A method for preparing fruit-flavored black tea

Abstract

The invention discloses a method for preparing fruit-flavored black tea, which belongs to the technical field of black tea preparation. The method is as follows: (1) withering and shaking tea leaves; (2) rolling the shaken tea leaves for the first time, spraying an adsorbent during the rolling process, allowing the tea leaves to stand after the rolling is completed, and simultaneously subjecting the tea leaves to ultraviolet irradiation treatment during the standing process to obtain tea leaves after the first treatment; (3) rolling the tea leaves for the first time, placing the tea leaves on a sieve after the second rolling is completed, and blowing hot air to obtain tea leaves after the second treatment; (4) fermenting the tea leaves after the second treatment; (5) withering the fermented tea leaves and rolling them for the third time to obtain coarse tea; (6) drying the coarse tea leaves to enhance the aroma, thereby obtaining fruit-flavored black tea, which solves the problem that black tea has a raw and astringent taste and a grassy smell.

Description

Technical Field

[0001] The invention relates to the technical field of black tea production, in particular to a method for producing fruit-flavored black tea. Background Art

[0002] Black tea is one of the main types of tea produced and exported in my country. A fully fermented tea, it boasts significant nutritional and health benefits and a high drinking value. Compared to green tea, its main difference lies in the degree of fermentation. During the black tea production process, chlorophyll must be destroyed. Incomplete chlorophyll degradation can affect the tea's color and flavor, resulting in a harsh, grassy taste. Therefore, it is necessary to destroy chlorophyll during the black tea production process to promote its decomposition. Traditional methods primarily rely on rolling and fermentation to promote chlorophyll degradation. These processes disrupt mesophyll cells, causing chlorophyll demagnesiation and a significant decrease in chlorophyll content. These traditional methods are currently widely used due to their simplicity, ease of operation, and low cost. However, incomplete chlorophyll degradation can still occur after rolling and fermentation.

[0003] Therefore, there is a need to find a method for making black tea that can promote the degradation of chlorophyll in black tea and solve the problem of incomplete degradation of chlorophyll in black tea resulting in a raw and grassy taste. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing fruit-flavored black tea, which promotes the degradation of chlorophyll in black tea through an improved rolling method, and solves the problem of incomplete chlorophyll degradation in the preparation process of black tea resulting in a raw and grassy taste of black tea.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] (1) Withering and shaking the tea leaves;

[0007] (2) rolling the tea leaves after the shaking process, spraying an adsorbent during the rolling process, allowing the tea leaves to stand after the rolling process, and simultaneously subjecting the tea leaves to ultraviolet light irradiation treatment during the standing process to obtain the tea leaves after the rolling process;

[0008] (3) rolling the tea leaves after the first treatment for a second time, placing the tea leaves on a sieve after the second rolling, blowing hot air to remove the adsorption film, and obtaining the tea leaves after the second treatment;

[0009] (4) fermenting the tea leaves after the second treatment;

[0010] (5) Fixing the fermented tea leaves and rolling them for the third time to obtain coarse tea;

[0011] (6) Drying the crude tea leaves to enhance their aroma and obtain fruity black tea.

[0012] Furthermore, the tea leaves in step (1) are fresh leaves with one bud and one leaf or one bud and two leaves, and the natural withering time is 18 hours.

[0013] Furthermore, the specific operation of shaking the green tea in step (1) is: shaking the green tea three times in total, each shaking for 15 minutes, and letting it stand for 2-3 hours after each shaking.

[0014] Furthermore, the specific operation in step (2) is: rolling the tea leaves after shaking for 30 minutes, spraying the adsorbent once every 10 minutes during the rolling process, letting it stand after rolling is completed, and performing ultraviolet light irradiation treatment during the standing process for 3-4 hours.

[0015] Furthermore, the specific operation of step (3) is as follows: the tea leaves treated for the first time are rolled for a second time for 20 minutes. After rolling, the tea leaves are placed in a sieve, the temperature is set to 35-45°C, and the tea leaves are blown at a wind speed of 5m / s for 15-20 minutes. The temperature is then raised to 50-60°C and the tea leaves are blown at a wind speed of 8m / s for 5-10 minutes.

[0016] Furthermore, during the fermentation process of step (4), the fermentation temperature is controlled to be 25-28° C., the fermentation humidity is controlled to be 90-95%, and the fermentation time is controlled to be 2.5-3 h.

