Preparation method of a compound lipid-lowering mulberry leaf tea drink and the compound lipid-lowering mulberry leaf tea drink

Abstract

The present invention relates to the technical field of lipid-lowering beverages, and particularly to a preparation method of a compound lipid-lowering mulberry leaf tea beverage and the compound lipid-lowering mulberry leaf tea beverage. The preparation method includes raw material pretreatment, primary fermentation conversion, co-inoculation of strains, compound fermentation culture, drying and aging, and preparation of the compound lipid-lowering mulberry leaf tea beverage. This process takes "the preparation of plant-derived functional beverages" as the core goal. By optimizing the pretreatment of the composite raw materials of mulberry leaves and dark tea, multi-strain co-fermentation conversion, directional blending and stability treatment of the beverage, the lipid-lowering effect is significantly verified by mouse experiments; at the same time, key problems such as the astringent taste, precipitation, and microbial safety of the beverage are solved, and a compound lipid-lowering mulberry leaf tea beverage with excellent sensory quality, convenient drinking, and safety and controllability is prepared.

Description

Technical Field

[0001] This invention relates to the field of lipid-lowering beverage technology, and in particular to a method for preparing a compound lipid-lowering mulberry leaf tea beverage and the compound lipid-lowering mulberry leaf tea beverage. Background Technology

[0002] The journal *Journal of Ningxia Medical College*, Volume 22, Issue 2, authored by Gao Ling et al., published an article titled "The Effects of Mulberry Leaf Tea on Lipid Metabolism and its Antioxidant Effects in Rats with Hyperlipidemia," which mentions that mulberry leaf tea can lower blood lipids and inhibit the formation of harmful peroxides.

[0003] The tea polyphenols, tea polysaccharides, and *Aspergillus cristatus* metabolites in dark tea have an auxiliary effect in regulating blood lipids. Combining these components to prepare functional beverages can achieve synergistic optimization of efficacy. However, in existing technologies, the compound processing of mulberry leaves and dark tea is mostly limited to traditional tea fermentation and brick-making processes. For example, CN104431124A discloses a compound mulberry leaf Fu brick tea, prepared through seasonal grading and picking, withering and watering, fixation, rolling, piling, baking and drying, crushing, sorting and sieving, blending, moisture testing and slurry injection, steaming, piling again, secondary steaming, metering and processing, and drying. Or, as in CN104431126A, a mulberry leaf Fu brick tea is prepared through seasonal grading and picking, withering and watering, fixation, rolling, piling, baking and drying, crushing and blending, moisture testing and slurry injection, steaming, piling again, secondary steaming, metering and processing, and drying. However, the above technical solutions all focus on the preparation of tea leaves themselves, without optimizing the process for the "beverage form," and have the following core defects in adapting to the preparation of functional beverages:

[0004] 1. Insufficient conversion of functional components and poor adaptability of lipid-lowering effects: Under the traditional brick fermentation mode, the raw material structure is dense, and the active ingredients of mulberry leaves and black tea are difficult to be fully released and synergistically converted, resulting in low content of lipid-lowering active ingredients in the finished beverage after brewing, and the efficacy cannot meet the core needs of functional beverages; in addition, the dissolution efficiency of ingredients has not been optimized for the beverage drinking scenario, and the utilization rate of effective ingredients after brewing is insufficient. 2. Lack of beverage processing, insufficient adaptability and convenience: Existing processing products are mostly brick tea or granular tea, which require steps such as breaking up the blocks, breaking them apart, and long brewing time before they can be consumed. They cannot be directly made into ready-to-drink or convenient brewing beverages. Moreover, key issues such as beverage stability and flavor blending have not been resolved, and beverage quality defects such as sedimentation and strong astringent taste are prone to occur. 3. Functional validation is not systematic and does not meet the requirements for functional beverage classification: Existing processes focus more on the sensory quality and safety of tea, and have not conducted systematic animal experiments to verify the lipid-lowering effects of beverages, thus failing to clarify the functional effectiveness of beverages.

[0005] 4. Insufficient synergy of plant raw materials makes it difficult to balance the flavor and safety of beverages: The astringent taste of mulberry leaves is difficult to completely remove through traditional fermentation, which directly affects the taste of the beverage; moreover, the risk of contamination by miscellaneous bacteria is high during the fermentation process. If not strictly controlled, it will lead to the beverage exceeding the microbial index, affecting drinking safety.

[0006] Based on the above-mentioned existing technologies, there are technical problems that urgently need to be solved, such as the inability of compound mulberry leaf tea to simultaneously achieve efficient conversion of functional components, convenient preparation as a beverage, clear verification of efficacy, and balance between safety and flavor. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides a method for preparing a compound lipid-lowering mulberry leaf tea beverage, comprising the following steps: Step 1, Raw Material Pretreatment: This includes pretreatment of mulberry leaves and black tea, as well as the preparation of compound raw materials. Step 2, primary fermentation and transformation: Spray tea syrup into the compound raw materials to obtain the prepared compound raw materials, then add the mold inoculum, stir evenly and then pile it up, spread it out to dry until the surface is dry to obtain the compound raw materials after primary fermentation; Step 3, Co-inoculation of microorganisms: Select *Aspergillus cristatus* strain and prepare *Aspergillus cristatus* suspension; select *Aspergillus oryzae* strain and prepare *Aspergillus oryzae* suspension; spray the two microbial suspensions simultaneously onto the compound raw material after the initial fermentation in Step 2, stir and mix, and then let it stand to colonize to obtain the inoculated compound raw material; Step 4, Compound Fermentation Culture: The inoculated compound raw materials from Step 3 are placed into a breathable fermentation basket and transferred to a sterile flower-growing workshop. After going through the flower-growing period, the flower-cultivating period, and the maturation period, the flower-growing compound raw materials are obtained. Step 5, Drying and Aging: After the fermentation process is completed, the material is dried by step-by-step heating, and then transferred to the aging workshop for aging to obtain the fermented compound raw material. Step 6: Preparation of compound lipid-lowering mulberry leaf tea beverage: After the compound raw materials in Step 5 have undergone fermentation and flowering, impurities are removed and screened. After passing quality inspection, the compound lipid-lowering mulberry leaf tea beverage is obtained by heating pure water, heating and sterilizing.

[0008] Furthermore, step 1 specifically includes the following steps: Step 1-1: Mulberry leaf pretreatment is as follows: spray the mulberry leaves with clean water, use steam to assisted in blanching, then knead until the leaves are curled into strips, pile them up while they are still hot and moist, break them up after piling, dry them, and crush them into granules to obtain mulberry leaf raw materials. Steps 1-2: Pre-treatment of dark tea: The dark tea is broken into granules and dried to obtain the raw material of dark tea. Steps 1-3: Preparation of composite raw materials: Mix and stir the mulberry leaf raw materials from Step 1-1 and the black tea raw materials from Step 1-2 to obtain composite raw materials.

[0009] Furthermore, the mulberry leaves selected in step 1-1 are fresh mulberry leaves that are free from pesticide contamination and pests.

[0010] Furthermore, the fresh mulberry leaves are graded according to leaf position: Grade 1, from the terminal bud to the third leaf; Grade 2, from the fourth to the seventh leaf, wherein Grade 1 fresh mulberry leaves account for 50-60% of the total fresh mulberry leaf weight, and Grade 2 fresh mulberry leaves account for 40-50% of the total fresh mulberry leaf weight.

[0011] Furthermore, the mass of the water sprayed in step 1-1 is 5-15% of the mass of the mulberry leaves.

[0012] Furthermore, the temperature for steam-assisted blanching in step 1-1 is 110-180℃, and the time is 2-5 minutes.

[0013] Furthermore, the moisture content of the mulberry leaves after blanching in step 1-1 is controlled at 45-50%.

[0014] Furthermore, the temperature of the wet heat fermentation in step 1-1 is 25-35℃, the relative humidity is 75-85%, and the time is 6-15h.

[0015] Furthermore, the drying temperature in step 1-1 is 70-75℃, and the moisture content is ≤11%.

[0016] Furthermore, the particle size of the particles described in step 1-1 is 1-3 mm.

