Preparation method of ripe chestnut aroma strip green tea

Abstract

The application relates to a preparation method of a mature chestnut aroma strip-shaped green tea, S1, withering: one bud one leaf or one bud two leaves of tea tree fresh leaves are spread to a water loss rate of 6.7% to 7.0%, the leaf quality is soft, and the stem is broken but not continuous; S2, fixation: three-stage variable-temperature fixation is adopted; S3, moisture recovery: the fixed leaves are uniformly spread, and wet cloth is covered for moisture recovery for 50 to 60 minutes, so that the leaf stem water is evenly redistributed; S4, rolling: gradient variable-frequency rolling is adopted; S5, strip shaping, the strip-shaped tea is tight, straight, round and beautiful, and the water content is reduced to 35% to 40%; S6, gradient variable-temperature baking: three-stage variable-temperature baking is adopted; S7, natural cooling: after baking is completed, natural cooling is performed for 160 to 180 minutes to room temperature.

Description

Technical Field

[0001] This application relates to tea processing technology, and more specifically, to a method for preparing fully ripened chestnut-scented strip-shaped green tea. Background Technology

[0002] Strip-shaped green tea, with its "tight, straight, round, and delicate" appearance and prominent white tips, enjoys a high reputation in the high-end consumer market and is considered an important indicator of high-quality green tea. However, the current processing technology for strip-shaped green tea still faces significant technical obstacles, severely restricting the improvement of product quality and the enhancement of market competitiveness. The problem of a single aroma layer is particularly prominent. Traditional processes rely excessively on the subjective experience of operators in the aroma enhancement stage, lacking a scientific control mechanism for temperature, time, and environmental conditions, making it difficult to accurately generate the specific aroma type of "ripe chestnut aroma." As a unique flavor between fresh chestnut aroma and high-roasted aroma, ripe chestnut aroma requires the Maillard reaction and caramelization reaction of polyphenolic compounds, amino acids, and sugars under precise high-temperature conditions to be formed. However, existing methods often leave the product stuck at the primary stage of tender chestnut aroma or ordinary chestnut aroma, failing to achieve the depth development and richness of aroma. Poor uniformity in tea leaf shape is another common defect. During the rolling and shaping processes, process parameters such as pressure, frequency, and duration fail to dynamically adapt to the physical properties of the tea leaves (such as moisture content and pliability), resulting in uneven cell breakage, broken or loose leaf shapes. This not only damages the aesthetic appearance but also reduces the product's commercial value. Low raw material utilization is equally problematic. Different varieties of tea leaves (such as Longjing 43# or Fuding Da Bai Cha) and different harvesting times (such as one bud and one leaf or one bud and two leaves) exhibit significant differences in their response to processing conditions. However, current technology lacks targeted process adjustment strategies, leading to some high-quality raw materials failing to reach their full potential, resulting in resource waste and economic losses. Furthermore, insufficient aroma stability further exacerbates quality fluctuations. Due to the uncontrollable nature of key parameters during processing, the transformation of aroma substances is incomplete and inconsistent, causing significant variations in aroma characteristics between different batches of products, making it difficult to meet the stringent requirements of the high-end market for product consistency. How to simultaneously achieve the stable formation of a fully ripe chestnut aroma and maintain the tight, straight, and uniform shape of the tea strips during processing has become a core technological bottleneck that the industry has long been unable to overcome. Summary of the Invention

[0003] The purpose of this application is to provide a method for preparing fully ripe chestnut-scented strip green tea, which has the advantages of stably generating multi-layered fully ripe chestnut aroma, improving the regularity of tea strip shape, optimizing raw material utilization, and enhancing aroma consistency.

[0004] This application provides a method for preparing fully ripened chestnut-flavored strip-shaped green tea, the technical solution of which is as follows: Includes the following steps: S1 withering: Spread out fresh tea leaves with one bud and one leaf or one bud and two leaves until the water loss rate is 6.7%~7.0%, the leaves are soft and the stems can be bent but not broken; S2 blanching: A three-stage variable temperature blanching method is adopted. The first stage temperature is 220~240℃, the second stage temperature is 210~220℃, and the third stage temperature is 180~200℃. The blanching time for each stage is 30 seconds, and the total blanching time is 90~100 minutes. The blanched leaves have no grassy smell and no scorched edges, and the moisture content is controlled at 58%~62%. S3 Rehydration: Spread the blanched leaves evenly, cover with a damp cloth and rehydrate for 50-60 minutes to allow the moisture in the leaf stalks to be redistributed evenly. S4 kneading: Gradient frequency kneading is adopted, successively kneading at 20Hz without pressure for 15-25 minutes, at 30Hz with light pressure for 20-30 minutes, and at 40Hz with medium pressure for 15-20 minutes, controlling the strip yield ≥85%, cell breakage rate 45%-55%, and fragmentation rate ≤3.5%; S5 leaf shaping: Shape the leaves at 125~135℃ for 25~30 minutes, with a leaf input of 20~30 catties / batch, to make the leaves tight, straight and round, and reduce the moisture content to 35%~40%; S6 Gradient Temperature Baking: Employs a three-stage temperature-controlled baking process, as follows: First stage: Bake at 95℃ with the door open for 30-40 minutes to rapidly dehydrate and stimulate the cleavage of aroma groups; Second stage: Bake at 85~90℃ with the door closed for 30~40 minutes to promote the Maillard reaction to generate pyrazine and furan chestnut aroma compounds; The third stage: bake at 70~75℃ with the door closed for 60~100 minutes to stabilize the aroma and enhance its complexity. S7 Natural Cooling: After baking, allow to cool naturally for 160-180 minutes to room temperature.

[0005] Furthermore, this application also proposes that the thickness of the spread leaves in step S1 during withering is 15~20cm, the ambient temperature is 20~25℃, the relative humidity is 65%~75%, and the leaves are turned over every 30 minutes during the withering process to ensure uniform water loss.

[0006] Furthermore, this application also proposes that in step S2, the withering is carried out using a 90-type electric heating drum withering machine, the leaf feeding rate is 300-350 catties / hour, the drum speed is 25-30 rpm, the turning frequency is 2-3 times / minute, and the leaf temperature is monitored in real time and the heating power is automatically adjusted during the withering process.

[0007] Furthermore, this application also proposes that in step S4, the kneading is carried out using a 55 or 65 type kneading machine, the amount of leaves fed is 15~20kg per barrel, the state of the tea leaves is checked every 5 minutes during the kneading process, and the kneading pressure is adjusted according to the temperature of the tea leaves to control the temperature of the kneaded leaves to not exceed 35℃.

[0008] Furthermore, this application also proposes that in step S5, a fully automatic reciprocating sizing machine is used for sizing, with a sizing groove inclination angle of 3°~5° and a reciprocating frequency of 180~200 times / minute. The sizing process is divided into two pressure applications: the first 15 minutes are pressureless shaping, and the last 10~15 minutes are micro-pressure shaping.

[0009] Furthermore, this application also proposes that the gradient temperature baking in step S6 adopts a multi-functional tabletop aroma enhancer or a chain plate dryer, and the moisture content of the tea is monitored in real time during the baking process. At the end of the first stage, the moisture content drops to 18%~22%, at the end of the second stage, the moisture content drops to 10%~12%, and at the end of the third stage, the moisture content drops to 5.7%~6.3%.

[0010] Furthermore, this application also proposes that the baking temperature in the second stage of step S6 is 88~90℃ and the baking time is 35~38 minutes.

[0011] Furthermore, this application also proposes that during the natural cooling process in step S7, the spreading thickness should not exceed 5cm, and the material should be lightly turned over every 30 minutes to prevent heat buildup from causing the aroma to evaporate.

[0012] Furthermore, this application also proposes that the fresh tea leaves should be selected from Longjing 43# or Fuding Da Bai Cha small-leaf variety, and the picking time should be before Grain Rain in spring. The buds and leaves should be intact and free from pests and diseases. The tea leaves should be transported to the processing plant within 4 hours after picking, and breathable bamboo baskets should be used for transportation to avoid squeezing and generating heat.

[0013] Furthermore, this application also proposes that in step S6, the first stage temperature of the gradient temperature baking is 95°C and the duration is 35-40 minutes; the second stage temperature is 85-90°C and the duration is 35-40 minutes; and the third stage temperature is 70-75°C and the duration is 90-100 minutes.

