Cold-pressing method of white tea cake

Abstract

The application discloses a cold-press processing method of white tea cakes, which comprises the steps of pre-freezing, natural moisture absorption, low-temperature dehumidification, cake pressing, low-temperature airing and drying. The application adopts the operation mode of first freezing the raw materials and then naturally absorbing moisture, so that the tea leaves are softened under the condition of low temperature, and then the tea cakes are pressed by sample division, so as to solve the problems that the tea leaves are soaked in the local area due to the high water content, the tea leaves are easily mashed and changed into paste on the surface, and the cakes are steamed due to high temperature and high humidity during drying.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of tea processing, and particularly relates to a cold-pressing processing method of white tea cake. BACKGROUND

[0002] White tea is pressed into a cake, which greatly reduces the volume of tea leaves, reduces the cost of packaging, storage and transportation, and promotes the development of white tea industry. The core process of white tea cake pressing is to steam the dry tea with steam to increase the moisture content and make the strips soft, and then press the tea leaves into a cake with a mold. The main process flow is: tea weighing → tea steaming → shaping → pressing → spreading and cooling → drying. However, the tea cake is pressed while it is hot after being treated by steam, which not only destroys the quality and flavor of the white tea, but also makes the tea leaves stay in a high-temperature and high-humidity environment for a long time, which further destroys the quality and flavor and the internal components of the tea, and significantly weakens or even loses the original quality and flavor of the white tea. The obtained tea cake has a dull yellow color, yellow soup, matured and smelly aroma, yellow and dark leaf bottom, and the like. In addition, the tea cake pressed by the steam steaming method is compact, and it needs to be brewed for a long time or a large number of times to obtain the tea soup taste and concentration.

[0003] In addition to using steam to soften the tea leaves, there is also a method of adding water to soften the tea leaves before pressing them into a cake. The methods of adding water to soften the tea leaves mainly include normal temperature water spraying, soaking and low temperature water adding. The normal temperature water spraying needs to be piled for a long time at normal temperature, which will produce a piling smell and destroy the quality and flavor of the tea leaves; the soaking method will easily cause the internal components of the tea leaves to be soaked out, resulting in the loss and oxidation of the internal components and the damage to the quality; and the low temperature water adding method will cause uneven water accumulation in local areas of the tea leaves due to uneven water adding or ice adding, and the surface of the tea leaves will be easily crushed into a paste. SUMMARY

[0004] In view of the problems of the current white tea cake pressing, such as the high water content in local areas of the tea leaves causing soaking, the surface of the tea leaves being easily crushed into a paste, and the piling smell caused by high temperature and high humidity during drying, the present application provides a cold-pressing processing method of white tea cake.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A cold-pressing processing method of white tea cake, the main process flow of which is: raw material pre-freezing → natural moisture absorption → low-temperature dehumidification → cake pressing → low-temperature spreading and cooling → drying. The operation of each step is as follows:

[0007] 1) Pre-freezing: the white tea raw material is placed in a cold storage below-5℃ for 24 hours to fully pre-cool the raw material;

[0008] 2) Natural moisture absorption: After pre-freezing the white tea, evenly spread it on a nylon screen, and then place it in a room with a temperature of 0-15℃ and a relative humidity of more than 95% for more than 3 hours of natural moisture absorption, so that the moisture absorption weight gain rate reaches 30%;

[0009] 3) Low-temperature dehumidification: After natural moisture absorption, place the obtained moisture absorption leaves in a room with a temperature of 0-15℃ and a humidity of less than 40% for 20 minutes of airing, with one-time stirring in between, so that the moisture inside and outside the moisture absorption leaves is evenly distributed; after airing, the moisture regain rate of the obtained moisture regain leaves is reduced to 25%, the tea leaves become soft, and the stems are not broken, with fresh and lively color;

[0010] 4) Cake pressing: weigh the moisture regain leaves according to the required tea cake weight and pour them into the mold for pressing, so that the tea cake is shaped and not loose;

[0011] 5) Low-temperature airing: Place the pressed tea cake flat on the shelves, arrange them in layers without stacking, and place them in a room with a temperature of 0-15℃ and a humidity of less than 40% for 12-24 hours of airing, while assisting with air blowing, so that the free water of the tea leaves is fully discharged;

[0012] 6) Drying: After airing is completed, the shelves on which the tea cakes are placed are directly sent to the drying room or oven, and under the condition of not being closed (a small gap is opened), 60±2℃ is dried for 4h, and then under the condition of being closed, 60±2℃ is dried until dry (about 6-8h).

[0013] Further, the thickness of the white tea spread in step 2) is 5-10cm.