[0017] Furthermore, the selection standard for the black tea mentioned in steps 1-2 is GB / T 32719.1-2016, and impurities and long stems are removed by sieving and sorting, wherein the tea stem content is ≤8%.

[0018] Furthermore, the particle size of the black tea mentioned in steps 1-2 is 1-2 mm.

[0019] Furthermore, the drying temperature in steps 1-2 is 60-70℃, and the drying time is 1-2 hours.

[0020] Furthermore, the mass ratio of mulberry leaf raw material to black tea raw material in steps 1-3 is (20-80):(20-80).

[0021] Furthermore, the tea syrup mentioned in step 2 is obtained by breaking mulberry leaf tea bricks, boiling them in water, and then filtering the mixture. The mass ratio of the mulberry leaf tea bricks to the water is 0.5:(90-100), and the boiling time is 30 minutes.

[0022] Furthermore, the moisture content of the prepared composite raw material in step 2 is 24-30%.

[0023] Furthermore, the amount of *Mucor* strain added in step 2 is 0.1-0.2% of the total mass of the prepared composite raw materials, wherein the *Mucor* strain is a non-toxin-producing strain with a viable count ≤10 × 10⁻⁶. 4 CFU / g.

[0024] Furthermore, in step 2, the temperature of the pile is 28-32℃, the relative humidity is 70-85%, and the time is 8-15 hours. During this period, the pile is turned over every 6 hours to promote the degradation of cellulose and pectin, laying the foundation for the conversion of lipid-lowering components.

[0025] Furthermore, the moisture content of the composite raw materials after the initial fermentation in step 2 is 22-25%.

[0026] Further, the *Eurotium cristatum* strain described in step 3 is activated and cultured for 24-36 hours at a temperature of 25-28℃ and a pH of 6.8-7.2 to prepare a (10-15)×10⁻⁶ culture. 4 CFU / mL bacterial suspension.

[0027] Further, the Aspergillus oryzae strain described in step 3 is activated and cultured at a temperature of 28-30℃ and a pH of 6.5-7.0 for 20-24 hours to prepare (8-10)×10 4 CFU / mL bacterial suspension.

[0028] Further, the mass ratio of the *Aspergillus cristatus* suspension and the *Aspergillus oryzae* suspension in step 3 is (1-2):(0.5-0.7).

[0029] Furthermore, the two bacterial suspensions mentioned in step 3 account for 0.3-0.5% of the total mass of the composite raw materials after the initial fermentation.

[0030] Furthermore, the settling time in step 3 is 2-3 hours to achieve co-inoculation of Aspergillus oryzae and Eurotium cristatum, and to directionally transform the lipid-lowering active ingredients in mulberry leaves and black tea.

[0031] Furthermore, in step 4, the thickness of the composite raw material after inoculation in the breathable fermentation basket is 10-15cm, and the basket's aperture is 0.8-1.2cm.

[0032] Furthermore, the preparatory environmental conditions for the aseptic flower-growing workshop described in step 4 before flower growing are ultraviolet disinfection for 30 minutes and oxygen concentration ≥15%.

[0033] Furthermore, the flowering period described in step 4 is 1-7 days, the temperature is 24-29℃, the relative humidity is 75-82%, and ventilation is 10 minutes every 2 hours.

[0034] Furthermore, the flower growing period described in step 4 is 8-10 days, with a temperature of 27-29℃, a relative humidity of 72-75%, and ventilation for 15 minutes every 3 hours.

[0035] Furthermore, the maturation period described in step 4 is 11-18 days, the temperature is 24-27℃, the relative humidity is 68-75%, and ventilation is carried out for 20 minutes every 4 hours.

[0036] Furthermore, during the flowering period in step 4, the mixture is turned over once a day to achieve orderly metabolism of Mucor, Aspergillus oryzae, and Eurotium cristatum, thereby removing the astringent taste of mulberry leaves and enhancing the lipid-lowering components.

[0037] Furthermore, during the blooming process in step 4, the number of *Eurotium cristatum* and the types of other bacteria are tested every 3 days using the method of GB 4789.15-2016. If the contamination rate of other bacteria exceeds 0.5%, the ventilation frequency and humidity parameters are adjusted immediately to ensure the safety of the raw materials.

[0038] Furthermore, the conditions for the stepped temperature drying in step 5 are: drying at 30-35℃ for 4 days, drying at 40-45℃ for 3 days, and drying at 50-55℃ for 2 days.

[0039] Furthermore, during the drying process described in step 5, the mixture is turned over once every 8 hours until the moisture content reaches 12-14%.

[0040] Furthermore, the ambient temperature conditions in the aging workshop described in step 5 are 20-25℃, the relative humidity is 65-75%, and the aging time is 7-10 days.

[0041] Furthermore, during the aging process described in step 5, the pile is turned over every two days to promote flavor blending and component stability.

[0042] Furthermore, in step 6, a 10-mesh sieve is used to remove impurities, and a 40-mesh sieve is used to screen for uniform particles.

[0043] Furthermore, the quality inspection standard described in step 6 is a live count of *Eurotium cristatum* ≥ 30 × 10⁻⁶. 4 CFU / g, contamination rate of miscellaneous bacteria ≤1%.

[0044] Furthermore, the mass of the pure water mentioned in step 6 is 30-40 times that of the composite raw materials after quality inspection, fermentation, and blooming.

[0045] Furthermore, the extraction temperature in step 6 is 95°C, and the extraction time is 20 minutes.

[0046] Furthermore, the cooling temperature described in step 6 is 40-45°C.

[0047] Furthermore, the sterilization temperature in step 6 is 100°C and the time is 15 minutes.

[0048] The present invention also provides a compound lipid-lowering mulberry leaf tea beverage, which is prepared by the above-mentioned preparation method of compound lipid-lowering mulberry leaf tea beverage.

[0049] Furthermore, the compound lipid-lowering mulberry leaf tea beverage showed no sedimentation or off-odor after standing for 6 months.

[0050] The beneficial effects of this invention are as follows: 1. This invention provides a method for preparing a compound lipid-lowering mulberry leaf tea beverage, including raw material pretreatment, primary fermentation transformation, synergistic inoculation of microorganisms, compound fermentation culture, drying and aging, and preparation of the compound lipid-lowering mulberry leaf tea beverage. This process takes "preparation of plant-derived functional beverages" as its core objective. By optimizing the pretreatment of mulberry leaf and black tea compound raw materials, synergistic fermentation transformation of multiple microorganisms, targeted blending of beverages, and stability treatment, the lipid-lowering effect has been verified by mouse experiments. At the same time, it solves key problems such as the astringent taste, sedimentation, and microbial safety of beverages, and prepares a compound lipid-lowering mulberry leaf tea beverage with excellent sensory quality, convenient drinking, and controllable safety. 2. Synergistic Enhancement of Lipid-Lowering Effects, Significant Results: Through the synergistic fermentation of mulberry leaf and dark tea compound raw materials with three microorganisms—Mucor, Aspergillus oryzae, and Aspergillus cristatus—active components such as flavonoids, polysaccharides, and tea polyphenols are directionally converted, forming a highly efficient lipid-lowering system. Mouse experiments have verified that the finished beverage can reduce serum TC by 57.3%-63.3%, LDL-C by 53.3%-59.6%, and TG by 26.5%-31.3% in high-lipidemia rats, while increasing HDL-C by 70.0%-90.0%. The lipid-lowering effect far exceeds that of comparative products with single raw materials or lacking any of the microorganisms, and it also possesses antioxidant activity (LPO reduction of 49.9%-54.9%), meeting the core requirements of a functional beverage. 3. Optimized Beverage Processing for Stable Quality: Abandoning traditional tea brick-making techniques, a beverage-oriented processing flow was designed specifically for this purpose. Through raw material crushing particle size control, step-by-step drying and aging, and sterilization, issues such as the astringent taste of mulberry leaves, beverage sedimentation, and insufficient dissolution of active ingredients were resolved. The finished beverage showed no sedimentation or off-odors after standing for 6 months, possessing a combination of mulberry leaf aroma, dark tea mellowness, and fungal aroma. It had a smooth and sweet aftertaste, a clear liquor, and sensory quality superior to traditional blended tea products. 4. High safety and controllability, wide applicability: Non-toxic *Mucor* and *Aspergillus* strains are selected, and the inoculum dosage and fermentation environment are strictly controlled, with a contamination rate of ≤1%; Acute toxicity tests (LD50) have been conducted. 50 >15g / kg The product was tested for bw and microbial indicators. The total bacterial count was ≤75CFU / mL. Coliform bacteria and pathogenic bacteria were not detected. It meets food hygiene standards. The product is a natural plant-based beverage with no artificial additives. It is suitable for daily health care for people with high blood lipids and preventive conditioning for healthy people. It is safe and burden-free to drink. 5. High raw material utilization and controllable cost: By grading and screening mulberry leaves (50%-60% of first-grade leaves and 40%-50% of second-grade leaves), optimizing the compound ratio and multi-strain synergistic fermentation, the active ingredients in mulberry leaves and black tea are fully released; moreover, the process does not require complicated equipment, simplifies the beverage processing steps, avoids redundant processes such as brick making and block breaking, reduces production losses and costs, and is suitable for large-scale mass production. 6. Flexible and adjustable formula to meet diverse needs: The ratio of mulberry leaves to black tea raw materials can be flexibly adjusted within the range of (20-80):(80-20) to form product series with different flavors and efficacy intensities (such as Group A, which emphasizes the mellowness of black tea; Group B, which has a balanced flavor; and Group C, which has a rich mulberry aroma). At the same time, it can be prepared in two forms, convenient brewing type and ready-to-drink type, according to market demand, to meet the taste preferences and usage scenarios of different consumer groups. It has strong market adaptability and broad industrialization prospects. Detailed Implementation

