Composite plant fermentation extract and preparation method thereof

Abstract

The invention relates to the field of natural flavone extraction, in particular to a composite plant fermentation extract and a preparation method thereof. The preparation method of the compound plant fermentation extract comprises the following steps: step 1, crushing mulberry leaves, pachyrhizua angulatus and cinnamon, and mixing with water to obtain a to-be-fermented material; step 2, cooking the to-be-fermented material for 25 to 40 minutes under the condition of 110 to 130 DEG C, so as to obtain a cooked mixture; step 3, cooling the cooked mixture to 25-30 DEG C, adding eurotium cristatum, lactobacillus acidophilus and geotrichum candidum into the cooked mixture, stirring and mixing, and soaking and fermenting for 5-10 days to obtain a fermented mixture; and step 4, sterilizing and centrifuging the fermentation mixture, and collecting supernate to obtain the composite plant fermentation extract. The method has the advantages of increasing the flavone extraction content, enhancing the antioxidant effect and the like.

Description

Technical Field

[0001] The present application relates to the field of natural flavonoid extraction, and more specifically, to a composite plant fermentation extract and a preparation method thereof. Background Art

[0002] In today's global context of increasing health awareness, natural plant extracts are becoming a research focus in many fields such as medicine, health products, and cosmetics because they are free of chemical additives, derived from nature, and rich in a variety of biologically active ingredients that are beneficial to the human body. Among them, flavonoids, as a large class of polyphenols widely found in the plant kingdom, are regarded as natural health ingredients with great potential due to their excellent biological activities such as antioxidant, anti-inflammatory, anti-tumor, hypoglycemic and immune regulation.

[0003] Flavonoids are widely distributed in nature. They are not only found in daily foods such as fruits, vegetables, and tea, but also in many medicinal plants, such as mulberry leaves, ginkgo leaves, and soybeans. These compounds have a positive impact on human health through multiple mechanisms, such as scavenging free radicals, inhibiting oxidative stress responses, and regulating cell signal transduction. However, despite the many health benefits of flavonoids, their direct extraction from plants faces considerable challenges.

[0004] Flavonoids in plants often exist in a bound form, tightly bound to plant cell walls, pectin, cellulose, etc., making it difficult to obtain them directly through conventional extraction methods. This not only leads to low extraction efficiency of flavonoids, but also makes the flavonoid content of the final extract relatively low, making it difficult to meet the needs of industrial production.

[0005] Therefore, in practical applications, how to stably improve the extraction efficiency and content of flavonoids has become an urgent problem to be solved. Summary of the invention

[0006] In order to increase the flavonoid extraction content and enhance the antioxidant effect, the present application provides a composite plant fermentation extract and a preparation method thereof.

[0007] In a first aspect, the present application provides a method for preparing a composite plant fermentation extract, using the following technical solution: A method for preparing a composite plant fermentation extract comprises the following steps: Step 1: Crush mulberry leaves, kudzu root and cinnamon bark and mix with water to obtain a product to be fermented; Step 2: cooking the fermented material at 110-130° C. for 25-40 minutes to obtain a cooking mixture; Step 3: Cool the cooking mixture to 25-30° C., add Eurotium cristatum, Lactobacillus acidophilus, and Geotrichum candidum into the cooking mixture, stir and mix, and soak and ferment for 5-10 days to obtain a fermentation mixture; Step 4: sterilize and centrifuge the fermentation mixture, collect the supernatant, and obtain the composite plant fermentation extract.

[0008] By adopting the above technical scheme, the plant raw materials of the present application are selected from mulberry leaves, kudzu vine, and cinnamon, and a special microbial combination of Aspergillus niger, Lactobacillus acidophilus, and Geotrichum candidum is selected. With the joint cooperation of the specially selected plant raw materials and microorganisms, the prepared composite plant fermentation extract is rich in flavonoids; and the antioxidant capacity of the composite plant fermentation extract can be further enhanced.

[0009] Mulberry leaves, kudzu vine and cinnamon, as plant materials rich in flavonoids, each has unique flavonoid components and biological activities. These flavonoids often exist in the form of glycosides in plants. When these plant materials are combined with microbial extracts such as Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum, a complex interaction system is formed.

