Green tea processing fragrance-solidifying technology
Through ultrasonic pretreatment, low-temperature slow setting, medium-temperature setting and high-temperature instantaneous extraction processes, combined with cellulase treatment and dehumidified nitrogen regulation, the problem of uncoordinated aroma components in green tea processing was solved, the linalool retention rate and tea aroma quality were improved, and the residual grass smell was reduced.
Patent Information
- Application Number
- CN202511138646.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-14
- Publication Date
- 2025-10-03
AI Technical Summary
The existing green tea processing technology has an imbalance in the synergy of aroma components when processing high-fragrance tea varieties, a low retention rate of linalool, a high decomposition rate of pyrazine substances, and serious residual grassy aroma in summer and autumn, which affects the aroma quality of the tea.
A four-stage aroma-condensing process of ultrasonic pretreatment, low-temperature slow solidification, medium-temperature setting and high-temperature instantaneous extraction is adopted, combined with cellulase treatment and dehumidification nitrogen regulation to dynamically adjust the moisture content and temperature of the tea leaves to ensure the retention and synergistic production of key aroma substances.
The retention rate of linalool was improved, the ratio of hexenol to β-ionone was optimized, the residual grassy smell was reduced, the aroma quality and sensory evaluation score of the tea were improved, and the processing energy consumption was reduced.
Smart Images
Figure CN120732018A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of tea processing, in particular to a green tea aroma condensation process. Background Art
[0002] In green tea processing, aroma frying, also known as aroma enhancement or aroma concentration, is a core process that determines the aroma quality of tea. This process promotes the formation and retention of volatile aroma components (such as linalool and pyrazines) in tea leaves through temperature, humidity, and physical field control. However, the existing aroma concentration process has the problem of imbalance in the synergy of aroma components when processing high-fragrant tea varieties (such as Meitan moss tea). Specifically, even after careful segmented temperature control, due to thermal shock, the retention of key aroma substances such as linalool is ≤85%. High temperatures above 70°C tend to increase the decomposition rate of linalool in the slightly burnt areas of the leaf surface. The production of pyrazines requires high temperature stimulation, but traditional processes cannot balance the retention of linalool and the increase of pyrazines, resulting in a loss of tea aroma quality.
[0003] Traditional methods have significant shortcomings, particularly when processing summer and autumn teas. Due to environmental factors during the production season, summer and autumn teas often have a noticeable grassy aroma, and increased polyphenol oxidase activity pushes the ratio of hexenol to β-ionone above 1.5:1. This increased ratio not only increases the tea's grassy aroma but also significantly degrades the aroma synergy of the tea.
[0004] Therefore, there is an urgent need to provide a green tea processing and aroma condensation process, which can improve the balance of aroma components in the processing and aroma condensation of high-fragrance tea varieties, increase the retention rate of key aroma substances while reducing the residual grass smell, and meet consumers' demand for high-quality green tea. Summary of the Invention
[0005] The purpose of the present invention is to overcome the above-mentioned background technical difficulties and provide a green tea processing aroma condensation process, which can improve the balance of aroma components in the processing of high-fragrance tea varieties, increase the retention rate of key aroma substances while reducing the residual grass smell.
[0006] In order to achieve the above purpose, the technical solution adopted is: a green tea processing and aroma condensation process, comprising the following processing steps: 1) Ultrasonic pretreatment: Place the green tea leaves with a moisture content of 28±2% after withering in an ultrasonic field at a frequency of 40±0.5kHz for 5±0.1min; 2) Low-temperature retarding stage: transfer the ultrasonically treated green tea leaves into a constant temperature hot air oven at 50±0.5℃ for 35±2min to reduce the moisture content of the green tea leaves to 22±0.3%; 3) Medium temperature setting stage: This includes a temperature rising stage and a constant temperature stage. In the temperature rising stage, the temperature of the green tea leaves is raised from 50°C to 65±0.5°C at a rate of 2.0±0.1°C / min. In the constant temperature stage, the temperature is maintained at 65±0.5°C for 12±0.5 minutes, while dehumidified nitrogen is introduced at a wind speed of 1.8±0.1m / s to reduce the moisture content to 18±0.2%. 4) High-temperature instant extraction stage: The green tea leaves are transferred to a negative pressure chamber with a pressure of 0.60±0.01 bar and treated at 80±0.3℃ for 30±0.5s, with the moisture content of the final product controlled at 5.5±0.3%.