[0017] Furthermore, the specific operation of step (5) is: the fermented tea leaves are withered at a temperature of 280° C. for 3-4 minutes, and then rolled for a third time after cooling to room temperature, with the rolling time being 30 minutes, to obtain coarse tea.

[0018] Furthermore, the specific operation of drying and enhancing fragrance in step (6) is: baking at 100° C. for 10 minutes, and then enhancing fragrance at 80° C. for 1 hour.

[0019] Furthermore, the adsorbent in step (2) includes the following raw materials:

[0020] Sodium alginate, sodium chloride, sodium hydroxide, anhydrous ethanol, potassium iodate, glutinous rice juice, 0.1 mol / L calcium chloride solution, the raw materials have the following mass ratio:

[0021] Sodium alginate, sodium chloride, sodium hydroxide, anhydrous ethanol, potassium iodate, glutinous rice juice, 0.1 mol / L calcium chloride solution = (5-7): (0.5-0.8): (0.06-0.08): (0.07-0.08): (0.02-0.04): (5-8): 260.

[0022] Furthermore, the specific preparation method of the adsorbent is:

[0023] Add anhydrous ethanol to 250 ml of deionized water and stir evenly to obtain an ethanol solution. Then add sodium chloride, sodium hydroxide, potassium iodate, and glutinous rice juice and continue stirring until completely dissolved. Then, slowly add sodium alginate while stirring. After complete dissolution, slowly add 0.1 mol / L calcium chloride solution and stir evenly to obtain an adsorbent.

[0024] The present invention improves the tea making process and promotes chlorophyll degradation and adsorption by spraying an adsorbent on tea leaves during the rolling process, thereby reducing the chlorophyll content in the tea leaves and thus avoiding the problem of the raw taste of black tea. The tea leaves are withered and shaken to destroy the cell walls of the tea leaves, and the chlorophyll begins to seep out. The tea leaves after shaking are then subjected to the first rolling. During the first rolling process, the cell walls of the tea leaves are further destroyed, and the amount of chlorophyll exuded from the tea leaves is increased. At this time, a certain amount of gel-state adsorbent is sprayed on the tea leaves, and the exuded chlorophyll is adsorbed and degraded during the standing process. At the same time, the tea leaves are subjected to ultraviolet irradiation treatment during the standing process, which can oxidize the chlorophyll and further promote the removal of the chlorophyll. The gel-state adsorbent can well wrap the tea leaves, so that the adsorbent can better act on the tea leaves, while not destroying the moisture content of the tea leaves, which would otherwise affect the fermentation effect due to the excessively high moisture content.

[0025] However, the presence of adsorbents can affect the taste and color of the finished tea, so they need to be removed. After a period of time, the adsorbent forms a thin film on the surface of the tea leaves, which is then broken down during the second rolling process, causing it to fall off the tea leaves. However, simple rolling alone cannot completely remove the film, so after the second rolling is completed, a step-by-step hot air blow is used to first blow off the remaining film from the tea leaves, and then the wind speed and temperature are increased to remove the detached film from the tea leaves, preventing the film from being mixed in with the tea leaves and affecting the quality of the tea leaves.

[0026] Beneficial effects:

[0027] The present invention adopts an improved black tea production process and utilizes an adsorbent to adsorb dissolved chlorophyll, thereby promoting the decomposition of chlorophyll. This solves the problem of incomplete chlorophyll degradation in fruit-flavored black tea, which leads to a rough taste and a grassy smell. In addition, the substances in the adsorbent do not destroy the nutrients in the tea leaves themselves, nor do they affect the taste of the tea soup. The fruit-flavored black tea prepared by the present invention has a mellow and refreshing taste, a distinct fruity aroma, and also has the functions of anti-oxidation, refreshing the mind, and lowering blood pressure. This further improves the quality of fruit-flavored fruit tea, making it more popular among the general public. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 : This is the natural withering process of the tea leaves in Example 1 of the present invention;

[0029] Figure 2: The fruity black tea finished product prepared by Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings:

[0031] Example 1: Preparation of fruity black tea

[0032] Before preparing fruit-flavored black tea, an adsorbent was prepared. Specifically, 0.07 g of anhydrous ethanol was added to 250 ml of deionized water, and the mixture was stirred evenly to obtain an ethanol solution. Subsequently, 0.5 g of sodium chloride, 0.06 g of sodium hydroxide, 0.02 g of potassium iodate, and 5 g of glutinous rice juice were added, and stirring was continued until the mixture was completely dissolved. Then, 5 g of sodium alginate was slowly added while stirring. After the mixture was completely dissolved, 260 g of 0.1 mol / L calcium chloride solution was slowly added, and the mixture was stirred evenly and allowed to stand to obtain an adsorbent.

