Processing technology of white tea

Abstract

According to the white tea processing technology, tender tea leaves are picked and subjected to secondary withering, light rolling, steam fermentation and rapid fragrance extraction with sufficient fire, so that substances contained in the tea are fully converted, nutrient substances in the tea are prevented from being damaged, the white tea is in appearance and color, buds and leaves are connected with branches, the leaf surfaces are emerald green, tight and uniform, and the liquor color is clear and bright yellow; the tea is fresh, tender, pure and refreshing in fragrance, fresh, cool and slightly sweet in taste, close to the mellowness of black tea, tender in leaf bottom and leaf and yellow green in color.

Description

Technical Field

[0001] This invention belongs to the field of white tea processing technology and relates to a white tea processing technique. Background Technology

[0002] White tea, a lightly fermented tea, is a special and precious variety of tea. It gets its name from the fact that the finished tea is mostly made of buds covered in white down, resembling silver and snow. It is one of the six major tea categories. White tea is characterized by its intact buds covered in down, its fresh and delicate aroma, its clear yellow-green liquor, and its light, sweet aftertaste. In recent years, with the discovery of its health benefits, white tea has gradually gained popularity among consumers.

[0003] Insufficient withering during the white tea processing stage prevents the full conversion of polyphenols in the tea leaves. Over-withering, on the other hand, deactivates polyphenol oxidase, affecting subsequent micro-fermentation. Poor temperature and humidity control during micro-fermentation can lead to a sour taste and a decline in tea quality.

[0004] This invention employs a segmented, two-stage withering process, gentle rolling, steam fermentation, and rapid aroma enhancement with sufficient heat. It precisely controls the time, temperature, and humidity of withering and fermentation, and rapidly enhances aroma with sufficient heat, thus preserving the full conversion of polyphenols in the tea while avoiding the destruction of nutrients. This results in white tea with a refreshing and slightly sweet taste, close to the mellowness of black tea. Summary of the Invention

[0005] The purpose of this invention is to provide a processing technology for white tea, which involves picking tender tea leaves, withering them a second time, gently rolling them, steaming and fermenting them, and then quickly roasting them to enhance their aroma. This process allows the internal substances in the tea to be fully transformed, avoiding the destruction of nutrients in the tea. The resulting white tea has a refreshing and slightly sweet taste, close to the mellowness of black tea.

[0006] The technical solution of this invention: A processing method for white tea, comprising the following steps: (1) Picking: Pick tender tea leaves of uniform size; (2) First withering: The first withering leaves are placed in a withering trough for sealed withering. The temperature for the first withering is 25-30℃ and the withering time for the first withering is 30-40min. (3) Secondary withering: The leaves that have withered in the first stage are subjected to a second withering in a ventilated environment for 8-10 hours to obtain withered leaves; (4) Gentle rolling: After withering, the tea leaves are gently rolled to break up the clumps, resulting in loosened leaves; (5) Steam fermentation: After withering, the tea leaves are placed in a fumigation room and spread flat on a bamboo winnowing basket for fermentation. The leaves are 5-10cm thick and covered with gauze. Steam enters the winnowing basket from under the basket through the gaps. The temperature in the steam room reaches 45-60℃ and the humidity is 60-80%. The steam fermentation time is 2-3 hours to obtain fermented leaves. (6) Thorough roasting for rapid aroma enhancement: Take fermented leaves and bake them at a temperature of 70-80℃ for 10-15 minutes. Then raise the temperature to 95-105℃ for 5-10 minutes to enhance the aroma, so that the moisture content of the tea leaves is below 8%. After the aroma-enhanced tea leaves are cooled, they are sterilized by ultraviolet light and packaged.

[0007] In step (2) above, the temperature for the first withering is 30°C and the withering time for the first withering is 35 min.

[0008] In step (3) above, the second withering time is 9 hours.

[0009] In the aforementioned step (5), the temperature in the steam chamber reaches 50-55℃, the humidity is 60-70%, and the steam fermentation time is 2.5h.

[0010] In step (5) above, after steam fermentation, the moisture content of the tea leaves is controlled at 20-25%.

[0011] In the aforementioned step (6), the aroma is quickly enhanced by roasting: the fermented leaves are roasted at 75°C for 15 minutes, and then the temperature is raised to 100°C for 5 minutes to enhance the aroma, so that the moisture content of the tea leaves is below 8%. After the aroma-enhanced tea leaves are cooled, the tea leaves are obtained. Compared with the prior art, the present invention has the following beneficial effects: 1. The invention maintains the full transformation of polyphenols in tea through segmented withering, while avoiding the deactivation of polyphenol oxidase, thus providing sufficient polyphenol oxidase for subsequent micro-fermentation. Furthermore, through steam fermentation and rapid aroma enhancement, the proper control of fermentation temperature and humidity prevents insufficient fermentation, which would result in the incomplete transformation of internal substances and a tea soup with a raw or sour taste. Sufficient heat for rapid aroma enhancement shortens the drying and aroma enhancement time, preventing the destruction of nutrients in the tea, and giving the white tea a refreshing and slightly sweet taste, close to the mellowness of black tea.