[0007] Furthermore, before step 1), 0.018±0.002 wt% cellulase solution is sprayed on the green tea leaves, and the tea leaves are left to stand in a humidified environment at 25±0.5° C. for 28±0.5 min.
[0008] Furthermore, in step 3), the dew point temperature of the dehumidified nitrogen is ≤-40° C., and the relative humidity is ≤10%.
[0009] Furthermore, in the constant temperature section of step 3), the real-time temperature difference between the temperature of the tea leaves and the temperature of the hot air is ≤0.8°C.
[0010] Furthermore, the final product in step 4) satisfies the following conditions: a linalool retention rate ≥ 92%, and a peak area ratio of vinyl alcohol to β-ionone of 0.85:1±0.05.
[0011] The green tea aroma condensation process provided by the present invention has the following beneficial effects: The present invention can effectively adjust the synergy between volatile aroma components through dynamic regulation of moisture content and four-stage coordinated temperature control, thereby improving the retention rate of key aroma substances while reducing processing energy consumption, and effectively solves the problem that the traditional aroma condensation process for high-fragrance tea varieties causes poor balance of aroma components, resulting in low retention rate of key aroma substances and residual grass smell. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 The figure is a flow chart of the aroma condensation process of green tea according to the present invention.
[0013] Figure 2 The present invention provides a flow chart for dynamically controlling the moisture content of the green tea aroma-condensing process. DETAILED DESCRIPTION
[0014] The technical solutions of the present invention are described clearly and completely below in conjunction with specific embodiments of the present invention. The described embodiments are only a portion of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.
[0015] Example 1 like Figure 1 The present invention provides a green tea processing and fragrance condensing process, and the green tea variety: This application uses one bud and two leaves of Meitan moss tea as raw materials, and this type of variety has a mesophyll thickness of 0.34±0.03mm and a cell wall density of 1.79±0.03g / cm³.
[0016] Fixing parameters: Use a drum-type fixing machine at a temperature of 240±5℃ for 90±5s to fix the raw materials, and control the moisture content after fixing to 28±2%.
[0017] The fragrance condensation process comprises the following processing steps: 1) Ultrasonic pretreatment: Place the green tea leaves with a moisture content of 28±2% after withering in an ultrasonic field with a frequency of 40±0.5kHz for 5±0.1min. Before the ultrasonic pretreatment of this application, 0.018±0.002wt% cellulase solution is sprayed on the green tea leaves and allowed to stand in a 25±0.5℃ rehumidification environment for 28±0.5min. Cellulase specifically hydrolyzes β-glucan to release bound carotenoid precursors. This application uses cellulase to hydrolyze the cell wall polysaccharides of the green tea leaves, thereby releasing bound β-ionone precursors, and then inhibits the activity of polyphenol oxidase by rehumidification at 25℃, reducing the amount of hexenol produced by 40%; and then undergoes a precise 28min window period control to avoid excessive enzymatic hydrolysis to produce impurities and odors, that is, this application first enzymatically releases the precursors and then inhibits the enzyme activity at low temperature.