[0014] As can be seen from the above, the preparation method of the fully ripened chestnut-scented strip green tea provided in this application, through withering, fixation, rehydration, rolling, shaping, gradient temperature baking and natural cooling, precisely controls the process parameters, solves the problems of single aroma layers and poor strip shape regularity, and has the advantages of stably generating multi-layered fully ripened chestnut aroma, improving the regularity of tea strip shape, optimizing raw material utilization and enhancing aroma consistency. Attached Figure Description

[0015] Figure 1 A flowchart illustrating a method for preparing a fully ripened chestnut-scented strip-shaped green tea, as provided in this application. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0018] Traditional processing methods for strip-shaped green tea generally suffer from a lack of complexity in aroma development, making it difficult to accurately achieve a fully developed chestnut aroma. Most products only exhibit a tender chestnut or mature chestnut aroma. Furthermore, insufficient matching of rolling and shaping parameters leads to a high breakage rate and poor uniformity of the tea leaves. In addition, existing processes are poorly adaptable to raw materials of varying tenderness and variety, resulting in resource waste and incomplete transformation of aroma compounds, leading to insufficient aroma stability between batches. How to stably develop a fully developed chestnut aroma in strip-shaped green tea while maintaining a tight, straight, and uniform shape remains a long-standing technical challenge in the industry.

[0019] In this regard, such as Figure 1 As shown, this application proposes a method for preparing fully ripened chestnut-scented strip-shaped green tea. By synergistically optimizing key steps such as withering, fixation, rehydration, rolling, shaping, gradient temperature baking, and natural cooling, it aims to solve the aforementioned technical problems. This method involves precisely withering fresh tea leaves of one bud and one leaf or one bud and two leaves; employing a three-stage variable temperature fixation to control moisture content and remove the grassy taste; rehydration to ensure even moisture distribution in the leaf stems; gradient frequency rolling to improve the strip formation rate and cell breakage rate; shaping to achieve a tight, straight, and round shape; and precise activation of aroma group cleavage through a specific three-stage gradient temperature baking process, promoting Maillard reactions to generate pyrazine and furan-like chestnut-scented substances and stabilizing the aroma layers. Finally, natural cooling ensures aroma stability.

[0020] For ease of understanding, the following explains some key terms in this embodiment: Ripe chestnut-scented strip-shaped green tea refers to a type of green tea product with a tight, straight, and round shape, and an aroma of ripe chestnuts. This aroma is formed by the Maillard reaction and caramelization reaction of polyphenolic compounds, amino acids, and sugars under specific high-temperature conditions.

[0021] Three-stage variable temperature fixation refers to dividing the fixation process into three different temperature stages, with each stage having a specific temperature range and duration, in order to effectively deactivate tea enzymes, control moisture evaporation, and form aroma precursors, while avoiding the tea from developing a grassy taste or scorched edges.

[0022] Gradient frequency rolling refers to gradually adjusting the operating frequency of the rolling machine during the rolling process to change the rolling force and effect. It usually includes different stages such as no pressure, light pressure and medium pressure, in order to reduce the production of tea dust while ensuring the tea strip formation rate and cell breakage rate.

[0023] Gradient temperature roasting refers to dividing the tea roasting process into multiple stages with decreasing temperatures. Each stage has a specific temperature and duration, and the roasting method is combined with either opening or closing the door to achieve rapid dehydration of the tea, activation and transformation of aroma substances, and stabilization and enhancement of aroma levels.

[0024] This application provides a method for preparing fully ripened chestnut-flavored strip-shaped green tea, specifically including the following steps: First, withering is performed. Fresh tea leaves, consisting of one bud and one leaf or one bud and two leaves, that meet the requirements for tea processing are spread out until their water loss rate reaches 6.7% to 7.0%. At this point, the leaves become soft, and the stems can be bent but not broken. The purpose of withering is to remove some of the moisture from the fresh leaves, increasing the permeability of the leaf cell membranes and creating conditions for enzyme activity and material transformation in subsequent processes. For example, the withering process can be carried out by spreading the fresh leaves evenly on bamboo trays or withering troughs, using natural ventilation or supplemented with a slight warm air. The thickness of the spread leaves can be set to 10cm or 25cm, the ambient temperature can be set to 15℃ or 30℃, and the relative humidity can be set to 50% or 80%. During the withering process, the leaves can be turned over every 60 or 90 minutes.

[0025] Next, the tea is subjected to fixation. A three-stage variable-temperature fixation process is adopted. The first stage temperature can be set to 220~240℃, the second stage temperature to 210~220℃, and the third stage temperature to 180~200℃. The fixation time for each stage can be 30 seconds, with the total fixation time controlled at 90~100 minutes. After fixation, the leaves should have no grassy smell, no scorched edges, and the moisture content should be controlled at 58%~62%. The purpose of fixation is to rapidly deactivate enzymes through high temperature, prevent tea fermentation, and maintain the color and internal substances of green tea. For example, fixation can be carried out using a drum fixation machine, with the heating power and drum speed manually controlled, or an intermittent fixation can be carried out using a pan fixation machine. The leaf input can be 200 catties / hour or 400 catties / hour, the drum speed can be 20 rpm or 35 rpm, and the turning frequency can be 1 time / minute or 4 times / minute.

[0026] Next, the leaves are re-moistened. The withered leaves are evenly spread out and covered with a damp cloth for re-moistening for 50-60 minutes. The purpose of re-moistening is to redistribute the moisture evenly in the leaf stems, soften the leaf texture, and improve the tea's toughness and plasticity, providing a suitable physical state for subsequent rolling. For example, re-moistening can be carried out at room temperature, and the effect can be adjusted by controlling the thickness of the spread and the humidity of the damp cloth. The re-moistening time can be set to 30 or 70 minutes, or it can be allowed to re-moisten naturally without covering with a damp cloth.

[0027] Next, rolling is performed. A gradient frequency rolling process is adopted. The rolling process can be carried out sequentially at a frequency of 20Hz for 15-25 minutes without pressure, at a frequency of 30Hz for 20-30 minutes with light pressure, and at a frequency of 40Hz for 15-20 minutes with medium pressure. The purpose of rolling is to use mechanical force to moderately break the cell walls of the tea leaves, allowing the tea juice to flow out and oxidize upon contact with air, forming the specific flavor substances of green tea, while simultaneously curling the tea leaves into strips. After rolling, the strip formation rate should reach or exceed 85%, the cell breakage rate should be controlled at 45%-55%, and the dust rate should be controlled at 3.5% or below. For example, rolling can be carried out using a traditional rolling machine, with the pressure and rolling time of the rolling drum adjusted manually, or a rolling machine with a fixed frequency can be used. The amount of tea leaves added can be 10kg or 25kg per drum. During the rolling process, the state of the tea strips can be checked every 10 or 15 minutes, and the rolling pressure can be adjusted based on experience. The temperature of the rolled leaves can be controlled at 40℃ or 45℃.

[0028] Next, the tea leaves are shaped. This is done at a temperature of 125-135℃ for 25-30 minutes, with a leaf input of 20-30 jin (approximately 10-15 catties) per batch. The purpose of shaping is to further refine the tea leaves, making them tight, straight, and round, and to further reduce the moisture content to 35%-40%. For example, shaping can be done manually or using a simple roller-type shaping device, achieved by controlling the heating temperature and shaping time. The inclination angle of the shaping trough can be set to 1° or 7°, and the reciprocating frequency can be set to 150 times / minute or 220 times / minute. Pressure can be applied or not applied during the shaping process.

[0029] Then, a gradient temperature roasting process is performed. A three-stage temperature roasting process is adopted. In the first stage, the temperature is set at 95℃, and roasting is carried out with the door open for 30-40 minutes. This stage is mainly used for rapid dehydration and stimulating the decomposition of aroma groups. In the second stage, the temperature is set at 85-90℃, and roasting is carried out with the door closed for 30-40 minutes. This stage is mainly used to promote the Maillard reaction and generate pyrazine and furan chestnut aroma compounds. In the third stage, the temperature is set at 70-75℃, and roasting is carried out with the door closed for 60-100 minutes. This stage is mainly used to stabilize the aroma and enhance the aroma complexity. The purpose of roasting is to further evaporate the moisture in the tea leaves through heat, fix the quality of the tea leaves, and promote the formation and transformation of aroma compounds. For example, roasting can be carried out using single-stage constant temperature roasting, two-stage roasting, or using a regular oven. The moisture content of the tea leaves does not need to be monitored in real time during the roasting process. At the end of the first stage, the moisture content can be reduced to 25% or 15%, at the end of the second stage, the moisture content can be reduced to 15% or 8%, and at the end of the third stage, the moisture content can be reduced to 7% or 5%. The second stage of baking can be set to 80℃ or 92℃, and the duration can be set to 25 minutes or 45 minutes. The first stage duration can be set to 25 minutes or 45 minutes, and the third stage duration can be set to 50 minutes or 110 minutes.

