There may be problems such as uneven distribution of the bacterial population and low fermentation efficiency. In addition, relying solely on high-temperature steaming can easily destroy the fiber structure of the tea leaves, resulting in a limited sterilization effect. Therefore, a preparation method of Jinhua Pu'er tea is proposed. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In response to the shortcomings of the existing technology, the present invention provides a method for preparing Jinhua Pu'er tea, which has the advantages of gradient steaming and microwave synergistic treatment, as well as dynamic fermentation regulation, and solves the problem that the existing Jinhua Pu'er tea process method in the above-mentioned background technology needs further improvement in bacterial fermentation and distribution and the effect of killing miscellaneous bacteria.

[0007] (2) Technical solution

[0008] To achieve the above-mentioned purpose of gradient steaming and microwave synergistic treatment and dynamic fermentation control, the present invention provides the following technical solution: a method for preparing Jinhua Pu'er tea, comprising using Pu'er raw tea containing natural strains as a preparation raw material, and further comprising the following implementation steps:

[0009] S1. Raw material pretreatment: Gradient steaming and microwave treatment are used to soften the tea leaves and activate the spores of Eurotium cristatum, effectively sterilizing the tea while preserving the activity of the fungus.

[0010] S2. Pressing process: 3D printing molds are used to press the tea cake to form a three-dimensional oxygen-permeable network system throughout the tea body;

[0011] S3. Fermentation: A dynamic three-stage fermentation control process is used to accelerate the destruction of tea cell walls, release endogenous enzymes, and promote the directional proliferation of the Eurotium cristatum colony.

[0012] S4. Post-processing: Dry the tea body after flowering, and stabilize the activity of the golden flower by spraying with salt water mist and high-pressure steam.

[0013] Preferably, the step of gradient steaming and microwave synergistic treatment comprises:

[0014] 1) In the first stage, the steam temperature is gradually increased from 90° C. to 100° C. and steamed for 5 to 8 seconds, and then the steam temperature is gradually increased from 100° C. to 120° C. and steamed for 8 to 10 seconds, and then the steam is stopped and gradually cooled to room temperature to activate the spores of Eurotium cristatum in the tea leaves;

[0015] 2) In the second stage, the tea leaves were microwaved at a frequency of 2300-2500 MHz for 30-40 seconds to accurately kill the bacteria and retain the activity of the fungus.

[0016] Preferably, a plurality of honeycomb micropores are preset on the surface of the 3D printing mold, and the pore diameter of each micropore is 0.5 to 1 mm to form a honeycomb oxygen-permeable gap. The tea leaves are placed inside the mold and pressed into a tea cake structure at a pressure of 7 to 8 MPa. The tea cake is 70% to 80% of the volume inside the mold.

[0017] Preferably, the fermentation treatment includes a dynamic stage blooming treatment and a composite bacterial fermentation treatment, wherein the dynamic stage blooming treatment step includes:

[0018] 1) The first stage lasts for 3 to 5 days, wherein the tea leaves are placed in a ventilated environment at a temperature of 22 to 25° C. and a humidity of 75%, with an air supply system providing one air change per hour to activate the metabolism of the fungus.

[0019] 2) setting the second stage duration to 5 to 7 days, placing the tea leaves in an ultrasonic environment at a temperature of 25 to 27° C. and a humidity of 65%, setting the ultrasonic frequency to 40 kHz and using intermittent ultrasonic treatment with an interval of 8 to 15 seconds to promote the penetration of the Eurotium cristatum flora into the tea leaves fibers;

[0020] 3) The third stage is set to last 15 to 18 days, and the tea leaves are placed in an infrared environment at a temperature of 30 to 32° C. and a humidity of 55%. Infrared-assisted drying is combined with a treatment to inhibit bacteria, the infrared wavelength is controlled to be 2.5 to 4 μm, and the distribution state of the golden flowers is solidified.