[0012] 2. This invention employs a unique process involving the secondary withering of tender tea leaves, gentle rolling, steam fermentation, and rapid aroma enhancement through thorough roasting. By controlling the fermentation time and aroma-enhancing techniques, the internal components of white tea undergo full transformation, and nutrients such as tea polyphenols and free amino acids are effectively preserved. The tea polyphenol content reaches over 25%, and even after three months of storage, it remains above 23%. The free amino acid content reaches over 5%, and even after three months of storage, the tea polyphenol content remains above 4.7%. Detailed Implementation

[0013] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the experimental materials used in the following examples were all purchased from commercial channels.

[0014] The following examples and comparative examples all use white tea varieties from Guizhou, specifically the White Peony variety.

[0015] Example 1: (1) Picking: Pick tender tea leaves of uniform size; (2) First withering: The first withering leaves are placed in a withering trough for closed withering. The withering temperature is 30℃ and the withering time is 35min. (3) Second withering: The first withered leaves are withered a second time in a ventilated environment for 9 hours to obtain withered leaves; (4) Gentle rolling: After withering, the tea leaves are gently rolled to break up the clumps, resulting in loosened leaves; (5) Steam fermentation: After withering, the tea leaves are placed in a fumigation room and spread flat on a bamboo winnowing basket for fermentation. The leaves are 5-10cm thick and covered with gauze. Steam enters the winnowing basket from under the basket through the gaps. The temperature in the steam room reaches 50-55℃ and the humidity is 60-70%. The steam fermentation time is 2.5h, so that the moisture content of the tea leaves reaches 20-25% and fermented leaves are obtained. (6) Thorough roasting for rapid aroma enhancement: Take fermented leaves and bake them at 75℃ for 15 minutes. Then raise the temperature to 100℃ for 8 minutes to enhance the aroma, so that the moisture content of the tea leaves is below 8%. After the aroma-enhanced tea leaves are cooled, they are sterilized by ultraviolet light and packaged.

[0016] Example 2: (1) Picking: Pick tender tea leaves of uniform size; (2) First withering: The first withering leaves are placed in a withering trough for sealed withering. The withering temperature is 25℃ and the withering time is 30min. (3) Second withering: The first withered leaves are subjected to a second withering in a ventilated environment for 8 hours to obtain withered leaves; (4) Gentle rolling: After withering, the tea leaves are gently rolled to break up the clumps, resulting in loosened leaves; (5) Steam fermentation: After withering, the tea leaves are placed in a steaming room and spread flat on a bamboo winnowing basket for fermentation. The leaves are 5-10cm thick and covered with gauze. Steam enters the winnowing basket from under the basket through the gaps. The temperature in the steaming room reaches 55-60℃ and the humidity is 60-70%. The steam fermentation time is 2 hours, so that the moisture content of the tea leaves reaches 20-25%, and fermented leaves are obtained. (6) Thorough roasting for rapid aroma enhancement: Take fermented leaves and bake them at 80℃ for 10 minutes. Then raise the temperature to 95℃ for 5 minutes to enhance the aroma, so that the moisture content of the tea leaves is below 8%. After the aroma-enhanced tea leaves are cooled, they are sterilized by ultraviolet light and packaged.

[0017] Example 3: (1) Picking: Pick tender tea leaves of uniform size; (2) First withering: The first withering leaves are placed in a withering trough for closed withering. The withering temperature is 30℃ and the withering time is 40min. (3) Second withering: The first withered leaves are withered a second time in a ventilated environment for 10 hours to obtain withered leaves; (4) Gentle rolling: After withering, the tea leaves are gently rolled to break up the clumps, resulting in loosened leaves; (5) Steam fermentation: After withering, the tea leaves are placed in a steaming room and spread flat on a bamboo winnowing basket for fermentation. The leaves are 5-10cm thick and covered with gauze. Steam enters the winnowing basket from under the basket through the gaps. The temperature in the steam room reaches 45-50℃ and the humidity is 70-80%. The steam fermentation time is 3 hours, so that the moisture content of the tea leaves reaches 20-25%, and fermented leaves are obtained. (6) Thorough roasting for rapid aroma enhancement: Take fermented leaves and bake them at 70℃ for 12 minutes. Then raise the temperature to 105℃ for 10 minutes to enhance the aroma, so that the moisture content of the tea leaves is below 8%. After the aroma-enhanced tea leaves are cooled, they are sterilized by ultraviolet light and packaged.

[0018] Comparative Example 1: Unlike Example 1, only the second wilting was performed, and the first wilting was not performed.

[0019] Comparative Example 2: Unlike Example 1, in step (5), the time for steam fermentation is 1 hour.

[0020] Comparative Example 3: Unlike Example 1, in step (5), the time for steam fermentation is 4 hours.