[0033] (1) Fresh tea leaves with one bud and two leaves were picked and naturally withered for 18 h. The tea leaves were then shaken three times, each time for 15 min. The tea leaves were then left to stand for 2 h after each shaking.

[0034] (2) The tea leaves that have been shaken are subjected to the initial rolling process for 30 minutes, and the adsorbent is sprayed every 10 minutes during the rolling process, with 30 g of adsorbent sprayed per 1 kg of tea leaves, so that the adsorbent and the tea leaves are fully in contact. The rolling process is continued for 30 minutes, and the tea leaves are allowed to stand after the rolling process is completed. At the same time, the tea leaves are irradiated with ultraviolet light of a wavelength of 320 nm for 3 hours during the standing process to obtain the initially treated tea leaves;

[0035] (3) The tea leaves treated for the first time were rolled for a second time for 20 minutes to crush and remove the adsorption film on the tea leaves. After rolling, the tea leaves were placed on a strainer, the temperature was set to 35°C, and the wind speed was 5 m / s for 15 minutes. The temperature was then raised to 50°C and the wind speed was 8 m / s for 5 minutes to obtain the tea leaves treated for the second time.

[0036] (4) fermenting the tea leaves after the second treatment, controlling the fermentation temperature at 25° C., the fermentation humidity at 90%, and the fermentation time at 2.5 h;

[0037] (5) The fermented tea leaves are placed in a rolling and fixing machine and fixed at 280°C for 3 minutes. After cooling to room temperature, they are rolled for the third time for 30 minutes to obtain coarse tea.

[0038] (6) Dry the crude tea at 100°C for 10 min and then heat it at 80°C for 1 h to obtain a fruity black tea.

[0039] Example 2: Preparation of fruity black tea

[0040] Before preparing fruit-flavored black tea, an adsorbent was prepared. Specifically, 0.075 g of anhydrous ethanol was added to 250 ml of deionized water, and the mixture was stirred evenly to obtain an ethanol solution. Subsequently, 0.65 g of sodium chloride, 0.07 g of sodium hydroxide, 0.03 g of potassium iodate, and 6 g of glutinous rice juice were added and stirred until completely dissolved. Then, 6 g of sodium alginate was slowly added while stirring. After the mixture was completely dissolved, 260 g of 0.1 mol / L calcium chloride solution was slowly added and stirred evenly to obtain an adsorbent.

[0041] (1) Fresh tea leaves with one bud and two leaves were picked and naturally withered for 18 h. The tea leaves were then shaken three times, each time for 15 min. The tea leaves were then left to stand for 2.5 h after each shaking.

[0042] (2) The tea leaves that have been shaken are initially rolled for 30 minutes, and an adsorbent is sprayed every 10 minutes during the rolling process. 30 g of adsorbent is sprayed per kg of tea leaves to allow the adsorbent to fully contact the tea leaves. The rolling time is 30 minutes, and the tea leaves are allowed to stand after rolling. During the standing period, the tea leaves are irradiated with ultraviolet light of a wavelength of 320 nm for 3.5 hours to obtain the initially treated tea leaves.

[0043] (3) The tea leaves treated for the first time were rolled for a second time for 20 minutes to crush and remove the adsorption film on the tea leaves. After rolling, the tea leaves were placed on a strainer, the temperature was set to 40°C, and the wind speed was 5 m / s for 18 minutes. The temperature was then raised to 60°C and the wind speed was 8 m / s for 8 minutes to obtain the tea leaves treated for the second time.

[0044] (4) fermenting the tea leaves after the second treatment, controlling the fermentation temperature at 26° C., the fermentation humidity at 93%, and the fermentation time at 2.8 h;

[0045] (5) The fermented tea leaves were placed in a rolling and fixing machine at 280°C for 3.5 minutes. After cooling to room temperature, they were rolled for the third time for 30 minutes to obtain coarse tea.

[0046] (6) Dry the crude tea at 100°C for 10 min and then heat it at 80°C for 1 h to obtain a fruity black tea.

