A method for preparing tea leaves for improving tea aroma

Abstract

The invention relates to a tea preparation method for improving the aroma of tea, belonging to the technical field of tea processing, comprising the steps of picking, withering, rolling and drying, wherein the withering step uses a variety of enzyme preparations, ultrasonic treatment means and hot air heating inactivation to synergistically improve the withering efficiency, and gradually promotes the transformation of internal components of the tea through three withering enzymatic hydrolysis, improves the overall taste of the tea, and realizes the multi-level improvement of the tea aroma.

Description

Technical Field

[0001] The invention belongs to the technical field of tea processing and relates to a tea preparation method for improving the aroma of tea. Background Art

[0002] In my country, tea processing technology has evolved over thousands of years, forming a series of traditional processes including picking, spreading, withering, rolling, drying, etc. These processes will selectively add targeted processing steps such as fermentation, shaking, and steaming for different types of tea, such as black tea, oolong tea, and yellow tea, according to their specific quality requirements. However, these traditional processing techniques have certain limitations in practical applications.

[0003] First, the fermentation, shaking and steaming steps have high requirements for environmental conditions, such as temperature fluctuations, humidity control, changes in oxygen content, etc. The fluctuations of these factors may lead to unstable fermentation effects and affect the quality of tea. Secondly, the traditional fermentation process relies on the natural microbial activity in tea leaves, which makes the fermentation process difficult to control and may cause the tea aroma to be lost or the brewed tea to be bitter and astringent.

[0004] In order to maintain or improve the aroma of tea, some teas are packaged with special packaging materials or some natural spices are added. However, these additives cannot directly change the aroma of the tea itself, but may cover or pollute the tea aroma, thus affecting the quality of the tea. Therefore, how to better enhance the aroma of natural tea has become an urgent problem for companies to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a tea preparation method for improving the aroma of tea, which mainly adopts multiple withering, and uses a variety of enzyme preparations, ultrasonic treatment and hot air heating inactivation during the withering process to synergistically improve the withering efficiency, promote the transformation of the chemical components inside the tea, increase the aroma compounds of the tea, and combine the picking, rolling, drying and other processes to further shorten the tea processing time, so as to effectively improve the aroma of tea while improving the quality and taste of the tea.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for preparing tea leaves for improving the tea aroma, the method comprising the following steps:

[0008] (1) Select one bud and two leaves of tea picked in the early morning, and remove old leaves and impurities;

[0009] (2) spreading the picked tea leaves evenly on a withering tank with a thickness of 4 to 6 cm, setting the indoor temperature to 22 to 24° C. and the humidity to 65 to 75° C., and withering the tea leaves three times to obtain tea leaves withered three times;

[0010] (3) cooling the tea leaves after three withering to room temperature and then rolling them;

[0011] (4) Place the rolled tea leaves in a drying machine with a thickness of 1 to 2 cm, and stop drying when the moisture content of the tea leaves drops to 4 to 5%. After cooling to room temperature, vacuum pack and store.

[0012] Furthermore, the first withering step of the three withering steps in step (2) is as follows: spraying the polyphenol oxidase solution evenly on the tea leaves, ultrasonically treating for 20 to 30 minutes, spreading for 30 to 40 minutes, and heating and inactivating with hot air to obtain tea leaves after the first withering;

[0013] The concentration of the polyphenol oxidase solution is 0.5-1g / L, and 5-10mL is sprayed per kilogram of tea leaves.

[0014] Furthermore, the second withering step in the three withering steps in step (2) is as follows: spraying the tannase solution evenly on the tea leaves after the first withering, ultrasonically treating for 12 to 18 minutes, and then spreading for 30 to 40 minutes, and heating and inactivating the tea leaves with hot air to obtain the tea leaves after the second withering;

[0015] The concentration of the tannase solution is 0.3-0.6 g / L, and 3-6 mL is sprayed per kilogram of tea leaves.

[0016] Furthermore, the third withering step in the three withering steps in step (2) is as follows: evenly spraying the lipase solution on the tea leaves after the second withering, ultrasonically treating for 10 to 20 minutes, then spreading for 30 to 40 minutes, and heating and inactivating with hot air to obtain tea leaves after the third withering;

[0017] The concentration of the lipase solution is 0.1-0.3 g / L, and 1-3 mL is sprayed per kilogram of tea leaves.