[0014] Further, in step 4), the amount of moisture regain leaves weighed each time is calculated as 1.25 times the weight of each dry tea cake.

[0015] Further, in step 4), the pressure of the pressing is 12~60 tons, and the pressure holding time is 3 seconds~3 minutes.

[0016] The present application adopts the operation mode of first freezing the raw materials and then naturally absorbing moisture to make the tea leaves soft in a low-temperature condition, and then pressing the tea cakes in batches, which has the following advantages:

[0017] 1. The raw materials are first frozen and then placed in a high-humidity environment. Due to the temperature difference between the tea leaves and the external environment, a uniform condensation layer can be quickly formed on the surface of the tea leaves, which can quickly and uniformly absorb moisture and make the tea leaves soft, and avoid the defects of uneven softening caused by steam heating and uneven softening caused by adding water.

[0018] 2. After the tea leaves are softened by moisture absorption, the moisture on the surface of the moisture absorption leaves is discharged by low-temperature dehumidification, so that the moisture inside and outside the moisture absorption leaves is uniformly distributed.

[0019] 3. The moisture-absorbing leaves are removed from the surface with low temperature and low humidity before being pressed into tea cakes. This avoids the problem of the tea leaves being crushed into a paste due to excessive moisture content and water soaking when pressed directly into cakes after softening.

[0020] 4. The pressed tea cakes are first spread out at a low temperature and low humidity to allow the free moisture of the tea leaves to fully dissipate before drying. This avoids the phenomenon of "suffocation" that occurs when the tea cakes are dried directly at high temperature and high humidity after pressing, thus reducing the quality changes of the tea after pressing. Detailed Implementation

[0021] A cold-pressing process for white tea cakes, the operation of which is as follows:

[0022] 1) Pre-freezing: Place the white tea raw materials in a cold storage at -5℃ or below for 24 hours to pre-freeze them and allow them to cool down fully;

[0023] 2) Natural moisture absorption: Spread the pre-frozen white tea evenly and thinly on a nylon screen, with a thickness of 5-10cm, and then place it in a room with a temperature of 0-15℃ and a relative humidity of over 95% for more than 3 hours to absorb moisture, so that the moisture absorption weight gain rate reaches 30%;

[0024] 3) Low-temperature dehumidification: After natural moisture absorption, place the moisture-absorbing leaves in an indoor environment with a temperature of 0-15℃ and humidity of less than 40% for 20 minutes, turning them over once in between to ensure that the moisture inside and outside the leaves is evenly distributed. After drying, the weight gain of the rehydrated leaves is reduced to 25%, the tea leaves become soft, can be squeezed into a ball with slight elasticity, the stems cannot be broken, and the color is fresh.

[0025] 4) Pressing the tea cake: Weigh 1.25 times the required weight of the tea cake (based on dry weight) of the rehydrated tea leaves (weighing error not exceeding 2%), pour them into the mold, and press them with a hydraulic press under a pressure of 12 to 60 tons, and hold the pressure for 3 seconds to 3 minutes to make the tea cake form and not loose.

[0026] 5) Low-temperature drying: Spread the pressed tea cakes flat on the rack, layer by layer without stacking, and place them indoors at 0-15℃ and humidity below 40% for 12-24 hours. At the same time, use air blowing to help the free water in the tea leaves to fully evaporate.

[0027] 6) Drying: After the tea cakes have been spread out, the racks on which the tea cakes are placed are sent directly into the drying room or oven. They are dried at 60±2℃ for 4 hours under non-sealed conditions (with a small gap), and then dried at 60±2℃ under sealed conditions until fully dry (lasting about 6-8 hours).

[0028] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0029] Example 1

[0030] A cold-press processing method of white tea cake, which operates as follows:

[0031] 1) Pre-freezing: the white peony white tea raw material (Fuding Dahao tea) is placed in a cold store below -5°C for pre-freezing for 24 hours, so as to fully pre-cool the raw material;

[0032] 2) Natural moisture absorption: the pre-frozen white tea is evenly and thinly spread on a nylon screen, with a spreading thickness of 5 cm, and then placed in a room at 15°C and a relative humidity of more than 95% for standing and moisture absorption for more than 3 hours, so as to make the moisture absorption weight gain rate reach 30%;

[0033] 3) Low-temperature dehumidification: after the natural moisture absorption is completed, the obtained moisture absorption leaves are spread and aired in a room at 15°C and a humidity of less than 40% for 20 minutes, with intermediate stirring once, so as to make the moisture inside and outside the moisture absorption leaves uniform; after the spreading and airing, the weight gain rate of the obtained moisture absorption leaves is reduced to 25%, the tea leaves become soft, and a handful of the tea leaves has slight elasticity, the stems are not broken, and the color is fresh and lively;

