Mildew-free odor-free lift tea fermentation process

Abstract

The invention discloses a mildew-free and odor-free off-ground tea fermentation process which comprises the following steps: S1, construction of a fermentation field: adopting a three-layer isolation type workshop, preparing a three-stage filtered air treatment system, an ozone circulating disinfection device and an odor adsorption layer, adopting a stainless steel hollow structure as a fermentation frame, and performing surface electrolytic polishing treatment; s2, raw material pretreatment; s3, fermentation process control: dynamically regulating and controlling temperature and humidity based on a PLC (Programmable Logic Controller); s4, peculiar smell control: real-time electronic nose monitoring; and S5, post-treatment: microwave drying is combined with ozone sterilization, nitrogen-filled sterile packaging is adopted, and a whole-process block chain tracing system is established. The safety of microorganisms is obviously improved, the mould pollution rate is greatly reduced, and the microbial community can be optimized; peculiar smell is controlled to be zero in residue, and flavor purity is improved. The method improves controllability and quality stability of the fermentation process, is suitable for clean production and industrialization, realizes pollution-free and intelligent monitoring and tracing in the whole process, has safety and economic advantages, improves food safety and reduces cost.

Description

Technical Field

[0001] The present invention relates to the technical field of tea fermentation, and particularly to a floor - off tea fermentation process without mold and peculiar smell. Background Art

[0002] In the field of tea processing, fermentation is a key link in shaping the unique quality of tea. However, there are many problems in traditional fermentation processes and some existing improved processes that urgently need to be solved. Traditional tea fermentation often uses the method of piling and wet - stacking on the ground, which makes the tea directly contact with the ground, posing serious hygiene and quality risks. On the one hand, the soil is rich in various molds, such as Aspergillus flavus and Penicillium, which are extremely likely to contaminate the tea. According to relevant research statistics, the mold - exceeding rate of tea fermented on the ground is as high as 23.7%, and the detection rate of aflatoxin B1 is 5.2%. Aflatoxin B1 is a strong carcinogen, which seriously threatens human health. This not only reduces the quality of tea but also poses a potential threat to the life safety of consumers. On the other hand, there are peculiar smells such as earthy smell and humus smell on the ground, and these peculiar smells will be adsorbed on the tea through capillary action. Eventually, the finished tea has a "warehouse smell" and "earthy smell", greatly affecting the flavor purity of the tea, reducing the taste and aroma of the tea, and unable to meet the needs of consumers for high - quality tea.

[0003] Currently, there are still some key technical problems in the field of tea fermentation that have not been effectively solved. How to build a three - dimensional antibacterial barrier throughout the entire process of tea fermentation, that is, from raw material pretreatment, fermentation process to post - treatment stage, so as to completely prevent the growth of molds, is a difficult problem that urgently needs to be overcome. How to use environmental engineering means to achieve zero residue of peculiar smells in the fermentation space and ensure that the tea ferments in a pure environment is also the focus of attention in the industry. In addition, how to optimize the processing flow of tea materials, avoid exogenous pollution while reducing the generation of endogenous peculiar smells of tea, and further improve the quality of tea is also the direction that needs to be broken through in the development of tea fermentation technology. Therefore, this solution proposes a floor - off tea fermentation process without mold and peculiar smell. Summary of the Invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, and provide a floor - off tea fermentation process without mold and peculiar smell, which can significantly improve microbial safety, greatly reduce the mold contamination rate, and can also optimize the microbial community; the control of peculiar smells reaches zero residue, improving the flavor purity. It improves the controllability and quality stability of the fermentation process, adapts to clean production and industrialization, realizes pollution - free and intelligent monitoring and traceability throughout the process, has both safety and economic advantages, improves food safety and reduces costs.

[0005] The present invention also provides a floor - off tea fermentation process without mold and peculiar smell, including the following steps: S1. Fermentation site construction: A three - layer isolation workshop is adopted, equipped with a three - stage filtered air treatment system, an ozone circulation disinfection device, and an odor adsorption layer. The fermentation rack is made of stainless - steel hollow structure and its surface is treated by electrolytic polishing; S2. Raw material pretreatment: Clean with chitosan solution and spray with a composite natural antibacterial liquid (which contains tea polyphenols, rosemary extract, and citric acid) to form an antibacterial protective layer on the surface of the tea leaves; S3. Fermentation process control: Based on PLC for dynamic temperature and humidity regulation, with the precision controlled within ±0.1℃ / ±1%RH, combined with ultrasonic de - caking and double - helix turning pile technology to ensure uniform fermentation of the tea pile; S4. Odor control: Real - time monitoring with an electronic nose, integrating a three - stage odor treatment system of UV photolysis, activated carbon adsorption, and ozone oxidation. A renewable odor adsorption layer is set at the bottom of the fermentation rack; S5. Post - treatment: Microwave drying combined with ozone sterilization, using nitrogen - filled aseptic packaging, and establishing a full - process blockchain traceability system.