[0018] Furthermore, the ultrasonic treatment parameters in the three withering steps in step (2) are: ultrasonic power of 150 to 250 W, and ultrasonic frequency of 20 to 60 kHz.

[0019] Furthermore, the hot air heating parameters in the three withering steps in step (2) are: heating temperature is 65-75° C., and heating time is 3-7 min.

[0020] Furthermore, the kneading parameters in step (3) are: kneading temperature is 20-30° C., kneading time is 10-20 min, and kneading speed is 10-30 rpm.

[0021] Furthermore, the drying parameters in step (4) are as follows: the initial temperature is 80-90°C, and the temperature is gradually increased by 5°C every 10 minutes to 110-120°C.

[0022] Beneficial effects of the present invention:

[0023] During the withering process of the present invention, polyphenol oxidase is sprayed to catalyze the oxidation of polyphenols in tea leaves to form compounds such as o-quinone, and these compounds are further polymerized to form tea pigments, thereby enhancing the aroma of the tea leaves and improving the taste; then tannin is added to hydrolyze ester-type catechins to decompose them into gallic acid and glucose, thereby reducing the astringency of the tea leaves and increasing the sweetness of the tea soup and the roundness of the taste; the first two enzymes reduce the content of tannic acid in the tea leaves, thereby reducing the substrates for competing reactions with lipase, and the addition of lipase at this time can better decompose the fat in the tea leaves, release volatile substances such as fatty acids, increase the aroma of the tea leaves, improve the overall taste of the tea leaves through gradual enzymolysis, and simultaneously promote the volatilization of aroma precursor substances in the tea leaves with the help of ultrasonic treatment, thereby achieving multi-level enhancement of the aroma of the tea leaves.

[0024] The present invention adopts multiple withering, and uses multiple enzyme preparations, ultrasonic treatment and hot air heating inactivation in the withering process to synergistically improve the withering efficiency, promote the transformation of chemical components inside the tea leaves, increase the aroma compounds of the tea leaves, and combine the picking, rolling, drying and other processes to further shorten the tea processing time, effectively improving the tea fragrance while improving the quality and taste of the tea leaves. DETAILED DESCRIPTION

[0025] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0026] Example 1

[0027] A method for preparing tea leaves for improving the tea aroma. The method for preparing tea leaves for improving the tea aroma of this embodiment comprises the following steps:

[0028] (1) Select one bud and two leaves of tea picked in the early morning, and remove old leaves and impurities;

[0029] (2) Spreading the picked tea leaves evenly on a withering tank with a thickness of 4 cm, setting the indoor temperature to 22° C. and the humidity to 65° C., and withering three times respectively to obtain tea leaves after three witherings;

[0030] (3) cooling the tea leaves after three withering to room temperature and then rolling them;

[0031] (4) Place the rolled tea leaves in a drying machine with a thickness of 1 cm and stop drying when the moisture content of the tea leaves drops to 4%. After cooling to room temperature, vacuum pack and store.

[0032] The first withering step of the three withering steps in step (2) of this embodiment is: spraying the polyphenol oxidase solution evenly on the tea leaves, ultrasonically treating for 20 minutes, then spreading for 30 minutes, and heating and inactivating with hot air to obtain tea leaves after the first withering;

[0033] The concentration of the polyphenol oxidase solution in this example is 0.5 g / L, and 5 mL is sprayed per kilogram of tea leaves.

[0034] The second withering step in the three withering steps in step (2) of this embodiment is: spraying the tannase solution evenly on the tea leaves after the first withering, ultrasonically treating for 12 minutes, spreading for 30 minutes, and heating and inactivating with hot air to obtain the tea leaves after the second withering;

[0035] The concentration of the tannase solution in this example is 0.3 g / L, and 3 mL is sprayed per kilogram of tea leaves.

[0036] The third withering step in the three withering steps in step (2) of this embodiment is: evenly spraying the lipase solution on the tea leaves after the second withering, ultrasonically treating for 6 minutes, spreading for 30 minutes, and heating and inactivating with hot air to obtain tea leaves after the third withering;

[0037] The concentration of the lipase solution in this example is 0.1 g / L, and 1 mL is sprayed per kilogram of tea leaves.