[0018] The test comparison is shown in Table 1: Treatment Hexenol (μg / g) β-ionone (μg / g) ratio Enzyme-free treatment 0.85 0.56 1.52:1 Enzyme treatment of the present invention 0.38 0.45 0.84:1 Table 1 Comparison of enzyme treatment tests 2) Low-temperature retarding stage: The ultrasonically treated green tea leaves are placed in a constant-temperature hot air oven at 50±0.5°C for 35±2 minutes to reduce the moisture content of the green tea leaves to 22±0.3%. This application inhibits lipoxygenase activity by maintaining a constant temperature of 50±0.5°C, thereby blocking the formation of hexenol. The moisture content of the green tea leaves is then controlled to 22±0.3%, establishing the water activity required for β-ionone synthesis in the subsequent heating stage.
[0019] The test comparison is shown in Table 2: Moisture content Aroma characteristics ＞23% High enzyme activity, residual grassy smell 22±0.3% β-ionone synthesis window opens ＜21% Metabolic stagnation and lack of costus root Table 2 Moisture content-aroma correlation table 3) Medium-temperature setting stage: It includes a temperature rising section and a constant temperature section. In the temperature rising section, the temperature of the green tea leaves is raised from 50°C to 65±0.5°C at a rate of 2.0±0.1°C / min; in the constant temperature section, the temperature is maintained at 65±0.5°C for 12±0.5min. The real-time temperature difference between the leaf surface temperature of the green tea leaves and the hot air temperature is ≤0.8°C. At the same time, dehumidified nitrogen is introduced at a wind speed of 1.8±0.1m / s to inhibit oxidase. The dew point temperature of the dehumidified nitrogen is ≤-40°C, and the relative humidity is ≤10%, so that the moisture content is reduced to 18±0.2%.
[0020] 4) High-temperature instantaneous extraction stage: the green tea is transferred to a negative pressure chamber with a pressure of 0.60±0.01 bar. The negative pressure chamber reduces the boiling point of water to below 72°C by reducing the pressure, thereby achieving low-temperature dehydration in an 80°C environment, and treating at 80±0.3°C for 30±0.5s to control the moisture content of the final product to 5.5±0.3%; in this application, the boiling point is reduced to 72°C by negative pressure, and the actual temperature of the green tea is ≤75°C, which can effectively avoid the thermal decomposition of β-ionone; through the pressure formula P=f(V_w) V_w is the water content of the green tea per unit mass (cm³ / g), it can dynamically adapt to the low moisture content of summer and autumn tea, thereby preventing excessive dehydration from causing insufficient conversion; the final product of this application meets the requirements of linalool retention rate ≥92%, and the peak area ratio of vinyl alcohol to β-ionone is 0.85:1±0.05.
[0021] The test comparison is shown in Table 3: Negative pressure solution Hexenol conversion rate β-ionone augmentation Normal pressure 80℃ 12% +8% This application dynamic negative pressure 41% +22% Table 3 Comparison of pressure treatment tests The aroma condensation process provided by this application and the traditional process were used to process equal amounts of one bud and two leaves of Meitan moss tea from the same batch, and the tea leaves after aroma condensation were tested. The test results are shown in Table 4: index Traditional crafts Process of the present invention Improvement Hexenol / β-ionone 1.52:1 0.84:1 Optimized by 80% Linalool retention rate 82% 93.2% 9% increase Sensory evaluation scores 72.3 93.8 Increased by 21.5% Energy consumption per ton of tea 1.8kWh 0.9kWh Reduce by 50% Table 4 Comparison of aroma condensation processes It can be seen from this that the fragrance condensation process provided by the present application can first effectively promote the structural remodeling of the cell wall of the tea leaves through the ultrasonic pretreatment step, provide a more uniform physical environment for the subsequent temperature control treatment, and secondly, combine the low-temperature slow condensation stage to further reduce the moisture content of the tea leaves through the constant temperature hot air box, which helps to stabilize the structure of the intracellular substance. Subsequently, combined with the medium-temperature shaping stage, through precise heating rate and constant temperature time, it is ensured that under suitable temperature and humidity conditions, the key aroma substances are effectively generated and retained. Finally, in the high-temperature instant extraction stage, negative pressure treatment and rapid heating are used to further optimize the preservation of aroma components and ensure the aroma quality of the final product. The fragrance condensation process provided by the present application not only improves the retention rate of linalool through precise regulation between steps, but also optimizes the ratio between hexenol and β-ionone. After GC-MS detection, the β-ionone precursor content is increased by 2.8 times after enzyme treatment, thereby significantly improving the aroma quality of green tea.
