High-temperature precise aroma extraction process according to tea leaf tenderness

Abstract

The application discloses a process for high-temperature precise aroma extraction according to the tenderness of tea leaves, which comprises three-stage stepwise temperature and speed rising drying and aroma extraction, and no essence is added in the whole process.S1 initial moisture content is greater than 15%, low-temperature and low-speed pre-drying, tender leaves 120 DEG C / 300 r / min, old leaves 80-100 DEG C / 260 r / min; the moisture content is reduced to less than 10% to enter S2 medium-temperature transition aroma extraction, tender leaves 150 DEG C / 350 r / min, old leaves 130 DEG C / 300 r / min; S3 high-temperature aroma release, tender leaves 200-210 DEG C / 400 r / min, old leaves 210-230 DEG C / 390 r / min, the three-stage tea leaf laying thickness is uniform 1 cm, and the speed is increased step by step. According to the temperature control of tea leaf tenderness difference, the application firstly dehydrates at low temperature, then activates aroma precursors at medium temperature, and finally fully stimulates endogenous natural aroma of tea leaves. Compared with traditional constant-temperature tea drying, the product scorched rate is greatly reduced, the content of aromatic substances is increased by nearly 90%, no exogenous aroma auxiliary material is needed, and the tea aroma is rich and pure.

Description

Technical Field

[0001] This invention belongs to the field of tea processing technology, and more specifically, it relates to a high-temperature precision aroma enhancement process based on the tenderness of tea leaves. Background Technology

[0002] Enhancing the aroma of tea is a crucial step in tea processing, shaping its flavor and quality. Traditional tea aroma enhancement involves a standardized, temperature-controlled processing method. Regardless of the tea's tenderness or initial moisture content, it is processed using a near-uniform temperature cycle for frying and drying, with the total number of cycles exceeding one hundred. This traditional method has significant drawbacks: First, it cannot adjust the processing temperature according to the tea's tenderness and moisture content. Low-temperature processing fails to fully stimulate the tea's inherent aromatic substances, resulting in a weak aroma in the finished tea. Conversely, simply increasing the overall processing temperature easily causes the tea to burn, resulting in a scorched or burnt taste that destroys the tea's original flavor. Second, given the insufficient release of inherent aromas, many small and medium-sized tea factories artificially add flavorings and other exogenous additives to enhance the aroma. This results in a loss of the tea's natural flavor, raises concerns about the use of food additives, and fails to meet the market's demand for additive-free, pure tea.

[0003] Traditional folk tea-making methods involve simple aroma enhancement techniques. Tea masters place a small amount of tea leaves in an iron can and continuously shake it over a stove to roast it, relying on alternating high and low temperatures to enhance the aroma. However, this method relies entirely on manual experience, lacking standardized control over temperature, rotation speed, and leaf thickness, resulting in extremely low processing efficiency and unsuitability for industrial mass production. Existing mechanized drying and aroma enhancement equipment can only achieve a single fixed temperature or a small range of temperature adjustment. It does not incorporate segmented, stepped heating and speed-up processes based on the tea's tenderness and moisture content, failing to fully release the tea's natural aroma while avoiding scorching. Summary of the Invention

[0004] To address the shortcomings of existing tea aroma enhancement processes, such as the inability to control temperature according to the differences in tea tenderness, insufficient release of natural aroma, easy scorching, and the need to add additional flavorings, this invention provides a process for high-temperature precise aroma enhancement based on the tenderness of tea leaves.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A high-temperature precision aroma enhancement process based on the tenderness of tea leaves includes three sequential aroma enhancement steps, the specific steps of which are as follows: Step S1: Low-temperature pre-drying and aroma enhancement: Spread the tea leaves to be processed evenly on the material layer of the drying and aroma enhancement machine, and control the thickness of the material layer to be 1cm. At this time, the initial moisture content of the tea leaves is higher than 15%, and the free water content inside the tea leaves is high. Use low temperature and low speed to slowly dehydrate the tea leaves, so as to avoid the surface of the tea leaves being scorched and the internal moisture being unable to be discharged due to direct high temperature baking.

[0006] In step S1, two types of processing parameters are distinguished according to the tenderness of the tea leaves: for tea leaves with better tenderness, the temperature is set at 120℃ for the first stage and the first speed of the drying and aroma-enhancing machine is 300 rpm; for tea leaves with more tenderness, the temperature is controlled in the range of 80℃~100℃ for the first stage and the first speed of the drying and aroma-enhancing machine is 260 rpm.

