Preparation process of compressed black tea and black tea brick

Abstract

The invention relates to the field of black tea preparation, and provides a preparation process of compressed black tea in order to solve the problem that an existing cold pressing process is difficult to be directly suitable for black tea, the preparation process of the compressed black tea comprises the steps of fresh leaf picking, withering, rolling, primary fermentation, gross fire drying, secondary fermentation, full fire drying, cold pressing and low-temperature slow baking. The cold pressing comprises the following steps: S100, adding clear water into the tea leaves obtained after full fire drying, wherein the water content of the tea leaves after water absorption is 10-25%; s200, spreading the water-absorbed tea leaves in a pile fermentation yard according to the thickness of 10-15 cm, and performing pile fermentation for 5-8 hours to obtain softened tea leaves; and S300, carrying out compression molding on the softened tea leaves by adopting a brick tea molding press to obtain the brick tea. The cold pressing process is improved according to the difference between black tea and dark tea, the leaf spreading thickness is reduced, and the pile fermentation time is prolonged; through the improvement of the pile fermentation process, the water absorption time of the black tea is shortened, the leaching rate of fluorine in the finished brick tea is reduced, the compressibility of the tea leaves is also improved, and the storage resistance of the tea leaves is further improved.

Description

Technical Field

[0001] The invention relates to the field of black tea preparation, and in particular to a preparation process of compressed black tea and a black tea brick. Background Art

[0002] Tea is one of the most common beverages. There are many types of tea, each with its own unique taste and efficacy. However, when brewing tea, excessive fluoride content in the tea soup will cause certain harm to the human body. The existing technology often reduces the user's fluoride intake by improving the tea making process or adding a defluoridating agent during the tea brewing stage.

[0003] The patent with publication number CN106306137A discloses a cold pressing method for compressed black tea, which realizes the cold pressing of black tea by improving the tea refining process, and reduces the fluorine leaching rate of the finished tea brick. However, it is a process improvement based on the characteristics of black tea, and it is difficult to be directly applied to other teas. The fluorine content in black tea is second only to that in black tea, so there is an urgent need for a cold pressing process that can be applied to black tea. Summary of the invention

[0004] The purpose of the present invention is to provide a compressed black tea preparation process to solve the problem that the existing cold pressing process is difficult to be directly applied to black tea.

[0005] Another object of the present invention is to provide a black tea brick which not only has a low fluorine leaching rate but also has significantly improved storage resistance.

[0006] The embodiments of the present invention are implemented by the following technical solutions:

[0007] A preparation process of compressed black tea, comprising fresh leaf picking, withering, rolling, primary fermentation, rough fire drying, secondary fermentation, full fire drying, cold pressing and low temperature slow baking;

[0008] The cold pressing comprises the following steps:

[0009] S100, adding clean water to the tea leaves obtained after sufficient drying, wherein the water content of the tea leaves after absorbing water is 10%-25%;

[0010] S200, spreading the tea leaves after absorbing water in a pile with a thickness of 10-15 cm, and pile them for 5-8 hours to obtain softened tea leaves;

[0011] S300, using a brick tea pressing machine to press the softened tea leaves into a shape to obtain a tea brick.

[0012] On August 24, 2016, the applicant applied for a patent with publication number CN106306137A, and the patent name was a cold-pressing processing method for compressed black tea. It disclosed that the cold-pressing molding of tea leaves was achieved by replacing the steaming process with blanching and moistening tea, thereby reducing the fluoride leaching rate in the finished tea bricks and better protecting the health of drinkers. The fluoride content of different types of tea is usually from low to high: green tea < scented tea < oolong tea < black tea < black tea. It can be seen that the fluoride content of black tea is also high. Therefore, the applicant hopes to apply the cold-pressing process used for black tea in the aforementioned patent to black tea to reduce the fluoride leaching rate in black tea bricks. However, direct application will cause several problems:

[0013] First, the aforementioned patent is applied to loose black tea, which has a higher degree of fermentation than black tea, and the degree of damage and softening of leaf tissue is higher than that of black tea. Therefore, its tea moistening process and related process parameters cannot be directly used.

[0014] Second, the enzyme activity of dark tea has been destroyed during the killing process, and its fermentation mainly relies on microorganisms. The enzymatic reaction during the fermentation of black tea is a major factor affecting the quality of black tea. After the cell tissue of the tea leaves is destroyed, polyphenol compounds come into contact with endogenous oxidases and react to produce , These substances give black tea its unique color and aroma. It can be seen that the unique flavor of black tea mainly depends on endogenous oxidases. If the tea moistening process in the aforementioned patent is directly used for black tea, the wet heat reaction will be more serious, not only causing the fluorine to leach out and finally dry and adhere to the surface of the tea leaves, but also causing the black tea to over-ferment. Especially in order to increase the compressibility of black tea, black tea requires a longer tea moistening time than dark tea, and black tea is more prone to over-fermentation. Therefore, the parameters in the tea moistening process in the aforementioned patent cannot be directly used.

[0015] Third, during the tea brewing process, the components on the surface and inside of the tea leaves will diffuse into the water until the inside and outside of the tea leaves are balanced. This will increase the dissolution rate of non-fluoride water-soluble substances when the inside and outside are balanced, and can also reduce the drinker's intake of fluoride. Since dark tea has a longer fermentation time, the amount or degree of conversion of large molecules into small molecules is higher. When the liquid inside and outside the tea leaves reaches equilibrium, the dissolution ratio of fluoride can be relatively reduced. However, the degree of damage to the tissue of conventional dark tea leaves is high, and most of them use old leaves with high fluoride content, which will increase the dissolution rate and amount of fluoride accordingly. Therefore, the final overall dissolution rate and amount of fluoride in conventional dark tea are still relatively high compared to other types of tea. The leaf tissue and volume ratio of the contents of finished black tea are quite different from those of dark tea. Therefore, it is difficult to achieve a good fluoride reduction effect when directly using the tea moistening process in the aforementioned patent.