[0034] 4) Cake pressing: 56.25 g of moisture absorption leaves (with a weighing error of not more than 2%) are weighed according to the amount of 5 g per cake, poured into a 1-mold 9-piece square mold (with a side length of 12 cm), and pressed by a hydraulic machine under the condition of a pressure of 12 tons, and pressure is maintained for 3 seconds, so as to make the tea cake shaped and not loose;

[0035] 5) Low-temperature spreading and airing: the pressed tea cake is laid flat on a shelf, arranged in layers without stacking, placed in a room at 15°C and a humidity of less than 40% for 12 hours of spreading and airing, while assisted blowing is performed, so as to fully evaporate the free water of the tea leaves;

[0036] 6) Drying: after the spreading and airing is completed, the shelf on which the tea cake is placed is directly sent into an oven room or an oven, and the tea cake is dried under the condition of being not closed (a small gap is opened) at 60±2°C for 4 h, and then dried under the condition of being closed at 60±2°C until dry (for about 6 h).

[0037] The obtained tea cake is square in appearance, with a side length of 4 cm and a thickness of 1-2 mm, the surface is uniform and smooth and rich in luster, the color is fresh and lively, and the tips are visible; the inner quality keeps the original flavor of white tea unchanged; the leaf bottom is soft and bright, and the leaf is complete.

[0038] Example 2

[0039] A cold-press processing method of white tea cake, which operates as follows:

[0040] 1) Pre-freezing: the white peony white tea raw material (Jinguanyin white tea) is placed in a cold store below -5°C for pre-freezing for 24 hours, so as to fully pre-cool the raw material;

[0041] 2) Natural moisture absorption: the pre-frozen white tea is evenly and thinly spread on a nylon screen, with a spreading thickness of 10 cm, and then placed in a room at 10°C and a relative humidity of more than 95% for standing and moisture absorption for more than 3 hours, so as to make the moisture absorption weight gain rate reach 30%;

[0042] 3) Low-temperature airing: after the end of natural moisture absorption, the obtained moisture-absorbed leaves are placed in a room with a temperature of 10°C and a humidity of less than 40% for 20 minutes, with an intermediate stirring, so as to make the moisture inside and outside the moisture-absorbed leaves uniform; after airing, the weight gain rate of the obtained moisture-restored leaves is reduced to 25%, the tea leaves become soft, and a group is slightly elastic when pinched by hand, the stems are not broken, and the color is fresh and lively;

[0043] 4) Cake pressing: 437.5g of moisture-restored leaves (with a weighing error of not more than 2%) are weighed according to the amount of 350g per tea cake, poured into a mold with a diameter of 19-20cm, and pressed by a hydraulic machine under a pressure of 60 tons, and pressure is maintained for 3 minutes, so that the tea cake is shaped and not loose;

[0044] 5) Low-temperature airing: the pressed tea cake is placed on a shelf, arranged in layers without stacking, and placed in a room with a temperature of 10°C and a humidity of less than 40% for 24 hours, while assisted blowing is performed, so that the free water of the tea leaves is fully discharged;

[0045] 6) Drying: after the airing is completed, the shelf on which the tea cake is placed is directly sent into an oven or an oven, and the tea cake is dried under the condition of not being closed (a small gap is opened) at 60±2°C for 4h, and then dried under the condition of being closed at 60±2°C until dry (about 8h).

[0046] The obtained tea cake has a thickness of about 1-1.2cm, an appearance surface that is uniform and smooth with a rich luster, a color that is dark green and fresh, and a consistent color inside and outside the tea cake; the original floral fragrance of the Jinguanyin white tea is unchanged; the leaf bottom is soft and bright, and the leaf is complete.

[0047] Comparative Example 1

[0048] A cold-pressing processing method of a white tea cake, which is operated as follows:

[0049] 1) Pre-freezing: the Bai Muyan white tea raw material (Jinguanyin white tea) is placed in a freezer below -5°C for 24 hours to fully pre-cool the raw material;

[0050] 2) Natural moisture absorption: the pre-frozen white tea is evenly and thinly spread on a nylon screen, and then placed in a room with a temperature of 10°C and a relative humidity of more than 95% for more than 3 hours to absorb moisture, so that the moisture absorption weight gain rate reaches 30%;

[0051] 3) Cake pressing: 437.5g of moisture-absorbed leaves (with a weighing error of not more than 2%) are weighed according to the amount of 350g per tea cake, poured into a mold with a diameter of 19-20cm, and pressed by a hydraulic machine under a pressure of 60 tons, and pressure is maintained for 3 minutes;

[0052] 4) Low-temperature airing: The pressed tea cakes are placed on shelves in layers without stacking, and are placed in a room at 10°C and below 40% humidity for 24 hours, while auxiliary blowing is assisted to fully evaporate the free water of the tea leaves;

[0053] 5) Drying: After the airing is completed, the shelves on which the tea cakes are placed are directly sent into the drying room or oven, and are dried at 60±2°C for 4h under the condition of not being closed (a small gap is opened), and then are dried at 60±2°C under the condition of being closed until they are dry enough (for about 8h).