[0007] Step S2: Second-stage medium-temperature transition for aroma enhancement: Continuously monitor the moisture content of the tea leaves. When the moisture content drops below 10%, switch to the second-stage processing condition. The second stage uses a higher processing temperature and a higher operating speed than the first stage. The medium temperature accelerates the volatilization of bound water in the tea leaves, gradually activating the aromatic precursors inside the tea leaves, laying the groundwork for high-temperature aroma enhancement. The parameters are matched according to the tenderness: for tea leaves with good tenderness: the second-stage temperature is 150℃, and the second speed of the drying and aroma enhancement machine is 350 rpm; for tea leaves with slightly older tenderness: the second-stage temperature is 130℃, and the second speed of the drying and aroma enhancement machine is 300 rpm.

[0008] Step S3: Three-stage high-temperature deep aroma enhancement: After two stages of dehydration, the moisture content of the tea leaves drops significantly, entering the core aroma release process. The temperature of the drying and aroma-enhancing machine is raised to a high-temperature range of 200℃~230℃, while switching to a third speed higher than the second stage. The high temperature quickly stimulates all the natural aromatic substances inside the tea leaves. The three-stage processing temperature range is strictly matched to the tenderness of the tea leaves, and the temperature and time are precisely controlled to avoid insufficient high temperature for short periods of time, resulting in a weak aroma, and excessive high temperature for long periods of time, causing the tea leaves to burn. For tea leaves with good tenderness: the third stage temperature is 200℃~210℃, and the third speed of the drying and aroma-enhancing machine is 400 rpm. For tea leaves with slightly older tenderness: the third stage temperature is 210℃~230℃, and the third speed of the drying and aroma-enhancing machine is 390 rpm.

[0009] This process features a stepped increase in the first, second, and third rotation speeds throughout the entire process. As the moisture content of the tea leaves gradually decreases and the rate of moisture evaporation continuously declines, the progressively increasing drum speed ensures that the tea leaves are constantly turned over, guaranteeing even heating of all parts of the tea and preventing localized overheating and scorching. Simultaneously, it accelerates the circulation of high-temperature aroma within the sealed drying equipment, enhancing aroma enrichment. Throughout the S1, S2, and S3 processes, the tea leaf layer thickness remains constant at 1cm. This uniform thickness ensures consistent heat penetration and eliminates the problem of uneven heating in certain areas of the tea leaves.

[0010] Compared with the prior art, the present invention has the following beneficial effects: (1) This scheme solves the drawback of the traditional process of uniformly drying tea leaves without distinguishing the tenderness of the leaves by distinguishing between two independent three-stage temperature parameters for tender leaves and older leaves. Tender leaves have low lignification and weak high temperature tolerance, so the three-stage high temperature is limited to 200-210℃. Older leaves have coarse fibers and are resistant to high temperatures, so the three-stage temperature is increased to 210-230℃ to maximize the release of the intrinsic aroma of different tea leaves.

[0011] (2) This scheme gradually dehydrates and releases aroma by first removing free water at low temperature, then removing bound water at medium temperature, and finally releasing aromatic substances at high temperature. The rotation speed is gradually increased with each processing stage, and the tea leaves are continuously turned over. With the addition of a uniform 1cm thin layer of material, the problem of local high-temperature scorching is eliminated, and there is no need to rely on manual repeated stirring.

[0012] (3) This solution relies on the high temperature range of 200-230℃ to fully stimulate the aroma precursors of tea leaves. It can achieve a rich and lasting tea aroma without the need to add fragrance, solving the industry pain point of existing tea factories relying on additives to enhance aroma. The finished tea leaves retain their natural flavor and are healthier and safer to drink. Attached Figure Description

[0013] Figure 1 This is the process flow diagram for this scheme. Detailed Implementation

[0014] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0015] like Figure 1 As shown, this invention sets up two sets of embodiments (tender leaves and old leaves) and two sets of traditional process comparison examples. All of them use the same model of drum drying and aroma-enhancing machine, and the tea leaf layer thickness is uniformly 1cm. The processing environment is 25℃ and 60% humidity. Each group of experiments is repeated 3 times and the average value is taken. At the same time, 4 sets of boundary verification experiments are set up to verify the technical necessity of the three temperature ranges, the stepped speed increase, and the layer thickness.

