A tea fermentation method

Abstract

This invention relates to the field of tea fermentation technology, specifically disclosing a tea fermentation method comprising the following steps: fixation, rolling, construction of a fermentation system, fermentation, termination and post-ripening, and drying. The first stage of fermentation involves inoculating a high-cellulase-producing Aspergillus niger strain N1. The second stage introduces thermophilic lactic acid bacteria and simultaneously adds catechin-β-cyclodextrin embeddings. The third stage involves adding Pichia pastoris, lowering the temperature to 32°C, and employing microaerobic fermentation with 3.5% O2 pulsed oxygen supply for 5 minutes every hour. This invention, based on the precise staged control of a complex microbial community, allows tea to achieve the transformation and generation of specific substances, enhancing the tea's antioxidant and blood pressure-lowering health benefits, while enriching the aroma components and flavor profile, thus satisfying consumers' pursuit of high-quality tea.

Description

Technical Field

[0001] This invention belongs to the field of tea fermentation technology, and specifically relates to a tea fermentation method. Background Technology

[0002] As a widely consumed beverage globally, tea's processing techniques have always been a key focus of the tea industry. Traditional tea fermentation processes have developed into relatively fixed patterns over a long period, but as consumers' demands for tea quality, functionality, and production efficiency continue to rise, traditional processes are gradually revealing many limitations.

[0003] In traditional tea fermentation processes, fermentation primarily relies on microorganisms in the natural environment or a single microbial strain. This method makes precise control of the fermentation process difficult, resulting in inconsistent tea quality. For example, theaflavins content is typically low, rarely exceeding 2.5%, and the γ-aminobutyric acid (GABA) content is also difficult to maintain above 200mg / 100g. This leads to poor performance in terms of antioxidant and blood pressure-lowering functionalities. Furthermore, the aroma components and taste of the tea are relatively simple, failing to meet consumers' demands for rich flavors and unique aromas. Summary of the Invention

[0004] The purpose of this invention is to provide a tea fermentation method to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for fermenting tea includes the following steps:

[0007] S1, Filming wrapped:

[0008] The freshly picked leaves are quickly placed into a microwave device and processed at 800W for 30 seconds, followed by steam blanching at 100℃ for 10 seconds.

[0009] S2. Rolling: After fixing, the tea leaves are rolled to break down the tea cell structure, allowing the tea juice to seep out and providing a material basis for fermentation. The rolling time is controlled at 20-30 minutes.

[0010] S3, Fermentation System Construction

[0011] Inoculation with microbial culture: Spread the rolled tea leaves evenly in the porous ceramic fermentation chamber, with a thickness controlled at 5cm, according to a total inoculation amount of 1×10⁻⁶. 6 The standard of CFU / g was used to sequentially inoculate the three-stage complex microbial community;

[0012] S4, Fermentation

[0013] Phase 1 (0-4 hours): Inoculate with Aspergillus niger strain N1, which produces high levels of cellulase, and maintain the temperature at 38°C.

[0014] Second stage (4-12 hours): Introduce thermophilic lactic acid bacteria Lactobacillus thermophilus TEA-7, raise the temperature to 45℃, and add catechin-β-cyclodextrin embedded body (particle size 200nm);

[0015] The third stage (12-24 hours): Add Pichia pastoris TF-3, lower the temperature to 32℃, use micro-aerobic fermentation, and provide 3.5% O2 pulse oxygen supply for 5 minutes every hour;

[0016] Throughout the fermentation process, the humidity is maintained at 85% - 92% RH through ultrasonic atomization;

[0017] S5, Termination and Post-ripening

[0018] After 24 hours of fermentation, spray 0.5% citric acid solution evenly to stop the fermentation reaction, and then transfer the tea leaves to a 4℃ environment for low-temperature maturation for 48 hours.

[0019] S5, Drying

[0020] The matured tea leaves are dried at 60-70℃ until the moisture content is below 6%.

[0021] Preferably, the microwave equipment in S1 includes, but is not limited to, the Worst model 24 tunnel microwave tea fixing equipment or the Zhiya model ZY-60HM continuous microwave fixing equipment.

[0022] Preferably, the ultrasonic atomizer used in the ultrasonic atomization process in S4 includes, but is not limited to, the Silerx T200 ultrasonic atomizer and the Yuwell 402A ultrasonic atomizer.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention, based on the phased and precise regulation of a complex microbial community, enables tea to undergo the transformation and generation of specific substances, enhancing its antioxidant and blood pressure-lowering health benefits. It also enriches the aroma components and flavor profile of the tea, satisfying consumers' pursuit of high-quality tea. Compared to traditional processes, this invention significantly reduces production time, improves equipment utilization, and allows companies to produce more batches of tea within the same timeframe, increasing production capacity. Furthermore, this invention shortens the fermentation cycle, reduces energy consumption, and minimizes resource waste and environmental burden during production, aligning with the principles of green and sustainable development. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1:

[0027] A method for fermenting tea includes the following steps:

[0028] The ZY-60HM continuous microwave blanching equipment from Zhiya was selected.

