A type of mulberry leaf bud powdered tea and its preparation method

Abstract

This invention discloses a loose mulberry leaf bud Fu brick tea and its preparation method. The method comprises: picking mulberry leaf buds, spreading them out, fixing them, and drying them to make mulberry leaf bud tea; extracting, filtering, and concentrating Anhua black tea to make a concentrated liquid; mixing 100 parts of mulberry leaf bud tea with 20-50 parts of the concentrated liquid, adjusting the moisture content of the mulberry leaf bud tea, and then piling it up; after drying, wrapping it in a sterile environment and then treating it at a short time with high temperature; mixing Fu brick tea with sterile water and boiling it three times, the first two times at 70-85℃ and the third time at 90-100℃, filtering it in a clean environment after each boiling, and continuing to boil the residue; combining the filtrates and concentrating them under reduced pressure to make a glaze; piling the glaze with the short-time high-temperature treated mulberry leaf bud tea in a sterile environment at 15-25℃ and 20%-60% humidity, then fermenting it in an environment with 50%-80% relative humidity for 7-12 days, and then drying it to obtain loose mulberry leaf bud Fu brick tea.

Description

Technical Field

[0001] This invention belongs to the field of preparation of Fu brick tea, which is both food and medicine, and specifically relates to a Fu brick tea made from mulberry leaf buds and its preparation method. Background Technology

[0002] The mulberry tree is a perennial woody plant belonging to the genus *Morus* in the family Moraceae, and it is widely distributed. Every part of the mulberry tree is valuable; its branches can be used medicinally, its mulberries are both edible and medicinal, and its leaves, besides being used to feed silkworms, have long been a traditional Chinese medicine. 64% of the above-ground parts of the mulberry tree are leaves, which are replaced annually, making them a renewable resource with a huge yield. Mulberry leaves are rich in active ingredients, containing polysaccharides, flavonoids, polyphenols, chlorogenic acid, rutin, quercetin, and isoquercitrin, as well as alkaloids such as buckwheat alkaloids, 1-deoxynojirimycin (DNJ), 2-O-α-D-galactopyranoside-1-DNJ (GAL-DNJ), and 1,4-dideoxy-1,4-imino-D-arabinitol (DAB). In addition, they contain abundant protein, vitamins, and minerals, and possess various pharmacological effects such as anticoagulation, lowering blood pressure, lowering blood sugar, antibacterial and anti-inflammatory properties, anti-aging, and anti-tumor effects, making them highly valuable for development.

[0003] The development and utilization of mulberry leaf resources is currently limited, mainly focusing on the processing of substitute teas, including mulberry leaf green tea, mulberry leaf black tea, and mulberry leaf Fu tea. (1) Mulberry leaf green tea not only has a strong beany and pungent smell, but also has a dark tea soup, for which there is currently no effective solution. (2) During the processing of mulberry leaf black tea, although fermentation reduces the beany and pungent smell to some extent, the improvement in sensory quality is still limited. At the same time, compared with tea leaves, mulberry leaves have a lower polyphenol content, making it difficult to produce enough thearubigins through enzymatic oxidation when making mulberry leaf black tea, resulting in the tea soup color not meeting the requirements. To solve this problem, some people have mixed fresh tea leaves with mulberry leaves in a certain proportion, using the abundant polyphenols in fresh tea leaves to compensate for the lack of polyphenols in mulberry leaves, thereby promoting the formation of its orange-red soup color. At the same time, the addition of fresh tea leaves also improves the taste, but this method produces a mixed product of mulberry leaves and tea leaves, rather than pure mulberry leaf black tea. (3) Mulberry leaf Fu brick tea is made from mulberry leaf green tea or frost-covered mulberry leaves through processes such as selection, piling, steaming, pressing, fermentation, drying, and aging. Its essence is a multi-microbial fermentation process dominated by *Aspergillus cristatus*. The tea liquor of mulberry leaf Fu brick tea made from mulberry leaf green tea is darker than that of green tea, but still appears green, quite different from the reddish-brown or dark brown color of traditional Fu brick tea. Mulberry leaf Fu brick tea made from frost-covered mulberry leaves is reddish-brown with a green tinge, showing some improvement in color. However, mulberry leaf Fu brick tea still has a certain beany and grassy odor, and the liquor is reddish-green, indicating that its quality is still not ideal. These defects greatly limit the promotion of mulberry leaf tea products.

[0004] Currently, there are two main processes for preparing loose Fu brick tea: ① Inoculation and fermentation: This process requires both using black tea leaves to make the glaze and isolating pure strains of *Aspergillus cristatus* and preparing *Aspergillus cristatus* seed culture (pure strain preparation and propagation take more than half a month), which is time-consuming and labor-intensive. ② Natural fermentation: Black tea leaves are screened, mixed with glaze, piled, steamed, and then subjected to controlled humidity and temperature. This process is simple to operate and has a short fermentation time, but the fermentation process is uncontrollable, and the product is highly susceptible to contamination by *Aspergillus niger*, *Penicillium*, etc., resulting in a very low yield. Mulberry buds are the tender buds of the mulberry tree. Their properties are slightly bitter, slightly sweet, and cold. In recent years, they have been mainly used to make mulberry bud vegetables and high-grade mulberry bud green tea. Like mulberry leaf green tea, mulberry bud green tea has a beany and pungent aroma after brewing, but due to its shorter growth period, the beany and pungent aromas are slightly weaker, and the tea liquor is lighter in color than mulberry leaf green tea. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and provide a mulberry leaf bud loose-leaf tea and its preparation method. It uses Fu brick tea instead of traditional black tea to make glaze, and integrates glazing and inoculation into one process, which greatly saves manpower and time costs and improves the appearance, aroma and taste of mulberry leaf bud tea.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing mulberry leaf bud loose-leaf tea includes the following steps:

[0008] S1, Mulberry leaf buds are picked and then processed through withering, fixation and drying to make mulberry leaf bud tea;

[0009] Anhua black tea is extracted, filtered, and concentrated to produce a concentrated liquid;

[0010] S2, by weight, 100 parts of mulberry leaf bud tea are mixed with 20 to 50 parts of concentrated liquid, and the moisture content of the mulberry leaf bud tea is adjusted to 20% to 50%. After fermentation at 15℃ to 32℃, and after drying, the fermented mulberry leaf bud tea is obtained. The fermented mulberry leaf bud tea is then wrapped in a sterile environment and then subjected to short-term high-temperature treatment at 110℃ to 121℃.