[0016] In order to prevent the tea leaves from getting too hot when stacked after absorbing water, the thickness of the leaves should be reduced to facilitate heat dissipation and air flow between the leaves. In order to make the black tea reach the appropriate softening degree, the stacking time should be increased.

[0017] The pressing time in S300 can be 50-60 minutes, and the pressure can be selected from 15 to 30 tons.

[0018] Preferably, the moisture content of the tea leaves after absorbing water is 10%-15%; in the S200, the tea leaves after absorbing water are first piled statically for 1-2 hours, and then turned over and piled for 3-4 hours under a spraying environment, turned over every 10-20 minutes, and finally the tea leaves are spread out to dry with a thickness of 3-5 cm. After the spreading and drying, the moisture content of the tea leaves is 20%-25%.

[0019] Reduce the water absorption of tea leaves in the blanching stage, and control the final water absorption of tea leaves by spraying in the subsequent process. During the spraying process, the heat between leaves and the leaf surface can be better taken away, and the leaching of fluorine can be reduced. The process of absorbing water while replenishing water can reduce the humidity of the leaf surface, reduce microbial fermentation, and avoid excessive fermentation of black tea. Under normal circumstances, the total fermentation time of black tea is as long as several months or even more, so the influence of a few hours of stacking time in the cold pressing process on the flavor of black tea is not obvious, but the total fermentation time of conventional black tea may be within one day and more aerobic fermentation, so the stacking process in the cold pressing process has a greater impact on the flavor pursued by black tea, and it is necessary to improve the stacking process to avoid excessive fermentation of black tea. In the present invention, the stacking process is divided into two sections. During the static stacking, due to the low spreading thickness, the tea leaves can be pressed and covered with a clean dry cloth on the surface of the tea leaves. During the second stage of flipping the stacking, the cloth is removed and the tea leaves are flipped, so that the gaps between the tea leaves are increased and filled with air. The purpose of the first static pile is to destroy the surface tissue of the leaves to a certain extent through the anaerobic action of external microorganisms and further decompose the leaf components, thereby reducing the dissolution rate of fluorine. Reducing the density of the internal tissue of the leaves can also accelerate the water return rate of the tea leaves and reduce the total time for the tea leaves to absorb water and soften. In addition, the enhancement of microbial activity can induce the formation of calcium precipitation that is difficult for the human body to absorb, and the organic acids or amino acids generated by microbial activity have good fluorine affinity. The purpose of the second stage of rolling pile is to reduce the degree of fermentation during the water absorption process of the tea leaves and make the tea leaves reach the expected water content for subsequent pressing and molding. The purpose of the final thin spreading is to air-dry the moisture on the surface of the tea leaves to avoid excessive surface moisture during subsequent pressing, which affects the bonding effect between the tea leaves and reduces the quality damage of the tea surface during pressing.

[0020] Preferably, the ambient temperature during the primary fermentation is 24-30°C, the relative humidity is greater than 90%, the natural stacking thickness of the tea leaves is 8-15cm, and the fermentation time is 3-5h; during the secondary fermentation, the natural stacking thickness is 20-30cm, and the fermentation time is 8-20h.

[0021] Since black tea will further ferment during the cold pressing process, in order to reduce the impact of black tea fermentation on the overall flavor or taste during the cold pressing process, the present invention also improves the process for preparing raw black tea. During the primary fermentation, a fermentation vehicle, a fermentation frame or a fermentation tank can be used, and natural fermentation is adopted. The rolled leaves are first deblocked into loose and strong strips, and naturally piled up to 8-15cm thick without compaction. The principle of "thin spreading of young leaves and thick spreading of old leaves" is mastered. The fermented leaf temperature does not exceed 35°C. During the fermentation process, the leaves are turned over once every about 1h, and ventilation and air permeability are maintained. The leaves are covered with a wet cloth to retain moisture. The fermentation time is 3-5h, until the fermentation is moderate: the leaves are yellow-red (spring) or red-yellow (summer and autumn), the green smell subsides, and a sweet floral or apple fragrance is shown. During the secondary fermentation, the product after raw fire drying is spread to room temperature and naturally piled up to 20-30cm thick. It can be piled in a withering tank or on the ground (with a clean dry cloth on top), and then the tea leaves are covered with a white cloth. It can be naturally left to stand for 12h (summer and autumn) or 24h (spring). During the two fermentation processes, the present invention reduces the secondary fermentation degree so as to match the fermentation degree of the subsequent cold pressing process, so that the final fermentation degree of the product is good and the flavor is not affected.

[0022] After one fermentation, the raw fire drying can quickly remove the moisture of the tea leaves and basically terminate the activity of the enzyme, preventing the tea leaves from continuing to ferment due to the enzyme activity, especially during the storage process, and increasing the storage time of the tea leaves. It can also basically fix the amount of key flavor substances of black tea generated by the enzyme activity reaction. Suitable conditions for raw fire drying: dry and neat, fresh air, good ventilation. Drying equipment: continuous hot air dryer. The hot air temperature is 120-130℃, the leaf thickness is 1-2cm, the drying time is 15-20cm, and the moisture content of the dried tea leaves is about 10-15%. At this time, the dry tea strands become black, slightly prickly, and have a strong tea fragrance.