[0016] To eliminate the errors caused by relying on manual experience to distinguish the tenderness of tea leaves in traditional tea making, this invention sets clear and quantifiable criteria for judging the tenderness of fresh leaves: tea leaves with better tenderness are made from fresh leaves with one bud and one leaf or one bud and two leaves. These fresh leaves have fine fibers, low lignification, and weak high-temperature resistance; tea leaves with older tenderness are made from fresh leaves with one bud and three leaves or one bud and four leaves. These fresh leaves have more coarse fibers, high lignification, and can withstand higher processing temperatures.

[0017] Testing Standards: Moisture Content: Detected using a rapid moisture analyzer and weighing drying method; Proportion of Scorched Leaves: 100g of dry tea was randomly selected, and leaves with scorched spots and burnt flavor were manually sorted, and the mass percentage was calculated; Total Aromatic Content: Detected by gas chromatography (μg / g) of total volatile aroma components; Sensory Aroma Score: Blind evaluation by 5 certified tea tasters, with a maximum score of 10 points, and the average score was taken. Dimensions included aroma concentration, purity, persistence, and presence of burnt flavor.

[0018] Example 1: This embodiment uses single buds, one bud and one leaf, spring high-mountain green tea; initial average moisture content is 16.3%; single feeding is 5kg, and the thickness of the flat layer is strictly 1cm.

[0019] The aroma enhancement process is performed according to the following steps: Step S1: First-stage aroma enhancement: Set temperature 120℃, drum speed 300r / min; continuous processing time 18min; Actual measurement: After 18min, the average moisture content of the tea leaves was 9.4%, dropping below 10%, reaching the threshold for the second-stage transition. Step S2: Second-stage aroma enhancement: Increase temperature to 150℃, increase drum speed to 350r / min; processing time 12min; Actual measurement: After the second stage, the average moisture content of the tea leaves was 5.1%, with free moisture basically removed and aromatic precursors fully activated. Step S3: Third-stage high-temperature aroma release: Set temperature 205℃, drum speed 400r / min; precise time control 4.5min; Actual measurement: After the third stage, the final moisture content of the finished tea leaves was 3.0%.

[0020] According to the test results, the moisture content of the finished product in Example 1 was 3.0%; the scorched leaf mass accounted for only 0.21%; the total content of volatile aromatic substances reached 118.6 μg / g; and the sensory aroma average score was 9.3 points after blind tasting by 5 tea tasters.

[0021] Example 2: Example 2 uses summer and autumn tea leaves with one bud and three or four leaves, which have a high degree of lignification; the initial average moisture content is 15.7%; the single feeding is 5kg, and the thickness of the spread is 1cm.

[0022] The aroma enhancement process is performed according to the following steps: Step S1: First-stage aroma enhancement: Set the base temperature to 90℃, drum speed to 260 r / min; processing time to 24 min; actual measurement: the average moisture content at the end of processing is 8.6%, below the 10% threshold, switch to the second stage. Step S2: Second-stage aroma enhancement: Increase the temperature to 130℃, increase the speed to 300 r / min; processing time to 15 min; actual measurement: the moisture content of the tea leaves at the end of the second stage is 4.8%, and a large amount of bound water inside the fibers has been removed. Step S3: Third-stage high-temperature aroma release: Set the temperature to 220℃ (within the range of 210~230℃), drum speed to 390 r / min; time control to 5 min; actual measurement: the moisture content of the finished product is 2.8%.

[0023] According to the test results, the moisture content of the finished product in this embodiment was 2.8%; the mass ratio of scorched leaves was 0.35%; the total content of volatile aromatic substances was 97.3 μg / g; and the average sensory aroma score was 9.0 points.

[0024] Comparative Example 1: Tender leaves were processed using a traditional, uniform, constant-temperature aroma enhancement process (existing conventional process). The raw materials are exactly the same as those in Example 1 (one bud and one leaf of tender leaves, initial moisture content of 16.3%, 5kg of material, 1cm of material spread); the traditional process is carried out at a fixed temperature of 130℃ throughout, with a constant drum speed of 320r / min, and uniform circulation drying for 40min, without segmented temperature control or high-temperature aroma release process.

[0025] Tests showed that the finished product had a moisture content of 3.2%; scorched leaves accounted for 1.87% of the total weight; the total content of volatile aromatic substances was only 62.4 μg / g; and the average sensory aroma score was only 6.1.