[0011] S3, mix Fu brick tea and sterile water and boil the glaze three times. The temperature for the first two times is 70℃~85℃, and the temperature for the third time is 90℃~100℃. After each boiling, filter in a clean environment, and continue to boil the residue. Combine the filtrates and concentrate under reduced pressure to make glaze.

[0012] S4. The glaze obtained in S3 and the mulberry leaf bud tea obtained in S2 after short-term high-temperature treatment are piled together in a sterile environment at 15℃~25℃ and 20%~60% relative air humidity. Then, the tea is fermented in an environment of 50%~80% relative air humidity for 7d~12d and then dried to obtain mulberry leaf bud loose tea.

[0013] Preferably, the mulberry leaf buds in S1 are spread out for 2 to 5 hours, the blanching temperature is 110℃ to 140℃, the blanching time is 5 to 8 minutes, and the drying is carried out at 80℃ to 110℃ for 1 to 3 hours.

[0014] Preferably, S1 obtains the concentrate according to the following process:

[0015] Anhua black tea and water are boiled at 80℃ to 100℃ for 30 to 50 minutes at a ratio of 1g:(7 to 10)ml. The mixture is filtered to obtain a filtrate. The residue and water are boiled again at the same temperature and time at a ratio of 1g:(7 to 10)ml. The mixture is boiled a total of 2 to 3 times. The filtrates are then combined and concentrated at 60℃ to 80℃ and a vacuum of -0.08MPa to -0.1MPa to obtain a concentrated liquid. The ratio of the concentrated liquid to the original Anhua black tea is (0.8 to 2)ml:1g.

[0016] Preferably, the fermentation in S2 is carried out for 2 to 5 hours at a relative humidity of 30% to 70%.

[0017] Preferably, the pressure of the S2 high-temperature treatment is 0.1 MPa, the time is 2 min to 5 min, and the amount used for each high-temperature treatment is 1.0 kg to 2.0 kg.

[0018] Preferably, the Fu brick tea in S3 should show no signs of mold and have abundant internal mold growth.

[0019] Preferably, in step S3, after removing the portion of Fu brick tea 1cm to 3cm from the edge, the remaining Fu brick tea is broken into 1cm pieces. 2 ~2cm 2 Then, the glaze is boiled with sterile water at a mass ratio of 1:(10-20) for 10-20 minutes, and then filtered through a 40-80 mesh sieve to obtain the first residue and the first filtrate.

[0020] The first residue and sterile water are boiled together at a mass ratio of 1:(10-20) for 10-20 minutes, and then filtered through a 40-80 mesh sieve to obtain the second residue and the second filtrate. The second residue and sterile water are boiled together at a mass ratio of 1:(30-50) for 40-60 minutes, and then filtered through an 80-100 mesh sieve to obtain the third filtrate.

[0021] The first, second, and third filtrates were combined to obtain the total filtrate, which was then concentrated to 0.5 to 0.8 times the volume of the total filtrate under conditions of 60℃ to 80℃ and a vacuum of -0.08MPa to -0.1MPa to obtain the glaze.

[0022] Preferably, the mass ratio of glaze to mulberry leaf bud tea in S4 is (0.35-0.6):1, and the fermentation process is carried out for 1-3 hours.

[0023] Preferably, the blooming process described in S4 is carried out at 25°C to 30°C.

[0024] Preferably, the drying in S2 is carried out at 50℃~60℃ for 1h~3h;

[0025] The drying process in S4 is carried out at 40℃~50℃ for 2h~5h.

[0026] A mulberry leaf bud loose-leaf tea prepared by any of the above methods.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects:

[0028] This invention discloses a method for preparing loose-leaf mulberry leaf bud tea. Using mulberry leaf buds as raw material, the addition of concentrated Anhua black tea extract allows the aroma, polyphenols, flavonoids, and caffeine to fully integrate with the mulberry leaf bud tea. As the fermentation process continues, the nutrients and active substances of both teas further fuse together, resulting in significant improvements in the color, aroma, and taste. This method not only preserves the original characteristics of mulberry leaf bud tea, giving it superior quality, but also retains the characteristics of traditional tea used as a substitute for other teas. However, no traditional tea leaves are visible in this loose-leaf mulberry leaf bud tea, unlike other mulberry leaf green teas and mulberry leaf black teas, which directly add traditional tea leaves to improve the color and taste. Caffeine has a stimulating effect, but mulberry leaf bud tea, due to its extremely low caffeine content, lacks this effect. Adding concentrated black tea extract not only enhances the sensory quality of the mulberry leaf bud tea but also increases its caffeine content (by 4140.12%), thus imparting or enhancing its stimulating effect. Under short-term high-temperature treatment, the Maillard reaction occurs, and chlorophyll is decomposed or loses magnesium ions, causing it to turn brown. This results in mulberry leaf bud tea changing from green to brownish-red, promoting the color transformation of mulberry leaf bud tea towards fermented teas such as black tea and dark tea, and improving the color of the tea liquor from green to orange-yellow and orange-red. Simultaneously, with appropriate dosage, short-term high-temperature treatment effectively kills unwanted bacteria, ensuring that the fermentation process is not contaminated by microorganisms. Furthermore, due to the short sterilization time, there is minimal damage to nutrients. Unlike roasting, the browning caused by short-term high-temperature steam treatment does not impart a smoky flavor to the mulberry leaf bud tea. In the process of using Fu brick tea instead of traditional black tea for glaze preparation, the *Aspergillus cristatus* fungus, with its closed-cell structure and high-temperature resistance, is extracted from the Fu brick tea using sterile water. After filtering out the tea residue, all *Aspergillus cristatus* in the Fu brick tea is concentrated in the filtrate. Furthermore, most other bacteria in the Fu brick tea are inactivated during the extraction process due to the high temperature. This allows for thorough mixing with mulberry leaf bud tea, providing suitable moisture for subsequent glaze development and a large supply of *Aspergillus cristatus*. This integrated production process of glaze mixing and inoculation significantly saves labor and time costs. In addition, the inactivation of most bacteria in the Fu brick tea during extraction ensures that the mulberry leaf bud Fu brick tea is not contaminated by other bacteria. This invention develops high-quality loose-leaf Fu brick tea made from mulberry leaf buds, promoting the high-value utilization of mulberry leaf resources.