[0051] Example 1 This embodiment of a compound lipid-lowering mulberry leaf tea beverage and its preparation method includes the following steps: Step 1, Raw Material Pretreatment: This includes pretreatment of mulberry leaves and black tea, as well as the preparation of compound raw materials. Specifically, step 1-1, mulberry leaf pretreatment: Select fresh mulberry leaves free from pesticide contamination and pests, including 50% of the total fresh mulberry leaves of Grade I and 50% of the total fresh mulberry leaves of Grade II. Spray the mulberry leaves with clean water, the mass of which is 5% of the mulberry leaf mass. Use steam-assisted blanching at a temperature of 110℃ for 5 minutes. After blanching, the moisture content of the mulberry leaves is 45%. Then knead the leaves until they curl into strips. While still hot and moist, pile them up at a temperature of 25℃ and a relative humidity of 85% for 15 hours. After piling, break up the clumps and dry them at a temperature of 75℃ until the moisture content is 11%. Crush them into particles with a particle size of 1-3mm to obtain the mulberry leaf raw material. Steps 1-2: Pre-treatment of dark tea: The selection standard for dark tea is GB / T 32719.1-2016. It is screened and sorted to remove impurities and long stems. The tea stem content is ≤8%. The dark tea is crushed into particles with a particle size of 1-2mm and dried at 60℃ for 2 hours to obtain dark tea raw material. Steps 1-3: Preparation of composite raw materials: Mix the mulberry leaf raw materials from Step 1-1 and the black tea raw materials from Step 1-2 at a mass ratio of 20:80 to obtain composite raw materials; Step 2, Primary Fermentation and Transformation: Tea slurry is sprayed onto the composite raw materials. This tea slurry is obtained by breaking mulberry leaf tea bricks, boiling them in water, and then filtering the mixture. The mass ratio of the mulberry leaf tea bricks to the water is 0.5:90, and the boiling time is 30 minutes to obtain the pre-composite raw materials with a moisture content of 24%. Then, *Mucor* fungi are added at a rate of 0.1% of the total mass of the pre-composite raw materials. The *Mucor* fungi strain is a non-toxic strain with a viable count ≤10 × 10⁻⁶. 4 After mixing CFU / g evenly, the mixture is piled up at a temperature of 28℃ and a relative humidity of 85% for 8 hours, with the pile turned over every 6 hours to promote the degradation of cellulose and pectin, laying the foundation for the conversion of lipid-lowering components. The mixture is then spread out and dried until the surface is dry to obtain the first fermented compound raw material with a moisture content of 25%. Step 3, Co-inoculation with fungal strains: *Aspergillus cristatus* strain was selected and activated at 28℃ and pH 6.8 for 24 hours to prepare 15×10⁻⁶ micrograms. 4 CFU / mL bacterial suspension; *Aspergillus oryzae* strain was selected and activated at 30℃ and pH 7.0 for 20 h to prepare 8×10⁸ CFU / mL bacterial suspension. 4 CFU / mL bacterial suspension; two bacterial suspensions were sprayed simultaneously onto the compound raw materials after primary fermentation in step 2. The mass ratio of Aspergillus cristatus bacterial suspension and Aspergillus oryzae suspension was 1:0.7, and the two bacterial suspensions accounted for 0.5% of the total mass of the compound raw materials after primary fermentation. After stirring and mixing, the mixture was allowed to stand for 2 hours to colonize, so as to achieve co-inoculation of Aspergillus oryzae and Aspergillus cristatus, and to directionally transform the lipid-lowering active ingredients in mulberry leaves and black tea, thus obtaining the inoculated compound raw materials; Step 4, Compound Fermentation Culture: The inoculated compound raw materials from Step 3 are placed into a breathable fermentation basket. The thickness of the inoculated compound raw materials in the breathable fermentation basket is 15cm, and the basket has a hole diameter of 0.8cm. The basket is then transferred to a sterile fermentation workshop. The sterile fermentation workshop is prepared under the following environmental conditions before fermentation: ultraviolet disinfection for 30 minutes, oxygen concentration ≥15%. After experiencing the fermentation, growth, and maturity stages, the fermentation period lasts 1 day at 29℃ and 75% relative humidity, with ventilation for 10 minutes every 2 hours; the growth period lasts 8 days at 27℃ and 75% relative humidity, with ventilation for 15 minutes every 3 hours; the maturity period lasts 18 days at 24℃ and 68% relative humidity, with ventilation for 20 minutes every 4 hours. During the fermentation period, the mixture is turned once daily to ensure the orderly metabolism of *Mucor*, *Aspergillus oryzae*, and *Eurotium cristatum*, removing the astringent taste of the mulberry leaves. GB standards are applied every 3 days. The method of 4789.15-2016 was used to detect the number of *Eurotium cristatum* and the types of other bacteria. If the contamination rate of other bacteria exceeded 0.5%, the lipid-lowering components were fortified to obtain the compound raw material after fermentation. Step 5, Drying and Aging: After the fermentation process is complete, a stepped temperature drying method is used, with the conditions being 30℃ for 4 days, 45℃ for 3 days, and 50℃ for 2 days. During the drying process, the material is turned over every 8 hours until the moisture content reaches 14%. After that, it is transferred to the aging workshop for aging. The ambient temperature conditions in the aging workshop are 20℃ and the relative humidity is 75%. The aging time is 10 days. During the aging process, the material is turned over every 2 days to promote flavor blending and component stability, resulting in the fermented compound raw material. Step 6: Preparation of compound lipid-lowering mulberry leaf tea beverage: After fermentation and blooming in Step 5, the compound raw materials are sieved through a 10-mesh sieve to remove impurities and then through a 40-mesh sieve. After passing quality inspection, the standard for passing the quality inspection is that the viable count of *Aspergillus cristatus* is ≥30 × 10⁻⁶. 4 With a CFU / g concentration and a contamination rate of ≤1%, the product is extracted with pure water by heating and then cooled and sterilized. The mass of the pure water is 40 times that of the compound raw material after fermentation and blooming following quality inspection. The extraction temperature is 95℃ and the time is 20 minutes. After cooling to 40℃, the sterilization temperature is 100℃ and the time is 15 minutes to obtain a compound lipid-lowering mulberry leaf tea beverage.

[0052] The compound lipid-lowering mulberry leaf tea beverage showed no sediment or off-odor after standing for 6 months.