[0038] In step (2) of this embodiment, the ultrasonic treatment parameters in the three witherings are: ultrasonic power of 150 W and ultrasonic frequency of 20 kHz.

[0039] In step (2) of this embodiment, the hot air heating parameters in the three witherings are: heating temperature is 65° C., and heating time is 3 min.

[0040] The kneading parameters in step (3) of this embodiment are: kneading temperature is 20° C., kneading time is 10 min, and kneading speed is 10 rpm.

[0041] The drying parameters in step (4) of this embodiment are: the initial temperature is 80° C., and the temperature is gradually increased by 5° C. every 10 minutes to 110° C.

[0042] Example 2

[0043] A method for preparing tea leaves for improving the tea aroma. The method for preparing tea leaves for improving the tea aroma of this embodiment comprises the following steps:

[0044] (1) Select one bud and two leaves of tea picked in the early morning, and remove old leaves and impurities;

[0045] (2) Spreading the picked tea leaves evenly on a withering tank with a thickness of 6 cm, setting the indoor temperature to 24° C. and the humidity to 75° C., and withering for three times respectively to obtain tea leaves after three witherings;

[0046] (3) cooling the tea leaves after three withering to room temperature and then rolling them;

[0047] (4) Place the rolled tea leaves in a drying machine with a thickness of 2 cm and stop drying when the moisture content of the tea leaves drops to 5%. After cooling to room temperature, vacuum pack and store.

[0048] The first withering step of the three withering steps in step (2) of this embodiment is: spraying the polyphenol oxidase solution evenly on the tea leaves, ultrasonically treating for 30 minutes, then spreading for 40 minutes, and heating and inactivating with hot air to obtain tea leaves after the first withering;

[0049] The concentration of the polyphenol oxidase solution in this example is 1 g / L, and 10 mL is sprayed per kilogram of tea leaves.

[0050] The second withering step in the three withering steps in step (2) of this embodiment is: spraying the tannase solution evenly on the tea leaves after the first withering, ultrasonically treating for 18 minutes, then spreading for 40 minutes, and heating and inactivating with hot air to obtain the tea leaves after the second withering;

[0051] The concentration of the tannase solution in this example is 0.6 g / L, and 6 mL is sprayed per kilogram of tea leaves.

[0052] The third withering step in the three withering steps in step (2) of this embodiment is: evenly spraying the lipase solution on the tea leaves after the second withering, ultrasonically treating for 10 minutes, spreading for 40 minutes, and heating and inactivating with hot air to obtain tea leaves after the third withering;

[0053] The concentration of the lipase solution in this example is 0.3 g / L, and 3 mL is sprayed per kilogram of tea leaves.

[0054] In step (2) of this embodiment, the ultrasonic treatment parameters in the three witherings are: ultrasonic power of 250 W and ultrasonic frequency of 60 kHz.

[0055] The hot air heating parameters in the three withering steps in step (2) of this embodiment are: heating temperature is 75° C., and heating time is 7 min.

[0056] The kneading parameters in step (3) of this embodiment are: kneading temperature is 30° C., kneading time is 20 min, and kneading speed is 30 rpm.

[0057] The drying parameters in step (4) of this embodiment are: the initial temperature is 90° C., and the temperature is gradually increased by 5° C. every 10 minutes to 120° C.

[0058] Example 3

[0059] A method for preparing tea leaves for improving the tea aroma. The method for preparing tea leaves for improving the tea aroma of this embodiment comprises the following steps:

[0060] (1) Select one bud and two leaves of tea picked in the early morning, and remove old leaves and impurities;

[0061] (2) Spreading the picked tea leaves evenly on a withering tank with a thickness of 5 cm, setting the indoor temperature to 23° C. and the humidity to 70° C., and withering the tea leaves three times respectively to obtain tea leaves withered three times;

[0062] (3) cooling the tea leaves after three withering to room temperature and then rolling them;

[0063] (4) Place the rolled tea leaves in a drying machine with a thickness of 1.5 cm. Stop drying when the moisture content of the tea leaves drops to 4.5%. After cooling to room temperature, vacuum pack and store.