[0047] Example 3: Preparation of fruity black tea

[0048] Before preparing fruit-flavored black tea, an adsorbent was prepared. Specifically, 0.08 g of anhydrous ethanol was added to 250 ml of deionized water, and the mixture was stirred evenly to obtain an ethanol solution. Subsequently, 0.8 g of sodium chloride, 0.08 g of sodium hydroxide, 0.04 g of potassium iodate, and 8 g of glutinous rice juice were added, and the mixture was stirred until completely dissolved. Then, 7 g of sodium alginate was slowly added while stirring. After the mixture was completely dissolved, 260 g of 0.1 mol / L calcium chloride solution was slowly added, the mixture was stirred evenly, and the mixture was allowed to stand to obtain an adsorbent.

[0049] (1) Fresh tea leaves with one bud and one leaf or one bud and two leaves were picked and naturally withered for 18 hours. The tea leaves were then shaken three times, each time for 15 minutes. The tea leaves were then left to stand for 2 hours after each shaking.

[0050] (2) The tea leaves that have been shaken are initially rolled for 30 minutes, and an adsorbent is sprayed every 10 minutes during the rolling process. 30 g of adsorbent is sprayed per kg of tea leaves to allow the adsorbent to fully contact the tea leaves. The rolling time is 30 minutes, and the tea leaves are allowed to stand after rolling. During the standing period, the tea leaves are irradiated with ultraviolet light of a wavelength of 320 nm for 4 hours to obtain the initially treated tea leaves.

[0051] (3) The tea leaves treated for the first time were rolled for a second time for 20 minutes to crush and remove the adsorption film on the tea leaves. After rolling, the tea leaves were placed on a strainer, the temperature was set to 45°C, and the wind speed was 5 m / s for 20 minutes. The temperature was then raised to 60°C and the wind speed was 8 m / s for 10 minutes to obtain the tea leaves treated for the second time.

[0052] (4) fermenting the tea leaves after the second treatment, controlling the fermentation temperature at 28° C., the fermentation humidity at 95%, and the fermentation time at 3 h;

[0053] (5) The fermented tea leaves were placed in a rolling and fixing machine at 280°C for 4 minutes. After cooling to room temperature, they were rolled for the third time for 30 minutes to obtain coarse tea.

[0054] (6) Dry the crude tea at 100°C for 10 min and then heat it at 80°C for 1 h to obtain a fruity black tea.

[0055] Comparative Example 1: Preparation of fruity black tea

[0056] This comparative example is in contrast to Example 1, the only difference being that different adsorbents are used in the tea making process. Specifically, no sodium chloride is added in the adsorbent preparation process. The specific preparation process is as follows:

[0057] Add 0.07 g of anhydrous ethanol to 250 ml of deionized water, stir evenly to obtain an ethanol solution, then add 0.06 g of sodium hydroxide, 0.02 g of potassium iodate, and 5 g of glutinous rice juice, continue stirring until completely dissolved, then slowly add 5 g of sodium alginate while stirring, until completely dissolved, slowly add 260 g of 0.1 mol / L calcium chloride solution, stir evenly and let stand to obtain an adsorbent.

[0058] The steps for preparing the fruity black tea are the same as those in Example 1.

[0059] Comparative Example 2: Preparation of fruity black tea

[0060] This comparative example is in contrast to Example 1, the only difference being that different adsorbents are used in the tea making process. Specifically, no sodium hydroxide is added in the adsorbent preparation process. The specific preparation process is as follows:

[0061] Add 0.07 g of anhydrous ethanol to 250 ml of deionized water, stir evenly to obtain an ethanol solution, then add 0.5 g of sodium chloride, 0.02 g of potassium iodate, and 5 g of glutinous rice juice, continue stirring until completely dissolved, then slowly add 5 g of sodium alginate while stirring, until completely dissolved, slowly add 260 g of 0.1 mol / L calcium chloride solution, stir evenly and let stand to obtain an adsorbent.

[0062] The steps for preparing the fruity black tea are the same as those in Example 1.

[0063] Comparative Example 3: Preparation of Fruity Black Tea

[0064] This comparative example is in contrast to Example 1, the only difference being that different adsorbents are used in the tea making process. Specifically, potassium iodate is not added in the adsorbent preparation process. The specific preparation process is as follows:

[0065] Add 0.07g of anhydrous ethanol to 250ml of deionized water, stir evenly to obtain an ethanol solution, then add 0.5g of sodium chloride, 0.06g of sodium hydroxide, and 5g of glutinous rice juice, continue stirring until completely dissolved, then slowly add 5g of sodium alginate while stirring, until completely dissolved, slowly add 260g of 0.1mol / L calcium chloride solution, stir evenly and let stand to obtain an adsorbent.