[0029] The harvested fresh leaves were placed in batches of 10 kg each into a microwave oven and treated at 800W for 30 seconds to rapidly raise the internal temperature of the leaves. Subsequently, a matching steam blanching device was used to steam the leaves at 100℃ for 10 seconds to deactivate some of the enzyme activity in the fresh leaves while retaining 92% of the polyphenol oxidase activity.

[0030] After the tea leaves are killed, they are put into the rolling machine while they are still hot to promote the full breaking of the tea cell tissue and the seepage of a large amount of tea juice; the entire rolling process lasts for 25 minutes to ensure that the tea leaves are rolled evenly.

[0031] (a) Preparing a porous ceramic fermentation chamber

[0032] A custom-designed porous ceramic fermentation chamber with an internal volume of 2 cubic meters was constructed, featuring meticulously designed honeycomb-shaped airflow channels to ensure uniform gas circulation. Simultaneously, high-precision IoT sensors were installed to monitor key environmental parameters within the fermentation chamber in real time, such as temperature, humidity, and oxygen concentration, and these parameters were precisely adjusted via an intelligent control system.

[0033] (ii) Inoculation with microbial flora

[0034] Spread the kneaded tea leaves evenly in the fermentation chamber, maintaining a thickness of 5cm. The total inoculum size is 1×10⁻⁶. 6 To meet the CFU / g standard, prepare a three-stage complex microbial community. First, inoculate with Aspergillus niger strain N1, which produces high levels of cellulase, to begin the first stage of fermentation.

[0035] (I) First stage (0-4 hours)

[0036] After inoculation with Aspergillus niger strain N1, the temperature was precisely controlled at 38℃ using the intelligent temperature control system of the fermentation chamber, and environmental parameters were monitored in real time via IoT sensors to ensure a stable fermentation environment. During this stage, the Aspergillus niger strain plays its role, breaking down the cell wall barrier of the tea leaves and releasing catechin precursors, providing the material basis for subsequent fermentation.

[0037] (II) Second stage (4-12 hours)

[0038] The thermophilic lactic acid bacteria Lactobacillus thermophilus TEA-7 was introduced, along with the addition of catechin-β-cyclodextrin encapsulation (particle size 200 nm).

[0039] When the temperature was raised to 45℃, thermophilic lactic acid bacteria directionally converted EGCG into theaflavins, while simultaneously generating γ-aminobutyric acid (GABA). The catechin-β-cyclodextrin encapsulation, through sustained-release action, prolonged the activity time of polyphenol oxidase, resulting in a significant increase in theaflavin content.

[0040] (III) Third stage (12-24 hours)

[0041] Pichia pastoris TF-3 was added, and the temperature was lowered to 32℃. Microaerobic fermentation was employed using specialized oxygen supply equipment, providing 3.5% O2 pulses for 5 minutes every hour. A Siler T200 ultrasonic nebulizer was used to maintain humidity at 85%-92% RH to prevent excessive oxidation of the leaf surface. Simultaneously, sensors monitored pH, conductivity, and volatile organic compounds (VOCs) throughout the process to ensure smooth fermentation.

[0042] After 24 hours of fermentation, a 0.5% citric acid solution is evenly sprayed using professional spraying equipment to quickly stop the fermentation reaction and prevent over-fermentation from affecting the tea quality. The tea leaves after fermentation are then transferred to a low-temperature cold storage at a constant temperature of 4°C for 48 hours of low-temperature maturation. During this process, the chemical components inside the tea leaves further react, the flavor gradually stabilizes, and the taste becomes more mellow.

[0043] After being aged at low temperature, the tea leaves are placed in a low-temperature drying device and dried at 65°C for 8 hours to reduce the moisture content of the tea leaves to 5%, thus meeting the appropriate standards for storage and packaging.

[0044] Example 2:

[0045] The Worster Model 24 tunnel-type microwave tea fixing equipment was used.

[0046] Fresh leaves were fed into a microwave oven in batches of 15 kg and processed at 800W for 30 seconds to rapidly raise their temperature. Subsequently, they were blanched for 10 seconds using 100°C steam from a steam generator.

[0047] Immediately after the tea leaves are processed (killed green), they are placed in a rolling machine and rolled in a series of steps: first, light rolling for 8 minutes; then, heavy rolling for 18 minutes; and finally, light rolling for 4 minutes. The light rolling stage initially shapes the tea leaves into strips, the heavy rolling stage breaks down the cells and allows the tea juice to fully seep out, and the final light rolling breaks up any clumps. The total rolling time is 30 minutes.

[0048] A custom-designed 3-cubic-meter porous ceramic fermentation chamber with an internal honeycomb airflow channel design ensures efficient gas circulation. High-precision temperature and humidity sensors, oxygen sensors, and an intelligent control center are installed to achieve precise monitoring and control of fermentation environmental parameters.