[0023] After the secondary fermentation, the residual moisture can be further removed by full fire drying. The hot air temperature of full fire drying is 80-90℃, the leaf thickness is 2-4cm, the drying time is 15-20 minutes, and the moisture content after drying is 6-7%. The tea leaves are obviously prickly when held slightly, and they are powdered by hand with a strong aroma. At this point, the processing of black tea is completed. The time of secondary fermentation is related to the season. The fermentation time in summer and autumn is shorter than that in spring. For example, 8 hours is selected in summer and autumn, while 24 hours is selected in spring.

[0024] After sufficient drying, the shape and purity of the black tea can be adjusted through screening machines, winnowing machines, color sorters, electrostatic stem pickers, etc., and it can be divided into tea of ​​different specifications, and unusual debris and fragments can be removed. Finally, the moisture content can be further reduced to about 4-5%, which is conducive to long-term storage and maintaining the aroma quality.

[0025] Preferably, the hot air temperature of the low-temperature slow baking is 50-60°C, the time is 48-60h, and the moisture content of the black tea after drying is 4%-7%.

[0026] Low temperature and slow baking can preserve the aroma and nutrients of tea leaves. However, in the patent application filed by the applicant on August 24, 2016, with the publication number CN106306137A and the patent name of a cold pressing method for compressed black tea, in order to achieve a good pressing effect, the water content of the tea brick is only reduced to 13.8%, which is higher than that of conventional tea bricks. In essence, it sacrifices part of the storage resistance in exchange for the advantage of low fluoride. Therefore, the purpose of the applicant's conversion to the cold pressing process is to reduce the final water content of the tea leaves and increase the storage time by changing the applicable objects and improving the process. The reason why the water content of the tea bricks in the aforementioned patent is relatively high is that cold pressing is essentially not conducive to the bonding effect of pectin or sugar substances on the surface of the tea leaves. In particular, in order to reduce the fluoride content, the water content of the tea leaves after the water is returned before cold pressing is still relatively high. During the drying process of the tea bricks, the volume of the tea leaves shrinks. In the case of a small bonding effect, the shrinkage rate needs to be controlled to ensure the compactness of the tea bricks, which ultimately leads to the water content of the tea bricks in the aforementioned patent cannot be lower. Although an external binder can be used to reduce the moisture content of the final tea brick, the external binder will affect the appearance of the tea leaves, the color or taste of the tea soup, etc.

[0027] There are big differences in the fermentation process between black tea and dark tea. Dark tea is heavily fermented and takes a long time to ferment. Under the action of microorganisms, pectin or other sugar substances are mostly decomposed into small molecule sugars. Therefore, the amount of pectin left is relatively small. The fermentation time of black tea is short and the fermentation conditions are mostly aerobic. The amount of pectin decomposed by microorganisms is relatively small. From the perspective of quantity, the bonding performance of black tea during pressing is better. This is one of the reasons why black tea was selected instead of other teas when cold pressing was converted in this case. At the process level, the present invention adds an air-drying step to remove moisture from the surface of the tea leaves after the original tea-running process. During the tea pressing process, some components in the tea leaves will inevitably seep out of the tea leaves with water and adhere to the surface of the tea leaves during the subsequent drying process. When the volume of the tea brick is constant after pressing, the initial moisture on the surface of the tea leaves will affect the seepage of the tea leaves' contents, which will not only affect the amount of non-fluorine water-soluble substances attached to the surface of the tea leaves, but also affect the bonding between the tea leaves.

[0028] Since the moisture content of the tea bricks in this case can be lower, the temperature and time of the drying process were adaptively adjusted.

[0029] Preferably, during rolling, the environment temperature is 20-25°C and the relative humidity is 60%-70%; during rolling, the tea leaves are first left to stand for 20-30 minutes, then rolled without pressure for 20-30 minutes, rolled with pressure for 15-20 minutes, rolled with heavy pressure for 10-15 minutes, and finally rolled without pressure for 5-10 minutes; the pressure of pressurized kneading is 120-200N, and the pressure of heavy kneading is 400-500N.

[0030] Rolling is an important step in tea processing, and its purpose is to break the tea leaf tissue and overflow the tea juice through external force, thereby promoting the mixing and transformation of the substances contained in the tea. Rolling can increase the flavor and aroma of the tea, making it more mellow; at the same time, rolling can also curl the tea leaves into shape, which is beneficial to the drying and subsequent brewing of the tea. In the process of this case, in addition to meeting the purpose of conventional rolling, we also focused on the changes in its flexibility to make it as flexible as possible. After increasing the flexibility of the tea through process improvements, greater pressure can be applied during pressing, making the tea bricks more compact, and the moisture content after drying can be lower.

[0031] Preferably, when picking fresh leaves, one bud and one two leaves and one bud and three or four leaves are selected; the mass ratio of one bud and one two leaves to one bud and three or four leaves is 3:2-8:3.

[0032] The aforementioned patent uses one bud and one or two leaves as the main raw materials, and the fiber content is relatively low. The present invention increases the fiber content in the fresh leaves while ensuring the quality of black tea through the ratio of two types of fresh leaves, thereby increasing the flexibility of the tea leaves when pressed. At the same time, the decomposition products of the tea fiber can also increase the adhesion of the tea leaves when pressed.

[0033] The quality requirements for fresh leaves are that the buds, leaves and tender stems are fresh, clean, free of pollution and other non-tea inclusions. The limit of pollutants in fresh leaves should comply with the provisions of GB 2762, and the maximum residue limit of pesticides should comply with the provisions of GB 2763. The picking time is sunny and cloudy, but not rainy or dewy leaves. Fresh leaves picked before 12:00 in the morning should be processed in the factory in the morning; fresh leaves picked before 19:00 in the afternoon should be processed in the factory on the same day. The purpose is to ensure the freshness of the fresh tea leaves and prevent them from spoiling and changing taste, which will affect the quality of the finished product.