[0026] Comparative Example 2: Old leaves were processed using a traditional, uniform, constant-temperature aroma enhancement process. The raw materials were exactly the same as those in Example 2 (old leaves with one bud and three or four leaves, initial moisture content of 15.7%); the temperature was kept constant at 120℃ throughout the process, the rotation speed was kept constant at 300r / min, and the drying process was carried out continuously for 44min, without three-stage step heating or high-temperature aroma release steps above 200℃.

[0027] Tests showed that the finished product had a moisture content of 3.1%; scorched leaves accounted for 2.24% of the total weight; the total content of volatile aromatic substances was only 51.9 μg / g; and the average sensory aroma score was 5.7.

[0028] Comparative Examples 1-2 and 2 show that the total aroma of the tender leaf group is increased by 90.1% compared with the traditional process; the aroma of the old leaf group is increased by 87.5%, and the aromatic precursors can be fully decomposed in the high temperature range of 200-230℃; in terms of anti-scorching effect, the scorching defect rate of the present invention is reduced by more than 80% compared with the traditional process; the aroma of the sample of the present invention is pure and high, while the aroma of the traditional process is thin and has a musty smell; the moisture content of the finished product of the present invention is concentrated in a certain range, and the batch stability is stronger.

[0029] To further demonstrate the innovativeness of this scheme, the following experimental examples were set up for comparative verification. Experimental Examples 1-4 were conducted under the same basic experimental conditions: the raw material used was the same tender leaves with one bud and one leaf as in Example 1, with an initial moisture content of 16.3%, a single feed of 5 kg, an ambient temperature of 25℃, and an ambient humidity of 60%; only a single target parameter was modified, while the remaining process parameters remained completely consistent with Example 1. Each group was repeated 3 times, and the average value was taken and compared with the standard data of Example 1.

[0030] Experimental Example 1: Three-stage aroma enhancement temperature S3 was set to 180℃ Variable settings: S1 parameters are 120℃ and 300r / min, S2 parameters are 150℃ and 350r / min, S3 is adjusted to 180℃ and 400r / min, the material thickness is kept constant at 1cm, and the processing time of each stage is exactly the same as in Example 1.

[0031] The trend of moisture content change at each stage of the processing was not significantly different from that in Example 1, and the moisture content of the finished product was 2.9%.

[0032] Test results: The proportion of scorched leaves was 0.19%, which was basically the same as 0.21% in Example 1; the total content of volatile aromatic substances was only 74.2 μg / g, which was far lower than 118.6 μg / g in Example 1; the sensory aroma score was only 7.0 points, which was significantly lower than 9.3 points in Example 1.

[0033] Experimental conclusion: When the temperature in the three stages is below the lower limit of 200℃, the endogenous aromatic substances in the tea cannot be fully stimulated, resulting in a significant decrease in the total aroma of the finished product and a weak aroma. This proves that 200℃ is the essential lower limit for high-temperature aroma release in the three stages.

[0034] Experiment Example 2: Three-stage aroma enhancement temperature S3 was set to 240℃ Variable settings: S1 and S2 parameters, material thickness, and processing time are kept the same as in Example 1, except that the S3 temperature is adjusted to 240℃ and the rotation speed is maintained at 400r / min.

[0035] When the drying equipment was heated for 2 minutes in the third stage, obvious burnt smoke appeared inside, and a large number of leaves had blackish-brown scorch spots after discharge.

[0036] Test results: The proportion of scorched leaves was as high as 12.60%, while that in Example 1 was only 0.21%; the total content of volatile aromatic substances was 89.5 μg / g, which was lower than that in Example 1; the sensory aroma score was only 4.2 points, with a significant burnt bitter taste masking the natural tea aroma.

[0037] Experimental conclusion: Temperatures exceeding 230℃ will cause rapid carbonization of tea fibers, significantly increasing the number of scorched and defective products, while also destroying the original aroma, proving that 230℃ is the upper limit of the safe aroma release temperature for this process.

[0038] Experiment Example 3: Disable the stepped speed increase setting and maintain a constant speed of 350 r / min throughout the entire process. Variable settings: The processing temperature of the three stages, the processing time of each stage, and the thickness of the material are all based on the standard of Example 1. The rotation speed is 350r / min throughout the process of S1, S2, and S3, and the step-increase rotation speed scheme is no longer used.