[0029] Compared with mulberry leaf bud tea, the loose mulberry leaf bud tea produced by this invention has significantly higher content of tea polyphenols and flavonoids. It has a reddish-brown appearance with abundant golden flowers. After brewing, the tea soup color changes from green to orange-yellow to orange-red. The green and spicy smell is reduced, the fishy smell is lighter, the fungal aroma is obvious, the tea soup is red and thick, and the taste is mellow. Attached Figure Description

[0030] Figure 1 This is an appearance diagram of the mulberry leaf bud loose-leaf tea processing section F1 (original mulberry leaf bud tea) in Embodiment 1 of the present invention.

[0031] Figure 2This is an appearance diagram of the mulberry leaf bud loose-leaf tea processing section F2 (mulberry leaf bud tea after one fermentation) in Embodiment 1 of the present invention.

[0032] Figure 3 This is an appearance diagram of the F3 processing section (sterilized mulberry leaf bud tea) of the mulberry leaf bud loose-leaf tea in Embodiment 1 of the present invention.

[0033] Figure 4 This is an appearance diagram of the F4 processing section (3-day fermented mulberry leaf bud tea) of the mulberry leaf bud loose-leaf tea in Comparative Example 1 of the present invention.

[0034] Figure 5 This is an appearance diagram of the F5 processing section (6-day-old mulberry leaf buds) of the mulberry leaf bud loose-leaf tea of ​​Comparative Example 2 of the present invention.

[0035] Figure 6 This is an appearance diagram of the F6 (9-day-old mulberry leaf buds) processing section of loose mulberry leaf tea in Embodiment 1 of the present invention.

[0036] Figure 7 The images show the brewing color of the first infusion of mulberry leaf bud loose-leaf tea from different processing stages according to the present invention.

[0037] Figure 8 The image shows the brewing color of the second infusion of mulberry leaf bud loose-leaf tea from different processing stages according to the present invention. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0039] This invention discloses a method for preparing mulberry leaf bud powdered tea, comprising the following steps:

[0040] (1) Pick mulberry leaf buds and process them in sequence through spreading, fixing and drying to make mulberry leaf bud tea;

[0041] The harvesting time for mulberry leaf buds is from late March to late April each year;

[0042] The drying time is 2 to 5 hours, the blanching temperature is 110℃ to 140℃, and the stir-frying time is 5 to 8 minutes. At this time, the leaves lose 35% to 60% of their water content.

[0043] The stir-fried mulberry leaf buds are then further dried at 80℃~110℃ for 1h~3h.

[0044] (2) Anhua black tea is extracted, filtered, and concentrated to make a concentrated liquid;

[0045] Among them, Anhua black tea and water are boiled at a ratio of 1g:(7-10)ml, the boiling temperature is 80℃-100℃, the extraction time is 30min-50min, and the extraction is carried out 2-3 times. Specifically, after extraction, the filtrate is filtered, and the residue and water are boiled at a ratio of 1g:(7-10)ml, and the boiling is continued in a similar manner.

[0046] Combine the filtrates and concentrate under reduced pressure (temperature 60℃~80℃, vacuum degree -0.08MPa~-0.1MPa) until the ratio of the concentrate to the original Anhua black tea is (0.8~2)ml:1g, to obtain the concentrate.

[0047] (3) Mix the concentrated liquid and mulberry leaf buds evenly, place them in a container for a first pile fermentation treatment, and dry them after the pile fermentation is completed.

[0048] In this mixture, by weight, 100 parts of mulberry leaf bud tea are mixed with 20 to 50 parts of concentrated liquid.

[0049] First fermentation: Adjust the moisture content (referring to mulberry leaf bud tea) to 20%–50%, that is, the mulberry leaf bud tea accounts for 20%–50% of the total mass of the mixed solution. The fermentation environment temperature is 15℃–32℃; the relative humidity of the fermentation environment is 30%–70%; and the fermentation time is 2 hours–5 hours.

[0050] The drying temperature is 50℃~60℃, and the drying time is 1h~3h.

[0051] (4) Wrap the mulberry leaf bud tea after the first fermentation in kraft paper (which needs to be sterilized) and perform short-term high-temperature treatment to ensure that the flowers bloom vigorously, are well preserved and free from contamination by bacteria.

[0052] Each package contains 1.0Kg to 2.0Kg, and undergoes a short-term high-temperature treatment at a temperature of 110℃ to 121℃, a pressure of 0.1MPa, and a time of 2 to 5 minutes, followed by cooling before use.