[0006] According to a mold - free and odor - free off - ground tea fermentation process provided by the present invention, the air treatment system includes a primary - intermediate - high - efficiency three - stage filtration device, with an air change rate ≥20 times / h, equipped with activated carbon adsorption and an ozone generator, where the iodine adsorption value ≥1000mg / g and the ozone concentration is controlled at 0.3 - 0.5ppm.

[0007] According to a mold - free and odor - free off - ground tea fermentation process provided by the present invention, the composite antibacterial liquid is composed of 0.5% - 1% tea polyphenols, 0.3% - 0.6% rosemary extract, and 0.2% - 0.4% citric acid by weight ratio. The atomization spraying technology is adopted, with the particle size controlled at 50 - 100μm and the spraying amount being 5% - 8% of the weight of the tea leaves.

[0008] According to a mold - free and odor - free off - ground tea fermentation process provided by the present invention, the fermentation rack is made of 304 stainless steel, with a surface roughness Ra≤0.2μm, a height off the ground ≥50cm, a layer spacing ≥60cm, and a detachable stainless - steel slag - receiving tray is set at the bottom.

[0009] According to a mold - free and odor - free off - ground tea fermentation process provided by the present invention, the temperature and humidity regulation adopts PID closed - loop control. The temperature in the initial stage of fermentation is 22 - 25℃ and the humidity is 85% - 90%, in the middle stage it is 25 - 28℃, for dark tea it is controlled at 30 - 32℃ and the humidity is 80% - 85%, and in the later stage it is 20 - 22℃ and the humidity is 70% - 75%.

[0010] According to a mold - free and odor - free off - ground tea fermentation process provided by the present invention, the odor treatment system includes a micro - negative pressure collection pipeline and a UV photolysis catalytic oxidation device, with its wavelength set at 254nm + 185nm, and the removal rate of volatile organic compounds ≥95%.

[0011] According to a mold-free and odorless off-ground tea fermentation process provided by the present invention, the turning frequency is once every 4 - 8 hours. A double-screw turning machine is used, and its rotation speed is controlled at 15 - 20 rpm. Combining with ultrasonic lump-breaking technology, the frequency is controlled at 40 kHz, the lump-breaking rate is ≥98%, and the leaf breakage rate is <3%.

[0012] According to a mold-free and odorless off-ground tea fermentation process provided by the present invention, in the secondary cleaning and drying step, microwave drying is used, with a power of 10 - 15 kW, combined with ozone sterilization, and the ozone concentration is set at 0.2 ppm, ensuring that the mold killing rate is ≥99.9% and the ozone residue is <0.01 mg / kg.

[0013] Compared with the prior art, a mold-free and odorless off-ground tea fermentation process of the present invention significantly improves microbial safety, greatly reduces the mold contamination rate, and can also optimize the microbial community; odor control reaches zero residue, improving flavor purity. It improves the controllability of the fermentation process and the quality stability; adapts to clean production and industrialization, realizes pollution-free and intelligent monitoring and traceability throughout the process; has both safety and economic advantages, improves food safety and reduces costs. Brief Description of the Drawings

[0014] The present invention will be further described below in conjunction with the drawings and embodiments; Figure 1 It is the overall flowchart of a mold-free and odorless off-ground tea fermentation process of the present invention. Detailed Embodiments

[0015] This part will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the drawings. The role of the drawings is to supplement the description in the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the protection scope of the present invention.

[0016] Example 1

[0017] Refer to Figure 1 , a mold-free and odorless off-ground tea fermentation process in an embodiment of the present invention includes the following steps: Step 1. Raw material preparation Fresh leaf screening: Pick the fresh tea leaves with one bud and one leaf in the initial unfolding stage, and screen out the damaged leaves through a color sorter, with the damage rate controlled at <3%, and weigh 500 kg.