[0064] The first withering step of the three withering steps in step (2) of this embodiment is: spraying the polyphenol oxidase solution evenly on the tea leaves, ultrasonically treating for 25 minutes, then spreading for 35 minutes, and heating and inactivating with hot air to obtain tea leaves after the first withering;

[0065] The concentration of the polyphenol oxidase solution in this example is 0.75 g / L, and 7.5 mL is sprayed per kilogram of tea leaves.

[0066] The second withering step in the three withering steps in step (2) of this embodiment is: evenly spraying the tannase solution on the tea leaves after the first withering, ultrasonically treating for 15 minutes, spreading for 35 minutes, and heating and inactivating with hot air to obtain the tea leaves after the second withering;

[0067] The concentration of the tannase solution in this example is 0.45 g / L, and 4.5 mL is sprayed per kilogram of tea leaves.

[0068] The third withering step in the three withering steps in step (2) of this embodiment is: evenly spraying the lipase solution on the tea leaves after the second withering, ultrasonically treating for 8 minutes, spreading for 35 minutes, and heating and inactivating with hot air to obtain tea leaves after the third withering;

[0069] The concentration of the lipase solution in this example is 0.2 g / L, and 2 mL is sprayed per kilogram of tea leaves.

[0070] In step (2) of this embodiment, the ultrasonic treatment parameters in the three witherings are: ultrasonic power of 200 W and ultrasonic frequency of 40 kHz.

[0071] In step (2) of this embodiment, the hot air heating parameters in the three witherings are: heating temperature is 70° C., and heating time is 5 min.

[0072] The kneading parameters in step (3) of this embodiment are: kneading temperature is 25° C., kneading time is 15 min, and kneading speed is 20 rpm.

[0073] The drying parameters in step (4) of this embodiment are: the initial temperature is 85° C., and the temperature is gradually increased by 5° C. every 10 minutes to 115° C.

[0074] Comparative Example 1

[0075] On the basis of Example 3, the first withering of the three withering steps in step (2) was removed, and the other conditions were the same as those in Example 3.

[0076] Comparative Example 2

[0077] On the basis of Example 3, the second withering of the three witherings in step (2) was removed, and the other conditions were consistent with those in Example 3.

[0078] Comparative Example 3

[0079] On the basis of Example 3, the third withering of the three witherings in step (2) was removed, and the other conditions were the same as those in Example 3.

[0080] Comparative Example 4

[0081] On the basis of Example 3, the withering step in step (2) is changed to uniformly spray a mixed enzyme solution of polyphenol oxidase, tannase and lipase on the tea leaves, wherein the polyphenol oxidase concentration in the mixed enzyme solution is 1.25 g / L, the tannase concentration is 0.45 g / L, and the lipase concentration is 0.09 g / L. 4.5 mL is sprayed per kilogram of tea leaves. After ultrasonic treatment for 30 minutes, the tea leaves are spread for 40 minutes and heated with 70°C hot air for 5 minutes for inactivation to obtain withered tea leaves. Other conditions are consistent with Example 3.

[0082] Comparative Example 5

[0083] On the basis of Example 3, the polyphenol oxidase solution used in the first withering in step (2) was removed and replaced with an equal weight portion of tannase solution. Other conditions were consistent with those in Example 3.

[0084] Comparative Example 6

[0085] On the basis of Example 3, the tannin solution used for the second withering in step (2) was removed and replaced with an equal weight portion of lipase solution. Other conditions were the same as those in Example 3.

[0086] Comparative Example 7

[0087] On the basis of Example 3, the lipase solution used in the third withering in step (2) was removed and replaced with an equal weight portion of polyphenol oxidase solution. Other conditions were the same as those in Example 3.

[0088] Comparative Example 8

[0089] On the basis of Example 3, the ultrasonic treatment step in the three withering steps in step (2) was removed, and the other conditions were consistent with those in Example 3.

[0090] Comparative Example 9

[0091] On the basis of Example 3, the hot air heating inactivation step in the three withering steps in step (2) was removed, and the other conditions were consistent with those in Example 3.

[0092] Take equal amounts of tea leaves prepared in Examples 1 to 3 and Comparative Examples 1 to 9 as samples, use 150 mL of pure water for every 3 g of tea leaves, and brew at 100° C. for 5 minutes. According to the GB / T23776-2009 scoring standard, 20 tea lovers evaluate the aroma, taste, soup color and leaf bottom of the tea leaves, with each index scoring standard ranging from 1 to 10 points. The specific results are shown in Table 1.