[0053] (5) Break the purchased Fu brick tea (which should be free of mold and have abundant internal blooms), remove the unbloomed part 1cm to 3cm away from the edge of the Fu brick tea, mix the remaining Fu brick tea with sterile water and boil it for glaze, boiling it a total of 3 times.

[0054] The first time, the Fu brick tea was pried open and broken into 1cm pieces. 2 ~2cm 2 Small pieces of Fu brick tea are further boiled with sterile water at a mass ratio of 1:(10-20) for 10-20 minutes at a temperature of 70-85℃. The mixture is then filtered through a 40-80 mesh sieve in a clean environment. The residue is then boiled a second time.

[0055] For the second time, add 10 to 20 times the amount of sterile water and boil for 10 to 20 minutes at a temperature of 70°C to 85°C. Filter the mixture through a 40-80 mesh sieve in a clean environment. Boil the resulting residue for the third time.

[0056] For the third time, add 30 to 50 times the amount of sterile water, boil for 40 to 60 minutes at a temperature of 90 to 100 degrees Celsius, and filter through an 80 to 100 mesh sieve.

[0057] (6) Combine the filtrates obtained from the three filtrations and concentrate them under reduced pressure to prepare the glaze.

[0058] The vacuum concentration process involves a temperature of 60℃ to 80℃ and a vacuum degree of -0.08MPa to -0.1MPa, concentrating the solution under reduced pressure to a ratio of 0.5 to 0.8 to obtain the glaze.

[0059] (7) In a clean room or ultra-clean workbench, mix the glaze and the mulberry leaf bud tea that has been cooled after a short-term high-temperature treatment evenly, and carry out a second fermentation.

[0060] The ratio of glaze to mulberry leaf bud tea is (0.35~0.6):1, the fermentation environment temperature is 15℃~25℃, the relative air humidity is 20%~60%, and the fermentation time is 1h~3h.

[0061] (8) Wrap the mulberry leaf bud tea after the second fermentation in sterilized kraft paper and wait for it to ferment. The fermentation conditions are as follows: temperature is 25℃~30℃, relative humidity is 50%~80%, fermentation time is 7d~12d, and after the fermentation is completed, it is dried (temperature is 40℃~50℃, time is 2h~5h) to obtain mulberry leaf bud loose tea.

[0062] Example 1

[0063] This invention discloses a method for preparing mulberry leaf bud powdered tea, comprising the following steps:

[0064] (1) Mulberry leaf buds are picked and then processed through spreading, fixing and drying to make mulberry leaf bud tea, namely F1;

[0065] The leaves were spread out to dry for 2 hours, the blanching temperature was 120℃, the leaves lost 55% of their moisture, and the stir-frying time was 7.5 minutes.

[0066] The stir-fried mulberry leaf buds were further dried at 85℃ for 2.5 hours.

[0067] (2) Anhua black tea is extracted, filtered, and concentrated to make a concentrated liquid;

[0068] The ratio of black tea to water was 1:10 (g / ml), the extraction temperature was 80℃, the extraction time was 50 min, and the extraction was performed twice.

[0069] The filtrates were combined and concentrated under reduced pressure (temperature 60℃, vacuum degree -0.08MPa) until the ratio of the filtrate to the original Anhua black tea was 0.8:1 (ml / g), thus obtaining the concentrated liquid.

[0070] (3) Mix the concentrated liquid and mulberry leaf bud tea evenly, place them in a container for a first fermentation process, and dry them after fermentation, i.e. F2;

[0071] In this mixture, by weight, 100 parts of mulberry leaf bud tea are mixed with 45 parts of the corresponding concentrate.

[0072] First fermentation: Adjust the moisture content to 38%, the fermentation temperature is 18℃, the relative humidity of the fermentation environment is 40%, and the fermentation time is 5 hours.

[0073] The drying temperature is 50℃ and the drying time is 2.5h.

[0074] (4) Wrap the mulberry leaf bud tea after the first fermentation in kraft paper and perform short-term high-temperature treatment, i.e., F3;

[0075] Each package contains 1.0 kg, and undergoes a short-term high-temperature treatment at 112°C, 0.1 MPa, and 4.5 min, followed by cooling before use.

[0076] (5) Break the Fu brick tea, remove the part 2cm away from the edge of the Fu brick tea, mix the remaining Fu brick tea with sterile water and boil the glaze, boil it 3 times in total.

[0077] The first step involves breaking the Fu brick tea into 2cm pieces. 2 For the small pieces, further boil the small pieces of Fu brick tea and sterile water at a mass ratio of 1:10 for 18 minutes at a temperature of 70℃. Filter the mixture through a 40-mesh sieve in a clean environment, and then boil the residue a second time.

[0078] For the second time, add 10 times the amount of sterile water, boil for 18 minutes at 70°C, filter through a 60-mesh sieve in a clean environment, and boil the resulting residue for the third time.

[0079] For the third time, add 30 times the amount of sterile water, boil for 60 minutes at 90℃, and filter through an 80-mesh sieve.

[0080] (6) Combine the filtrates obtained from the three filtrations and concentrate them under reduced pressure to prepare the glaze.

[0081] The vacuum concentration process involves a vacuum temperature of 60℃ and a vacuum degree of -0.10MPa, concentrating the solution to 0.5 times its original volume to obtain the glaze.

[0082] (7) In a clean room, the glaze and the mulberry leaf bud tea that has been cooled after a short period of high temperature treatment are mixed evenly and then fermented for a second time.

[0083] The ratio of glaze to mulberry leaf bud tea was 0.5:1, the fermentation environment temperature was 20℃, the relative humidity was 45%, and the fermentation time was 2 hours.