[0021] Preferably, the composite bacterial community fermentation treatment is sprayed with a fermentation promoter after steaming, and the fermentation promoter is a tangerine peel extract containing polysaccharides and flavonoids active ingredients to promote the proliferation of the Eurotium cristatum bacterial community.

[0022] Preferably, the bloomed Pu'er tea body is subjected to stage-by-stage drying at an ambient temperature of 38-42° C., and the moisture content is detected to be ≤14%. The stage-by-stage drying process includes:

[0023] 1) Dry with hot air at 38°C for 2-3 minutes;

[0024] 2) Dry with hot air at 40°C for 1 minute;

[0025] 3) Dry with hot air at 42°C for 30 seconds.

[0026] Preferably, the segmented dried flowering tea body is sprayed with 1% salt water atomization, the steam temperature is set to 150° C., the pressure is 10-12 MPa, and the high-pressure steam treatment is performed for 10 minutes to stabilize the activity state of the golden flower.

[0027] (3) Beneficial effects

[0028] Compared with the prior art, the present invention provides a method for preparing Jinhua Pu'er tea, which has the following beneficial effects:

[0029] 1. The preparation method of Jinhua Pu'er tea adopts staged gradient steaming combined with microwave treatment, which can accurately kill miscellaneous bacteria while retaining the activity of Aspergillus niger, effectively improving the sterilization efficiency and solving the problem of damage to tea leaves and fungi caused by traditional high-temperature treatment.

[0030] 2. The preparation method of the Golden Flower Pu'er tea designs a honeycomb mold, and forms a three-dimensional oxygen network with preset honeycomb micropores on the surface, ensuring uniform oxygen penetration into the tea body from the inside of the mold and improving the density of the golden flowers inside.

[0031] 3. The preparation method of Jinhua Pu'er tea combines dynamic three-stage fermentation technology with complex bacterial community fermentation intervention technology, and uses temperature and humidity control as well as ultrasonic and infrared synergistic technology to effectively shorten the fermentation cycle and increase the number of Aspergillus niger flora.

[0032] 4. The preparation method of Jinhua Pu'er tea adopts segmented hot air drying and high-pressure steam treatment to effectively reduce and maintain the moisture content, ensure the stability of the activity of the golden flower, improve the product shelf life and batch stability, and avoid the risk of mold in traditional processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of the method for preparing Jinhua Pu'er tea of ​​the present invention; DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] Example 1

[0036] In this embodiment, by adopting gradient steaming and microwave synergistic processing technology, precise sterilization can be achieved, and the activity of Eurotium cristatum can be retained to optimize the tea structure. The processing steps include:

[0037] 1) Gradient steaming stage

[0038] a. Stage 1 (Low-temperature activation): Steam treatment at a temperature of 90-100°C for 8 seconds is used to soften the tea leaves and activate the spores of Eurotium cristatum.

[0039] b. Second stage (high temperature sterilization): Gradually raise the temperature to 120°C and maintain for 10 seconds to kill harmful bacteria such as Penicillium and Aspergillus niger;

[0040] During this process, the steam flow rate is controlled at 0.5-1.0 kg / h to ensure uniform penetration of the tea surface;

[0041] 2) Microwave-assisted processing stage

[0042] Set the microwave frequency to 2450MHz and the microwave power to 500-800W for 30-40s to ensure that the microwaves penetrate the tea leaves, selectively heat the water molecules, further inactivate the heat-resistant bacteria, and avoid excessive damage to the tea fibers caused by high-temperature steam, effectively preserving active substances such as tea polyphenols.

[0043] By adopting a coordinated process of gradient steaming followed by microwave treatment, microwave interference with steam penetration can be avoided, and microwave treatment can be carried out immediately after steaming, with an interval of no more than 30 seconds to prevent the cooling of the tea leaves from affecting the sterilization effect. At the same time, the microwave power can be adjusted according to the moisture content of the tea leaves, which is controlled at 18% to 22%, to avoid local overheating.