[0039] During processing, localized accumulation of tea leaves was observed inside the drum, with insufficient tumbling of tea leaves in the center of the material layer, resulting in uneven heating. Test results showed that the proportion of scorched leaves was 1.13%, significantly higher than the 0.21% in Example 1; the total content of volatile aromatic substances was 92.7 μg / g, lower than the standard process; and the sensory aroma score was 7.8 points, lower than the 9.3 points in Example 1.

[0040] Experimental conclusion: After eliminating the stepwise speed increase, the tea leaves were heated unevenly, resulting in localized high temperatures and scorching. At the same time, the aromatic substances were not fully released. This confirms that the stepwise speed increase is the core technical feature to ensure uniform heating of the tea leaves and improve the aroma release effect.

[0041] Experiment Example 4: The thickness of the paving material was adjusted from the standard 1cm to 2cm. Variable settings: The processing temperature, rotation speed and processing time of each stage are all based on the standard of Example 1, except that the thickness of the tea leaves is increased to 2cm.

[0042] After processing, samples were taken from each layer for testing. The surface tea leaves were slightly scorched, while the bottom tea leaves had not been sufficiently dehydrated.

[0043] Test results: The proportion of scorched leaves was 0.96%, which was higher than that in Example 1; the total content of volatile aromatic substances was 92.5 μg / g, which was lower than that in the standard process; the sensory aroma score was 7.6 points, which was significantly different from that in the standard process.

[0044] Experimental conclusion: A layer thickness exceeding 1cm will hinder heat penetration, preventing the inner layer of tea leaves from fully releasing their aromatic substances, while the outer layer of tea leaves is prone to scorching due to excessive heating. This verifies the technical necessity of uniformly controlling the layer thickness to 1cm.

[0045] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A high-temperature precision aroma enhancement process based on the tenderness of tea leaves, characterized in that, Includes the following steps: Step S1: First stage of aroma enhancement: Place the tea leaves to be processed into the drying and aroma enhancement machine, set the first temperature and the first speed for drying; Step S2: Second stage aroma enhancement: When the moisture content of the tea leaves decreases to the preset threshold, adjust the parameters of the drying and aroma enhancement machine, set a second temperature higher than the first temperature and a second speed higher than the first speed to continue drying; Step S3: Three-stage aroma enhancement: With the moisture content of the tea leaves further reduced, high-temperature rapid aroma enhancement is carried out. The temperature of the drying and aroma enhancement machine is adjusted to between 200℃ and 230℃, and a third speed higher than the second speed is set.

2. The high-temperature precision aroma enhancement process based on tea leaf tenderness according to claim 1, characterized in that, For tea leaves with good tenderness, the specific parameters for steps S1 to S2 are as follows: First stage: temperature controlled at 120℃, drying and aroma-enhancing machine speed at 300 rpm; Second stage: temperature controlled at 150℃, drying and aroma-enhancing machine speed at 350 rpm. The third stage: the temperature is controlled at 200℃ to 210℃, and the speed of the drying and aroma-enhancing machine is 400 rpm.

3. The high-temperature precision aroma enhancement process based on tea leaf tenderness according to claim 1, characterized in that, For tea leaves that are too tender, the specific parameters for steps S1 to S3 are as follows: First stage: temperature controlled at 80℃ to 100℃, and the speed of the drying and aroma-enhancing machine is 260 rpm; Second stage: temperature controlled at 130℃, and the speed of the drying and aroma-enhancing machine is 300 rpm. The third stage: the temperature is controlled between 210℃ and 230℃, and the speed of the drying and aroma-enhancing machine is 390 rpm.

4. A high-temperature precision aroma enhancement process based on the tenderness of tea leaves according to any one of claims 1 to 3, characterized in that: In steps S1, S2 and S3, the thickness of the tea leaves spread on the drying and aroma-enhancing machine is uniformly controlled at 1 cm.

5. The high-temperature precision aroma enhancement process based on tea leaf tenderness according to claim 1, characterized in that: In step S1, the initial moisture content of the tea leaves to be processed is higher than 15%.

6. The high-temperature precision aroma enhancement process based on tea leaf tenderness according to claim 1, characterized in that: The specific standard for determining whether the moisture content of tea leaves has decreased to a preset threshold in step S2 is: the moisture content of tea leaves decreases to less than 10%.

7. The high-temperature precision aroma enhancement process based on tea leaf tenderness according to claim 1, characterized in that: The first, second, and third rotation speeds increase in a stepwise manner to match the rate of moisture evaporation and the uniformity of heating of tea leaves at different moisture content stages.

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