[0010] The secondary metabolites produced by Eurotium cristatum during the fermentation process, such as enzymes and organic acids, can affect the release and conversion of flavonoids. These metabolites may promote the release of flavonoids from the inside to the outside of the cell by regulating the permeability of the plant cell wall. At the same time, organic acids such as lactic acid produced by Lactobacillus acidophilus help to regulate the pH value of the extract, thereby optimizing the solubility and stability of flavonoids. The fermentation of Geotrichum candidum is more direct. The enzymes such as cellulase and pectinase it produces can directly act on the plant cell wall, destroying its structure and making flavonoids easier to be extracted by solvents. This enzymatic hydrolysis not only improves the extraction rate of flavonoids, but also makes the flavonoid components in the extract richer and more diverse.

[0011] There is a synergistic antioxidant effect between these microbial metabolites and plant flavonoids. The antioxidant substances produced by microorganisms and plant flavonoids work together in the extract to form a powerful antioxidant system. This synergistic effect not only enhances the antioxidant capacity of the extract, but also may give it a wider range of biological activity.

[0012] Preferably, the mass ratio of mulberry leaf, kudzu vine and cinnamon bark is (6-8):(2-4):(0.5-1.5).

[0013] By adopting the above technical scheme, the mass ratio of mulberry leaves, kudzu vine and cinnamon can be further limited, so as to maximize their respective flavonoid extraction potentials and promote the synergistic effect between flavonoid compounds, thereby obtaining an extract with higher flavonoid content and stronger biological activity.

[0014] Preferably, the mass ratio of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 1:(0.1-0.3):(0.1-0.3).

[0015] By adopting the above technical scheme, the mass ratio of Echinops cristatus, Lactobacillus acidophilus and Geotrichum candidum is further limited, which can optimize the interaction between microorganisms, thereby maximizing the extraction amount of flavonoids and enhancing the antioxidant properties of metabolites.

[0016] Preferably, the total mass of the Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 0.01-0.05% of the total mass of the mulberry leaves, Pueraria lobata and cinnamon bark.

[0017] By adopting the above technical scheme, the total mass of Eurotium cristatum, Lactobacillus acidophilus, and Geotrichum candidum is further limited to the total mass of mulberry leaves, Pueraria lobata, and cinnamon bark, which can optimize the fermentation process, promote the release and conversion of flavonoids, and effectively improve the antioxidant properties of the composite plant fermentation extract.

[0018] Preferably, in step 1, the total mass of mulberry leaves, kudzu vine and cinnamon bark to the mass of water is 1:(1-3).

[0019] Preferably, the sterilization conditions of step 4 are 75-85° C. and 5-10 min.

[0020] Preferably, the mulberry leaves, kudzu vine and cinnamon bark are crushed to 1-5 mm.

[0021] By adopting the above technical scheme, mulberry leaves, kudzu vine and cinnamon are crushed to specific specifications, which is conducive to the contact and fermentation of Aspergillus niger, Lactobacillus acidophilus and Geotrichum candidum, thereby effectively enhancing the flavonoid content in the extract and improving the antioxidant property of the complex.

[0022] In a second aspect, the present application provides a composite plant fermentation extract.

[0023] By adopting the above technical scheme, by selecting mulberry leaves, kudzu vine and cinnamon as raw materials, and combining with a special microbial combination of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum, the content of flavonoids and antioxidant capacity of the prepared composite plant fermentation extract are significantly improved.

[0024] Microbial metabolites such as enzymes and organic acids promote the release, transformation and stability optimization of flavonoids, while improving the flavonoid extraction rate and component diversity.

[0025] In addition, microbial antioxidants work synergistically with plant flavonoids to build a powerful antioxidant system, giving the extracts a wider range of biological activities and showing many beneficial effects.

[0026] In summary, this application has the following beneficial effects: 1. The composite plant fermentation extract is made by selecting plant raw materials rich in flavonoids such as mulberry leaves, kudzu vine, and cinnamon, and combining them with special microbial combinations such as Eurotium cristatum, Lactobacillus acidophilus, and Geotrichum candidum, so that the content of flavonoids in the extract is significantly increased. During the fermentation process, secondary metabolites produced by microorganisms, such as enzymes and organic acids, can affect the release and conversion of flavonoids and optimize their solubility and stability. Enzymes such as cellulase and pectinase produced by Geotrichum candidum directly act on the plant cell wall, making flavonoids easier to extract, increasing the extraction rate of flavonoids, and making the flavonoid components in the extract richer and more diverse.

[0027] 2. There is a synergistic antioxidant effect between the microbial metabolites and plant flavonoids in the composite plant fermentation extract. The antioxidant substances produced by microorganisms and plant flavonoids work together in the extract to form a powerful antioxidant system. This synergistic effect not only enhances the antioxidant capacity of the extract, making it more resistant to oxidative stress factors such as free radicals, but also may give it a wider range of biological activity.