[0018] Compound cleaning: Primary cleaning: Use warm water at 35°C, with its conductivity controlled at ≤5 μS / cm, spray and clean for 15 seconds to remove surface dust and eggs.

[0019] Secondary cleaning: 0.15% chitosan solution with a molecular weight controlled between 100,000 and 200,000 Da and a deacetylation degree controlled at ≥90%. Soak for 8 minutes to form an antibacterial film to inhibit the attachment of molds.

[0020] Dehydration treatment: The centrifugal dehydrator rotates at 1200 rpm for 2 minutes, controlling the moisture content after cleaning at 72%.

[0021] Step 2: Pretreatment before fermentation Preparation and spraying of the composite antibacterial solution: Composition: 0.8% tea polyphenols with a purity controlled at ≥98%, 0.5% rosemary extract with carnosic acid controlled at ≥20%, and 0.3% food-grade citric acid, dissolved in purified water at 35°C.

[0022] Spraying process: Using atomized spraying technology with an atomization particle size of 80 μm and a spraying pressure of 0.5 MPa, spray evenly at 6% of the fresh leaf weight to form an antibacterial protective layer of 0.05 - 0.1 mm.

[0023] Construction of the tea pile: Stainless steel fermentation rack with a surface roughness controlled at Ra ≤ 0.2 μm, a layer spacing of 60 cm, a spreading density of 2.5 kg / m², a pile height of 90 cm, covered with a food-grade silica gel film with a gas permeability of 80 g / m²·24 h, and sealed with a magnetic strip at the edge.

[0024] Step 3: Fermentation process control Initial setting 0 - 24 h: Temperature 23°C, humidity 88%, start the bottom heat exchanger with a temperature difference controlled at ≤ ±0.3°C, and the ultrasonic humidifier with an atomization amount of 8 L / h.

[0025] Turn the pile once every 4 hours using a double - helix pile turner with a rotation speed of 18 rpm and a turning depth of 30 cm to ensure a mixing uniformity of ≥95%.

[0026] Medium - term setting 24 - 48 h: The temperature rises to 26°C, humidity 85%, turn on the side ventilation system with a wind speed set at 0.4 m / s.

[0027] Use an electronic nose to monitor the acetaldehyde concentration in real - time with a target value of 15 ppb, and release phenylacetaldehyde through a flavor diffusion device with a concentration controlled at 10 - 20 ppb to induce the generation of rose - flower fragrance substances.

[0028] Late - term setting 48 - 60 h: The temperature gradually drops to 22°C, humidity 75%, start the top negative - pressure dehumidification device with a dehumidification amount of 12 m³ / h, control the moisture content reduction rate at 0.8% / h, and terminate the fermentation when the moisture content reaches 55%.

[0029] Step 4. Post-treatment Deblocking and screening: An ultrasonic deblocking device with a frequency of 40 kHz and a power of 150 W is used to process agglomerated tea balls with a particle size > 2 cm. The deblocking rate is ≥ 98%, and the leaf breakage rate is < 3%.

[0030] A vibrating screen with a screen hole of 2 mm is used to remove debris.

[0031] Drying and sterilization: A tunnel-type microwave drying line with a power of 12 kW, a frequency of 2450 MHz, and a drying time of 5 minutes is used to control the moisture content ≤ 10%.

[0032] Ozone sterilization is synchronously started with a concentration of 0.2 ppm and an action time of 5 minutes. The mold killing rate is ≥ 99.9%, and the ozone residue is < 0.01 mg / kg.

[0033] Sterile packaging: Nitrogen filling packaging is carried out in a Class 10,000 clean workshop. The nitrogen purity is ≥ 99.99%, the residual oxygen concentration is < 0.5%, the packaging material is an aluminum foil composite film, and its oxygen permeability is < 5 cm³ / m²·24h.

[0034] Attach a special QR code to record the whole-process data, including temperature and humidity curves, bacteriostatic agent dosage, etc., to achieve blockchain traceability.

[0035] Step 5. Quality inspection Microbial indicators: The total number of molds is 5 CFU / g, and coliforms and pathogenic bacteria are not detected.

[0036] Flavor indicators: Through QDA evaluation, there is no musty smell or earthy smell, and it has a typical sweet potato fragrance and floral fragrance. The thearubigin content is 6.2%.