[0022] Example 2 Based on the above embodiment, this embodiment uses a sensor to monitor the moisture content in real time and performs adaptive adjustment of the moisture content of summer and autumn tea as shown in Table 5; Moisture content range Low temperature retarding time Medium temperature setting constant temperature time Negative pressure compensation coefficient 26-27% 33 12 +0.03bar 28-29% 35 14 Baseline value 30-31% 37 16 -0.03bar Table 5 Process parameter dynamic table This embodiment is adjusted according to the above moisture content. When the moisture content of the green tea is greater than 30%, it is first pre-dehydrated to 28±2% with cold air at 25°C before entering step 1); 1) Ultrasonic pretreatment: Place the green tea leaves with a moisture content of 28±2% after withering in an ultrasonic field at a frequency of 40±0.5kHz for 5±0.1min; 2) Low-temperature retarding stage: The ultrasonically treated green tea leaves were placed in a 50°C constant temperature hot air oven for 37 minutes to reduce the moisture content of the green tea leaves to 22±0.3%; 3) Medium temperature setting stage: This includes a temperature rise stage and a constant temperature stage. In the temperature rise stage, the temperature of the green tea leaves is raised from 50°C to 65±0.5°C at a rate of 2.0±0.1°C / min. In the constant temperature stage, the temperature is maintained at 65±0.5°C for 12.5 minutes, while dehumidified nitrogen is introduced at a wind speed of 1.8±0.1m / s to reduce the moisture content to 18.2%. 4) High-temperature instant extraction stage: The green tea leaves are transferred to a negative pressure chamber with a pressure of 0.60±0.01 bar and treated at 80°C for 30 seconds to control the moisture content of the final product to 5.5%.
[0023] The moisture content dynamic adjustment process of this embodiment and the traditional fixed parameter process are used to perform fragrance condensation process on one bud and two leaves of Meitan moss tea of the same batch. The detection of the tea leaves after fragrance condensation by the traditional fixed parameter process is 84.7% of linalool retention rate, 35% of ethylene alcohol conversion rate, and 12% of leaf bottom burnt rate. The detection of the tea leaves after fragrance condensation by the moisture content dynamic adjustment process of this application is 93.2% of linalool retention rate, 68% of ethylene alcohol conversion rate, and 0% of leaf bottom burnt rate. It can be seen that the present invention dynamically adjusts the processing steps according to the moisture content of the tea leaves in combination with low-medium-high temperature control and adjustment means, so as to effectively adjust the synergy between volatile aroma components, thereby improving the retention rate of key aroma substances, and effectively solving the problem that the traditional fragrance condensation process for high-fragrance tea varieties causes poor balance of aroma components, resulting in low retention rate of key aroma substances and residual grass smell.
[0024] Control group 1 On the basis of the above embodiment, the difference between this control group and the embodiment is that the process characteristics are switched at a fixed time, and the parameters are set at low temperature for 35 minutes, medium temperature for 15 minutes, and negative pressure of 0.60 bar.
[0025] Control group 2 On the basis of the above embodiment, the difference between this control group and the embodiment is that the process characteristics have no moisture content feedback, and the parameter setting is based on manual experience to determine the switching point.
[0026] Control group three On the basis of the above-mentioned embodiment, the difference between this control group and the embodiment is that the process characteristics are independently controlled in sections and there is no moisture content feedback mechanism.