[0034] Preferably, the ambient temperature during withering is 25-28°C and the relative humidity is 60%-70%; first, sunlight withering is performed for 0.5-1h, with the leaves spread to a thickness of 1-2cm, then natural withering is performed indoors for 12-18h, with no overlap between leaves when spreading, and finally, withering is performed in a withering trough for 12-18h, with the leaves spread to a thickness of 10-15cm; in the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0035] The withering process is accompanied by a reduction in moisture, softening of leaves, reduction in leaf area, and fermentation. Withering can promote the damage of leaf tissue and the compactness of leaf fibers during rolling. Since the leaf shape ratio is used in this case, in order to better promote the improvement of tea toughness through subsequent rolling through withering, when withering in the withering trough, one bud and three or four leaves are located at the bottom to avoid insufficient withering and affect the changes in tea structure or fiber tissue.

[0036] Preferably, S100 comprises: adding tea leaves obtained after sufficient drying and calcium salt into clean water; the molar ratio of calcium salt to clean water is 1:2000-1:1000.

[0037] Adding calcium salt during the process of tea leaves absorbing water can increase the stability of pectin calcium, and can also make the pectin decomposition product pectin acid combine with calcium to produce pectin calcium, reducing the decomposition of pectin during the composting process, which not only makes the tea leaves more elastic, but also increases the adhesion between tea leaves, further improving the compressibility. During the composting process, the conversion process of organic fluorine can also be more converted into calcium fluoride precipitation, reducing the impact of fluorine on the teeth or bones of the drinker.

[0038] Preferably, in S100, the amount of clean water used is 1.2-1.5 times the amount of water required for the tea leaves to absorb; and the method for determining the end point of tea leaves' water absorption includes:

[0039] D100, pre-measure the volume V1 of tea leaves after full fire drying and the volume V2 of tea leaves when the water content is the water content after water absorption, and obtain V3=V2-V1; calculate the water volume V4 absorbed by the tea leaves, and obtain the ratio n of V3 to V4;

[0040] D200, according to the actual required water absorption volume V4' and n, calculate the actual volume change V3', obtain the volume change value △V of the water outside the tea leaves through V4'-V3', and finally calculate the water level drop value h according to △V;

[0041] D300. During the operation of S100, the water surface height is measured in real time. When the water surface height drops by h, the water absorption is completed.

[0042] Since the amount of clean water used in S100 is greater than the weight of the tea leaves that need to absorb water, the operation of determining the water content of the tea leaves by the weight change of the tea leaves in the process will be more complicated, and it is necessary to drain or air-dry the water on the surface of the tea leaves that absorb water before weighing. In order to more conveniently determine the end point of water absorption during the preparation process, the present invention adopts a new determination method. Tea leaves have a porous structure, so when they absorb water, there are mainly two paths for water to enter the pores and the other is to enter the cell tissue. The original space of the pores is part of the volume of the tea leaves, so the expansion of the volume of the tea leaves is less than the amount of water absorbed. After the tea leaves absorb water, the water level will decrease. After the present invention measures the relationship between the water absorption volume and the expansion volume of the tea leaves by D100, the expansion volume of the tea leaves under the expected water absorption in S100 can be calculated, and then the volume drop value of the water outside the tea leaves is obtained by subtracting the expansion volume from the water absorption volume, and then the water level drop height is determined, and the water absorption end point of the tea leaves is determined by the water level drop height. D100 is the measurement process before preparation. The properties of each production area or batch of tea are somewhat different, so the present invention does not directly limit the specific water level drop value. The measurement of the n value in D100 can be obtained by taking the average value of multiple tests, and 0.5 kg of fully dried tea can be taken for each test. If the drainage method is used to measure the volume of tea, the density of dry tea is small, and the tea floats on the water surface, which is difficult to measure. The tea can be restricted below the water surface by a mesh. The value of h is related to the specifications of the container used in S100, so the present invention does not make a specific limitation.

[0043] Since the final water absorption required by the present invention is relatively low, the pore size changes very little, and the impact on the measurement results is almost unchanged. After verification by conventional water content measurement methods, it is confirmed that the method of determining the water absorption end point by water level drop is feasible.

[0044] A black tea brick made by a preparation process for compressed black tea.

[0045] The present invention has at least the following beneficial effects:

[0046] The present invention improves the cold pressing process according to the difference between black tea and dark tea, reduces the thickness of the spread leaves, and increases the heaping time; through the improvement of the heaping process, the water absorption time of the black tea is reduced, the fluorine leaching rate in the finished tea bricks is reduced, and the compressibility of the tea leaves is increased, thereby improving its storage resistance; in order to increase the compressibility of the black tea, reduce the water content of the tea bricks, and extend the shelf life while reducing the fluorine leaching rate of the tea bricks, the present invention improves the raw material selection, withering, rolling process and cold pressing process; in order to cooperate with the control of the water absorption of the tea leaves in the cold pressing process, the present invention also provides a water content determination method suitable for the tea cold pressing process of this case, and the water absorption end point can be determined by only measuring the water level drop. DETAILED DESCRIPTION

[0047] In order to make the purpose, method scheme and advantages of the embodiments of the present invention clearer, the method scheme in the embodiments of the present invention is clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0048] Embodiment 1: A process for preparing compressed black tea comprises:

[0049] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0050] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0051] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0052] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0053] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0054] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0055] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0056] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the water content of the tea leaves after absorbing water is 20%;

[0057] S200, spreading the tea leaves after absorbing water in a thickness of 10 cm in a pile pit, piling for 5 hours to obtain softened tea leaves, and stirring them every 20 minutes;

[0058] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0059] Low temperature slow baking: hot air temperature is 45℃ and time is 10h.