[0053] Example 2 This embodiment of a compound lipid-lowering mulberry leaf tea beverage and its preparation method includes the following steps: Step 1, Raw Material Pretreatment: This includes pretreatment of mulberry leaves and black tea, as well as the preparation of compound raw materials. Specifically, step 1-1, mulberry leaf pretreatment: Select fresh mulberry leaves free from pesticide contamination and pests, including 60% of the total fresh mulberry leaf weight of Grade 1 fresh mulberry leaves and 40% of the total fresh mulberry leaf weight of Grade 2 fresh mulberry leaves. Spray the mulberry leaves with clean water, the mass of which is 15% of the mulberry leaf weight. Use steam-assisted blanching at a temperature of 180℃ for 2 minutes. After blanching, the moisture content of the mulberry leaves is 50%. Then knead the leaves until they curl into strips. While still hot and moist, pile them up at a temperature of 35℃ and a relative humidity of 75% for 6 hours. After piling, break up the clumps and dry them at a temperature of 70℃ until the moisture content is 10%. Crush them into particles with a particle size of 1-3mm to obtain the mulberry leaf raw material. Steps 1-2: Pre-treatment of dark tea: The selection standard for dark tea is GB / T 32719.1-2016. It is screened and sorted to remove impurities and long stems. The tea stem content is ≤8%. The dark tea is crushed into particles with a particle size of 1-2mm and dried at 70℃ for 1 hour to obtain dark tea raw material. Steps 1-3: Preparation of composite raw materials: Mix the mulberry leaf raw materials from Step 1-1 and the black tea raw materials from Step 1-2 in a mass ratio of 80:20 to obtain composite raw materials; Step 2, Primary Fermentation and Transformation: Tea slurry is sprayed onto the composite raw materials. This tea slurry is obtained by breaking mulberry leaf tea bricks, boiling them in water, and then filtering the mixture. The mass ratio of the mulberry leaf tea bricks to the water is 0.5:100, and the boiling time is 30 minutes to obtain the pre-composite raw materials with a moisture content of 30%. Then, *Mucor* fungi are added at a rate of 0.2% of the total mass of the pre-composite raw materials. The *Mucor* fungi strain is a non-toxic strain with a viable count ≤10 × 10⁻⁶. 4 After mixing CFU / g evenly, the mixture is piled up at a temperature of 32℃ and a relative humidity of 70% for 15 hours, with the pile turned over every 6 hours to promote the degradation of cellulose and pectin, laying the foundation for the conversion of lipid-lowering components. The mixture is then spread out and dried until the surface is dry to obtain the first fermented compound raw material with a moisture content of 22%. Step 3, Co-inoculation with fungal strains: *Aspergillus cristatus* strain was selected and activated at 25℃ and pH 7.2 for 36 hours to prepare 10×10⁻⁶ strains. 4 CFU / mL bacterial suspension; *Aspergillus oryzae* strain was selected and activated at 28℃ and pH 6.5 for 24 h to prepare a 10×10⁻⁶ CFU / mL bacterial suspension. 4 CFU / mL bacterial suspension; two bacterial suspensions were sprayed simultaneously onto the compound raw materials after primary fermentation in step 2. The mass ratio of Aspergillus cristatus bacterial suspension and Aspergillus oryzae suspension was 2:0.5, and the two bacterial suspensions accounted for 0.3% of the total mass of the compound raw materials after primary fermentation. After stirring and mixing, the mixture was allowed to stand for 3 hours to colonize, so as to achieve co-inoculation of Aspergillus oryzae and Aspergillus cristatus, and to directionally transform the lipid-lowering active ingredients in mulberry leaves and black tea, thus obtaining the inoculated compound raw materials; Step 4, Compound Fermentation Culture: The inoculated compound raw materials from Step 3 are placed into a breathable fermentation basket. The thickness of the inoculated compound raw materials in the breathable fermentation basket is 10cm, and the basket has a hole diameter of 1.2cm. The basket is then transferred to a sterile fermentation workshop. The sterile fermentation workshop is prepared under the following environmental conditions before fermentation: ultraviolet disinfection for 30 minutes, oxygen concentration ≥15%. After experiencing the fermentation, growth, and maturity stages, the fermentation period lasts 7 days at 24℃ and 82% relative humidity, with ventilation for 10 minutes every 2 hours; the growth period lasts 10 days at 29℃ and 72% relative humidity, with ventilation for 15 minutes every 3 hours; and the maturity period lasts 11 days at 27℃ and 75% relative humidity, with ventilation for 20 minutes every 4 hours. During the fermentation period, the mixture is turned once daily to ensure the orderly metabolism of *Mucor*, *Aspergillus oryzae*, and *Eurotium cristatum*, removing the astringent taste of the mulberry leaves. GB standards are applied every 3 days. The method of 4789.15-2016 was used to detect the number of *Eurotium cristatum* and the types of other bacteria. If the contamination rate of other bacteria exceeded 0.5%, the lipid-lowering components were fortified to obtain the compound raw material after fermentation. Step 5, Drying and Aging: After the fermentation process, the material is dried using a stepped temperature increase method: 35℃ for 4 days, 40℃ for 3 days, and 55℃ for 2 days. During the drying process, the material is turned over every 8 hours until the moisture content reaches 14%. Then, it is transferred to the aging workshop for aging. The ambient temperature in the aging workshop is 25℃, the relative humidity is 65%, and the aging time is 7 days. During the aging process, the material is turned over every 2 days to promote flavor blending and component stability, resulting in the fermented compound raw material. Step 6: Preparation of compound lipid-lowering mulberry leaf tea beverage: After fermentation and blooming in Step 5, the compound raw materials are sieved through a 10-mesh sieve to remove impurities and then through a 40-mesh sieve. After passing quality inspection, the standard for passing the quality inspection is that the viable count of *Aspergillus cristatus* is ≥30 × 10⁻⁶. 4 With a CFU / g concentration and a contamination rate of ≤1%, the product is extracted with pure water by heating and then sterilized by cooling. The mass of the pure water is 30 times that of the compound raw material after fermentation and blooming following quality inspection. The extraction temperature is 95℃ and the time is 20 minutes. After cooling to 45℃, the sterilization temperature is 100℃ and the time is 15 minutes to obtain a compound lipid-lowering mulberry leaf tea beverage.

[0054] The compound lipid-lowering mulberry leaf tea beverage showed no sediment or off-odor after standing for 6 months.