[0054] The obtained tea cakes are deformed due to the swelling of the tea leaves after being pressed, the surface of the obtained tea cakes appears to be raised or has burrs, the color becomes dark, and the color inside and outside the tea cakes is inconsistent.

[0055] Comparative Example 2

[0056] A cold-pressing processing method of a white tea cake is as follows:

[0057] 1) Pre-freezing: The Bai Muyun white tea raw material (Jinguanyin white tea) is placed in a freezer below -5°C for pre-freezing for 24 hours to fully pre-cool the raw material;

[0058] 2) Natural moisture absorption: The pre-frozen white tea is evenly and thinly spread on a nylon screen, the spreading thickness is 10 cm, and then is placed in a room at 10°C and above 95% relative humidity for standing and moisture absorption for more than 3 hours to make the moisture absorption weight gain rate reach 30%;

[0059] 3) Low-temperature dehumidification: After the natural moisture absorption is completed, the obtained moisture absorption leaves are placed in a room at 10°C and below 40% humidity for airing for 20 minutes, and are stirred once in the middle to make the moisture inside and outside the moisture absorption leaves uniform; after the airing, the weight gain rate of the obtained moisture absorption leaves is reduced to 25%, the tea leaves become soft, and are slightly elastic when being kneaded by hand, the stems are not broken, and the color is fresh and lively;

[0060] 4) Cake pressing: 437.5g of the moisture absorption leaves (the weighing error is not more than 2%) are weighed according to the amount of 350g per cake, are poured into a mold with a diameter of 19-20cm, and are pressed by a hydraulic machine under the condition of a pressure of 60 tons and for 3 minutes to make the tea cakes shaped and not loose;

[0061] 5) Drying: The pressed tea cakes are placed on shelves in layers without stacking, and are sent into a drying room or oven, and are dried at 60±2°C for 4h under the condition of not being closed (a small gap is opened), and then are dried at 60±2°C under the condition of being closed until they are dry enough (for about 8h).

[0062] The obtained tea cakes are deformed due to the swelling of the tea leaves after being pressed, the surface of the obtained tea cakes appears to be raised or has burrs, the color becomes dark, and the color inside and outside the tea cakes is inconsistent.

[0063] The above merely describes preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the present application should be included in the scope of the present application.

Claims

1. A cold-press processing method of white tea cake, characterized by, Comprising the following steps: 1) Pre-freezing: placing the white tea raw material in a freezer below -5°C for 24 hours; 2) Natural moisture absorption: evenly spreading the pre-frozen white tea on a nylon screen, and then placing it in a room with a temperature of 0-15°C and a relative humidity of more than 95% for more than 3 hours of moisture absorption, so that the moisture absorption weight gain rate reaches 30%; 3) Low-temperature dehumidification: after the natural moisture absorption is completed, the obtained moisture absorption leaves are placed in a room with a temperature of 0-15°C and a humidity of less than 40% for 20 minutes of airing, with an intermediate stirring, so that the moisture inside and outside the moisture absorption leaves is uniform; after the airing, the moisture regain leaves obtained have a weight gain rate reduced to 25%, the tea leaves become soft, and a handful of them has slight elasticity, the stems are not broken, and the color is fresh and lively; 4) Cake pressing: weighing the moisture regain leaves according to the required tea cake weight and pouring them into a mold for pressing, so that the tea cake is shaped and not loose; 5) Low-temperature airing: placing the pressed tea cake flat on a shelf, arranging it in layers without stacking, and placing it in a room with a temperature of 0-15°C and a humidity of less than 40% for 12-24 hours of airing, while assisting with air blowing, so that the free water of the tea leaves is fully discharged; 6) Drying: after the airing is completed, the shelf on which the tea cake is placed is sent to a drying room or oven for drying under non-closed conditions at 60±2°C for 4 hours, and then under closed conditions at 60±2°C until dry; In step 2), the spreading thickness of the white tea is 5-10 cm; In step 4), the amount of moisture regain leaves weighed each time is calculated at 1.25 times the weight of each dry tea cake; the pressure of the pressing is 12-60 tons, and the pressure holding time is 3 seconds-3 minutes.