[0037] Example 2, referring to Figure 1 , a mold-free and odorless off-ground tea fermentation process according to an embodiment of the present invention includes the following steps: Step 1. Raw material preparation Raw tea screening: Select the third-grade raw tea. After passing through a metal detector with a detection sensitivity of Fe ≥ 0.8 mm, impurities are removed, 1000 kg is weighed, and the moisture content is 11.5%.

[0038] Compound cleaning: Primary cleaning: Spray with warm water at 40°C for 20 seconds to remove surface dust.

[0039] Secondary cleaning: Immerse in a 0.1% chitosan solution for 10 minutes, then centrifuge and dehydrate at 1500 rpm for 3 minutes to control the moisture content at 32%.

[0040] Step 2. Pretreatment before fermentation Preparation and spraying of compound bacteriostatic liquid: Composition: 1% tea polyphenols, 0.6% rosemary extract, 0.4% citric acid, dissolved in purified water at 40°C.

[0041] Spraying process: Spray at 8% of the weight of raw tea, with an atomization particle size of 100 μm and a pressure of 0.6 MPa to form a bacteriostatic protective layer.

[0042] Construction of tea pile: Adopt the "cross-shaped" high-altitude method. The bottom layer of the tea pile is 30 cm above the ground, the distance between the stainless steel wire meshes between layers is 20 cm, the pile height is 120 cm, and the spreading density is 2.5 kg / m².

[0043] Step 3. Fermentation process control Initial setting 0 - 48 h: Temperature 28°C, humidity 90%, start the ultrasonic humidifier with a discharge rate of 10 L / h, and the bottom heat exchanger with a temperature difference controlled within ≤ ±0.5°C.

[0044] Turn the pile once every 6 hours. The double - helix pile - turning machine rotates at 20 rpm and the turning depth is 50 cm to ensure uniform fermentation of the tea pile.

[0045] Mid - term setting 48 - 72 h: The temperature rises to 30°C, humidity 85%. Through the low - voltage electrostatic spraying technology, inoculate the spore suspension of Eurotium cristatum with a voltage of 8 kV, a spore concentration of 1×10 6 CFU / mL, and the addition amount is 0.02% to promote the growth of "Golden Flower" bacteria.

[0046] Late - term setting 72 - 96 h: The temperature drops to 25°C, humidity 80%. Start the odor adsorption layer at the bottom of the fermentation rack, which includes zeolite molecular sieve and attapulgite, with a thickness of 5 cm. The trimethylamine concentration monitored by the electronic nose is < 0.3 ppb.

[0047] Turn on the lateral ventilation with the wind speed controlled at 0.5 m / s to control the tea moisture content decrease rate at 1% / h.

[0048] Step 4. Post - treatment Unblocking and screening: Ultrasonic unblocking with a frequency of 40 kHz and a power of 200 W to process the agglomerated tea balls, and the unblocking rate is ≥98%.

[0049] Use a vibrating screening machine to remove debris with a sieve hole of 2 mm.

[0050] Drying and sterilization: Tunnel drying at a temperature of 60°C for 2 hours to control the moisture content ≤12%.

[0051] Ozone sterilization, with a concentration of 0.2 ppm and an action time of 5 minutes, and the mold killing rate ≥ 99.9%.

[0052] Sterile packaging: Nitrogen-filled packaging, with a nitrogen pressure of 0.2 MPa, a moisture permeability of the packaging material < 1 g / m²·24 h, and a blockchain traceability QR code attached.

[0053] Step Five: Quality Inspection Microbial indicators: The total number of molds is 8 CFU / g, the number of "Golden Flower" spores is 5×10 4 CFU / g, and coliforms and pathogenic bacteria are not detected.

[0054] Flavor indicators: No earthy smell or rancid smell, the soup color is bright red and thick, the aged fragrance is pure, and the gallic acid content is 3.5%. Embodiment

[0055] Core technology: Construct an antibacterial layer for raw materials through chitosan cleaning and spraying with a composite antibacterial solution, control environmental microorganisms by combining a stainless steel clean fermentation rack and a three-stage air filtration system, ensure uniform fermentation by using PLC temperature and humidity intelligent regulation + ultrasonic deblocking, and finally achieve aseptic post-treatment through microwave drying combined with ozone sterilization.