[0060] Embodiment 2: A process for preparing compressed black tea comprises:

[0061] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0062] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0063] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0064] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0065] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0066] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0067] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0068] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the water content of the tea leaves after absorbing water is 20%;

[0069] S200, spreading the tea leaves after absorbing water in a thickness of 10 cm in a pile, piling for 8 hours to obtain softened tea leaves, and stirring them every 20 minutes;

[0070] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0071] Low temperature slow baking: hot air temperature is 45℃ and time is 10h.

[0072] Embodiment 3: A process for preparing compressed black tea comprises:

[0073] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0074] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0075] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0076] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0077] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0078] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0079] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0080] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the water content of the tea leaves after absorbing water is 20%;

[0081] S200, spreading the tea leaves after absorbing water in a thickness of 10 cm in a pile, piling for 7 hours to obtain softened tea leaves, and stirring them every 20 minutes;

[0082] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0083] Low temperature slow baking: hot air temperature is 45℃ and time is 10h.

[0084] Embodiment 4: A process for preparing compressed black tea comprises:

[0085] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0086] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0087] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0088] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0089] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0090] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0091] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0092] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the water content of the tea leaves after absorbing water is 20%;

[0093] S200, spreading the tea leaves after absorbing water in a thickness of 15 cm in a pile, piling for 7 hours to obtain softened tea leaves, and stirring them every 20 minutes;

[0094] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0095] Low temperature slow baking: hot air temperature is 45℃ and time is 10h.

[0096] Embodiment 5: A process for preparing compressed black tea comprises:

[0097] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0098] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0099] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0100] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0101] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0102] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0103] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0104] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the water content of the tea leaves after absorbing water is 20%;

[0105] S200, spreading the tea leaves after absorbing water in a 12 cm thickness on a pile site, piling for 7 hours to obtain softened tea leaves, and stirring them every 20 minutes;

[0106] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0107] Low temperature slow baking: hot air temperature is 45℃ and time is 10h.

[0108] Comparative Example 1: A process for preparing compressed black tea comprises:

[0109] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0110] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0111] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0112] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0113] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0114] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0115] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0116] Steaming: Use 600℃ high temperature steam, weigh the blended finished tea, steam for 20-30 seconds, quickly put it into the mold box while it is still hot, press it with 15-30 tons of pressure for 120 seconds, and then exit the mold.

[0117] Low temperature slow baking: hot air temperature is 45℃ and time is 10h.

[0118] Comparative Example 2: A process for preparing compressed black tea comprises:

[0119] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0120] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0121] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0122] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0123] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0124] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0125] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0126] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the water content of the tea leaves after absorbing water is 20%;

[0127] S200, spreading the tea leaves after absorbing water in a thickness of 20 cm in a pile pit, piling for 7 hours to obtain softened tea leaves, and stirring them every 20 minutes;

[0128] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0129] Low temperature slow baking: hot air temperature is 45℃ and time is 10h.

[0130] Comparative Example 3: A process for preparing compressed black tea comprises:

[0131] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0132] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0133] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0134] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0135] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0136] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0137] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0138] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the water content of the tea leaves after absorbing water is 20%;

[0139] S200, spreading the tea leaves after absorbing water in a thickness of 12 cm in a pile, piling for 4 hours to obtain softened tea leaves, and stirring them every 20 minutes;

[0140] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0141] Low temperature slow baking: hot air temperature is 45℃ and time is 10h.

[0142] Test 1: The tea bricks prepared according to the preparation process of Examples 1-5 and Comparative Examples 1-3 were subjected to fluorine content testing of tea water extracts and water content testing of tea bricks.

[0143] Method for detecting fluoride content in water extracts: 5 g of tea leaves were added into 250 ml of water at 95°C, and the fluoride content in the water extracts was detected after 10 minutes. After 5 tests were conducted on the tea leaves prepared by the preparation method in each embodiment, the experimental data were averaged. The experimental data are shown in Table 1.

[0144] Table 1

[0145] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Water extract (mg / L) 4.15 4.27 4.09 4.23 4.01 6.46 5.19 4.54 Water content of tea brick (%) 13.4 13.5 13.4 13.5 13.3 13.5 13.4 13.4

[0146] From the comparison between Examples 1-5 and Comparative Example 1, it can be seen that the cold pressing process in the patent publication number CN106306137A can also effectively reduce the fluoride content in black tea when applied to the black tea preparation process. The preparation parameters in the preparation process of Example 5 are optimal.

[0147] From the comparison between Example 5 and Comparative Example 2, it can be seen that the stacking thickness and stacking time both affect the defluorination effect to a certain extent.

[0148] From the moisture content data of the tea bricks in Examples 1-5 and Comparative Examples 1-3, it can be seen that the storage resistance of the tea bricks is poor.

[0149] Test 2: The tea bricks prepared by the preparation process of Examples 1-5 and Comparative Examples 1-3 were subjected to sensory evaluation by 10 judges. After removing the highest and lowest scores, the average score was calculated, and the average score was the final score. Among them, the soup color accounted for 25 points, the aroma accounted for 35 points, and the taste accounted for 40 points. The test results are shown in Table 2.