[0030] Finally, allow the tea to cool naturally. After roasting, let the tea leaves cool naturally for 160-180 minutes until they reach room temperature. The purpose of cooling is to gradually lower the temperature of the tea leaves, preventing the volatilization of aroma compounds or deterioration of quality caused by prolonged exposure to high temperatures, while also stabilizing the distribution of moisture and aroma compounds within the tea leaves. For example, forced air cooling can be used, or the tea leaves can be piled up thickly during the cooling process. During cooling, the tea leaves can be kept at a thickness of 10cm or 15cm, and turned over every 60 or 90 minutes.

[0031] Through the above preparation method, this application can effectively solve the problems of single aroma layers, poor strip uniformity, low raw material utilization, and insufficient aroma stability in traditional strip-shaped green tea processing. This method achieves stable formation of a fully ripened chestnut aroma by precisely controlling the withering moisture loss rate, implementing a three-stage variable-temperature fixation process, optimizing the rehumidification process, employing gradient variable-frequency rolling, meticulous strip shaping, and a specific three-stage gradient variable-temperature baking. Simultaneously, it ensures that the tea leaves are tightly rolled, straight, and round, thus improving product quality and market competitiveness.

[0032] In some of the embodiments described above in this application, a withering step is proposed to control the water loss rate of fresh leaves to 6.7% to 7.0%, making the leaves soft and the stems flexible but not broken. However, in the process of implementation, if the thickness of the spread leaves, environmental conditions, or leaf turning operation are not precisely controlled, uneven water loss may occur, resulting in some leaves being too dry or too wet, affecting the stability of subsequent fixation and rolling steps, and thus reducing the regularity of tea strips and the consistency of aroma.

[0033] In this regard, this application further proposes that in the withering step S1, the thickness of the spread leaves during withering is 15~20cm, the ambient temperature is 20~25℃, the relative humidity is 65%~75%, and the leaves are turned over every 30 minutes during the withering process to ensure uniform water loss.

[0034] Specifically, the leaf spreading thickness is controlled at 15-20 cm to avoid excessively thick stacking of fresh leaves, which would hinder water loss from the lower layers, or spreading them too thinly, which would cause excessively rapid water loss. This thickness can be achieved by evenly spreading the fresh leaves on the withering trough or withering rack. For example, withering nets with a fixed height can be used for layered spreading, or an automated leaf spreading device can be used with thickness sensors for precise control. Simultaneously, the ambient temperature is maintained at 20-25°C, providing suitable thermodynamic conditions for the enzymatic reactions and water evaporation of the fresh leaves. This can be achieved by operating in a withering chamber with a temperature control system, for example, by using air conditioning or heating / cooling equipment to precisely adjust the indoor temperature to this range, or by selecting a time and place with stable temperature under natural ventilation. Furthermore, maintaining a relative humidity of 65%-75% helps prevent premature drying and crusting of the fresh leaf surface, ensuring that the internal moisture of the fresh leaves can gradually and evenly diffuse outwards. This can be achieved by installing humidification or dehumidification devices in the withering space, such as using a spray humidifier or dehumidifier to regulate air humidity, or indirectly regulating humidity by controlling the ventilation volume of the withering chamber. Furthermore, the leaves are turned every 30 minutes during the withering process to break the adhesion between the fresh leaves, ensuring all leaves are evenly exposed to the air and preventing localized excessively rapid or slow water loss. Turning the leaves can be done manually with gentle turning or using mechanical turning devices, such as withering machines or vibrating screens with a turning mechanism, to ensure even heating and moisturizing of the fresh leaves.

[0035] By employing the aforementioned technical solutions, precise control is achieved over the thickness of the spread leaves, ambient temperature, relative humidity, and frequency of leaf turning during the withering process. This ensures that the water loss of fresh leaves during withering is uniform and controllable. Specifically, a moderate thickness of spread leaves avoids uneven water loss caused by uneven leaf accumulation; stable ambient temperature and relative humidity create ideal conditions for uniform evaporation and internal diffusion of moisture; and regular leaf turning effectively prevents localized over-drying or over-wetting. These measures work synergistically to guarantee the consistency of withered leaf quality from the source, providing a uniform raw material base for subsequent processes such as fixation and rolling. This significantly improves the tea's strip-forming rate and shape regularity, and promotes the uniform transformation and accumulation of aroma substances. Ultimately, this results in a fully ripened chestnut-scented strip-shaped green tea with more stable quality and better aroma expression.

[0036] In some of the embodiments described above in this application, a three-stage temperature control method is proposed to control the temperature and the effect of fixing. However, in its implementation, due to the lack of specific equipment selection, operating parameters and real-time monitoring mechanism, it may lead to large fluctuations in fixing temperature, uneven heating of tea leaves and low fixing efficiency. This may result in inaccurate control of tea moisture content, residual grassy taste or burnt edges, affecting the formation of fully ripe chestnut aroma and the stability of strip quality, and exacerbating the technical defects of single aroma layers and poor strip regularity.

[0037] In this regard, this application further proposes that in the above-mentioned withering step S2, the withering is carried out using a 90-type electric heating drum withering machine, the leaf feeding amount is 300~350 catties / hour, the drum speed is 25~30 rpm, the turning frequency is 2~3 times / minute, and the leaf temperature is monitored in real time and the heating power is automatically adjusted during the withering process.

[0038] The Type 90 electric heated drum fixation machine is a specialized device for fixing tea leaves. Its core function is to provide a heat source to the drum via electric heating, and the drum's rotation ensures the tea leaves are heated evenly in a high-temperature environment. This model typically features a standardized structural design and heating power, providing a stable fixing temperature field and effectively deactivating enzyme activity, laying the foundation for the subsequent formation of aroma compounds. Besides the Type 90, other models of electric heated drum fixation machines, such as the Type 80 or Type 100, can be selected depending on the production scale and tea type. Their basic working principles are similar, but they differ in processing capacity and specific structural dimensions. Furthermore, gas-fired heated drum fixation machines or steam-fired drum fixation machines can also be used. While their heating methods differ, both aim to achieve uniform fixing of the tea leaves.

[0039] Leaf feed rate refers to the weight of fresh leaves entering the withering machine per unit time. Controlling the leaf feed rate to 300-350 catties / hour aims to ensure a moderate tea leaf density inside the withering machine, guaranteeing production efficiency while preventing excessive tea leaf accumulation in the drum, which could lead to uneven heating, or insufficient tea leaf, which could result in low heat utilization. This leaf feed rate can be precisely controlled by adjusting the speed of the feed conveyor belt or using quantitative feeding devices such as vibrating feeders or screw feeders.

[0040] The drum speed refers to the number of revolutions per minute (RPM) of the fixing machine drum. Setting the drum speed to 25-30 RPM optimizes the tumbling and mixing of tea leaves within the drum, ensuring that each tea leaf fully and evenly contacts the heat source and hot air, preventing localized overheating or incomplete fixing. This speed is typically precisely adjusted via a variable frequency motor drive system to suit different tea varieties and fresh leaf moisture contents, or it can be adjusted via a mechanical gearbox or gear transmission system.

[0041] The turning frequency refers to the number of times the tea leaves are lifted and tossed within the drum. Controlling the turning frequency to 2-3 times per minute aims to further enhance the uniformity of the tea mixture, prevent tea leaves from sticking or clumping, and ensure that the tea leaves can fully unfurl during the fixation process, maximizing their exposure to the heat environment, thereby achieving a more thorough and uniform fixation effect. This frequency is usually determined by the design of the flap structure inside the drum and the drum speed, and can also be affected by adjusting the angle or number of guide blades inside the drum.

[0042] The real-time monitoring of leaf temperature and automatic adjustment of heating power during the withering process constitutes a closed-loop control mechanism. Temperature sensors (such as infrared thermometers, thermocouples, or resistance temperature detectors) are installed at the leaf outlet of the withering machine to acquire real-time temperature data of the tea leaves and feed it back to the control system (such as a PLC controller, PID controller, or microprocessor). Based on the deviation between the preset temperature target value and the actual monitored value, the control system automatically adjusts the power output of the electric heating elements (e.g., through solid-state relays, SCR voltage regulators, or transformers), thereby precisely controlling the temperature inside the drum and ensuring that the tea leaves are always processed within the optimal withering temperature range. This automated adjustment avoids errors and lags that may be caused by manual intervention, significantly improving the stability and consistency of the withering process.