[0021] Comparative Example 4: Unlike Example 1, in step (6), the product was directly dried at 105°C for 20 minutes to enhance aroma.

[0022] Sensory evaluation in Experiment Example 1 According to the national standard for sensory evaluation of tea (GB / T23776-2018), the white tea produced was evaluated from five aspects: appearance, liquor color, aroma, taste and infused leaves (Examples 1-3, Comparative Examples 1-4). The results are shown in Table 1.

[0023] Table 1 Sensory Evaluation Table for White Tea As shown in Table 1, the sensory evaluation results of the white tea in Examples 1-3 reveal that the tea leaves in Examples 1-3 are characterized by their continuous buds and leaves, vibrant green color, tight and uniform shape, clear and bright yellow liquor, fresh, pure, and fragrant aroma, and a refreshing, slightly sweet taste, approaching the richness of black tea. The infused leaves are tender and yellowish-green. Comparative Example 1, having only undergone one withering process, suffers from insufficient oxidation and aroma transformation, resulting in a pale yellow liquor and weak aroma. Comparative Example 2, due to its short steam fermentation time, exhibits incomplete transformation of its internal substances, failing to develop a unique flavor, lacking the richness of black tea, with a weak aroma, grayish-green leaves, and a dull liquor. Comparative Example 3, with its excessively long steam fermentation time, results in dark green leaves, a deep yellow liquor, poor clarity, and a slightly coarse taste. Comparative Example 4, using high-temperature rapid aroma enhancement, results in a slightly bitter taste, weak aroma, and a darker yellow liquor.

[0024] Experimental Example 2: Physicochemical Analysis of Tea Polyphenols and Amino Acids The polyphenol and amino acid content of the prepared white tea (Examples 1-3, Comparative Examples 1-4) was detected, and the changes in polyphenol and amino acid content after 3 months of storage were investigated. The results are shown in Table 2.

[0025] Table 2 Results of white tea component analysis As shown in Table 2, the tea polyphenol content of Examples 1-3 reached over 25%, and even after 3 months of storage, the tea polyphenol content remained above 23%, and the free amino acid content reached over 5%, with the tea polyphenol content still above 4.7% after 3 months of storage. In contrast, the highest tea polyphenol content of Comparative Examples 1-4 was only 20.32%, and the highest free amino acid content was only 3.68%. It is evident that the present invention, through a special process of picking tender tea leaves, secondary withering, light rolling, steam fermentation, and rapid aroma enhancement, along with controlling the fermentation time and aroma enhancement techniques, allows for the full transformation of the internal components in white tea, and effectively preserves nutrients such as tea polyphenols and free amino acids.

Claims

1. A processing method for white tea, characterized in that: Follow these steps: (1) Picking: Pick tender tea leaves of uniform size; (2) First withering: The first withering leaves are placed in a withering trough for sealed withering. The temperature for the first withering is 25-30℃ and the withering time for the first withering is 30-40min. (3) Secondary withering: The leaves that have withered in the first stage are subjected to a second withering in a ventilated environment for 8-10 hours to obtain withered leaves; (4) Gentle rolling: After withering, the tea leaves are gently rolled to break up the clumps, resulting in loosened leaves; (5) Steam fermentation: After withering, the tea leaves are placed in a fumigation room and spread flat on a bamboo winnowing basket for fermentation. The leaves are 5-10cm thick and covered with gauze. Steam enters the winnowing basket from under the basket through the gaps. The temperature in the steam room reaches 45-60℃ and the humidity is 60-80%. The steam fermentation time is 2-3 hours to obtain fermented leaves. (6) Thorough roasting for rapid aroma enhancement: Take fermented leaves and bake them at a temperature of 70-80℃ for 10-15 minutes. Then raise the temperature to 95-105℃ for 5-10 minutes to enhance the aroma, so that the moisture content of the tea leaves is below 8%. After the aroma-enhanced tea leaves are cooled, they are sterilized by ultraviolet light and packaged.

2. The processing technology for white tea according to claim 1, characterized in that: In step (2), the temperature for the first withering is 30°C and the withering time for the first withering is 35 min.

3. The processing technology for white tea according to claim 1, characterized in that: In step (3), the second withering time is 9 hours.

4. The processing technology for white tea according to claim 1, characterized in that: In step (5), the temperature in the steam chamber reaches 50-55℃, the humidity is 60-70%, and the steam fermentation time is 2.5h.

5. The processing technology for white tea according to claim 1, characterized in that: In step (5), after steam fermentation, the moisture content of the tea leaves is controlled at 20-25%.

6. The processing technology for white tea according to claim 1, characterized in that: In step (6), the aroma is quickly enhanced by roasting: the fermented leaves are baked at 75°C for 15 minutes, and then the temperature is raised to 100°C for 5 minutes to enhance the aroma, so that the moisture content of the tea leaves is below 8%. After the aroma-enhanced tea leaves are cooled, the tea leaves are obtained.

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