[0055] Example 3 This embodiment of a compound lipid-lowering mulberry leaf tea beverage and its preparation method includes the following steps: Step 1, Raw Material Pretreatment: This includes pretreatment of mulberry leaves and black tea, as well as the preparation of compound raw materials. Specifically, step 1-1, mulberry leaf pretreatment: Select fresh mulberry leaves free from pesticide contamination and pests, including 55% of the total fresh mulberry leaves of Grade I and 45% of the total fresh mulberry leaves of Grade II. Spray the mulberry leaves with clean water, the mass of which is 10% of the mulberry leaf mass. Use steam-assisted blanching at a temperature of 140℃ for 4 minutes. After blanching, the moisture content of the mulberry leaves is 45%. Then knead the leaves until they curl into strips. While still hot and moist, pile them up at a temperature of 30℃ and a relative humidity of 80% for 10 hours. After piling, break up the clumps and dry them at a temperature of 70℃ until the moisture content is 10%. Crush them into particles with a particle size of 1-3mm to obtain the mulberry leaf raw material. Steps 1-2: Pre-treatment of dark tea: The selection standard for dark tea is GB / T 32719.1-2016. Impurities and long stems are removed by sieving and sorting. The tea stem content is ≤8%. The dark tea is crushed into particles with a diameter of 1-2mm and dried at 65℃ for 1.5h to obtain dark tea raw materials. Step 1-3, Preparation of composite raw materials: Mix the mulberry leaf raw material from step 1-1 and the black tea raw material from step 1-2 in a mass ratio of 50:50 to obtain the composite raw materials; Step 2, Primary Fermentation and Transformation: Tea slurry is sprayed onto the composite raw materials. This tea slurry is obtained by breaking mulberry leaf tea bricks, boiling them in water, and then filtering the mixture. The mass ratio of the mulberry leaf tea bricks to the water is 0.5:95, and the boiling time is 30 minutes to obtain the pre-composite raw materials with a moisture content of 27%. Then, *Mucor* fungi are added at a rate of 0.2% of the total mass of the pre-composite raw materials. The *Mucor* fungi strain is a non-toxic strain with a viable count ≤10 × 10⁻⁶. 4 After mixing CFU / g evenly, the mixture is piled up at a temperature of 30℃ and a relative humidity of 75% for 12 hours, with the pile turned over every 6 hours to promote the degradation of cellulose and pectin, laying the foundation for the conversion of lipid-lowering components. The mixture is then spread out and dried until the surface is dry to obtain the first fermented compound raw material with a moisture content of 23%. Step 3, Co-inoculation with bacterial strains: *Aspergillus cristatus* strain was selected and activated at 25℃ and pH 7.0 for 30 hours to prepare 12×10⁻⁶ strains. 4 CFU / mL bacterial suspension; *Aspergillus oryzae* strain was selected and activated at 28℃ and pH 6.5 for 22 h to prepare a 9×10⁻⁶ CFU / mL suspension. 4 CFU / mL bacterial suspension; two bacterial suspensions were sprayed simultaneously onto the compound raw materials after primary fermentation in step 2. The mass ratio of Aspergillus cristatus suspension and Aspergillus oryzae suspension was 1:0.6, and the two bacterial suspensions accounted for 0.4% of the total mass of the compound raw materials after primary fermentation. After stirring and mixing, the mixture was allowed to stand for 3 hours to colonize, so as to achieve co-inoculation of Aspergillus oryzae and Aspergillus cristatus, and to directionally transform the lipid-lowering active ingredients in mulberry leaves and black tea, thus obtaining the inoculated compound raw materials; Step 4, Compound Fermentation Culture: The inoculated compound raw materials from Step 3 are placed into a breathable fermentation basket. The thickness of the inoculated compound raw materials in the breathable fermentation basket is 12cm, and the basket has a hole diameter of 1.0cm. The basket is then transferred to a sterile fermentation workshop. The sterile fermentation workshop is prepared under the following environmental conditions before fermentation: ultraviolet disinfection for 30 minutes, oxygen concentration ≥15%. After experiencing the fermentation, growth, and maturity stages, the fermentation period lasts 4 days at 26℃ and 82% relative humidity, with ventilation for 10 minutes every 2 hours; the growth period lasts 9 days at 28℃ and 72% relative humidity, with ventilation for 15 minutes every 3 hours; and the maturity period lasts 14 days at 25℃ and 70% relative humidity, with ventilation for 20 minutes every 4 hours. During the fermentation period, the mixture is turned once daily to ensure the orderly metabolism of *Mucor*, *Aspergillus oryzae*, and *Eurotium cristatum*, removing the astringent taste of the mulberry leaves. GB standards are applied every 3 days. The method of 4789.15-2016 was used to detect the number of *Eurotium cristatum* and the types of other bacteria. If the contamination rate of other bacteria exceeded 0.5%, the lipid-lowering components were fortified to obtain the compound raw material after fermentation. Step 5, Drying and Aging: After the fermentation process, the material is dried using a stepped temperature increase method: 32℃ for 4 days, 42℃ for 3 days, and 52℃ for 2 days. During the drying process, the material is turned over every 8 hours until the moisture content reaches 14%. Then, it is transferred to the aging workshop for aging. The ambient temperature in the aging workshop is 23℃, the relative humidity is 70%, and the aging time is 8 days. During the aging process, the material is turned over every 2 days to promote flavor blending and component stability, resulting in the fermented compound raw material. Step 6: Preparation of compound lipid-lowering mulberry leaf tea beverage: After fermentation and blooming in Step 5, the compound raw materials are sieved through a 10-mesh sieve to remove impurities and then through a 40-mesh sieve. After passing quality inspection, the standard for passing the quality inspection is that the viable count of *Aspergillus cristatus* is ≥30 × 10⁻⁶. 4 With a CFU / g and a contamination rate of ≤1%, the product is extracted with pure water by heating and then sterilized by cooling. The mass of the pure water is 35 times that of the compound raw material after fermentation and blooming following quality inspection. The extraction temperature is 95℃ and the time is 20 minutes. After cooling to 42℃, the sterilization temperature is 100℃ and the time is 15 minutes to obtain a compound lipid-lowering mulberry leaf tea beverage.

[0056] The compound lipid-lowering mulberry leaf tea beverage showed no sediment or off-odor after standing for 6 months.

[0057] Comparative Example 1 Comparative Example 1, compared to Example 1, does not include black tea. It prepares a mulberry leaf tea beverage and its preparation method, comprising the following steps: Step 1, Raw Material Pretreatment: This includes pretreatment of mulberry leaves to prepare mulberry leaf raw materials. Specifically, the process involves selecting fresh mulberry leaves free from pesticide contamination and pests, including 50% of the total fresh mulberry leaves being Grade 1 fresh leaves and 50% being Grade 2 fresh mulberry leaves. The leaves are then sprayed with water at a concentration of 5% of the leaf weight. Steam-assisted blanching is performed at 110℃ for 5 minutes, resulting in a moisture content of 45%. The leaves are then kneaded until they curl into strips and piled up while still warm and moist at 25℃ and 85% relative humidity for 15 hours. After piling, the leaves are broken up and dried at 75℃ until the moisture content reaches 11%. Finally, they are crushed into particles with a diameter of 1-3 mm to obtain the mulberry leaf raw material. Step 2, Primary Fermentation and Transformation: Tea slurry is sprayed onto the mulberry leaf raw material. This tea slurry is obtained by breaking up mulberry leaf tea bricks, boiling them in water, and then filtering the mixture. The mass ratio of the mulberry leaf tea bricks to the water is 0.5:90, and the boiling time is 30 minutes to obtain the prepared mulberry leaf raw material with a moisture content of 24%. Then, *Mucor* fungi are added at a rate of 0.1% of the total mass of the prepared mulberry leaf raw material. The *Mucor* fungi strain is a non-toxic strain with a viable count ≤10 × 10⁻⁶. 4After mixing CFU / g evenly, the mixture is piled up at a temperature of 28℃ and a relative humidity of 85% for 8 hours, with the pile turned over every 6 hours to promote the degradation of cellulose and pectin, laying the foundation for the conversion of lipid-lowering components. The mixture is then spread out and dried until the surface is dry to obtain the mulberry leaf raw material after the first fermentation, with a moisture content of 25%. Step 3, Co-inoculation with fungal strains: *Aspergillus cristatus* strain was selected and activated at 28℃ and pH 6.8 for 24 hours to prepare 15×10⁻⁶ micrograms. 4 CFU / mL bacterial suspension; *Aspergillus oryzae* strain was selected and activated at 30℃ and pH 7.0 for 20 h to prepare 8×10⁸ CFU / mL bacterial suspension. 4 CFU / mL bacterial suspension; two bacterial suspensions were sprayed simultaneously onto the mulberry leaf raw material after the initial fermentation in step 2. The mass ratio of Aspergillus cristatus bacterial suspension and Aspergillus oryzae suspension was 1:0.7. The two bacterial suspensions accounted for 0.5% of the total mass of the composite raw material after the initial fermentation. After stirring and mixing, the mixture was allowed to stand for 2 hours to colonize, so as to achieve co-inoculation of Aspergillus oryzae and Aspergillus cristatus, and obtain the inoculated mulberry leaf raw material. Step 4, Compound Fermentation Culture: The inoculated mulberry leaf raw material from Step 3 is placed into a breathable fermentation basket. The thickness of the inoculated mulberry leaf raw material in the breathable fermentation basket is 15cm, and the basket body has a hole diameter of 0.8cm. It is then transferred to a sterile fermentation workshop. The sterile fermentation workshop is prepared with ultraviolet disinfection for 30 minutes and an oxygen concentration ≥15% before fermentation. After going through the fermentation period, the flowering period, and the ripening period, the fermentation period lasts for 1 day at a temperature of 29℃ and a relative humidity of 75%, with ventilation for 10 minutes every 2 hours; the flowering period lasts for 8 days at a temperature of 27℃ and a relative humidity of 75%, with ventilation for 15 minutes every 3 hours; the ripening period lasts for 18 days at a temperature of 24℃ and a relative humidity of 68%, with ventilation for 20 minutes every 4 hours. During the fermentation period, the mixture is turned over once a day to achieve orderly metabolism of Mucor, Aspergillus oryzae, and Aspergillus cristatus, removing the green taste of mulberry leaves. GB standards are applied every 3 days. The method of 4789.15-2016 was used to detect the number of *Eurotium cristatum* and the types of other bacteria. If the contamination rate of other bacteria exceeded 0.5%, the lipid-lowering components were fortified to obtain mulberry leaf raw material after flowering. Step 5, Drying and Aging: After the fermentation process, the leaves are dried using a stepped temperature increase method: 30℃ for 4 days, 45℃ for 3 days, and 50℃ for 2 days. During the drying process, the leaves are turned over every 8 hours until the moisture content reaches 14%. After drying, the leaves are transferred to an aging workshop for aging. The ambient temperature in the aging workshop is 20℃, the relative humidity is 75%, and the aging time is 10 days. During the aging process, the leaves are turned over every 2 days to promote flavor blending and component stability, resulting in fermented mulberry leaf raw material. Step 6: Preparation of compound lipid-lowering mulberry leaf tea beverage: After fermentation and flowering in Step 5, the mulberry leaf raw materials are sieved through a 10-mesh sieve to remove impurities and then through a 40-mesh sieve. After passing quality inspection, the standard for passing the quality inspection is that the viable count of *Aspergillus cristatus* is ≥30 × 10⁻⁶. 4 The mulberry leaf tea beverage of this comparative example was obtained by heating pure water with a CFU / g concentration and a contamination rate of ≤1% and then cooling and sterilizing it. The mass of the pure water was 40 times that of the compound raw materials after fermentation and blooming following quality inspection. The extraction temperature was 95℃ and the time was 20 min. After cooling to 40℃, the sterilization temperature was 100℃ and the time was 15 min.