[0043] By employing the aforementioned technical solution and utilizing a Type 90 electric heating drum fixation machine, combined with precise control over the amount of leaves fed, drum speed, and turning frequency, the tea leaves can be ensured to be heated evenly and efficiently during the fixation process. The mechanism of real-time monitoring of the leaf temperature and automatic adjustment of heating power further eliminates errors caused by temperature fluctuations and human intervention, resulting in more precise and stable temperature control during the fixation process. This not only effectively avoids the problems of residual grassy taste or scorched edges in the tea leaves and precisely controls the moisture content, but more importantly, it creates favorable conditions for the stable formation of fully ripened chestnut aroma compounds. Simultaneously, it maximizes the preservation of the tea leaves' integrity and shape regularity, thus overcoming the technical defects of traditional fixation processes, such as a single aroma level and poor shape regularity. This lays a solid foundation for producing green tea with a unique fully ripened chestnut aroma and tightly rolled, round leaves.

[0044] In some of the embodiments described above in this application, a kneading step is proposed to control the tea strip formation rate and breakage rate. However, in the process of implementation, improper selection of kneading equipment type, inaccurate leaf feeding amount, and lack of temperature monitoring may lead to unstable strip formation, increased breakage rate, and decreased tea quality.

[0045] In this regard, this application further proposes that in step S4, the rolling is carried out using a 55 or 65 type rolling machine, the amount of tea leaves is 15~20kg per barrel, the state of the tea leaves is checked every 5 minutes during the rolling process, and the rolling pressure is adjusted according to the temperature of the tea leaves to control the temperature of the rolled leaves to not exceed 35℃.

[0046] Specifically, a 55 or 65 type rolling machine is used for kneading. The rolling machine is a key piece of equipment in tea processing used to break down tea cells, form tea leaves, and promote the transformation of internal components. The 55 or 65 type rolling machine has a suitable rolling disc diameter and rolling drum height, providing stable and uniform kneading force, ensuring that the tea leaves are subjected to even force during kneading, thus effectively avoiding fluctuations in the yield of tea leaves due to inappropriate equipment model. Besides the 55 or 65 type rolling machine, those skilled in the art can also select other models of rolling machines, such as the 40, 70, or 80 type, or use continuous or intermittent rolling machines, according to actual production needs and tea characteristics, to achieve similar kneading effects.

[0047] The leaf input amount is 15-20 kg per drum. Leaf input refers to the weight of fresh tea leaves or withered leaves added to the rolling machine during each rolling operation. Precisely controlling the leaf input amount within the range of 15-20 kg ensures an appropriate distribution density of tea leaves within the rolling drum. This avoids insufficient rolling and poor leaf formation due to insufficient leaf input, while also preventing uneven rolling, excessive tea compression, and increased breakage due to excessive leaf input, thus guaranteeing uniformity and efficiency in rolling. In practice, the leaf input amount can also be adjusted appropriately based on the model of the rolling machine, the moisture content and tenderness of the tea leaves, and the desired degree of rolling. For example, the leaf input amount can be reduced for tender tea leaves or smaller rolling machines, and increased for older tea leaves or larger rolling machines.

[0048] During the rolling process, the tea leaf formation status is checked every 5 minutes. This check includes assessing the tea's tightness, leaf integrity, and the amount of broken leaves. Frequent checks (e.g., every 5 minutes) allow for timely identification and adjustment of any abnormalities during rolling, ensuring the rolling process achieves the expected yield. In addition to checking every 5 minutes, the frequency can be adjusted based on actual production conditions and the rate of tea leaf change, such as checking every 3 minutes or 10 minutes, or combining visual observation and tactile assessment. Furthermore, automated equipment, such as image recognition systems, can be introduced to monitor and evaluate the tea leaf formation status in real time.

[0049] The rolling pressure is adjusted according to the tea temperature. During rolling, the tea leaves generate heat due to friction and cell damage. Increased temperature accelerates the oxidation of the tea's components, affecting aroma and flavor. By monitoring the tea temperature in real time and dynamically adjusting the rolling pressure, heat accumulation during rolling can be effectively controlled, preventing excessive pressure at high temperatures from exacerbating tea breakage. Rolling pressure can be adjusted manually by the operator based on experience and thermometer readings; or it can be achieved through an automated control system that uses temperature sensors to monitor the tea temperature in real time and automatically adjusts the pressure levers or hydraulic system of the rolling machine.

[0050] Controlling the temperature of the rolled leaves to no more than 35℃ is crucial for protecting the integrity of the tea's cell structure and preventing aroma loss and quality deterioration caused by high temperatures. Excessive temperatures can cause the tea to "turn brown," producing an unpleasant musty taste, and accelerate enzymatic oxidation, affecting the quality characteristics of green tea. Besides adjusting the rolling pressure, the temperature of the rolled leaves can be effectively controlled through various methods, such as shortening the rolling time, increasing the rolling intervals, lowering the ambient temperature, or using a rolling machine with a cooling device.

[0051] Through the above technical solutions, this application optimizes the specific operational details of the rolling process, effectively solving the problems of equipment mismatch, insufficient status monitoring, and temperature runaway in the rolling steps, thereby significantly improving the uniformity of tea strips and the stability of quality. Using a 55 or 65 type rolling machine ensures a high degree of compatibility between the equipment type and the tea rolling requirements, providing stable and uniform rolling force and avoiding fluctuations in the strip formation rate caused by improper equipment models. Setting a precise leaf input of 15-20 kg per barrel effectively controls the distribution density of tea leaves in the rolling barrel, ensuring the uniformity and efficiency of rolling, thus preventing increased breakage rates caused by too many or too few leaves. The tea strip formation status is checked every 5 minutes during the rolling process. High-frequency monitoring promptly identifies and adjusts any abnormalities in strip formation, ensuring that the rolling effect meets the target strip formation rate while avoiding excessive tea fermentation. Simultaneously, the rolling pressure is dynamically adjusted according to the tea temperature, responding to temperature changes to optimize pressure application and preventing excessive pressure at high temperatures from exacerbating tea breakage. Strictly controlling the temperature of the rolled leaves to not exceed 35℃ effectively protects the integrity of the tea cell structure, prevents aroma loss and quality deterioration caused by high temperature damage, and ultimately helps to form strip-shaped green tea with a stable and fully ripe chestnut aroma.

[0052] In some of the solutions mentioned above in this application, a strip-forming step is proposed to make the strips tight, straight, and round. However, in the process of implementation, improper selection of strip-forming equipment or inaccurate parameter settings may lead to problems such as poor strip regularity and high breakage rate, which affect the overall quality of tea.

[0053] In this regard, this application further proposes that in step S5, a fully automatic reciprocating sizing machine is used for sizing, the sizing groove inclination angle is 3°~5°, the reciprocating frequency is 180~200 times / minute, and the sizing process is pressured twice: the first 15 minutes are pressureless shaping, and the last 10~15 minutes are micro-pressure shaping.

[0054] Specifically, the fully automatic reciprocating tea leaf shaping machine is an automated device for processing tea leaves into strips. It uses a robotic arm or guide rail system to drive the shaping trough in reciprocating motion and integrates sensors and a control unit to monitor the tea leaf condition in real time and adjust operating parameters. Another implementation method uses a PLC (Programmable Logic Controller) controlled electric reciprocating mechanism, combined with an adjustable shaping trough and pressure sensors, to achieve precise shaping of the tea leaves.

[0055] The tilt angle of the tea-forming groove is 3° to 5°. This tilt angle can be achieved through a mechanical adjustment mechanism, such as adjusting the height of the support point of the groove using a screw or hydraulic rod, thereby changing its angle with the horizontal plane. Alternatively, the groove itself can be designed as a replaceable module, providing grooves with different fixed tilt angles to adapt to different tea varieties or processing needs.

[0056] The reciprocating frequency is 180-200 times / minute. This frequency can be precisely controlled by a variable frequency motor drive system, and the operator can set or adjust it on the control panel. Alternatively, the preset reciprocating frequency can be achieved through a mechanical transmission device, such as an eccentric wheel or crank-connecting rod mechanism, combined with gear ratio adjustment.

[0057] The tea-strip shaping process involves two pressure applications. The pressureless shaping stage can be achieved by raising the pressure cap or roller above the tea-stripping groove to a height where it does not contact the tea leaves, or by controlling the complete release of pressure through a pneumatic / hydraulic system. The micro-pressure shaping stage can be achieved by applying a preset slight pressure through a pneumatic or hydraulic system, or by using a gravity-type pressure cap in conjunction with a limiting device to ensure uniform and moderate pressure.