[0084] (8) Wrap the mulberry leaf bud tea after the second fermentation in sterilized kraft paper and wait for it to ferment. The fermentation conditions are as follows: temperature 28℃, relative humidity 70%, and a total fermentation time of 9 days. Samples are taken on days 3 and 6 of the fermentation process, and after drying, they are recorded as F4 and F5, respectively. After the fermentation is completed (on day 9), the tea is dried (at 50℃ for 2 hours) to obtain loose mulberry leaf bud tea, F6.

[0085] from Figure 1 You can see that the mulberry leaf bud tea is uniform and green, from Figure 2 You can see that after one pile fermentation process, the mulberry leaf bud tea changes from green to brown. Figure 3 As can be seen, after a short period of high-temperature sterilization, the color of the mulberry leaf bud tea deepened further, turning a distinct brown. Figure 4 As can be seen, after fermentation, the color of the mulberry leaf bud tea darkens slightly. Figure 5 As can be seen, after 6 days of flowering, the surface of the mulberry leaf bud tea has a large number of yellowish-green *Eurotium cristatum* (golden flower fungus). Figure 6 As can be seen, after 9 days of flowering, there are many yellow-green *Eurotium cristatum* (golden flower fungus) on the surface of the mulberry leaf bud tea.

[0086] Figure 7 and Figure 8 The images show the brewing colors of the first and second infusions of loose-leaf mulberry bud Fu brick tea at different processing stages, corresponding from top to bottom to processing stages F1, F2, F3, F4, F5, and F6. Each of the first and second infusions (F1, F2, F3, F4, F5, and F6) corresponds to four cups of tea (four parallel samples were taken for each tea sample from F1 to F6, evaluated according to national standards; the tea leaves remaining after draining the first infusion were re-brewed to obtain the second infusion). Figure 7 It can be seen that after brewing, the mulberry leaf bud tea has a green color, a strong grassy aroma, and a distinct bean-like smell. After one fermentation, the color changes from green to reddish-brown, with a relatively strong grassy aroma and bean-like smell. After further sterilization and fermentation (3 days), the color of the tea soup darkens slightly, the grassy aroma weakens, and the taste becomes more mellow. By the 6th day of fermentation, the color of the tea soup darkens further to brownish-brown, with a slight grassy aroma and a noticeable floral fragrance, and the taste becomes more mellow. By the 9th day of fermentation, the color of the tea soup darkens further than that of the 6th day of fermentation, with a slight grassy aroma, a richer floral fragrance, and a mellow taste.

[0087] from Figure 8It can be seen that the tea liquor color of all samples after the second infusion of mulberry leaf bud tea was lighter than that after the first infusion, and the trend of change was the same as that of the first infusion. The second infusion of mulberry leaf bud tea was green with a strong aroma and a noticeable beany smell. After the first fermentation, the liquor color changed from green to orange-yellow, and the grassy smell and beany smell were slightly reduced. After further sterilization and fermentation (3 days), the liquor color deepened slightly, the grassy smell was reduced, and the taste was more mellow. By the 6th day of fermentation, the tea liquor color deepened further to brownish-red, with a slight grassy smell and a noticeable floral aroma, and the taste was more mellow. By the 9th day of fermentation, the tea liquor color was further deepened compared to the 6th day of fermentation, with a slight grassy smell, a stronger floral aroma, and a mellow taste.

[0088] Example 2

[0089] This invention discloses a method for preparing mulberry leaf bud powdered tea, comprising the following steps:

[0090] (1) Pick mulberry leaf buds and process them in sequence through spreading, fixing and drying to make mulberry leaf bud tea;

[0091] The drying time is 2.5 hours, the blanching temperature is 125℃, the leaves lose 50% of their water, and the stir-frying time is 7 minutes.

[0092] The stir-fried mulberry leaf buds were further dried at 90℃ for 2.3 hours.

[0093] (2) Anhua black tea is extracted, filtered, and concentrated to make a concentrated liquid;

[0094] The ratio of black tea to water was 1:8 (g / ml), the extraction temperature was 85℃, the extraction time was 45min, and the extraction was performed twice.

[0095] The filtrates were combined and concentrated under reduced pressure (temperature 70℃, vacuum degree -0.09MPa) until the ratio with the original Anhua black tea was 1:1 (ml / g), to obtain the black tea extract concentrate.

[0096] (3) Mix the concentrated liquid and mulberry leaf bud tea evenly, place them in a container for a first fermentation process, and dry them after fermentation.

[0097] In this process, every 100 parts by weight of mulberry leaf bud tea are mixed with 40 parts of the corresponding extract concentrate.

[0098] First fermentation: Adjust the moisture content to 40%, the fermentation temperature is 20℃, the relative humidity is 45%, and the fermentation time is 4.5 hours;

[0099] The drying temperature was 52℃ and the drying time was 2.3h.

[0100] (4) Wrap the mulberry leaf bud tea after the first fermentation in kraft paper and perform short-term high-temperature treatment;

[0101] Each package contains 1.2 kg, and undergoes a short-term high-temperature treatment at 113°C, 0.1 MPa, and 4 min, followed by cooling before use.

[0102] (5) Break the Fu brick tea, remove the part 2.2cm away from the edge of the Fu brick tea, mix the remaining Fu brick tea with sterile water and boil it for glaze, boil it a total of 3 times;

[0103] The first time, the Fu brick tea was pried open and broken into 1cm pieces. 2 For the small pieces, further boil the small pieces of Fu brick tea and sterile water at a mass ratio of 1:12 for 16 minutes at a temperature of 73℃. Filter the mixture through a 40-mesh sieve in a clean environment, and then boil the residue a second time.

[0104] For the second time, add 12 times the amount of sterile water, boil for 16 minutes at a temperature of 73°C, filter through a 60-mesh sieve in a clean environment, and boil the resulting residue for the third time.