[0058] Comparative Example 2 Comparative Example 2, compared to Example 1, does not contain any Mucor mold strains and provides a compound mulberry leaf tea beverage and its preparation method, comprising the following steps: Step 1, Raw Material Pretreatment: This includes pretreatment of mulberry leaves and black tea, as well as the preparation of compound raw materials. Specifically, step 1-1, mulberry leaf pretreatment: Select fresh mulberry leaves free from pesticide contamination and pests, including 50% of the total fresh mulberry leaves of Grade I and 50% of the total fresh mulberry leaves of Grade II. Spray the mulberry leaves with clean water, the mass of which is 5% of the mulberry leaf mass. Use steam-assisted blanching at a temperature of 110℃ for 5 minutes. After blanching, the moisture content of the mulberry leaves is 45%. Then knead the leaves until they curl into strips. While still hot and moist, pile them up at a temperature of 25℃ and a relative humidity of 85% for 15 hours. After piling, break up the clumps and dry them at a temperature of 75℃ until the moisture content is 11%. Crush them into particles with a particle size of 1-3mm to obtain the mulberry leaf raw material. Steps 1-2: Pre-treatment of dark tea: The selection standard for dark tea is GB / T 32719.1-2016. It is screened and sorted to remove impurities and long stems. The tea stem content is ≤8%. The dark tea is crushed into particles with a particle size of 1-2mm and dried at 60℃ for 2 hours to obtain dark tea raw material. Steps 1-3: Preparation of composite raw materials: Mix the mulberry leaf raw materials from Step 1-1 and the black tea raw materials from Step 1-2 at a mass ratio of 20:80 to obtain composite raw materials; Step 2, Primary Fermentation and Transformation: Spray tea slurry onto the composite raw materials. The tea slurry is obtained by breaking mulberry leaf tea bricks, boiling them in water, and filtering the mixture. The mass ratio of the mulberry leaf tea bricks to the water is 0.5:90, and the boiling time is 30 minutes to obtain the prepared composite raw materials with a moisture content of 24%. Then, the materials are piled up at a temperature of 28℃ and a relative humidity of 85% for 8 hours, turning the pile every 6 hours to promote the degradation of cellulose and pectin, laying the foundation for the transformation of lipid-lowering components. The pile is then spread out and dried until the surface is dry to obtain the primary fermented composite raw materials with a moisture content of 25%. Step 3, Co-inoculation with fungal strains: *Aspergillus cristatus* strain was selected and activated at 28℃ and pH 6.8 for 24 hours to prepare 15×10⁻⁶ micrograms. 4 CFU / mL bacterial suspension; *Aspergillus oryzae* strain was selected and activated at 30℃ and pH 7.0 for 20 h to prepare 8×10⁸ CFU / mL bacterial suspension. 4 CFU / mL bacterial suspension; two bacterial suspensions were sprayed simultaneously onto the compound raw materials after primary fermentation in step 2. The mass ratio of Aspergillus cristatus bacterial suspension and Aspergillus oryzae suspension was 1:0.7, and the two bacterial suspensions accounted for 0.5% of the total mass of the compound raw materials after primary fermentation. After stirring and mixing, the mixture was allowed to stand for 2 hours to colonize, so as to achieve co-inoculation of Aspergillus oryzae and Aspergillus cristatus, and to directionally transform the lipid-lowering active ingredients in mulberry leaves and black tea, thus obtaining the inoculated compound raw materials; Step 4, Compound Fermentation Culture: The inoculated compound raw materials from Step 3 are placed into a breathable fermentation basket. The thickness of the inoculated compound raw materials in the breathable fermentation basket is 15cm, and the basket has a hole diameter of 0.8cm. The basket is then transferred to a sterile fermentation workshop. The sterile fermentation workshop is prepared under the following environmental conditions before fermentation: ultraviolet disinfection for 30 minutes, oxygen concentration ≥15%. After experiencing the fermentation, growth, and maturity stages, the fermentation period lasts 1 day at 29℃ and 75% relative humidity, with ventilation for 10 minutes every 2 hours; the growth period lasts 8 days at 27℃ and 75% relative humidity, with ventilation for 15 minutes every 3 hours; the maturity period lasts 18 days at 24℃ and 68% relative humidity, with ventilation for 20 minutes every 4 hours. During the fermentation period, the mixture is turned once daily to ensure the orderly metabolism of *Mucor*, *Aspergillus oryzae*, and *Eurotium cristatum*, removing the astringent taste of the mulberry leaves. GB standards are applied every 3 days. The method of 4789.15-2016 was used to detect the number of *Eurotium cristatum* and the types of other bacteria. If the contamination rate of other bacteria exceeded 0.5%, the lipid-lowering components were fortified to obtain the compound raw material after fermentation. Step 5, Drying and Aging: After the fermentation process is complete, a stepped temperature drying method is used, with the conditions being 30℃ for 4 days, 45℃ for 3 days, and 50℃ for 2 days. During the drying process, the material is turned over every 8 hours until the moisture content reaches 14%. After that, it is transferred to the aging workshop for aging. The ambient temperature conditions in the aging workshop are 20℃ and the relative humidity is 75%. The aging time is 10 days. During the aging process, the material is turned over every 2 days to promote flavor blending and component stability, resulting in the fermented compound raw material. Step 6: Preparation of compound mulberry leaf tea beverage: After fermentation and blooming in Step 5, the compound raw materials are sieved through a 10-mesh sieve to remove impurities and then through a 40-mesh sieve. After passing quality inspection, the standard for passing the quality inspection is a viable count of *Eurotium cristatum* ≥ 30 × 10⁻⁶. 4With a CFU / g and a contamination rate of ≤1%, the product is extracted with pure water by heating and then sterilized by cooling. The mass of the pure water is 40 times that of the compound raw material after fermentation and blooming following quality inspection. The extraction temperature is 95℃ and the time is 20 minutes. After cooling to 40℃, the sterilization temperature is 100℃ and the time is 15 minutes to obtain a compound mulberry leaf tea beverage.