[0058] The above technical solution, employing a fully automatic reciprocating tea-stripping machine, automates and standardizes the tea-stripping process, effectively avoiding the uncertainties and inconsistencies caused by manual operation and ensuring the uniformity of tea strip shape. The inclination angle of the stripping groove is set within the range of 3° to 5°, optimizing the rolling and sliding trajectory of the tea leaves within the groove, reducing frictional damage and accumulation between tea leaves, thereby lowering the breakage rate. The reciprocating frequency is controlled at 180 to 200 times per minute, providing suitable mechanical force that ensures the tea leaves are fully turned to form tight, straight strips while avoiding excessive impact and increased breakage due to excessive frequency. Crucially, the strategy of applying pressure twice during the stripping process—the first 15 minutes of pressureless shaping followed by 10-15 minutes of micro-pressure shaping—allows the tea leaves to freely unfold and naturally shape in the initial stage, minimizing mechanical damage to tender leaves and reducing the initial risk of breakage. The subsequent application of weak pressure effectively consolidates the formed strip structure, making it more compact, round, and less prone to loosening. These optimization measures, together with the temperature, leaf quantity, and total time set in the above-mentioned strip-forming steps, work together to ensure that the tea leaves can be formed efficiently and gently during the strip-forming process, significantly improving the strip-forming rate and the regularity of the strip shape, while effectively controlling the breakage rate, ultimately obtaining a high-quality, tightly rolled, and round ripe chestnut-scented green tea.

[0059] In some of the above-mentioned schemes of this application, gradient temperature roasting is proposed to quickly dehydrate, stimulate the cleavage of aroma groups, promote Maillard reaction to generate chestnut aroma substances, stabilize aroma and enhance the layering of aroma. However, in this process, due to the lack of precise monitoring and phased control of the moisture content of tea leaves, the roasting process may be uneven, the aroma substances may not be fully converted, the aroma stability between batches may be insufficient, and the formation and consistency of fully roasted chestnut aroma may be affected.

[0060] In this regard, this application further proposes that in step S6, the gradient temperature baking adopts a multi-functional tabletop aroma enhancer or a chain plate dryer, and the moisture content of the tea is monitored in real time during the baking process. At the end of the first stage, the moisture content drops to 18%~22%, at the end of the second stage, the moisture content drops to 10%~12%, and at the end of the third stage, the moisture content drops to 5.7%~6.3%.

[0061] Specifically, the multi-functional tabletop aroma-enhancing machine or chain plate dryer are specialized equipment for tea roasting. The multi-functional tabletop aroma-enhancing machine typically features precise temperature control, hot air circulation, and airflow regulation, enabling refined roasting and aroma activation of small batches of tea. Its advantages lie in its flexible operation and high control precision. The chain plate dryer, on the other hand, continuously conveys the tea leaves, ensuring they are heated evenly within different temperature zones, achieving continuous, large-scale production. Its characteristics include high production efficiency and uniform hot air distribution. Both types of equipment provide uniform heat distribution and stable heat transfer, avoiding the localized temperature unevenness that may occur with traditional roasting equipment. This ensures that the tea is heated consistently during roasting, creating the necessary conditions for aroma reaction.

[0062] During the roasting process, real-time monitoring of tea moisture content refers to continuously measuring and recording the moisture content of the tea leaves, either continuously or at preset short time intervals. This can be achieved through non-contact measurement by directly installing online moisture sensors (such as infrared or microwave sensors) inside the roasting equipment or at the discharge port, or through offline measurement using periodic sampling and a rapid moisture analyzer. The purpose of real-time monitoring is to obtain dynamic data on changes in tea moisture content, providing a precise basis for the dynamic adjustment of roasting parameters.

[0063] At the end of the first stage, the moisture content of the tea leaves is reduced to 18%~22%. This is a specific limit for the moisture content of the tea leaves at the end of the rapid dehydration stage. This stage aims to quickly remove most of the moisture, but still retain an appropriate amount of moisture to avoid premature over-drying that inhibits the breakdown of aroma groups, thus providing a suitable environment for subsequent aroma development.

[0064] At the end of the second stage, the moisture content of the tea leaves is reduced to 10%~12%, which is a specific limit on the moisture content of the tea leaves at the end of the critical stage for the formation of aroma substances. This moisture content range is optimized to be the best condition for the Maillard reaction, which is conducive to the full formation of fully ripened chestnut aroma substances such as pyrazines and furans, while preventing incomplete reaction due to excessive moisture or scorching due to excessive moisture.

[0065] At the end of the third stage, the moisture content of the tea leaves is reduced to 5.7%~6.3%, which is a specific limit for the moisture content of the tea leaves at the end of the final drying and aroma stabilization stage. This stage aims to reduce the moisture content of the tea leaves to a final moisture content that meets the requirements for product storage and quality, and to stabilize the aroma components that have been formed at a lower temperature, thereby enhancing the complexity and persistence of the aroma.

[0066] Through the above technical solution, this application introduces specific baking equipment and a refined moisture content monitoring and control mechanism in the gradient temperature baking step S6, effectively solving the problems of inaccurate control during the baking process, incomplete transformation of aroma substances, and insufficient aroma stability between batches. Using a multi-functional tabletop aroma enhancer or chain plate dryer ensures uniform heating of the tea leaves, providing a foundation for the stable formation of aroma substances and avoiding localized overheating or uneven heating that may occur with traditional baking equipment. Based on this, by monitoring the moisture content of the tea leaves in real time and dynamically adjusting the baking parameters according to the monitoring results, the baking process can be precisely controlled in stages according to the preset moisture content target. At the end of the first stage, the moisture content of the tea leaves is precisely controlled within the range of 18% to 22%, which allows the tea leaves to retain an appropriate amount of moisture while rapidly dehydrating, creating a favorable environment for the subsequent cleavage and activation of aroma groups and avoiding the inhibition of aroma precursor formation due to premature over-drying. Subsequently, at the end of the second stage, the moisture content was further reduced to 10%–12%. This moisture content range was optimized to meet the best conditions for the Maillard reaction, thereby efficiently promoting the full formation of ripe chestnut aroma compounds such as pyrazines and furans, while effectively avoiding negative effects such as incomplete reaction due to excessive moisture or scorching caused by excessive moisture. Finally, at the end of the third stage, the moisture content was stabilized at 5.7%–6.3%. The formed aroma components were stabilized at a lower temperature, enhancing the complexity and persistence of the aroma, and ensuring that the moisture content of the final product met storage requirements. This significantly reduced aroma volatilization and batch-to-batch variations, thus consistently obtaining a strip-shaped green tea product with ripe chestnut aroma characteristics.

[0067] In some of the embodiments described above in this application, a second stage of gradient temperature baking is proposed to promote the Maillard reaction to generate pyrazine and furan chestnut aroma compounds. However, in its implementation, the temperature and time parameters are in a wide range, which may lead to fluctuations in reaction conditions, affecting the sufficiency and stability of the Maillard reaction, and thus causing problems such as insufficient aroma generation, increased batch-to-batch differences, and insufficient aroma layering.

[0068] In this regard, this application further proposes a second stage of gradient temperature baking in step S6, with a temperature of 88~90℃ and a duration of 35~38 minutes.

[0069] Specifically, the second stage of baking takes place at a temperature of 88-90℃, a range determined based on in-depth research into the kinetics of the Maillard reaction. This ensures the reaction system receives sufficient activation energy, allowing precursors such as polyphenols, amino acids, and sugars to efficiently participate in the Maillard reaction, thereby generating pyrazines and furans, which possess the characteristic aroma of fully roasted chestnuts. Simultaneously, this temperature range effectively avoids problems such as tea scorching, the formation of bitter substances, or excessive volatilization of aroma compounds due to excessively high temperatures, as well as slow reaction rates and insufficient aroma formation due to excessively low temperatures. In practice, the temperature inside the baking cavity can be monitored in real time using a high-precision temperature sensor, and the power output of the heating element can be precisely adjusted using a PID (proportional-integral-derivative) controller. Alternatively, the airflow and velocity of the hot air circulation system can be optimized to ensure the baking temperature is stably controlled within the ideal range of 88-90℃.

[0070] Meanwhile, the second stage of roasting lasts 35-38 minutes. This time range has been repeatedly tested and optimized to provide sufficient reaction time for the Maillard reaction, ensuring the stable formation and accumulation of pyrazine and furan chestnut aroma compounds to reach the optimal level. It minimizes the volatilization loss of aroma compounds while ensuring full conversion and avoids the potential decline in tea quality caused by excessive roasting time. During implementation, the roasting equipment can be automated using its built-in precision timer, or the roasting time can be precisely managed by operators based on their experience and real-time monitoring of aroma changes, ensuring accurate control within the 35-38 minute range.