[0056] Parameter range: Applicable to all categories of tea. By adjusting the components of the antibacterial solution, such as focusing on tea polyphenols for green tea and increasing the inoculation of Eurotium cristatum for dark tea. For the temperature and humidity curve, it is set at 22 - 25 °C for green tea and 25 - 32 °C for dark tea, and the turning frequency is controlled at 4 - 8 h / time to achieve personalized fermentation control.

[0057] Advantages: Compared with the traditional process, the mold contamination rate drops by more than 95%, the removal rate of odor substances ≥ 90%, and the flavor purity of the finished tea is improved by 30%.

[0058] The above has described the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge scope of those of ordinary skill in the art.

Claims

1. A fermentation process for mold-free and odorless ground tea, characterized in that, It includes the following steps: S1. Fermentation site construction: A three-layer isolation workshop is adopted, equipped with a three-stage filtered air treatment system, an ozone circulation disinfection device and an odor adsorption layer. The fermentation rack is made of stainless steel with a hollow structure and its surface is treated by electrolytic polishing; S2. Raw material pretreatment: Clean with a chitosan solution and spray a composite natural antibacterial solution which contains tea polyphenols, rosemary extract and citric acid to form an antibacterial protective layer on the surface of the tea leaves; S3. Fermentation process control: Based on PLC, the temperature and humidity are dynamically regulated, and the precision is controlled within ±0.1°C / ±1%RH. Combined with ultrasonic deblocking and double helix turning pile technology, ensure uniform fermentation of the tea pile; S4. Odor control: Real-time electronic nose monitoring, integrating a three-stage odor treatment system of UV photolysis, activated carbon adsorption and ozone oxidation. A renewable odor adsorption layer is set at the bottom of the fermentation rack; S5. Post-treatment: Microwave drying combined with ozone sterilization, using nitrogen-filled aseptic packaging, and establishing a whole-process blockchain traceability system.

2. The mold-free and odorless ground tea fermentation process according to claim 1, characterized in that, The air treatment system includes a primary - intermediate - high - efficiency three - stage filtration device, the air change rate is ≥20 times / h, equipped with activated carbon adsorption and an ozone generator, in which the iodine adsorption value is ≥1000mg / g and the ozone concentration is controlled at 0.3 - 0.5ppm.

3. A mold-free and odorless off-ground tea fermentation process according to claim 1, characterized in that, The composite antibacterial solution is composed of 0.5% - 1% tea polyphenols, 0.3% - 0.6% rosemary extract and 0.2% - 0.4% citric acid by weight ratio. The atomization spraying technology is adopted, the particle size is controlled at 50 - 100μm, and the spraying amount is 5% - 8% of the weight of the tea leaves.

4. The mold-free and odorless off-the-ground tea fermentation process according to claim 1, characterized in that, The fermentation rack is made of 304 stainless steel, the surface roughness Ra≤0.2μm, the height from the ground is ≥50cm, the layer spacing is ≥60cm, and a detachable stainless steel slag receiving tray is set at the bottom.

5. A mold-free and odorless off-ground tea fermentation process according to claim 1, characterized in that, The temperature and humidity regulation adopts PID closed - loop control. The temperature in the initial stage of fermentation is 22 - 25°C and the humidity is 85% - 90%. In the middle stage, it is 25 - 28°C. For dark tea, it is controlled at 30 - 32°C and the humidity is 80% - 85%. In the later stage, it is 20 - 22°C and the humidity is 70% - 75%.

6. The mold-free and odorless off-ground tea fermentation process according to claim 1, characterized in that, The odor treatment system includes a micro - negative pressure collection pipeline and a UV photolysis catalytic oxidation device, the wavelength is set at 254nm + 185nm, and the removal rate of volatile organic compounds is ≥95%.

7. A mold-free and odorless ground tea fermentation process according to claim 1, characterized in that, The turning pile frequency is once every 4 - 8h. A double - helix turning pile machine is adopted, its rotation speed is controlled at 15 - 20rpm, combined with ultrasonic deblocking technology, the frequency is controlled at 40kHz, the deblocking rate is ≥98%, and the leaf breakage rate is <3%.

8. A mold-free and odorless off-the-ground tea fermentation process according to claim 1, characterized in that, The secondary cleaning and drying step adopts microwave drying with a power of 10 - 15kW, combined with ozone sterilization, the ozone concentration is set at 0.2ppm, ensure that the mold killing rate is ≥99.9% and the ozone residue is <0.01mg / kg.

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