[0066] The steps for preparing the fruity black tea are the same as those in Example 1.

[0067] Comparative Example 4: Preparation of Fruity Black Tea

[0068] This comparative example is compared with Example 1, and the only difference is that the adsorbent used in the tea making process is different. Specifically, the addition amounts of sodium hydroxide, anhydrous ethanol, and potassium iodate in the preparation of the adsorbent are 0.6 g, 0.7 g, and 0.2 g, respectively. The specific preparation process is as follows:

[0069] Add 0.7 g of anhydrous ethanol to 250 ml of deionized water, stir evenly to obtain an ethanol solution, then add 0.5 g of sodium chloride, 0.6 g of sodium hydroxide, 0.2 g of potassium iodate, and 5 g of glutinous rice juice, continue stirring until completely dissolved, then slowly add 5 g of sodium alginate while stirring, until completely dissolved, slowly add 260 g of 0.1 mol / L calcium chloride solution, stir evenly and let stand to obtain an adsorbent.

[0070] The steps for preparing the fruity black tea are the same as those in Example 1.

[0071] Comparative Example 5: Preparation of Fruity Black Tea

[0072] This comparative example is compared with Example 1, and the only difference is that the adsorbent used in the tea making process is different. Specifically, in the process of preparing the adsorbent, the added amounts of sodium hydroxide, anhydrous ethanol, and potassium iodate are 0.006g, 0.007g, and 0.002g, respectively. The specific preparation process is as follows:

[0073] Add 0.007g of anhydrous ethanol to 250ml of deionized water, stir evenly to obtain an ethanol solution, then add 0.5g of sodium chloride, 0.006g of sodium hydroxide, 0.002g of potassium iodate, and 5g of glutinous rice juice, continue stirring until completely dissolved, then slowly add 5g of sodium alginate while stirring, and after complete dissolution, slowly add 260g of 0.1mol / L calcium chloride solution, stir evenly and let stand to obtain an adsorbent.

[0074] The steps for preparing the fruity black tea are the same as those in Example 1.

[0075] Comparative Example 6: Preparation of Fruity Black Tea

[0076] This comparative example is in contrast to Example 1, the only difference being that no adsorbent treatment is used in the tea making process. The specific tea making process is as follows:

[0077] (1) Fresh tea leaves with one bud and two leaves were picked and naturally withered for 18 h. The tea leaves were then shaken three times, each time for 15 min. The tea leaves were then left to stand for 2 h after each shaking.

[0078] (2) rolling the tea leaves for the first time for 30 minutes, allowing them to stand for 30 minutes, and irradiating them with ultraviolet light at a wavelength of 320 nm for 3 hours to obtain the tea leaves after the first treatment;

[0079] (3) The tea leaves that have been treated for the first time are rolled for a second time for 20 minutes. After rolling, they are placed on a screen, the temperature is set to 35°C, and the air is blown at a wind speed of 5 m / s for 15 minutes. The temperature is then raised to 50°C and the air is blown at a wind speed of 8 m / s for 5 minutes to obtain the tea leaves that have been treated for the second time.

[0080] Steps (4) to (6) are the same as those in Example 1.

[0081] Comparative Example 7: Preparation of Fruity Black Tea

[0082] This comparative example is in contrast to Example 1, the only difference being that the adsorbent used in the tea making process is in a solution state, i.e., no sodium alginate is added. The specific tea making process is as follows:

[0083] 0.07 g of anhydrous ethanol was added to 250 ml of deionized water, and the mixture was stirred evenly to obtain an ethanol solution. Subsequently, 0.5 g of sodium chloride, 0.06 g of sodium hydroxide, 0.02 g of potassium iodate, and 5 g of glutinous rice juice were added, and the mixture was stirred until completely dissolved to obtain an adsorbent.

[0084] The steps for preparing the fruity black tea are the same as those in Example 1.

[0085] Comparative Example 8: Preparation of Fruity Black Tea

[0086] This comparative example is in contrast to the embodiment, except that an adsorbent is sprayed during the second rolling and ultraviolet irradiation is performed during the tea making process, the second rolling time is 30 minutes, and hot air blowing is performed after the third rolling. The specific tea making process is as follows:

[0087] (1) Fresh tea leaves with one bud and two leaves were picked and naturally withered for 18 h. The tea leaves were then shaken three times, each time for 15 min. The tea leaves were then left to stand for 2 h after each shaking.