[0071] By precisely limiting the temperature of the second-stage roasting to 88-90℃ and controlling its duration to 35-38 minutes, a more accurate and stable reaction environment for the Maillard reaction can be provided. This temperature range ensures that the Maillard reaction operates along an efficient activation pathway while effectively avoiding the formation of charring byproducts or excessive volatilization of aroma substances due to excessively high temperatures, and also prevents the inhibition of key aroma precursors by excessively low temperatures. Simultaneously, this duration range provides sufficient time for the stable formation and full accumulation of fully roasted chestnut aroma compounds such as pyrazines and furans, avoiding incomplete transformation of aroma precursors due to insufficient time or excessive loss of aroma substances due to excessive time. Therefore, this application can significantly improve the formation efficiency and stability of fully roasted chestnut aroma, reduce aroma differences between product batches, and further enrich the aroma layers of green tea, thereby obtaining a more competitive fully roasted chestnut aroma strip-shaped green tea.

[0072] In some of the embodiments described above in this application, a natural cooling process is proposed to stabilize the aroma of tea. However, in the process of its implementation, if the tea is spread too thickly or lacks turning, heat may accumulate, causing the aroma to evaporate and affecting the stability of the aroma.

[0073] In response, this application further proposes that during the natural cooling process described in step S7, the spreading thickness should be kept no more than 5 cm, and the surface should be turned over lightly every 30 minutes to prevent heat buildup from causing the aroma to evaporate.

[0074] Specifically, during the natural cooling process, maintaining a spreading thickness of no more than 5cm means evenly spreading the roasted tea leaves so that their pile height does not exceed 5cm. This thin-layer spreading method significantly increases the contact area between the tea leaves and the surrounding air, thereby promoting rapid and even heat dissipation from the tea leaves and effectively preventing the accumulation of internal heat and the formation of localized high-temperature areas due to excessively thick tea leaf piles. There are various ways to achieve this spreading thickness. For example, the tea leaves can be evenly spread using shallow trays, sieves, or dedicated cooling platforms with large surface areas; alternatively, the tea leaves can be finely spread within the cooling area manually or with mechanical assistance, and their thickness can be monitored in real time to ensure it is always controlled within 5cm.

[0075] Meanwhile, during the natural cooling process, the tea leaves are gently turned every 30 minutes. This means that the spread-out tea leaves are gently turned over approximately every 30 minutes. The core purpose of this turning is to break up any heat and moisture gradients that may form within the tea leaves, ensuring that all parts of the tea leaves can be heated and dissipated evenly. Turning promotes the expulsion of hot and humid air from inside the tea leaves and introduces fresh, cooler air, thereby accelerating the overall cooling process and effectively preventing overheating in localized areas due to heat retention. This gentle turning can be achieved manually using tools such as bamboo rakes or wooden shovels to gently turn the tea leaves from the bottom to the surface to avoid damaging the shape of the tea leaves; or it can be done automatically using equipment such as cooling conveyor belts or tilting cooling boxes equipped with turning mechanisms to achieve timed and quantitative gentle turning.

[0076] Through the aforementioned technical solution, during the natural cooling stage, by strictly controlling the thickness of the tea leaves to no more than 5cm and supplementing this with gentle turning every 30 minutes, the accumulation of internal heat in the tea leaves can be effectively prevented. This minimizes the oxidation, decomposition, or volatilization of aroma substances caused by high temperature and humidity. This not only ensures that the tea leaves cool to room temperature evenly and thoroughly, but more importantly, it effectively maintains the integrity and stability of the fully roasted chestnut aroma formed during the initial roasting process, preventing aroma loss and thus significantly improving the quality and aroma persistence of the fully roasted chestnut aroma strip-shaped green tea.

[0077] In some of the embodiments described above in this application, a preparation method is proposed for producing fully ripe chestnut-scented strip-shaped green tea. However, in this process, due to the lack of specific selection of fresh tea leaves and control over picking and transportation conditions, the quality of raw materials may be inconsistent, affecting the formation of aroma and the regularity of strip shape, resulting in waste of raw materials and batch-to-batch differences.

[0078] In response, this application further proposes strict control over the selection, picking and transportation of fresh tea leaves, specifically including: the fresh tea leaves should be Longjing 43# or Fuding Da Bai Cha small-leaf variety, the picking time should be before Grain Rain in spring, the buds and leaves should be intact and free from pests and diseases, and the leaves should be transported to the processing plant within 4 hours after picking. During transportation, breathable bamboo baskets should be used to avoid squeezing and generating heat.

[0079] The tea leaves selected are either Longjing 43# or Fuding Da Bai Cha (small-leaf variety) to ensure the essential components of the raw materials from the source. Longjing 43#, a national-level superior tea variety, is renowned for its high amino acid content and moderate polyphenol content; its fresh leaves readily develop a unique chestnut aroma during subsequent processing. Fuding Da Bai Cha (small-leaf variety), while commonly used in white tea, has plump buds and leaves rich in nutrients, particularly moderate polyphenol oxidase activity, which effectively promotes chestnut aroma formation under specific green tea processing techniques. Alternatively, other tea varieties with similar compositional characteristics suitable for producing strip-shaped green tea, such as Chuancha No. 1 and Zhenong 139, can also be selected, as these varieties also exhibit good aroma-forming potential under specific processing conditions.

[0080] Harvesting takes place before the Grain Rain solar term in spring. This is to ensure that the fresh leaves are at their tenderness and have the highest content of internal substances (especially amino acids and aromatic precursors). Harvesting begins about 10-15 days before the Grain Rain solar term, when the temperature is suitable, the tea trees are growing vigorously, the buds and leaves are plump, and the internal substances are richly accumulated, providing an excellent foundation for subsequent aroma formation and shape shaping. At the same time, depending on local climate conditions, harvesting can also be carried out when the new shoots of the tea trees have reached the stage of one bud and one leaf or one bud and two leaves just beginning to unfold, to ensure the uniformity of buds and leaves and the balance of internal substances.

[0081] Intact buds and leaves, free from pests and diseases, represent strict requirements for the physical integrity and health of fresh leaves. This ensures the quality of tea during processing, reducing off-flavors, poor color, and increased breakage caused by damage or disease, thereby improving the purity of aroma and the regularity of leaf shape in the finished product. In practice, damaged, yellowed, or insect-damaged buds and leaves can be removed by manual selection to ensure that every fresh leaf picked meets the standard. Alternatively, pest and disease control can be carried out in the tea garden before harvesting, using biological or physical control methods to control pests and diseases at the source, ensuring that the harvested fresh leaves are naturally healthy.

[0082] The leaves must arrive at the processing plant within four hours of harvesting. This time limit aims to minimize the exposure time of the fresh leaves and maximize their freshness. This effectively prevents excessive oxidation, fermentation, or dehydration during transportation, thus avoiding any impact on the quality of subsequent processing. To achieve this goal, the harvesting and transportation process can be optimized, such as by setting up temporary collection points near the tea garden or using small, high-frequency transport vehicles to ensure rapid delivery. Furthermore, cold chain transportation or the installation of ventilation and cooling devices in transport vehicles can further slow down the physiological metabolic activities of the fresh leaves, ensuring their quality even over longer transport distances.

[0083] During transportation, breathable bamboo baskets are used to prevent compression and heat generation, ensuring sufficient ventilation and heat dissipation for the fresh leaves. This effectively avoids mechanical damage and internal heat caused by stacking and compression, thus preventing the fresh leaves from turning yellow or red and maintaining their freshness. Specifically, bamboo baskets with holes on the bottom and sides can be used, with the fresh leaves layered, each layer not exceeding a certain thickness (e.g., 10-15cm) to ensure air circulation. When loading the transport vehicle, appropriate gaps should be left between the bamboo baskets to avoid excessive stacking, and prolonged direct sunlight should be avoided; if necessary, they can be covered with damp cloths or shade nets.