[0059] Comparative Example 3 Comparative Example 3, compared to Example 1, does not contain Aspergillus oryzae strain and provides a compound mulberry leaf tea beverage and its preparation method, comprising the following steps: Step 1, Raw Material Pretreatment: This includes pretreatment of mulberry leaves and black tea, as well as the preparation of compound raw materials. Specifically, step 1-1, mulberry leaf pretreatment: Select fresh mulberry leaves free from pesticide contamination and pests, including 50% of the total fresh mulberry leaves of Grade I and 50% of the total fresh mulberry leaves of Grade II. Spray the mulberry leaves with clean water, the mass of which is 5% of the mulberry leaf mass. Use steam-assisted blanching at a temperature of 110℃ for 5 minutes. After blanching, the moisture content of the mulberry leaves is 45%. Then knead the leaves until they curl into strips. While still hot and moist, pile them up at a temperature of 25℃ and a relative humidity of 85% for 15 hours. After piling, break up the clumps and dry them at a temperature of 75℃ until the moisture content is 11%. Crush them into particles with a particle size of 1-3mm to obtain the mulberry leaf raw material. Steps 1-2: Pre-treatment of dark tea: The selection standard for dark tea is GB / T 32719.1-2016. It is screened and sorted to remove impurities and long stems. The tea stem content is ≤8%. The dark tea is crushed into particles with a particle size of 1-2mm and dried at 60℃ for 2 hours to obtain dark tea raw material. Steps 1-3: Preparation of composite raw materials: Mix the mulberry leaf raw materials from Step 1-1 and the black tea raw materials from Step 1-2 at a mass ratio of 20:80 to obtain composite raw materials; Step 2, Primary Fermentation and Transformation: Tea slurry is sprayed onto the composite raw materials. This tea slurry is obtained by breaking mulberry leaf tea bricks, boiling them in water, and then filtering the mixture. The mass ratio of the mulberry leaf tea bricks to the water is 0.5:90, and the boiling time is 30 minutes to obtain the pre-composite raw materials with a moisture content of 24%. Then, *Mucor* fungi are added at a rate of 0.1% of the total mass of the pre-composite raw materials. The *Mucor* fungi strain is a non-toxic strain with a viable count ≤10 × 10⁻⁶. 4 After mixing CFU / g evenly, the mixture is piled up at a temperature of 28℃ and a relative humidity of 85% for 8 hours, with the pile turned over every 6 hours to promote the degradation of cellulose and pectin, laying the foundation for the conversion of lipid-lowering components. The mixture is then spread out and dried until the surface is dry to obtain the first fermented compound raw material with a moisture content of 25%. Step 3, Inoculation: A strain of *Aspergillus cristatus* was selected and activated at 28°C and pH 6.8 for 24 hours to prepare 15 × 10⁻⁶ micrograms. 4 CFU / mL bacterial suspension; spray the *Aspergillus cristatus* bacterial suspension onto the composite raw material after primary fermentation in step 2, wherein the bacterial suspension accounts for 0.5% of the total mass of the composite raw material after primary fermentation, stir and mix, and let stand for 2 hours to colonize, to obtain the inoculated composite raw material; Step 4, Compound Fermentation Culture: The inoculated compound raw material from Step 3 is placed into a breathable fermentation basket. The thickness of the inoculated compound raw material in the breathable fermentation basket is 15cm, and the basket has a hole diameter of 0.8cm. It is then transferred to a sterile fermentation workshop. The sterile fermentation workshop is prepared under the following environmental conditions before fermentation: ultraviolet disinfection for 30 minutes and oxygen concentration ≥15%. After going through the fermentation period, the growing period, and the maturation period, the fermentation period lasts for 1 day at a temperature of 29℃ and a relative humidity of 75%, with ventilation for 10 minutes every 2 hours; the growing period lasts for 8 days at a temperature of 27℃ and a relative humidity of 75%, with ventilation for 15 minutes every 3 hours; and the maturation period lasts for 18 days at a temperature of 24℃ and a relative humidity of 68%, with ventilation for 20 minutes every 4 hours. During the fermentation period, the mixture is turned over once a day. Every 3 days, the number of *Eurotium cristatum* and the types of other bacteria are tested using the method of GB 4789.15-2016. If the contamination rate of other bacteria exceeds 0.5%, the lipid-lowering components are fortified to obtain the fermented compound raw material. Step 5, Drying and Aging: After the fermentation process is complete, a stepped temperature drying method is used, with the conditions being 30℃ for 4 days, 45℃ for 3 days, and 50℃ for 2 days. During the drying process, the material is turned over every 8 hours until the moisture content reaches 14%. After that, it is transferred to the aging workshop for aging. The ambient temperature conditions in the aging workshop are 20℃ and the relative humidity is 75%. The aging time is 10 days. During the aging process, the material is turned over every 2 days to promote flavor blending and component stability, resulting in the fermented compound raw material. Step 6: Preparation of compound mulberry leaf tea beverage: After fermentation and blooming in Step 5, the compound raw materials are sieved through a 10-mesh sieve to remove impurities and then through a 40-mesh sieve. After passing quality inspection, the standard for passing the quality inspection is a viable count of *Eurotium cristatum* ≥ 30 × 10⁻⁶. 4 With a CFU / g and a contamination rate of ≤1%, the product is extracted with pure water by heating and then sterilized by cooling. The mass of the pure water is 40 times that of the compound raw material after fermentation and blooming following quality inspection. The extraction temperature is 95℃ and the time is 20 minutes. After cooling to 40℃, the sterilization temperature is 100℃ and the time is 15 minutes to obtain a compound mulberry leaf tea beverage.

[0060] Test Example 1 This test case examines the safety of the compound lipid-lowering mulberry leaf tea beverage prepared using Example 1, including: 1. Acute Toxicity Test: Sixty SPF-grade ICR mice (half male and half female, weighing 18-22g) were randomly divided into four groups (three dose groups + one blank control group), with 15 mice in each group. The compound lipid-lowering mulberry leaf tea beverage prepared in Example 1 was prepared into suspensions of corresponding concentrations using sterile physiological saline. Mice in the three dose groups were administered a single gavage at doses of 5g / kg·bw, 9g / kg·bw, and 15g / kg·bw, with a gavage volume of 0.2mL / 10g body weight. The blank control group was administered an equal volume of sterile physiological saline. Mice were observed for 14 consecutive days, with daily records of weight, diet, activity, and mental state. After the experiment, the mice were sacrificed and their organs were dissected. Results showed that within 14 days, no mice in any dose group died, exhibited abnormal behavior (such as lethargy, convulsions, or anorexia), and showed normal weight gain (average gain of 4.2-5.1g). No pathological damage was observed in organs (heart, liver, spleen, lungs, and kidneys), indicating that the product has extremely low acute toxicity (LD50). 50 >15g / kg·bw), safe for consumption; see Table 1 for detailed comparison.

[0061] Table 1 Acute Toxicity Test Record Sheet

[0062] 2. Microbiological Indicator Testing: The finished beverages from Examples 1-3 were tested according to GB 14881-2013 "General Hygiene Standard for Food Production" and the GB 4789 series standards. Results showed that the total bacterial count in all three groups of beverages was ≤100 CFU / mL; coliform bacteria were not detected; mold and yeast counts were ≤10 CFU / mL; and pathogenic bacteria such as Salmonella and Staphylococcus aureus were not detected, meeting food hygiene standards. See Table 2 for detailed comparisons.

[0063] Table 2 Microbiological Indicator Detection

[0064] Test Example 2 This test example is a test experiment comparing the compound lipid-lowering mulberry leaf tea beverages prepared in Examples 1-3 and the beverages prepared in Comparative Examples 1-3 in lipid-lowering applications. Specifically: 1. Experimental Materials and Grouping: 1) Animals: Eighty-four male SPF-grade Wistar rats, weighing 200±18g, were randomly divided into seven groups of 12 rats each after 3 days of acclimatization feeding. The groups were: normal control group, model control group, Example 1 group, Example 2 group, Example 3 group, Comparative Example 1 group, Comparative Example 2 group, and Comparative Example 3 group.

[0065] 2) Feed: The normal control group was given a normal feed; the other groups were given a high-fat feed (68% normal feed, 15% lard, 10% egg yolk powder, 5% cholesterol, and 2% sodium cholate) to replicate the hyperlipidemia model.