[0044] Compared with the traditional steaming treatment method, the optimization and improvement of steaming and microwave synergistic treatment are as follows:

[0045]

[0046] Example 2

[0047] In this embodiment, the pressing process steps of the oxygen-permeable network system include:

[0048] 1) Evenly air-dry the tea leaves (moisture content 18% to 22%) after steaming and microwave treatment to 40 to 45°C to restore their elasticity;

[0049] 2) Weigh tea leaves according to the target tea cake weight and evenly spread them into a 3D-printed honeycomb mold (the mold has a pore size of 0.5-1mm and a porosity of 30%). The honeycomb mold has pre-set micropores to form biomimetic oxygen channels to promote uniform oxygen penetration during the later fermentation period.

[0050] 3) Pressure Control: Use a progressive pressure method of 7-8 MPa, with a holding time of 30 seconds. Preheat the mold to 50-60°C to avoid cold pressing and cracking of the tea leaves. Low pressure control reduces fiber breakage and preserves the pore channels within the tea leaves.

[0051] 4) After pressing, use cold air at 20-25℃ to set the shape for 5 minutes, and then demould it to control the density of the tea cake to 0.85-0.90g / cm 3 , and then remove the burrs of the tea cake to ensure the integrity of the microporous structure.

[0052] The pressing process of the oxygen network system is used to reduce the problems of high-pressure densification, random gaps and thermal damage in the traditional tea pressing process. The optimization and improvements are as follows:

[0053]

[0054] Example 3

[0055] In this embodiment, by precisely controlling the temperature, humidity, oxygen, and microbial environment, the dominant growth of Eurotium cristatum is promoted to form a uniformly distributed golden flower structure while suppressing contamination by miscellaneous bacteria. The specific steps include:

[0056] 1) Confirm the moisture content, density, and microporous structural integrity of the pressed tea cakes. Sterilize the fermentation room with ozone for 30 minutes and then wipe the shelves with 75% alcohol to disinfect them. Stack the tea cakes in a crisscross pattern, 5 cm apart, with no more than 8 cakes per layer to ensure airflow.

[0057] 2) During the golden flower activation period, the temperature was set at 22-25°C and the humidity was 75% to promote the germination of Eurotium cristatum spores and inhibit competition from other bacteria. Ultrasonic atomization was used for humidification and fresh air was exchanged once every hour.

[0058] 3) During the golden flower proliferation period, the temperature was set at 25-28°C and the humidity was 65% to promote the proliferation of mycelium and the secretion of extracellular enzymes. The temperature was monitored by infrared thermal imaging, and intermittent hypoxia stimulation was used to control the oxygen concentration to 15%-18%.

[0059] 4) During the golden flower stabilization period, the temperature was set at 28-32°C and the humidity was maintained at 55% to promote the formation of closed capsules and the accumulation of metabolites in the golden flower fungus. Pulsed infrared drying was performed with a controlled wavelength of 2.5-4 μm and a composite probiotic spray was used;

[0060] The steps for monitoring the quality of flower blooming include:

[0061] 1) Using multi-probe IoT sensors, data is uploaded to the cloud in real time to automatically adjust the air conditioning and humidification system devices;

[0062] 2) A microporous ventilation system was used to deliver filtered air into the tea cake pile, briefly reducing the O2 content to 15% during the proliferation phase to stimulate the production of antioxidant enzymes by the golden flower fungus. On the fifth day, tangerine peel extract was sprayed to promote the colonization of the golden flower fungus.

[0063] 3) Take samples every 48 hours and use an ATP fluorescence detector to measure the number of viable bacteria, setting the target value to ≥1×10 5 CFU / g, theaflavin content is monitored online by near-infrared spectroscopy, and theaflavin content is controlled to be ≥0.8mg / g at the end of fermentation, the golden flower coverage rate is ≥80%, there is no mold spot or odor, and the fungus aroma is rich.