[0105] For the third time, add 35 times the amount of sterile water, boil for 55 minutes at 92℃, and filter through an 80-mesh sieve.

[0106] (6) Combine the filtrates obtained from the three filtrations and concentrate them under reduced pressure to prepare the glaze.

[0107] The vacuum concentration process involves a vacuum temperature of 65℃ and a vacuum degree of -0.10MPa, concentrating the solution to 0.6 times its original volume to obtain the glaze.

[0108] (7) In a clean room, the glaze and the mulberry leaf bud tea that has been cooled after a short period of high temperature treatment are mixed evenly and then fermented for a second time.

[0109] The ratio of glaze to mulberry leaf bud tea was 0.45:1, the fermentation environment temperature was 18℃, the relative humidity was 40%, and the fermentation time was 2.8h.

[0110] (8) Wrap the mulberry leaf bud tea after the second fermentation in sterilized kraft paper and wait for it to ferment. The fermentation conditions are as follows: temperature 27℃, relative humidity 60%, and fermentation time 10 days. After fermentation, dry the tea leaves (40℃, time 5h) to obtain loose mulberry leaf bud tea.

[0111] Example 3

[0112] This invention discloses a method for preparing mulberry leaf bud powdered tea, comprising the following steps:

[0113] (1) Pick mulberry leaf buds and process them in sequence through spreading, fixing and drying to make mulberry leaf bud tea;

[0114] The leaves were spread out to dry for 3 hours, the blanching temperature was 128℃, the leaves lost 45% of their water content, and the stir-frying time was 6.5 minutes.

[0115] The stir-fried mulberry leaf buds were further dried at 95℃ for 2.0 hours.

[0116] (2) Anhua black tea is extracted, filtered, and concentrated to make a concentrated liquid;

[0117] The ratio of black tea to water was 1:9 (g / ml), the extraction temperature was 90℃, the extraction time was 46 min, and the extraction was performed twice.

[0118] The filtrates were combined and concentrated under reduced pressure (temperature 80℃, vacuum degree -0.1MPa) until the ratio of the filtrate to the original Anhua black tea was 1.2:1 (ml / g), thus obtaining the black tea extract concentrate.

[0119] (3) Mix the concentrated liquid and mulberry leaf bud tea evenly, place them in a container for a first fermentation process, and dry them after fermentation.

[0120] In this process, every 100 parts by weight of mulberry leaf bud tea are mixed with 35 parts of the corresponding extract concentrate.

[0121] First fermentation: Adjust the moisture content to 45%, the fermentation temperature is 25℃, the relative humidity is 50%, and the fermentation time is 3.6 hours;

[0122] The drying temperature is 55℃ and the drying time is 2 hours.

[0123] (4) Wrap the mulberry leaf bud tea after the first fermentation in kraft paper and perform short-term high-temperature treatment;

[0124] Each package contains 1.5 kg of the product. The product undergoes a short-term high-temperature treatment at 115°C, a pressure of 0.1 MPa, and a time of 3.5 min, followed by cooling before use.

[0125] (5) Break the Fu brick tea, remove the part 2.4cm away from the edge of the Fu brick tea, mix the remaining Fu brick tea with sterile water and boil it for glaze, boil it a total of 3 times;

[0126] The first step involves breaking the Fu brick tea into 2cm pieces. 2 For the small pieces, further boil the small pieces of Fu brick tea and sterile water at a mass ratio of 1:15 for 15 minutes at a temperature of 75℃. Filter the mixture through a 60-mesh sieve in a clean environment, and then boil the residue a second time.

[0127] For the second time, add 15 times the amount of sterile water, boil for 15 minutes at a temperature of 75°C, filter through a 40-mesh sieve in a clean environment, and boil the resulting residue for the third time.

[0128] For the third time, add 40 times the amount of sterile water, boil for 50 minutes at 94℃, and filter through a 100-mesh sieve.

[0129] (6) Combine the filtrates obtained from the three filtrations and concentrate them under reduced pressure to prepare the glaze.

[0130] The vacuum concentration process involves a vacuum temperature of 68℃ and a vacuum degree of -0.09MPa, concentrating the solution to 0.7 times its original volume to obtain the glaze.

[0131] (7) In a clean room, the glaze and the mulberry leaf bud tea that has been cooled after a short period of high temperature treatment are mixed evenly and then fermented for a second time.

[0132] The ratio of glaze to mulberry leaf bud tea was 0.4:1, the fermentation environment temperature was 22℃, the relative humidity was 50%, and the fermentation time was 2.5h.

[0133] (8) Wrap the mulberry leaf bud tea after the second fermentation in sterilized kraft paper and wait for it to ferment. The fermentation conditions are as follows: temperature 26℃, relative humidity 65%, and fermentation time 12 days. After fermentation, dry the tea (45℃, time 3h) to obtain loose mulberry leaf bud tea.

[0134] Example 4

[0135] This invention discloses a method for preparing mulberry leaf bud powdered tea, comprising the following steps:

[0136] (1) Pick mulberry leaf buds and process them in sequence through spreading, fixing and drying to make mulberry leaf bud tea;

[0137] The drying time is 3.5 hours, the blanching temperature is 130℃, the leaves lose 47% of their water content, and the stir-frying time is 6 minutes.

[0138] The stir-fried mulberry leaf buds were further dried at 100℃ for 1.5 hours.

[0139] (2) Anhua black tea is extracted, filtered, and concentrated to make a concentrated liquid;

[0140] The ratio of black tea to water was 1:10 (g / ml), the extraction temperature was 88℃, the extraction time was 38 min, and the extraction was performed twice.