[0150] Table 1

[0151] Soup color (25%) Aroma (35%) Taste (40%) Total score Example 1 22.5 34.7 39.1 96.3 Example 2 23.8 34.8 39.4 98.0 Example 3 21.6 34.5 39.2 95.3 Example 4 23.5 34.6 39.3 97.4 Example 5 23.7 35.0 39.3 98.0 Comparative Example 1 22.6 34.4 39.4 96.4 Comparative Example 2 23.4 30.1 37.6 91.1 Comparative Example 3 23.3 33.5 39.1 95.9

[0152] It can be seen from the test results of Examples 1-5 and Comparative Example 1 that the black tea bricks prepared by the preparation method of the present invention are comparable to the results of the conventional black tea brick preparation process in terms of flavor and taste.

[0153] It can be seen from the test results of Example 5 and Comparative Example 2 that a higher pile height will affect the flavor and taste of the finished black tea. The applicant speculates that this is caused by over-fermentation of the black tea.

[0154] From the test results of Example 5 and Comparative Example 3, it can be seen that the lower composting time has less effect on the sensory evaluation results, mainly reducing the aroma score. However, the compactness of the tea brick obtained after preparation is lower than that of Examples 1-5.

[0155] Embodiment 6: A process for preparing compressed black tea comprises:

[0156] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0157] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0158] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0159] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0160] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0161] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0162] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0163] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the moisture content of the tea leaves after absorbing water is 15%;

[0164] S200, the tea leaves after absorbing water are piled still for 1 hour, and then turned over and piled for 4 hours under a spraying environment, turning over every 20 minutes, with a pile thickness of 12 cm. Finally, the tea leaves are spread out to dry with a thickness of 3 cm. After the spreading and drying, the moisture content of the tea leaves is 20%;

[0165] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0166] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0167] Example 7: A process for preparing compressed black tea comprises:

[0168] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0169] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0170] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0171] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0172] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0173] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0174] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0175] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the moisture content of the tea leaves after absorbing water is 15%;

[0176] S200, the tea leaves after absorbing water are first piled still for 2 hours, and then turned over and piled for 4 hours under a spraying environment, turning over every 20 minutes, with a pile thickness of 12 cm. Finally, the tea leaves are spread out to a thickness of 3 cm. After the spreading and drying, the moisture content of the tea leaves is 20%;

[0177] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0178] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0179] Embodiment 8: A process for preparing compressed black tea comprises:

[0180] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0181] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0182] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0183] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0184] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0185] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0186] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0187] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the moisture content of the tea leaves after absorbing water is 15%;

[0188] S200, the tea leaves after absorbing water are first piled still for 2 hours, and then turned over and piled for 3 hours under a spraying environment, turning over every 20 minutes, with a pile thickness of 12 cm. Finally, the tea leaves are spread out to dry with a thickness of 3 cm. After the spreading and drying, the moisture content of the tea leaves is 20%;

[0189] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0190] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0191] Example 9: A process for preparing compressed black tea comprises:

[0192] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0193] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0194] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0195] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0196] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0197] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0198] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0199] Cold pressing: S100, add the tea leaves obtained after sufficient drying and calcium chloride into clean water, the moisture content of the tea leaves after absorbing water is 15%; the molar ratio of calcium chloride to clean water is 1:2000-1:1000.

[0200] S200, the tea leaves after absorbing water are first piled still for 2 hours, and then turned over and piled for 3 hours under a spraying environment, turning over every 20 minutes, with a pile thickness of 12 cm. Finally, the tea leaves are spread out to dry with a thickness of 3 cm. After the spreading and drying, the moisture content of the tea leaves is 20%;

[0201] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0202] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0203] Comparative Example 4: A process for preparing compressed black tea comprises:

[0204] Picking fresh leaves: select one bud and one or two leaves.

[0205] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, and spread the leaves to a thickness of 10 cm. During the withering process, if the fresh leaves appear to be stuck together, they can be turned over to loosen them, keeping the leaf layer ventilated and breathable. Turn the leaves over 5 times throughout the process to promote uniform withering.

[0206] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0207] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0208] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0209] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0210] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0211] Cold pressing: S100, add the tea leaves obtained after sufficient drying and calcium chloride into clean water, the moisture content of the tea leaves after absorbing water is 15%; the molar ratio of calcium chloride to clean water is 1:2000-1:1000.

[0212] S200, the tea leaves after absorbing water are first piled still for 2 hours, and then turned over and piled for 3 hours under a spraying environment, turning over every 20 minutes, with a pile thickness of 12 cm. Finally, the tea leaves are spread out to dry with a thickness of 3 cm. After the spreading and drying, the moisture content of the tea leaves is 20%;

[0213] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0214] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0215] Comparative Example 5: A process for preparing compressed black tea comprises:

[0216] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0217] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0218] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0219] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0220] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0221] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0222] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0223] Cold pressing: S100, add the tea leaves obtained after sufficient drying and calcium chloride into clean water, the moisture content of the tea leaves after absorbing water is 15%; the molar ratio of calcium chloride to clean water is 1:2000-1:1000.

[0224] S200, the tea leaves after absorbing water are first piled still for 2 hours, and then turned over and piled for 3 hours under a spraying environment, turning over every 20 minutes, and the pile thickness is 12 cm;

[0225] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0226] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0227] Comparative Example 6: A process for preparing compressed black tea comprises:

[0228] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0229] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0230] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0231] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0232] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0233] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0234] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0235] Cold pressing: S100, add the tea leaves obtained after sufficient drying and calcium chloride into clean water, the moisture content of the tea leaves after absorbing water is 15%; the molar ratio of calcium chloride to clean water is 1:2000-1:1000.

[0236] S200, the tea leaves after absorbing water are first piled still for 2 hours, and then turned over and piled for 3 hours under a spraying environment, turning over every 20 minutes, with a pile thickness of 12 cm. Finally, the tea leaves are spread out to dry with a thickness of 3 cm. After the spreading and drying, the moisture content of the tea leaves is 20%;

[0237] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0238] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0239] Comparative Example 7: A process for preparing compressed black tea comprises:

[0240] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0241] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0242] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 500N.