[0064] Example 4

[0065] In this embodiment, real-time monitoring of the biomass and metabolites of golden flower fungus during Pu'er tea fermentation requires the use of online detection equipment and dynamic sampling and analysis technology, specifically including:

[0066] 1) Biomass monitoring (OD value detection)

[0067] The ZWYF-290 cell growth curve intelligent detection bioreactor was used to monitor the changes in microbial cell concentration in real time through non-contact optical density (OD) detection with a wavelength set at 600-660 nm.

[0068] 2) Metabolite monitoring

[0069] Near-infrared spectroscopy (NIRS) technology was used to detect the content of tea polyphenols, theaflavins, polysaccharides and other metabolites in the fermentation broth in real time through an online NIRS probe. High-performance liquid chromatography (HPLC) was used to regularly sample and analyze metabolites such as organic acids, amino acids, and tea pigments.

[0070] 3) Bacterial activity monitoring

[0071] Using an ATP fluorescence detector based on the luciferase and luciferin system, the ATP content is detected to reflect the number of viable bacteria, and the automatic colony counter is used to accurately count the number of golden flower fungi colonies and their morphological characteristics;

[0072] Specific monitoring steps include:

[0073] 1) Adjust the moisture content of tea leaves to 18% to 22%, perform gradient steam sterilization, and retain the activity of Eurotium cristoideum. Calibrate the OD detection module of ZWYF-290, set the wavelength to 600 nm, and adjust the baseline OD to 0.03-2.5.

[0074] 2) Tea leaves were placed in a custom-made conical shake flask in a ZWYF-290 reactor. The shaking frequency was set at 150-200 rpm, the temperature was maintained at 25-30°C, and the humidity was maintained at 60%-80%. OD values ​​were monitored online.

[0075] 3) Samples were collected every 24 hours, and the content of tea polyphenols and theaflavins was measured by NIRS or HPLC. The proportion of viable bacteria was evaluated by ATP detector, and metabolites were analyzed.

[0076] 4) Regularly take fermented tea samples and use an automatic colony counter to analyze the density and uniformity of golden flower fungi and evaluate the bacterial distribution;

[0077] 5) Draw an S-shaped growth curve based on the OD value to determine the lag phase, logarithmic phase, and stable phase of the golden flower fungus, establish the correlation between the OD value and theaflavin content, and optimize the fermentation endpoint.

[0078] Compared with the traditional monitoring method, the effects of the improved method are as follows:

[0079]

[0080] The beneficial effects of the present invention are as follows: the method for preparing Jinhua Pu'er tea can accurately kill miscellaneous bacteria while retaining the activity of Eurotium cristatum by adopting staged gradient steaming combined with microwave treatment, effectively improving the sterilization efficiency and solving the problem of damage to tea leaves and fungi caused by traditional high-temperature treatment;

[0081] By designing a honeycomb mold, a three-dimensional oxygen network is formed with the preset honeycomb micropores on the surface, ensuring uniform oxygen penetration into the tea body from the inside of the mold and increasing the density of the internal golden flowers;

[0082] By combining dynamic three-stage fermentation technology with complex bacterial community fermentation intervention technology, and utilizing temperature and humidity control as well as ultrasonic and infrared synergistic technology, the fermentation cycle can be effectively shortened and the number of Eurotium cristatum flora can be increased.

[0083] By adopting segmented hot air drying and high-pressure steam treatment, the moisture content is effectively reduced and maintained, ensuring the stability of the golden flower activity, improving the product shelf life and batch stability, and avoiding the risk of mold in traditional processes.