[0141] The filtrates were combined and concentrated under reduced pressure (temperature 75℃, vacuum degree -0.09MPa) until the ratio of the filtrate to the original Anhua black tea was 1.5:1 (ml / g), thus obtaining the black tea extract concentrate.

[0142] (3) Mix the concentrated liquid and mulberry leaf bud tea evenly, place them in a container for a first fermentation process, and dry them after fermentation.

[0143] In this process, every 100 parts by weight of mulberry leaf bud tea are mixed with 30 parts of the corresponding extract concentrate.

[0144] First fermentation: Adjust the moisture content to 45%, the fermentation temperature to 26℃, the relative humidity to 55%, and the fermentation time to 3 hours.

[0145] The drying temperature is 57℃ and the drying time is 1.5h.

[0146] (4) Wrap the mulberry leaf bud tea after the first fermentation in kraft paper and perform short-term high-temperature treatment;

[0147] Each package contains 1.6 kg of the product. The product undergoes a short-term high-temperature treatment at 116°C, a pressure of 0.1 MPa, and a time of 3.4 min, followed by cooling before use.

[0148] (5) Break the Fu brick tea, remove the part 2.5cm away from the edge of the Fu brick tea, mix the remaining Fu brick tea with sterile water and boil it for glaze, boil it a total of 3 times;

[0149] The first time, the Fu brick tea was pried open and broken into 1cm pieces. 2 For the small pieces, further boil the small pieces of Fu brick tea and sterile water at a mass ratio of 1:16 for 12 minutes at a temperature of 80℃. Filter the mixture through a 60-mesh sieve in a clean environment, and then boil the residue a second time.

[0150] For the second time, add 16 times the amount of sterile water, boil for 12 minutes at 80°C, filter through a 40-mesh sieve in a clean environment, and boil the resulting residue for the third time.

[0151] For the third time, add 45 times the amount of sterile water, boil for 45 minutes at a temperature of 96℃, and filter through a 100-mesh sieve.

[0152] (6) Combine the filtrates obtained from the three filtrations and concentrate them under reduced pressure to prepare the glaze.

[0153] The vacuum concentration process involves a vacuum temperature of 75℃ and a vacuum degree of -0.09MPa, with the glaze concentrated to 0.8 times its original volume.

[0154] (7) In a clean room, the glaze and the mulberry leaf bud tea that has been cooled after a short period of high temperature treatment are mixed evenly and then fermented for a second time.

[0155] The ratio of glaze to mulberry leaf bud tea was 0.4:1, the fermentation temperature was 23℃, the relative humidity was 55%, and the fermentation time was 1.8h.

[0156] (8) Wrap the mulberry leaf bud tea after the second fermentation in sterilized kraft paper and wait for it to ferment. The fermentation conditions are as follows: temperature 29℃, relative humidity 75%, and fermentation time 8 days. After fermentation, dry the tea (44℃, time 4h) to obtain loose mulberry leaf bud tea.

[0157] Example 5

[0158] This invention discloses a method for preparing mulberry leaf bud powdered tea, comprising the following steps:

[0159] (1) Pick mulberry leaf buds and process them in sequence through spreading, fixing and drying to make mulberry leaf bud tea;

[0160] The leaves were spread out for 4 hours, the blanching temperature was 135℃, the leaves lost 38% of their water content, and the stir-frying time was 5 minutes.

[0161] The stir-fried mulberry leaf buds were further dried at 106℃ for 1.3 hours.

[0162] (2) Anhua black tea is extracted, filtered, and concentrated to make a concentrated liquid;

[0163] The ratio of black tea to water was 1:8 (g / ml), the extraction temperature was 95℃, the extraction time was 35 min, and the extraction was performed twice.

[0164] The filtrates were combined and concentrated under reduced pressure (temperature 65℃, vacuum degree -0.08MPa) until the ratio with the original Anhua black tea was 2:1 (ml / g), to obtain the black tea extract concentrate.

[0165] (3) Mix the concentrated liquid and mulberry leaf bud tea evenly, place them in a container for a first fermentation process, and dry them after fermentation.

[0166] In this process, every 100 parts by weight of mulberry leaf bud tea are mixed with 20 parts of the corresponding extract concentrate.

[0167] First fermentation: Adjust the moisture content to 40%, the fermentation temperature is 28℃, the relative humidity is 60%, and the fermentation time is 2.5 hours;

[0168] The drying temperature is 58℃ and the drying time is 1.2h.

[0169] (4) Wrap the mulberry leaf bud tea after the first fermentation in kraft paper and perform short-term high-temperature treatment;

[0170] Each package contains 1.8 kg, and undergoes a short-term high-temperature treatment at 120°C, 0.1 MPa, and 3.5 min, followed by cooling before use.

[0171] (5) Break the Fu brick tea, remove the part 2.8cm away from the edge of the Fu brick tea, mix the remaining Fu brick tea with sterile water and boil it for glaze, boil it a total of 3 times;

[0172] The first step involves breaking the Fu brick tea into 2cm pieces. 2For the small pieces, further boil the small pieces of Fu brick tea and sterile water at a mass ratio of 1:20 for 10 minutes at a temperature of 83℃. Filter the mixture through an 80-mesh sieve in a clean environment, and then boil the residue a second time.

[0173] For the second time, add 20 times the amount of sterile water, boil for 10 minutes at 83°C, filter through a 60-mesh sieve in a clean environment, and boil the resulting residue for the third time.

[0174] For the third time, add 50 times the amount of sterile water, boil for 40 minutes at 98℃, and filter through an 80-mesh sieve.

[0175] (6) Combine the filtrates obtained from the three filtrations and concentrate them under reduced pressure to prepare the glaze.

[0176] The vacuum concentration process involves a temperature of 78°C and a vacuum degree of -0.08 MPa, concentrating the solution to 0.8 times its original volume to obtain the glaze.