[0049] Spread the kneaded tea leaves evenly in the fermentation chamber, maintaining a thickness of 5cm. The total inoculum quantity is 1×10⁻⁶. 6 The standard CFU / g was used to prepare a three-stage complex microbial community. First, a high-cellulase-producing Aspergillus niger strain N1 was inoculated to start the fermentation process.

[0050] (I) First stage (0-4 hours)

[0051] After inoculating with Aspergillus niger strain N1, the temperature in the fermentation chamber was stabilized at 38℃ using the temperature control system. Environmental data was monitored in real time using sensors to ensure a stable fermentation environment. The Aspergillus niger strain then began to work, breaking down the cell walls of the tea leaves and releasing catechin precursors.

[0052] (II) Second stage (4-12 hours)

[0053] Thermophilic lactic acid bacteria (Lactobacillus thermophilus TEA-7) were inoculated with catechin-β-cyclodextrin encapsulation (particle size 200 nm), and the temperature was raised to 45℃. The thermophilic lactic acid bacteria converted EGCG into theaflavins and simultaneously generated γ-aminobutyric acid (GABA). The encapsulation prolonged the activity time of polyphenol oxidase, resulting in a significant increase in theaflavin content.

[0054] (III) Third stage (12-24 hours)

[0055] Add Pichia pastoris TF-3, lower the temperature to 32℃, and use a professional oxygen generator to provide 3.5% O2 pulse oxygen supply for 5 minutes every hour. Maintain 85%-92% RH humidity using a Yuwell 402A ultrasonic nebulizer to prevent oxidation of the tea surface. During this stage, the Pichia pastoris synthesizes large amounts of phenethyl acetate, linalool, and other floral and fruity esters, enriching the tea aroma. Simultaneously, monitor pH, conductivity, and volatile organic compounds (VOCs) throughout the process to ensure smooth fermentation.

[0056] After 24 hours of fermentation, use a professional spraying device to evenly spray a 0.5% citric acid solution to quickly stop fermentation and prevent the tea quality from deteriorating.

[0057] The tea leaves that have stopped fermenting are transferred to a cold storage room set at 4°C for 48 hours of low-temperature maturation, allowing the internal substances of the tea leaves to further transform and stabilize the flavor.

[0058] After aging, the tea leaves are placed in a low-temperature drying oven and dried at 68°C for 7 hours to reduce the moisture content to 5.5%, achieving the ideal state for storage and packaging. The drying process is strictly controlled in terms of temperature and time to prevent damage to the quality of the tea leaves.

[0059] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0060] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for fermenting tea, characterized in that, Includes the following steps: S1, Filming wrapped: The freshly picked leaves are quickly placed into a microwave device and processed at 800W for 30 seconds, followed by steam blanching at 100℃ for 10 seconds. S2. Rolling: After fixing, the tea leaves are rolled to break down the tea cell structure, allowing the tea juice to seep out and providing a material basis for fermentation. The rolling time is controlled at 20-30 minutes. S3, Fermentation System Construction Inoculation with microbial culture: Spread the rolled tea leaves evenly in the porous ceramic fermentation chamber, with a thickness controlled at 5cm, according to a total inoculation amount of 1×10⁻⁶. 6 The standard of CFU / g was used to sequentially inoculate the three-stage complex microbial community; S4, Fermentation Phase 1 (0-4 hours): Inoculate with Aspergillus niger strain N1, which produces high levels of cellulase, and maintain the temperature at 38°C. Second stage (4-12 hours): Introduce thermophilic lactic acid bacteria Lactobacillus thermophilus TEA-7, raise the temperature to 45℃, and add catechin-β-cyclodextrin embeddings (particle size 200nm); The third stage (12-24 hours): Add Pichia pastoris TF-3, lower the temperature to 32℃, use micro-aerobic fermentation, and provide 3.5% O2 pulse oxygen supply for 5 minutes every hour; Throughout the fermentation process, the humidity is maintained at 85% - 92% RH through ultrasonic atomization; S5, Termination and Post-ripening After 24 hours of fermentation, spray 0.5% citric acid solution evenly to stop the fermentation reaction, and then transfer the tea leaves to a 4℃ environment for low-temperature maturation for 48 hours. S5, Drying The matured tea leaves are dried at 60-70℃ until the moisture content is below 6%.

2. The tea fermentation method according to claim 1, characterized in that: The microwave equipment in S1 includes, but is not limited to, the Worst model 24 tunnel microwave tea fixing equipment or the Zhiya model ZY-60HM continuous microwave fixing equipment.

3. The tea fermentation method according to claim 1, characterized in that: The ultrasonic atomizers used in the ultrasonic atomization process in S4 include, but are not limited to, the Silerx T200 ultrasonic atomizer and the Yuwell 402A ultrasonic atomizer.