[0243] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0244] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0245] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0246] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0247] Cold pressing: S100, add the tea leaves obtained after sufficient drying and calcium chloride into clean water, the moisture content of the tea leaves after absorbing water is 15%; the molar ratio of calcium chloride to clean water is 1:2000-1:1000.

[0248] S200, the tea leaves after absorbing water are first piled still for 2 hours, and then turned over and piled for 3 hours under a spraying environment, turning over every 20 minutes, with a pile thickness of 12 cm. Finally, the tea leaves are spread out to dry with a thickness of 3 cm. After the spreading and drying, the moisture content of the tea leaves is 20%;

[0249] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0250] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0251] Comparative Example 8: A process for preparing compressed black tea comprises:

[0252] Picking fresh leaves: select one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2.

[0253] Withering: The ambient temperature during withering is 25℃ and the relative humidity is 60%. First, wither in sunlight for 1 hour, spread the leaves to a thickness of 2 cm, turn the leaves twice during this period to promote uniform withering, and the withering time is between 9 and 11 am; then wither naturally indoors for 16 hours. When spreading the leaves, there is no overlap between the leaves, and the weight is 2 catties / m 2 ; Finally, wither in the withering trough for 12 hours, with the leaves spread to a thickness of 10 cm. During the withering process, if the fresh leaves are stuck together, they can be loosened to keep the leaf layer ventilated and breathable. Turn the leaves 5 times throughout the process to promote uniform withering; In the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

[0254] Rolling: When rolling, the environment temperature is 20℃ and the relative humidity is 60%; when rolling, the tea leaves are first left to stand for 30 minutes, then rolled without pressure for 20 minutes, rolled with pressure for 15 minutes, rolled with heavy pressure for 10 minutes, and finally rolled without pressure for 5 minutes; the pressure of pressurized rolling is 180N, and the pressure of heavy rolling is 400N.

[0255] Primary fermentation: The ambient temperature is 25℃, the relative humidity is 92%, the air is fresh and the ventilation is good. The rolled leaves are first broken into loose strips, and then naturally piled up to 12cm thick. The fermentation time is 4h. During the fermentation process, turn it over every 1h, keep it ventilated and breathable, and cover it with a wet cloth to retain moisture.

[0256] Raw fire drying: Suitable conditions: dry and clean, fresh air, good ventilation. Drying equipment: continuous hot air dryer. Hot air temperature 130℃, leaf thickness 1.5cm, drying time 15min, the moisture content of the dried tea leaves is about 15%. At this time, the dry tea leaves become black, slightly prickly, and have a strong tea fragrance.

[0257] Secondary fermentation: After the raw fire-dried product is cooled to room temperature, the natural stacking thickness is 20cm, and the tea leaves are covered with breathable white cloth. The fermentation time is 8 hours.

[0258] Full fire drying: The hot air temperature of full fire drying is 80℃, the leaves are spread 3cm, the drying time is 20 minutes, the moisture content after drying is 7%, the tea leaves are obviously prickly when held slightly, and they can be powdered by hand with a strong aroma. At this point, the processing of black tea is completed.

[0259] Cold pressing: S100, add clean water to the tea leaves obtained after full fire drying, and the water content of the tea leaves after absorbing water is 20%;

[0260] S200, spreading the tea leaves after absorbing water in a 12 cm thickness on a pile site, piling for 7 hours to obtain softened tea leaves, and stirring them every 20 minutes;

[0261] S300, using a brick tea press machine to press the softened tea leaves into tea bricks. The pressing time is 60 minutes and the pressure is 20 tons.

[0262] Low temperature slow baking: hot air temperature is 50℃ and time is 50h.

[0263] Experiment 3: Referring to Experiment 1, the tea bricks prepared according to the preparation process of Examples 6-9 and Comparative Examples 4-7 were tested for fluorine content in tea water extracts and water content in tea bricks. The experimental data are shown in Table 3.

[0264] Table 3

[0265] Example 6 Example 7 Example 8 Example 9 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Water extract (mg / L) 3.78 3.85 3.70 3.12 3.16 3.57 3.45 3.50 Water content of tea brick (%) 5.3 5.4 5.2 5.3 5.3 5.4 5.3 5.4

[0266] From the comparison between Examples 1-5 and Examples 6-9, it can be seen that the improvement of the heaping process can reduce the fluorine content in the tea water extract.

[0267] It can be seen from the comparison between Examples 6-8 and Example 9 that the addition of calcium chloride can reduce the fluoride content in the tea water extract.

[0268] Test 4: The tea bricks prepared according to the preparation process of Examples 6-9 and Comparative Examples 4-7 were evaluated for their apparent quality by 10 judges. After removing the highest and lowest scores, the average score was calculated. The average score was the final score, of which the degree of damage to the surface of the tea brick accounted for 50 points and the compactness of the tea brick accounted for 50 points. The evaluation results are shown in Table 4.

[0269] Table 4

[0270] Destruction (50%) Firmness (50%) Total score Example 6 49.5 47.6 97.1 Example 7 49.7 48.0 97.7 Example 8 49.6 47.5 97.1 Example 9 49.7 48.2 97.9 Comparative Example 4 33.7 40.6 74.3 Comparative Example 5 42.6 43.7 86.3 Comparative Example 6 41.8 45.6 87.4 Comparative Example 7 44.3 40.1 84.4 Comparative Example 8 34.7 30.2 64.9

[0271] From the evaluation results of Examples 6-9, it can be seen that even if the moisture content of the final finished tea brick is 5.2%-5.4%, the tea brick has a good molding effect and its storage resistance is improved.