[0093] Among them, the aroma is used to evaluate the richness, type and persistence of the aroma; the taste is used to evaluate the freshness, astringency, aftertaste and mellowness of the taste; the soup color is used to evaluate the redness, brightness and clarity of the tea soup; the leaf bottom is used to evaluate the softness, color and completeness of the leaf bottom.

[0094] Table 1 Sensory evaluation of tea leaves obtained by each treatment

[0095]

[0096]

[0097] As can be seen from Table 1, the tea leaves prepared by the tea preparation method for improving the tea aroma shown in Examples 1 to 3 are rich in aroma, distinct in layers, mellow in taste, excellent in aftertaste, bright red soup base, complete and bright in color, and good overall quality. Compared with Comparative Examples 1 to 9, it can be seen that the complete withering treatment step in the preparation method of the present invention has a significant effect on the extraction and enhancement of the tea aroma while improving the quality and taste of the tea leaves. The present invention adopts multiple enzymatic withering, improves the overall taste of the tea leaves through layer-by-layer enzymatic hydrolysis, and synergistically improves the withering efficiency by means of ultrasonic treatment and hot air heating inactivation, which can effectively promote the transformation of the internal chemical components of the tea leaves, and achieve a multi-level improvement of the tea aroma, thereby improving the tea aroma.

[0098] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing tea leaves for improving the aroma of tea leaves, characterized in that: The tea preparation method for improving tea aroma comprises the following steps: (1) Choose tea leaves with one bud and two leaves picked in the early morning, and remove old leaves and impurities; (2) Spread the picked tea leaves evenly on the withering trough with a thickness of 4 to 6 cm, set the indoor temperature to 22 to 24°C and the humidity to 65 to 75%, and wither for three times respectively to obtain tea leaves after three witherings; (3) Cooling the tea leaves after three withering to room temperature and then rolling them; (4) Place the rolled tea leaves in a dryer with a thickness of 1-2 cm. Stop drying when the moisture content of the tea leaves drops to 4-5%. After cooling to room temperature, vacuum pack and store. The first withering step of the three withering steps in step (2) is: spraying the polyphenol oxidase solution evenly on the tea leaves, ultrasonically treating for 20 to 30 minutes, spreading for 30 to 40 minutes, and heating and inactivating with hot air to obtain tea leaves after the first withering; The concentration of the polyphenol oxidase solution is 0.5-1 g / L, and 5-10 mL is sprayed per kilogram of tea leaves; The second withering step in the three withering steps in step (2) is as follows: spraying the tannase solution evenly on the tea leaves after the first withering, ultrasonically treating for 12 to 18 minutes, spreading for 30 to 40 minutes, and heating and deactivating with hot air to obtain the tea leaves after the second withering; The concentration of the tannase solution is 0.3-0.6 g / L, and 3-6 mL is sprayed per kilogram of tea leaves; The third withering step in the three withering steps in step (2) is: evenly spraying the lipase solution on the tea leaves after the second withering, ultrasonically treating for 6 to 10 minutes, spreading for 30 to 40 minutes, and heating and inactivating with hot air to obtain tea leaves after the third withering; The concentration of the lipase solution is 0.1-0.3 g / L, and 1-3 mL is sprayed per kilogram of tea leaves; The ultrasonic treatment parameters in the three withering steps in step (2) are: ultrasonic power of 150-250W, and ultrasonic frequency of 20-60kHz.

2. A method for preparing tea leaves for improving tea aroma according to claim 1, characterized in that: The hot air heating parameters in the three withering steps in step (2) are: heating temperature of 65-75° C., heating time of 3-7 min.

3. The method for preparing tea leaves for improving tea aroma according to claim 1, characterized in that: The kneading parameters in step (3) are: kneading temperature of 20-30° C., kneading time of 10-20 min, and kneading speed of 10-30 rpm.

4. The method for preparing tea leaves for improving tea aroma according to claim 1, characterized in that: The drying parameters in step (4) are as follows: the initial temperature is 80-90°C, and the temperature is gradually increased by 5°C every 10 minutes to 110-120°C.

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