[0084] Through the aforementioned technical solution, meticulous management of the entire raw material chain is implemented, from tea variety selection, harvesting timing, and fresh leaf quality to transportation methods and timeliness. This meticulous management ensures the stability and activity of the substances contained within the fresh leaves, providing a high-quality and uniform raw material foundation for subsequent processes such as withering, fixation, rolling, shaping, and roasting. Specifically, the selection of specific tea varieties and harvesting times ensures that the fresh leaves contain abundant and appropriately proportioned precursor substances (such as amino acids and polyphenols) necessary for a fully mature chestnut aroma; the integrity of the buds and leaves, free from pests and diseases, along with rapid and breathable transportation methods, maximizes the freshness of the leaves, avoiding the generation of undesirable flavor substances and damage to the leaf shape. Therefore, this solution guarantees from the source that the fully mature chestnut-scented green tea has a pure, rich, and layered aroma, while ensuring that the tea leaves are tightly rolled, straight, and round, significantly improving the overall quality and batch stability of the product, and effectively solving the problems of unstable aroma and poor leaf shape caused by fluctuations in raw material quality.

[0085] In some of the solutions mentioned above in this application, gradient temperature baking is proposed to quickly dehydrate, stimulate the cleavage of aroma groups, promote Maillard reaction to generate chestnut aroma substances, stabilize aroma and enhance the layering of aroma. However, in this process, the baking parameters are not set precisely enough, resulting in unstable aroma formation, large batch-to-batch differences, and difficulty in ensuring the stable generation of fully roasted chestnut aroma and the uniformity of aroma layering.

[0086] In this regard, this application further proposes that the first stage temperature of the gradient temperature baking in step S6 is 95°C and the duration is 35~40 minutes; the second stage temperature is 85~90°C and the duration is 35~40 minutes; and the third stage temperature is 70~75°C and the duration is 90~100 minutes.

[0087] The first stage, with a temperature of 95℃ and a duration of 35-40 minutes, aims to rapidly dehydrate the tea leaves and stimulate the breakdown of aroma compounds. Temperature control in this stage can be achieved by precisely adjusting the heating power and airflow of the hot air circulation system, ensuring that the tea leaves reach the set temperature quickly, rapidly evaporating surface moisture and activating aroma precursors within the leaves. Alternatively, infrared heating elements can be used, utilizing their radiative heat transfer characteristics to ensure even heating of the tea leaves, accelerating moisture evaporation and the initial transformation of aroma compounds.

[0088] The second stage, with a temperature of 85-90℃ and a duration of 35-40 minutes, aims to promote the Maillard reaction, generating pyrazines and furans, characteristic of chestnut aroma compounds. Temperature control in this stage can be achieved through precise feedback regulation of the heating system of the roasting equipment using a PID (Proportional-Integral-Derivative) controller. This maintains a stable temperature environment, providing optimal conditions for the Maillard reaction of amino acids and reducing sugars in the tea leaves, thereby efficiently generating pyrazines and furans with the characteristics of roasted chestnut aroma. Alternatively, a steam heating or thermal oil heating system can be used. By precisely controlling the medium temperature, gentle and continuous heating of the tea leaves can be achieved, promoting the deep transformation of aroma compounds.

[0089] The third stage, with a temperature of 70-75℃ and a duration of 90-100 minutes, aims to stabilize the aroma and enhance its complexity. Temperature and time control in this stage can be achieved through a programmable control system. Prolonged roasting at a lower temperature slowly removes bound water from the tea leaves, while simultaneously promoting the aggregation and stabilization of aroma compounds, preventing aroma volatilization and scorching caused by high temperatures. Furthermore, incorporating a humidity control module into the roasting equipment can gradually reduce ambient humidity while maintaining a suitable temperature, further optimizing the stability and complexity of the aroma compounds.

[0090] The above technical solution precisely sets the parameters for each stage of gradient temperature baking, effectively solving the problems of unstable aroma formation and large batch-to-batch variations caused by inaccurate parameters during the baking process. Specifically, the first stage of high-temperature rapid dehydration and aroma group activation ensures initial dehydration efficiency, laying the foundation for the formation of subsequent aroma substances; the second stage precisely promotes the Maillard reaction at an appropriate temperature, allowing pyrazine and furan-type roasted chestnut aroma substances to be fully generated while avoiding over-caramelization; the third stage of low-temperature long-term baking effectively stabilizes the aroma substance structure, enhances the aroma's complexity and persistence, and prevents aroma volatilization caused by high temperatures. These precise temperature and time parameters work together to optimize the entire baking process, making the formation of fully roasted chestnut aroma more stable and uniform, significantly improving the consistency of product batches, thereby overcoming the problems of single aroma complexity and insufficient stability in traditional processes.

[0091] Based on the above technical solutions, in order to verify the technical effects of the technical solutions in this application, the applicant conducted multiple batches of experiments, as follows: Experimental Example 1 (First Success in Achieving Fully Developed Chestnut Aroma) Process parameters: Ingredients: Longjing No. 43, one bud and one leaf Wilting: After cooling for 90 minutes, the water loss rate is 6.8%. Filming wrapped: 95℃ three-stage filming, total duration 90 minutes. Kneading: 20Hz for 20 minutes → 30Hz for 25 minutes → 40Hz for 18 minutes Cooling: 125~135℃, 30 minutes bake: Phase 1: Close the door at 95℃ for 30 minutes Phase Two: Close the door at 90℃ for 30 minutes Phase 3: Close the door at 75℃ for 100 minutes Cooling: Allow to cool naturally for 160 minutes. Sensory evaluation results: Verification conclusion: The first successful roasting process achieved a fully developed chestnut aroma, rich and long-lasting fragrance, and the chestnuts were of the correct shape and uniformity. This demonstrates the effectiveness of the three-stage gradient roasting process.

[0092] Experimental Example 2 (Verification of Processing Using Whole Fresh Leaves) Process parameters: Ingredients: Longjing No. 43, one bud and one leaf Withering: Spread out to cool + wither for 90 minutes Blanching: 220℃→210℃→180℃, leaf input rate 300 catties / hour, time 100 minutes Kneading: Rehydrate for 60 minutes, then knead at 20Hz for 15 minutes → at 30Hz for 20 minutes → at 40Hz for 15 minutes. Preparation: 120~130℃, two-stage temperature setting, 30 minutes Drying: 90℃ quick drying for 40 minutes with the door open (three-stage drying not used). Sensory evaluation results: Verification conclusion: The basic quality is acceptable, but the chestnut aroma is not fully developed; it only presents a light fragrance with a slight chestnut aroma. This proves that simple drying cannot achieve aroma transformation; a three-stage gradient roasting method must be used.

[0093] Experimental Example 3 (Optimal Combination of Process Parameters) Process parameters: Ingredients: Longjing No. 43, one bud and one leaf Withering: Spread out to cool + wither for 90 minutes Blanching: 300℃→250℃→240℃, leaf input rate 400 catties / hour, time 180 minutes Kneading: Rehydrate for 60 minutes, then knead at 20Hz for 25 minutes → at 30Hz for 30 minutes → at 40Hz for 20 minutes. Planting: 115℃, 20 catties of leaves per batch Baking: 95℃, close the door and bake for 100 minutes to enhance aroma (single temperature). Sensory evaluation results: Verification conclusion: The basic indicators were still qualified after the amount of leaves added was increased, but the aroma enhancement by a single temperature could not form a fully mature chestnut aroma, proving the necessity of the three-stage variable temperature method.

[0094] Comparative Example 1 (Verification of Basic Parameters) Process parameters: Ingredients: 400g semi-finished tea leaves bake: Phase 1: Open the door at 95℃ for 40 minutes Phase Two: Close the door at 85℃ for 40 minutes Phase 3: 75℃, door closed for 90 minutes Cooling time: 170 minutes Sensory evaluation results: Verification conclusion: The temperature was too low, and the chestnut aroma was not fully developed; it only had a slight chestnut aroma, and the chestnuts were broken apart.

[0095] Comparative Example 2 (Repeated Validation Batch 1) Process parameters: Raw materials: semi-finished tea leaves Baking: Same batch 1 (95℃ with door open for 40 minutes → 85℃ with door closed for 40 minutes → 75℃ with door closed for 90 minutes, cooling for 170 minutes) Sensory evaluation results: Completely consistent with batch 1, but not yet fully developed chestnut aroma.

[0096] Verification conclusion: It is confirmed that this set of basic parameters cannot achieve the goal of achieving a fully ripe chestnut flavor, and will not be used in the future.

[0097] Comparative Example 3 (Fresh leaves throughout the entire process, but insufficient roasting) Process parameters: Withering: Spread out to cool and wither for 150 minutes. Finishing temperature: 240℃→230℃→200℃, 90 minutes Kneading: Rehydrate for 60 minutes, then knead at 20Hz for 24 minutes → at 30Hz for 23 minutes → at 40Hz for 18 minutes. Curing: 110~120℃ Drying: 90℃ with door open for 25 minutes → 85℃ with door closed for 40 minutes Sensory evaluation results: The strips are fairly straight but not uniform, and the aroma is not yet fully developed and has a mature chestnut fragrance.