[0088] (2) rolling the tea leaves for the first time for 30 minutes to obtain the first processed tea leaves;

[0089] (3) The tea leaves treated initially were rolled for a second time for 30 minutes, and the adsorbent was sprayed every 10 minutes during the rolling process, with 30 g of adsorbent sprayed per kg of tea leaves, allowing the adsorbent to fully contact the tea leaves. After the rolling process was completed, the tea leaves were allowed to stand and were irradiated with ultraviolet light of a wavelength of 320 nm for 3 hours to obtain the tea leaves after the second treatment.

[0090] (4) fermenting the tea leaves after the second treatment, controlling the fermentation temperature at 25° C., the fermentation humidity at 90%, and the fermentation time at 2.5 h;

[0091] (5) The fermented tea leaves were placed in a rolling and frying machine and withered at 280°C for 3 minutes. After cooling to room temperature, the tea leaves were rolled for a third time for 30 minutes to crush and remove the adsorption film on the tea leaves. After rolling, the tea leaves were placed on a sieve, the temperature was set at 35°C, and the air was blown at a wind speed of 5m / s for 15 minutes. The temperature was then raised to 50°C and the air was blown at a wind speed of 8m / s for 5 minutes to obtain coarse tea.

[0092] (6) Dry the crude tea at 100°C for 10 min and then heat it at 80°C for 1 h to obtain a fruity black tea.

[0093] The adsorbent used in this comparative example is the same as that in Example 1.

[0094] Comparative Example 9: Preparation of Fruity Black Tea

[0095] This comparative example is in contrast to Example 1, the only difference being that no ultraviolet irradiation treatment is used during the tea making process. The specific tea making process is as follows:

[0096] (1) Fresh tea leaves with one bud and two leaves were picked and naturally withered for 18 h. The tea leaves were then shaken three times, each time for 15 min. The tea leaves were then left to stand for 2 h after each shaking.

[0097] (2) The tea leaves that have been shaken are initially rolled for 30 minutes, and the adsorbent is sprayed every 10 minutes during the rolling process. 30 g of adsorbent is sprayed per kg of tea leaves to allow the adsorbent to fully contact the tea leaves. The rolling time is 30 minutes, and after the rolling is completed, the tea leaves are allowed to stand for 3 hours to obtain the initially treated tea leaves.

[0098] Steps (3) to (6) are the same as those in Example 1.

[0099] The adsorbent used in this comparative example is the same as that in Example 1.

[0100] The sensory quality of the fruity black teas prepared in Example 1 and Comparative Examples 1-9 was evaluated, and the results are shown in Table 1. The scoring standard was based on GB / T 23776-2009.

[0101] Table 1

[0102]

[0103]

[0104] From the analysis of Table 1, we can see that:

[0105] 1. Compared with Example 1 and Comparative Examples 1-7, the only difference is the adsorbent. The black tea prepared in Example 1 has a compact appearance, brown and oily with golden hairs, a bright red soup color, a strong aroma with floral and fruity fragrance, a fresh and mellow taste, and a bright red leaf bottom, which is of good quality. However, the fruit-flavored black tea prepared in Comparative Examples 1-7 has a poor soup color, taste, and leaf bottom color. Especially Comparative Example 6 is the worst, with a compact and dark appearance, a relatively red soup color, a relatively green leaf bottom, and a raw taste, indicating that the chlorophyll degradation is incomplete, which seriously affects the quality. The only difference between Comparative Examples 8-9 and Example 1 is the different preparation processes. The fruit-flavored black tea prepared in Comparative Examples 8-9 has a poor soup color, taste, and leaf bottom color. This shows that the fruit-flavored black tea prepared in Example 1 is of better quality and the chlorophyll degradation is more thorough.

[0106] 2. The only difference between Comparative Examples 1-3 and Example 1 is the raw materials used to prepare the adsorbent. No sodium chloride was added in Comparative Example 1, no sodium hydroxide was added in Comparative Example 2, and no potassium iodate was added in Comparative Example 3. The black tea prepared in Comparative Examples 1-3 was of poor quality compared to Example 1. This is because sodium chloride can change the permeability inside and outside cells and promote the precipitation of chlorophyll; sodium hydroxide can saponify the chlorophyll in tea leaves, thereby achieving the effect of degradation; potassium iodate can oxidize chlorophyll, thereby achieving the purpose of degrading chlorophyll. No matter which raw material is missing, it will cause incomplete degradation of chlorophyll. Therefore, sodium chloride, sodium hydroxide, ethanol, and potassium iodate work synergistically to promote the exudation of chlorophyll from tea leaves, and then degrade it, reducing the chlorophyll content in tea leaves.