[0177] (7) In a clean room, the glaze and the mulberry leaf bud tea that has been cooled after a short period of high temperature treatment are mixed evenly and then fermented for a second time.

[0178] The ratio of glaze to mulberry leaf bud tea was 0.35:1, the fermentation environment temperature was 25℃, the relative humidity was 60%, and the fermentation time was 1.5h.

[0179] (9) Wrap the mulberry leaf bud tea after the second fermentation in sterilized kraft paper and wait for it to ferment. The fermentation conditions are as follows: temperature 30℃, relative humidity 67%, and fermentation time 10 days. After fermentation, dry the tea (42℃, time 4h) to obtain loose mulberry leaf bud tea.

[0180] Based on non-targeted metabolomics analysis, liquid chromatography-mass spectrometry (LC-MS) was used to analyze samples F1 and F6. The most typical compounds identified are shown in Table 1, mainly including 6 phenolic acids and catechins, 11 flavonoids and flavonoid glycosides, and 5 alkaloids. Comparing the peak area of ​​F6 with F1, the increased peak area indicates an increase in content. Epicatechin, epigallocatechin, and epigallocatechin gallate were newly added, while gallic acid, paeonol, and cryptochlorogenic acid all increased by more than 100%. Myricetin, hesperidin, quercetin, and quercetin glycoside were also newly added, while luteolin, apigenin, dihydroquercetin, and isovitexin increased by 222.42%–42247.37%, respectively. In addition, after processing, the caffeine content in F6 increased by 4140.12% compared to F1, while theobromine and theophylline increased by 4134.24% and 4343.99%, respectively.

[0181] Table 1. Analysis of active ingredients in mulberry leaf bud powdered Fu tea before and after processing based on non-targeted metabolomics.

[0182]

Claims

1. A method for preparing mulberry leaf bud loose-leaf tea, characterized in that, Includes the following steps: S1, Mulberry leaf buds are picked and processed into mulberry leaf bud tea through withering, fixation and drying. The withering time is 2h to 5h, the fixation temperature is 110℃ to 140℃ and the time is 5min to 8min, and the drying is carried out at 80℃ to 110℃ for 1h to 3h. Anhua black tea and water are boiled at 80℃ to 100℃ for 30 to 50 minutes in a ratio of 1g:(7 to 10)ml. The mixture is filtered to obtain a filtrate. The residue and water are boiled again at the same temperature and time in a ratio of 1g:(7 to 10)ml. The mixture is boiled a total of 2 to 3 times. The filtrates are then combined and concentrated at 60℃ to 80℃ and a vacuum of -0.08MPa to -0.1MPa to obtain a concentrated liquid. The ratio of the concentrated liquid to the original Anhua black tea is (0.8 to 2)ml:1g. S2, by weight, 100 parts of mulberry leaf bud tea are mixed with 20-50 parts of concentrated liquid, and the moisture content of the mulberry leaf bud tea is adjusted to 20%-50%. After fermentation at 15℃-32℃, and after drying, a first-fermented mulberry leaf bud tea is obtained. The first-fermented mulberry leaf bud tea is then wrapped in a sterile environment and subjected to a short-term high-temperature treatment at 110℃-121℃ and 0.1MPa pressure for 2-5 minutes. The amount used for each high-temperature treatment is 1.0Kg-2.0Kg. S3, mix Fu brick tea and sterile water and boil the glaze three times. The temperature for the first two times is 70℃~85℃, and the temperature for the third time is 90℃~100℃. After each boiling, filter in a clean environment, and continue to boil the residue. Combine the filtrates and concentrate under reduced pressure to make glaze. In this process, the undeveloped flower-like parts (1cm to 3cm from the edge) of the Fu brick tea are first removed, and then the remaining Fu brick tea is broken into 1cm pieces. 2 ~2cm 2 Then, the glaze is boiled with sterile water at a mass ratio of 1:(10-20) for 10-20 minutes, and then filtered through a 40-80 mesh sieve to obtain the first residue and the first filtrate. The first residue and sterile water are boiled together at a mass ratio of 1:(10-20) for 10-20 minutes, and then filtered through a 40-80 mesh sieve to obtain the second residue and the second filtrate. The second residue and sterile water are boiled together at a mass ratio of 1:(30-50) for 40-60 minutes, and then filtered through an 80-100 mesh sieve to obtain the third filtrate. The first, second, and third filtrates were combined to obtain the total filtrate, which was then concentrated to 0.5 to 0.8 times the volume of the total filtrate under conditions of 60℃ to 80℃ and a vacuum of -0.08MPa to -0.1MPa to obtain the glaze. S4. The glaze obtained in S3 and the mulberry leaf bud tea obtained in S2 after short-term high-temperature treatment are piled together in a sterile environment at 15℃~25℃ and 20%~60% relative air humidity. Then, the tea is fermented for 7d~12d at 25℃~30℃ and 50%~80% relative air humidity, and then dried to obtain loose mulberry leaf bud tea.

2. The method for preparing mulberry leaf bud loose-leaf tea according to claim 1, characterized in that, The fermentation process in S2 is carried out for 2 to 5 hours at a relative humidity of 30% to 70%.

3. The method for preparing mulberry leaf bud loose-leaf tea according to claim 1, characterized in that, The mass ratio of glaze to mulberry leaf bud tea in S4 is (0.35-0.6):1, and the fermentation process lasts for 1-3 hours.

4. The method for preparing mulberry leaf bud loose-leaf tea according to claim 1, characterized in that, The drying in S2 is carried out at 50℃~60℃ for 1h~3h; The drying process in S4 is carried out at 40℃~50℃ for 2h~5h.

5. A mulberry leaf bud loose-leaf tea obtained by the preparation method of any one of claims 1 to 4.

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