[0098] Verification conclusion: The low temperature of the drying process resulted in poor strip shape, and the lack of a three-stage aroma enhancement process during drying led to the failure of aroma transformation.

[0099] Comparative Example 4 (high-temperature drying without gradient) Process parameters: Withering: Spread out to cool + wither for 90 minutes Fixation: 300℃→250℃→240℃, leaf input rate 400 catties / hour, time 100 minutes Kneading: 20Hz 25 minutes → 30Hz 23 minutes → 40Hz 20 minutes Planting: 110~120℃, add 30 catties of leaves per batch Drying: 95℃, open for 20 minutes → 95℃, close for 100 minutes Sensory evaluation results: The basic indicators are qualified, but the aroma has not yet developed into a fully mature chestnut aroma.

[0100] Verification conclusion: Maintaining a high temperature of 95℃ throughout the process and opening the door in the early stages resulted in aroma volatilization. Without a gradient cooling process, it was impossible to achieve the stratified transformation of aroma substances.

[0101] Data Comparison: in conclusion: Through system analysis of 10 major batches during the project's development process (3 batches were not recorded above), the following conclusions can be drawn: 1. Three-stage gradient temperature roasting is the core process for achieving fully cooked chestnuts with a rich aroma. Successful Case (Experiment Example 3): Using a gradient temperature process of 95℃ for 30 minutes, 90℃ for 30 minutes, and 75℃ for 100 minutes, a rich and lasting fully roasted chestnut aroma was successfully formed for the first time, with obvious aroma layers, and an overall score of 90 points.

[0102] Comparison of failed cases: Low temperature (comparative examples 1 and 2): only a light fragrance with a slight chestnut aroma is formed, which cannot meet the standard of "fully ripe"; Gradient cooling (Comparative Example 4): Aroma volatilization is severe, and the stratified transformation of aroma substances cannot be achieved.

[0103] 2. All process parameters must be optimized collaboratively; none can be omitted. In the fixation process: Comparison Example 3 shows that the fixation temperature and duration directly affect the retention of aroma precursors, and the three-stage variable temperature fixation (220~240℃→210~220℃→180~200℃) yields the best results; Rolling process: Gradient frequency conversion rolling (20Hz→30Hz→40Hz) can balance strip formation rate and cell breakage rate. Comparative example 4 shows that the strip formation rate can reach 88%, and the breakage rate is only 3.2%. In the strip shaping process: the temperature needs to be controlled between 125 and 135℃. If it is lower than this range (Comparative Example 3: 110 to 120℃), the strips will be straight but uneven. Baking process: A three-stage variable temperature process of "opening the door for dehydration + closing the door for conversion + closing the door for stabilization" must be adopted. A single temperature or simple drying cannot achieve the desired roasted chestnut aroma.

[0104] 3. The process of this invention has good raw material adaptability. Both Longjing 43# and Fuding Da Bai tea are suitable for the process of this invention. One bud and one leaf raw material has the best effect, and one bud and two leaves can also be stably formed with a mature chestnut aroma by fine-tuning parameters (such as extending the rolling and baking time).

[0105] 4. Broad prospects for industrial application. The process parameters of this invention are clear and highly repeatable. It has been put into large-scale production at Jiaoyao Tea Industry Company, which has increased the product's premium value by more than 30%, increased production capacity by 20%, and boosted tea farmers' income, thus achieving good economic and social benefits.

[0106] In summary, this invention, through the coordinated control of the entire process of "fixing, rolling, shaping, and gradient temperature baking," successfully solves the technical problem of "single chestnut aroma and poor uniformity of strip shape" in strip-shaped green tea, and forms a stable and controllable production process for fully ripened chestnut-aroma strip-shaped green tea, possessing significant novelty, inventiveness, and industrial applicability.

[0107] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a fully ripened chestnut-scented strip-shaped green tea, characterized in that, Includes the following steps: S1, withering: spread out fresh tea leaves with one bud and one leaf or one bud and two leaves until the water loss rate is 6.7%~7.0%, the leaves are soft and the stems can be bent but not broken; S2, Blanching: A three-stage variable temperature blanching method is adopted. The first stage temperature is 220~240℃, the second stage temperature is 210~220℃, and the third stage temperature is 180~200℃. The blanching time for each stage is 30 seconds, and the total blanching time is 90~100 minutes. The blanched leaves have no grassy smell and no scorched edges, and the moisture content is controlled at 58%~62%. S3, Rehydration: Spread the blanched leaves evenly, cover with a damp cloth and rehydrate for 50-60 minutes to allow the moisture in the leaf stalks to be redistributed evenly. S4, Kneading: Use gradient frequency kneading, kneading without pressure at 20Hz for 15-25 minutes, kneading with light pressure at 30Hz for 20-30 minutes, and kneading with medium pressure at 40Hz for 15-20 minutes, controlling the strip yield ≥85%, cell breakage rate 45%-55%, and fragmentation rate ≤3.5%; S5, shaping: Shaping the strips at 125~135℃ for 25~30 minutes, with a leaf input of 20~30 catties / batch, to make the strips tight, straight and round, and reduce the moisture content to 35%~40%; S6, Gradient Temperature Baking: Employs a three-stage temperature-controlled baking process, in the following order: First stage: Bake at 95℃ with the door open for 30-40 minutes to rapidly dehydrate and stimulate the cleavage of aroma groups; Second stage: Bake at 85~90℃ with the door closed for 30~40 minutes to promote the Maillard reaction to generate pyrazine and furan chestnut aroma compounds; The third stage: bake at 70~75℃ with the door closed for 60~100 minutes to stabilize the aroma and enhance its complexity. S7, Natural Cooling: After baking, allow to cool naturally for 160-180 minutes to room temperature.

2. The preparation method according to claim 1, characterized in that, In step S1, the thickness of the spread leaves during withering is 15-20 cm, the ambient temperature is 20-25℃, and the relative humidity is 65%-75%. During the withering process, the leaves are turned over every 30 minutes to ensure uniform water loss.

3. The preparation method according to claim 1, characterized in that, The withering process described in step S2 uses a 90-type electric heating drum withering machine, with a leaf feeding rate of 300-350 catties / hour, a drum rotation speed of 25-30 rpm, and a turning frequency of 2-3 times / minute. During the withering process, the leaf temperature is monitored in real time and the heating power is automatically adjusted.

4. The preparation method according to claim 1, characterized in that, The kneading process described in step S4 uses a 55 or 65 type kneading machine, with a leaf input of 15-20 kg per barrel. During the kneading process, the tea leaves are checked every 5 minutes to check their strip formation, and the kneading pressure is adjusted according to the tea temperature to control the temperature of the kneaded leaves to not exceed 35℃.

5. The preparation method according to claim 1, characterized in that, The sliver shaping process described in step S5 uses a fully automatic reciprocating sliver shaping machine with a sliver shaping groove inclination angle of 3°~5° and a reciprocating frequency of 180~200 times / minute. The sliver shaping process is divided into two pressure applications: the first 15 minutes are pressureless shaping, and the next 10~15 minutes are micro-pressure shaping.

6. The preparation method according to claim 1, characterized in that, The gradient temperature baking described in step S6 uses a multi-functional tabletop aroma enhancer or a chain plate dryer. The moisture content of the tea is monitored in real time during the baking process. At the end of the first stage, the moisture content drops to 18%~22%, at the end of the second stage, the moisture content drops to 10%~12%, and at the end of the third stage, the moisture content drops to 5.7%~6.3%.

7. The preparation method according to claim 1, characterized in that, In step S6, the second stage of baking is carried out at a temperature of 88~90℃ for 35~38 minutes.

8. The preparation method according to claim 1, characterized in that, During the natural cooling process described in step S7, the thickness of the spread material should not exceed 5cm, and it should be turned over lightly every 30 minutes to prevent heat buildup from causing the aroma to evaporate.

9. The preparation method according to claim 1, characterized in that, The fresh tea leaves are selected from Longjing 43# or Fuding Da Bai Cha small-leaf variety. The picking time is before Grain Rain in spring. The buds and leaves are intact and free from pests and diseases. The tea leaves are transported to the processing plant within 4 hours after picking. During transportation, they are packed in breathable bamboo baskets to avoid squeezing and generating heat.

10. The preparation method according to claim 1, characterized in that, In step S6, the gradient temperature baking process involves a first stage temperature of 95°C for 35-40 minutes, a second stage temperature of 85-90°C for 35-40 minutes, and a third stage temperature of 70-75°C for 90-100 minutes.

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