[0272] From the comparison between Comparative Example 4 and Example 9, it can be seen that the ratio of young leaves to old leaves can improve the compressibility of tea bricks.

[0273] From the comparison between Comparative Example 5 and Example 9, it can be seen that adding an air-drying step in the stacking process can improve the compressibility of the tea brick.

[0274] From the comparison between Comparative Examples 6-7 and Example 9, it can be seen that the improvement of the kneading process can improve the compressibility of the tea brick.

[0275] From the comparison between Comparative Example 8 and Example 9, it can be seen that if the temperature or time of the low-temperature slow baking is increased on the basis of Example 5 to reduce the final water content of the tea brick, it is almost difficult to meet the tea brick molding conditions.

[0276] Test 5: The tea bricks prepared by the preparation process of Examples 6-9 were subjected to sensory evaluation by 10 judges. After removing the highest and lowest scores, the average score was calculated, and the average score was the final score. Among them, the soup color accounted for 25 points, the aroma accounted for 35 points, and the taste accounted for 40 points. The test results are shown in Table 5.

[0277] Table 5

[0278] Soup color (25%) Aroma (35%) Taste (40%) Total score Example 6 23.6 34.2 39.2 97.0 Example 7 22.5 34.7 39.1 96.3 Example 8 24.1 33.4 39.3 96.8 Example 9 23.2 34.5 39.1 96.8

[0279] It can be seen from the evaluation results of Examples 6-9 that the tea bricks prepared by the preparation process provided in Examples 6-9 of the present invention have improved the storage resistance while the evaluation scores remain basically stable.

[0280] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preparing compressed black tea, characterized in that: Including fresh leaf picking, withering, rolling, primary fermentation, rough fire drying, secondary fermentation, full fire drying, cold pressing and low temperature slow baking; The cold pressing comprises the following steps: S100, adding clean water to the tea leaves obtained after sufficient drying, wherein the water content of the tea leaves after absorbing water is 10%-25%; S200, spreading the tea leaves after absorbing water in a pile with a thickness of 10-15 cm, and pile them for 5-8 hours to obtain softened tea leaves; S300, using a brick tea pressing machine to press the softened tea leaves into a shape to obtain a tea brick.

2. The preparation process according to claim 1, characterized in that: The moisture content of the tea leaves after absorbing water is 10%-15%; in the S200, the tea leaves after absorbing water are first piled statically for 1-2 hours, and then turned over and piled for 3-4 hours under a spraying environment, turned over every 10-20 minutes, and finally the tea leaves are spread out to a thickness of 3-5 cm. After the spreading and drying, the moisture content of the tea leaves is 20%-25%.

3. The preparation process according to claim 1, characterized in that: During the primary fermentation, the ambient temperature is 24-30°C, the relative humidity is greater than 90%, the natural stacking thickness of the tea leaves is 8-15cm, and the fermentation time is 3-5h; during the secondary fermentation, the natural stacking thickness is 20-30cm, and the fermentation time is 8-20h.

4. The preparation process according to claim 1, characterized in that: The hot air temperature of low-temperature slow baking is 50-60℃, the time is 48-60h, and the moisture content of black tea after drying is 4%-7%.

5. The preparation process according to claim 1, characterized in that: During rolling, the environment temperature is 20-25℃ and the relative humidity is 60%-70%; during rolling, the tea leaves are first left to stand for 20-30 minutes, then rolled without pressure for 20-30 minutes, rolled with pressure for 15-20 minutes, rolled with heavy pressure for 10-15 minutes, and finally rolled without pressure for 5-10 minutes; the pressure of pressurized rolling is 120-200N, and the pressure of heavy rolling is 400-500N.

6. The preparation process according to claim 1, characterized in that: When picking fresh leaves, choose one bud and one or two leaves and one bud and three or four leaves; the mass ratio of one bud and one or two leaves to one bud and three or four leaves is 3:2-8:

3.

7. The preparation process according to claim 6, characterized in that: The ambient temperature during withering is 25-28℃, and the relative humidity is 60%-70%; first wither in sunlight for 0.5-1h, with the leaves spread to a thickness of 1-2cm, then wither naturally indoors for 12-18h, with no overlap between leaves when spreading, and finally wither in a withering trough for 12-18h, with a leaf thickness of 10-15cm; in the withering trough, one bud and three or four leaves are located below one bud and one or two leaves.

8. The preparation process according to claim 1, characterized in that: The step S100 comprises: adding tea leaves obtained after sufficient drying and calcium salt into clean water; the molar ratio of calcium salt to clean water is 1:2000-1:1000.

9. The preparation process according to any one of claims 1 to 8, characterized in that: In the step S100, the amount of clean water used is 1.2-1.5 times the amount of water that the tea leaves need to absorb; The methods for determining the endpoint of tea water absorption include: D100, pre-measure the volume V1 of the tea leaves after full fire drying and the volume V2 of the tea leaves when the moisture content is the moisture content after water absorption, and obtain V3=V2-V1; Calculate the volume of water V4 absorbed by the tea leaves and obtain the ratio n of V3 to V4; D200, according to the actual required water absorption volume V4' and n, calculate the actual volume change V3', obtain the volume change value △V of the water outside the tea leaves through V4'-V3', and finally calculate the water level drop value h according to △V; D300. During the operation of S100, the water surface height is measured in real time. When the water surface height drops by h, the water absorption is completed.

10. A black tea brick made by the process for preparing compressed black tea according to any one of claims 1 to 9.