[0107] 3. Comparative Example 4 increased the amount of sodium hydroxide, anhydrous ethanol, and potassium iodate added, and the quality of the black tea prepared was significantly lower than that of Example 1. This is because the excessively high concentrations of sodium hydroxide, anhydrous ethanol, and potassium iodate affect the exudation of chlorophyll and the degradation of chlorophyll by the adsorbent, thereby reducing the adsorption efficiency. Comparative Example 5 reduced the amount of sodium hydroxide, anhydrous ethanol, and potassium iodate added, and the quality of the black tea prepared was poor. This is because the concentration of the active ingredient that can degrade chlorophyll in the adsorbent is too low, resulting in incomplete degradation of chlorophyll in the tea leaves. Therefore, selecting a mass ratio of sodium hydroxide: anhydrous ethanol: potassium iodate = (0.06-0.08): (0.07-0.08): (0.02-0.04) to prepare an adsorbent can effectively degrade chlorophyll in tea leaves.

[0108] 4. Comparative Example 6 did not use an adsorbent to treat the tea leaves during the tea making process, and the resulting black tea soup was still red but not bright, the bottom of the leaves was red with a bluish hue, and the taste was astringent. This indicates that the lack of adsorbent treatment will result in the chlorophyll not being completely degraded, which has a greater impact on the quality of the finished black tea product. Comparative Example 7 prepared the adsorbent into a solution and treated the tea leaves, but the resulting tea soup was still red but not bright, and had a slightly astringent taste with a bluish hue, and was of poor quality. This is because the adsorbent in a gel state can wrap the tea leaves very well, allowing the adsorbent to better interact with the tea leaves, while the adsorbent in a solution state has an increased water content, which will lead to an increase in the water content of the tea leaves, and further lead to poor fermentation effects or fermentation failures in subsequent fermentation processes, resulting in the tea leaves being less bright in color and having a poor taste.

[0109] 5. Comparative Example 8 sprayed the adsorbent during the second rolling process and removed the adsorption film during the third rolling process. The quality of the tea produced was inferior to that of Example 1. This was because the adsorption film remained attached to the tea leaves during the fermentation process, affecting the fermentation process and thus the quality of the tea leaves.

[0110] 6. Comparative Example 9 did not use ultraviolet light irradiation treatment during the static process, and the finished tea product produced was not as good as Example 1. This is because ultraviolet light irradiation treatment can cooperate with the adsorbent to promote the oxidation of chlorophyll, and the lack of this step in Comparative Example 9 will result in incomplete degradation of chlorophyll in the tea leaves, thereby affecting the quality of the tea leaves.

[0111] experiment:

[0112] The adsorbent used in the tea making process of the present invention can be removed to avoid the adsorbent affecting the taste of black tea, so the following experiment was conducted.

[0113] Experimental group: An adsorbent was prepared according to the method of Example 1, and 10 mg of fluorescein was added to obtain an adsorbent containing fluorescein. Subsequently, the method of Example 1 was used to prepare fruit-flavored black tea.

[0114] Control group: An adsorbent was prepared according to the method of Example 1, and 10 mg of fluorescein was added to obtain an adsorbent containing fluorescein. The specific black tea preparation process is as follows:

[0115] Steps (1)-(2) are the same as those in Example 1;

[0116] (3) The tea leaves that have been treated for the first time are rolled for a second time for 20 minutes to crush and remove the adsorption film on the tea leaves. After rolling, the tea leaves are placed on a filter screen, the temperature is set to 50°C, and the tea leaves are blown at a wind speed of 8 m / s for 15 minutes to obtain the tea leaves that have been treated for the second time.

[0117] Steps (4) to (6) are the same as those in Example 1.

[0118] Blank control:

[0119] (1) Fresh tea leaves with one bud and two leaves were picked and naturally withered for 18 h. The tea leaves were then shaken three times, each time for 15 min. The tea leaves were then left to stand for 2 h after each shaking.

[0120] (2) The tea leaves that have been shaken are rolled for the first time for 30 minutes, and fluorescein is sprayed every 10 minutes during the rolling process, for a total of 10 mg;

[0121] Steps (3) to (6) are the same as those in Example 1.

[0122] The tea products prepared by the experimental group, control group and blank control were tested for residual fluorescein using fluorescence spectrophotometry. The results are shown in Table 2.