[0084] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing golden flower Pu'er tea, characterized in that: The method includes using Pu'er raw tea containing natural bacteria as a preparation raw material, and further includes the following implementation steps: S1. Raw material pretreatment: Gradient steaming and microwave treatment are used to soften the tea leaves and activate the spores of Eurotium cristatum, effectively sterilizing the tea while preserving the activity of the fungus. S2. Pressing process: 3D printing molds are used to press the tea cake to form a three-dimensional oxygen-permeable network system throughout the tea body; S3. Fermentation: A dynamic three-stage fermentation control process is used to accelerate the destruction of tea cell walls, release endogenous enzymes, and promote the directional proliferation of the Eurotium cristatum colony. S4. Post-processing: Dry the tea body after flowering, and stabilize the activity of the golden flower by spraying with salt water mist and high-pressure steam.

2. The method for preparing Jinhua Pu'er tea according to claim 1, wherein: The steps of gradient steaming and microwave collaborative treatment include: 1) In the first stage, the steam temperature is gradually increased from 90° C. to 100° C. and steamed for 5 to 8 seconds, and then the steam temperature is gradually increased from 100° C. to 120° C. and steamed for 8 to 10 seconds, and then the steam is stopped and gradually cooled to room temperature to activate the spores of Eurotium cristatum in the tea leaves; 2) In the second stage, the tea leaves were microwaved at a frequency of 2300-2500 MHz for 30-40 seconds to accurately kill the bacteria and retain the activity of the fungus.

3. The method for preparing Jinhua Pu'er tea according to claim 1, wherein: A plurality of honeycomb-shaped micropores are preset on the surface of the 3D printing mold, and the pore diameter of each micropore is 0.5 to 1 mm to form a honeycomb-shaped oxygen-permeable gap. Tea leaves are placed inside the mold and pressed into a tea cake structure at a pressure of 7 to 8 MPa. The tea cake occupies 70% to 80% of the volume inside the mold.

4. The method for preparing Jinhua Pu'er tea according to claim 1, wherein: The fermentation treatment includes a dynamic stage blooming treatment and a composite bacterial fermentation treatment, wherein the dynamic stage blooming treatment step includes: 1) The first stage lasts for 3 to 5 days, wherein the tea leaves are placed in a ventilated environment at a temperature of 22 to 25° C. and a humidity of 75%, with an air supply system providing one air change per hour to activate the metabolism of the fungus. 2) setting the second stage duration to 5 to 7 days, placing the tea leaves in an ultrasonic environment at a temperature of 25 to 27° C. and a humidity of 65%, setting the ultrasonic frequency to 40 kHz and using intermittent ultrasonic treatment with an interval of 8 to 15 seconds to promote the penetration of the Eurotium cristatum flora into the tea leaves fibers; 3) The third stage is set to last 15 to 18 days, and the tea leaves are placed in an infrared environment at a temperature of 30 to 32° C. and a humidity of 55%. Infrared-assisted drying is combined with a treatment to inhibit bacteria, the infrared wavelength is controlled to be 2.5 to 4 μm, and the distribution state of the golden flowers is solidified.

5. The method for preparing Jinhua Pu'er tea according to claim 4, characterized in that: The composite bacterial community fermentation treatment adopts spraying of a fermentation promoter after steaming. The fermentation promoter is a tangerine peel extract containing polysaccharide and flavonoid active ingredients to promote the proliferation of the Eurotium cristatum bacterial community.

6. The method for preparing Jinhua Pu'er tea according to claim 1, wherein: The Pu'er tea leaves after blooming are dried in stages at an ambient temperature of 38-42° C., and the moisture content is detected to be ≤14%. The staged drying process includes: 1) Dry with hot air at 38°C for 2-3 minutes; 2) Dry with hot air at 40°C for 1 minute; 3) Dry with hot air at 42°C for 30 seconds.

7. The method for preparing Jinhua Pu'er tea according to claim 6, characterized in that: The segmented dried flowering tea body is sprayed with 1% salt water atomization, the steam temperature is set to 150℃, the pressure is 10-12MPa, and the high-pressure steam treatment is performed for 10 minutes to stabilize the activity of the golden flower.

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