[0027] The aroma condensation process provided by the present application and the control group 1, control group 2 and control group 3 were used to produce the same amount of Meitan moss tea and then test the tea leaves. The results are shown in Table 6, where the energy consumption is based on processing 1 ton of withered leaves. index Dynamic Process Control group 1 Control group 2 Control group three Moisture content qualified rate 100% 68% 55% 72% Linalool retention rate 93.2% 84.7% 79.2% 86.3% Leaf burn rate 0% 17% 23% 14% Energy consumption (kWh / kg) 0.9 1.1 1.25 1.04 Equipment stability CV≤1.5% CV≤12.8% CV≤28.3% CV≤9.7% Table 6 Process production test comparison table In the above comparison table, the equipment stability CV of the second control group is ≤28.3%, which is significantly higher than that of the dynamic process group or other control groups. The increase in fluctuation is caused by manual operation.
[0028] Experimental group Based on the above examples, this experimental group conducted a water content threshold verification; In one test group, the temperature trigger point was 24%, and the linalool retention rate was 85.3%. There was too much water content, and the condensation of water vapor during heating caused a stuffy odor.
[0029] In the second test group, the temperature trigger point was 23%, the linalool retention rate was 88.7%, and there was a slight residual grassy smell.
[0030] In the third test group, the temperature trigger point was 22.3%, the linalool retention rate was 93.2%, no grassy smell remained, and the hexenol / β-ionone ratio was 0.84:1; In the fourth experimental group, the temperature trigger point was 21.5%, the linalool retention rate was 90.2%, and the leaf margins were slightly curled.
[0031] In the fifth test group, the temperature trigger point was 20%, the linalool retention rate was 86.1%, and there was low water content and hardened leaf surface.
[0032] It can be seen from this that the real-time moisture content threshold of this application controls the moisture content at 22.3% as the switching point from 50°C to 65°C. This threshold is applicable to varieties with a cell wall density of 1.75-1.85g / cm³. Other varieties need to be calibrated. It can target the thermal conduction lag of Meitan moss tea and improve the retention rate of the tea aroma after condensation.
[0033] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.
[0034] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.
Claims
1. A green tea aroma condensation process, characterized in that: The processing steps include: 1) Ultrasonic pretreatment: Place the green tea leaves with a moisture content of 28±2% after withering in an ultrasonic field at a frequency of 40±0.5kHz for 5±0.1min; 2) Low-temperature retarding stage: transfer the ultrasonically treated green tea leaves into a constant temperature hot air oven at 50±0.5℃ for 35±2min to reduce the moisture content of the green tea leaves to 22±0.3%; 3) Medium temperature setting stage: This includes a temperature rising stage and a constant temperature stage. In the temperature rising stage, the temperature of the green tea leaves is raised from 50°C to 65±0.5°C at a rate of 2.0±0.1°C / min. In the constant temperature stage, the temperature is maintained at 65±0.5°C for 12±0.5 minutes, while dehumidified nitrogen is introduced at a wind speed of 1.8±0.1m / s to reduce the moisture content to 18±0.2%. 4) High-temperature instant extraction stage: The green tea leaves are transferred to a negative pressure chamber with a pressure of 0.60±0.01 bar and treated at 80±0.3℃ for 30±0.5s, with the moisture content of the final product controlled at 5.5±0.3%.
2. The green tea aroma condensation process according to claim 1, characterized in that: Before step 1), 0.018±0.002 wt% cellulase solution is sprayed on the green tea leaves, and the tea leaves are left to stand in a humidified environment at 25±0.5° C. for 28±0.5 min.
3. The green tea aroma condensation process according to claim 1, characterized in that: In step 3), the dew point temperature of the dehumidified nitrogen is ≤-40° C., and the relative humidity is ≤10%.
4. The green tea aroma condensation process according to claim 1, characterized in that: In the constant temperature section of step 3), the real-time temperature difference between the tea leaf surface temperature and the hot air temperature is ≤0.8°C.
5. The green tea aroma condensation process according to claim 1, characterized in that: The final product in step 4) satisfies the following requirements: a linalool retention rate of ≥92%; and a peak area ratio of vinyl alcohol to β-ionone of 0.85:1±0.05.