[0123] Table 2

[0124] Experimental Project Experimental group control group Blank control Fluorescein content (mg / kg) 0.04 4.2 8.5

[0125] From the analysis of Table 2, we can see that:

[0126] The difference between the experimental and control groups was the hot air purge step during the tea-making process. The experimental group used a multi-step hot air purge, while the control group used a single-step hot air purge. The control group's finished tea had significantly higher levels of fluorescein than the experimental group. Using multi-step hot air purge, the remaining film can be first blown off the tea leaves, and then the broken adsorption film can be removed by increasing the air speed and temperature. However, with a single-step hot air purge, the tea leaves are exposed to the high-temperature hot air for too long, and the adsorption film may be affected by the temperature and become liquid, resulting in incomplete removal of the adsorption film.

[0127] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that the technical solutions of the present invention may be modified or replaced with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and such modifications or equivalents shall be encompassed by the claims of the present invention. Any techniques, shapes, and structures not described in detail herein are well known.

Claims

1. A method for producing fruit-flavored black tea, characterized in that: The method comprises the following steps: (1) Withering and shaking the tea leaves; (2) rolling the tea leaves after shaking for the first time, spraying an adsorbent during the rolling process, allowing the tea leaves to stand after rolling, and irradiating them with ultraviolet light during the standing process to obtain the first-treated tea leaves; (3) rolling the tea leaves after the first treatment for the second time, placing them on a sieve after the second rolling is completed, and blowing them with hot air to obtain the tea leaves after the second treatment; (4) fermenting the tea leaves after the second treatment; (5) The fermented tea leaves are withered and rolled for the third time to obtain coarse tea; (6) Drying the crude tea to obtain fruity black tea; The specific operation in step (2) is as follows: rolling the tea leaves after shaking for 30 minutes, spraying the adsorbent every 10 minutes during the rolling process, letting the tea leaves stand after the rolling is completed, and irradiating them with ultraviolet light for 3-4 hours during the standing process; The specific operation of step (3) is as follows: the tea leaves treated initially are rolled for a second time for 20 minutes, and after rolling, the tea leaves are placed in a sieve, the temperature is set to 35-45°C, and the air is blown at a wind speed of 5 m / s for 15-20 minutes, and then the temperature is raised to 50-60°C and the air is blown at a wind speed of 8 m / s for 5-10 minutes; The adsorbent in step (2) includes the following raw materials: Sodium alginate, sodium chloride, sodium hydroxide, anhydrous ethanol, potassium iodate, glutinous rice juice, 0.1 mol / L calcium chloride solution, the raw materials have the following mass ratio: Sodium alginate, sodium chloride, sodium hydroxide, anhydrous ethanol, potassium iodate, glutinous rice juice, 0.1 mol / L calcium chloride solution = (5-7): (0.5-0.8): (0.06-0.08): (0.07-0.08): (0.02-0.04): (5-8): 260; The specific preparation method of the adsorbent is: Add anhydrous ethanol to 250 ml of deionized water and stir evenly to obtain an ethanol solution. Then add sodium chloride, sodium hydroxide, potassium iodate, and glutinous rice juice and continue stirring until completely dissolved. Then, slowly add sodium alginate while stirring. After complete dissolution, slowly add 0.1 mol / L calcium chloride solution and stir evenly to obtain an adsorbent.

2. The method for making a fruity black tea according to claim 1, wherein: The tea leaves in step (1) are fresh leaves with one bud and one leaf or one bud and two leaves, and the natural withering time is 18 hours.

3. The method for making a fruity black tea according to claim 2, wherein: The specific operation of shaking the green tea in step (1) is as follows: shaking the green tea three times in total, each time for 15 minutes, and letting the green tea stand for 2-3 hours after each shaking.

4. The method for making a fruit-flavored black tea according to claim 3, wherein: During the fermentation process of step (4), the fermentation temperature is controlled to be 25-28° C., the fermentation humidity is controlled to be 90-95%, and the fermentation time is controlled to be 2.5-3 h.

5. The method for producing a fruit-flavored black tea according to claim 4, wherein: The specific operation of step (5) is: withering the fermented tea leaves at a temperature of 280° C. for 3-4 minutes, cooling them to room temperature, and then rolling them for the third time for 30 minutes to obtain coarse tea.

6. The method for producing fruit-flavored black tea according to claim 5, characterized in that: The specific operation of drying and aromatizing in step (6) is: baking at 100°C for 10 minutes, and then aromatizing at 80°C for 1 hour.

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