[0066] 3) Administration method: The normal control group and the model control group were administered an equal volume of sterile saline by gavage daily; the groups in Examples 1-3 were administered the corresponding prepared beverage by gavage at a dose of 1.0 g / kg·bw; the groups in Comparative Examples 1-3 were administered the beverage by gavage at a dose of 1.0 g / kg·bw. All groups had free access to water and were fed continuously for 4 weeks.

[0067] Table 3 Comparison of Experimental Materials and Group Feeding

[0068] 2. Detection indicators and methods: After the experiment, the mice were fasted for 12 hours (but water was not restricted), blood was collected from the orbital cavity, and serum was separated by centrifugation. The levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) in the serum were detected using a fully automated biochemical analyzer. The level of lipid peroxidation (LPO) in the serum was detected using the thiobarbituric acid method, and the HDL-C / TC ratio was calculated.

[0069] 3. Experimental Results: The serum markers of each group of rats are shown in Table 4 below (x±s, mmol / L): Table 4. Results of lipid-lowering efficacy test (x±s, mmol / L)

[0070] Note: △△P<0.001 (compared with the normal control group); P < 0.001, P < 0.01, P < 0.05 (compared with the model control group).

[0071] Table 5 Comparative analysis of lipid-lowering effects (differences in lipid reduction / increase compared to the model control group)

[0072] 4. Results Analysis: 1) Compared with the model control group: The levels of TC, LDL-C, TG and LPO in the Example 1-3 groups were significantly reduced, while the levels of HDL-C and HDL-C / TC ratio were significantly increased (P<0.001 or P<0.01). Among them, the lipid-lowering and antioxidant effects of the Example 3 group far exceeded those of the model control group, and the various indicators were closer to those of the normal control group.

[0073] 2) Compared with the control group: The lipid-lowering effect of the control group is obvious. The main reason is that the control group lacks black tea raw materials, the control group lacks Mucor, and the control group lacks Aspergillus oryzae. As a result, the synergistic lipid-lowering system of "mulberry leaf-black tea-three strains" cannot be formed, the active ingredients are not fully converted, and the lipid-lowering effect is greatly reduced.

[0074] 3) Comparison between examples: Example 3 showed the best lipid-lowering effect, followed by Example 2, and Example 1 was slightly weaker. This indicates that the combination of mulberry leaves and black tea in a 5:5 ratio, along with the synergistic fermentation of Mucor, Aspergillus oryzae and Aspergillus cristatus, can maximize the conversion of lipid-lowering active ingredients and achieve the strongest synergistic effect.

[0075] 5. Conclusion: The compound lipid-lowering mulberry leaf tea beverage prepared by this invention can significantly reduce the serum TC, LDL-C, TG and LPO levels in hyperlipidemic rats, and increase the HDL-C level and HDL-C / TC ratio. Its lipid-lowering effect and antioxidant activity are superior to the comparative products that lack core raw materials or strains, and it has high safety, meeting the application requirements of functional lipid-lowering beverages.

[0076] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing a compound lipid-lowering mulberry leaf tea beverage, characterized in that, Includes the following steps: Step 1, Raw Material Pretreatment: This includes pretreatment of mulberry leaves and black tea, as well as the preparation of compound raw materials. Step 2, primary fermentation and transformation: Spray tea syrup into the compound raw materials to obtain the prepared compound raw materials, then add the mold inoculum, stir evenly and then pile it up, spread it out to dry until the surface is dry to obtain the compound raw materials after primary fermentation; Step 3, Co-inoculation of microorganisms: Select *Aspergillus cristatus* strain and prepare *Aspergillus cristatus* suspension; select *Aspergillus oryzae* strain and prepare *Aspergillus oryzae* suspension; spray the two microbial suspensions simultaneously onto the compound raw material after the initial fermentation in Step 2, stir and mix, and then let it stand to colonize to obtain the inoculated compound raw material; Step 4, Compound Fermentation Culture: The inoculated compound raw materials from Step 3 are placed into a breathable fermentation basket and transferred to a sterile flower-growing workshop. After going through the flower-growing period, the flower-cultivating period, and the maturation period, the flower-growing compound raw materials are obtained. Step 5, Drying and Aging: After the fermentation process is completed, the material is dried by step-by-step heating, and then transferred to the aging workshop for aging to obtain the fermented compound raw material. Step 6: Preparation of compound lipid-lowering mulberry leaf tea beverage: After the compound raw materials in Step 5 have undergone fermentation and flowering, impurities are removed and screened. After passing quality inspection, the compound lipid-lowering mulberry leaf tea beverage is obtained by heating pure water, heating and sterilizing.

2. The preparation method of the compound lipid-lowering mulberry leaf tea beverage according to claim 1, characterized in that, Step 1 specifically includes the following steps: Step 1-1: Mulberry leaf pretreatment is as follows: spray the mulberry leaves with clean water, use steam to assisted in blanching, then knead until the leaves are curled into strips, pile them up while they are still hot and moist, break them up after piling, dry them, and crush them into granules to obtain mulberry leaf raw materials. Steps 1-2: Pre-treatment of dark tea: The dark tea is broken into granules and dried to obtain the raw material of dark tea. Steps 1-3: Preparation of composite raw materials: Mix and stir the mulberry leaf raw materials from Step 1-1 and the black tea raw materials from Step 1-2 to obtain composite raw materials.

3. The preparation method of the compound lipid-lowering mulberry leaf tea beverage according to claim 2, characterized in that, The mass ratio of mulberry leaf raw material to black tea raw material in steps 1-3 is (20-80):(20-80).

4. The preparation method of the compound lipid-lowering mulberry leaf tea beverage according to claim 1, characterized in that, The tea syrup mentioned in step 2 is obtained by breaking mulberry leaf tea bricks, boiling them in water, and then filtering the mixture. The mass ratio of the mulberry leaf tea bricks to the water is 0.5:(90-100), and the boiling time is 30 minutes.

5. The preparation method of the compound lipid-lowering mulberry leaf tea beverage according to claim 1, characterized in that, The amount of *Mucor* strain added in step 2 is 0.1-0.2% of the total mass of the prepared compound raw materials. The *Mucor* strain is a non-toxin-producing strain with a viable count ≤ 10 × 10⁻⁶. 4 CFU / g.

6. The preparation method of the compound lipid-lowering mulberry leaf tea beverage according to claim 1, characterized in that, The *Eurotium cristatum* strain described in step 3 was activated and cultured for 24-36 hours at a temperature of 25-28℃ and a pH of 6.8-7.2 to prepare a (10-15)×10⁻⁶ culture. 4 CFU / mL bacterial suspension.

7. The preparation method of the compound lipid-lowering mulberry leaf tea beverage according to claim 1, characterized in that, The Aspergillus oryzae strain described in step 3 is activated and cultured at a temperature of 28-30℃ and a pH of 6.5-7.0 for 20-24 hours to prepare (8-10)×10⁻⁶ strains. 4 CFU / mL bacterial suspension.

8. The preparation method of the compound lipid-lowering mulberry leaf tea beverage according to claim 1, characterized in that, The flowering period described in step 4 is 1-7 days, with a temperature of 24-29℃, a relative humidity of 75-82%, and ventilation for 10 minutes every 2 hours; The flower growing period described in step 4 is 8-10 days, with a temperature of 27-29℃, a relative humidity of 72-75%, and ventilation for 15 minutes every 3 hours; The maturation period described in step 4 is 11-18 days, with a temperature of 24-27℃, a relative humidity of 68-75%, and ventilation for 20 minutes every 4 hours.

9. The preparation method of the compound lipid-lowering mulberry leaf tea beverage according to claim 1, characterized in that, The conditions for the stepped temperature drying in step 5 are: drying at 30-35℃ for 4 days, drying at 40-45℃ for 3 days, and drying at 50-55℃ for 2 days.

10. A compound lipid-lowering mulberry leaf tea beverage, characterized in that, The compound lipid-lowering mulberry leaf tea beverage is prepared by the preparation method of the compound lipid-lowering mulberry leaf tea beverage according to any one of claims 1-9.

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