[0028] 3. The compound plant fermentation extract has a wide range of biological activities because it is rich in a variety of flavonoids and microbial metabolites. Flavonoids themselves have a variety of biological activities, such as anti-oxidation, anti-inflammatory, and anti-tumor, and microbial metabolites may also have similar biological activities. The synergistic effect between the two makes the extract more diverse and comprehensive in terms of biological activity. This wide and diverse biological activity makes the compound plant fermentation extract have broad application prospects in the fields of health products, functional foods, etc. DETAILED DESCRIPTION

[0029] The present application is further described in detail below with reference to the embodiments.

[0030] The raw materials used in the following examples and comparative examples are all commercially available products.

[0031] The following are some sources of raw materials: Eurotium cristatum was purchased from Wuhan Huizao Biotechnology Co., Ltd. and C426.

[0032] Lactobacillus acidophilus was purchased from Wuhan Huizao Biotechnology Co., Ltd. and BIOMA 5800.

[0033] Geotrichum candidum was purchased from Ningbo Mingzhou Biotechnology Co., Ltd., BMZ135236.

[0034] Aspergillus niger was purchased from Ningbo Testo Biotechnology Co., Ltd., TS277286.

[0035] Lactobacillus plantarum was purchased from Ningbo Testo Biotechnology Co., Ltd., FRI2008085 B468 Cellulase was purchased from Zhejiang Yicun Biotechnology Co., Ltd. Example 1

[0036] A method for preparing a composite plant fermentation extract comprises the following steps: Step 1: Use clean water to clean the mulberry leaves, kudzu root and cinnamon, and wash away the dust and other dirt on the surface. Then put the mulberry leaves, kudzu root and cinnamon into the grinder and grind them into 1-5mm.

[0037] The mass ratio of mulberry leaves, kudzu vine and cinnamon is 7:3:1.

[0038] In the present embodiment, the amount of mulberry leaves is 7 kg, the amount of kudzu root is 3 kg, and the amount of cinnamon bark is 1 kg.

[0039] The crushed mulberry leaves, kudzu vine root and cinnamon bark are mixed with water in a ratio of 1:2 to obtain a material to be fermented.

[0040] Step 2: Cook the fermented material at 120° C. for 30 min to obtain a cooking mixture.

[0041] Step 3: Cool the cooked mixture to 28°C.

[0042] Then, Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum are added into the cooking mixture, the mixture is kept at 28° C., stirred and mixed, and soaked and fermented for 7 days to obtain a fermentation mixture.

[0043] The total mass of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 0.03% of the total mass of mulberry leaves, Pueraria lobata and cinnamon bark.

[0044] The mass ratio of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 1:0.2:0.2.

[0045] Step 4: Sterilize the fermentation mixture at 80°C for 8 minutes.

[0046] The sterilized fermentation mixture is centrifuged, and the supernatant is collected to obtain a composite plant fermentation extract. Example 2

[0047] A method for preparing a composite plant fermentation extract comprises the following steps: Step 1: Use clean water to clean the mulberry leaves, kudzu root and cinnamon, and wash away the dust and other dirt on the surface. Then put the mulberry leaves, kudzu root and cinnamon into the grinder and grind them into 1-5mm.

[0048] The mass ratio of mulberry leaves, kudzu vine and cinnamon is 6:4:1.5.

[0049] In the present embodiment, the amount of mulberry leaves is 6 kg, the amount of kudzu root is 4 kg, and the amount of cinnamon bark is 1.5 kg.

[0050] The crushed mulberry leaves, kudzu vine root and cinnamon bark are mixed with water in a ratio of 1:1 to obtain a material to be fermented.

[0051] Step 2: Cook the fermented material at 110° C. for 40 minutes to obtain a cooking mixture.

[0052] Step 3: Cool the cooked mixture to 30°C.

[0053] Then, Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum are added into the cooking mixture, the mixture is kept at 30° C., stirred and mixed, and soaked and fermented for 5 days to obtain a fermentation mixture.

[0054] The total mass of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 0.05% of the total mass of mulberry leaves, Pueraria lobata and cinnamon bark.

[0055] The mass ratio of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 1:0.1:0.3.

[0056] Step 4: Sterilize the fermentation mixture at 75°C for 10 min.

[0057] The sterilized fermentation mixture is centrifuged, and the supernatant is collected to obtain a composite plant fermentation extract. Example 3

[0058] A method for preparing a composite plant fermentation extract comprises the following steps: Step 1: Use clean water to clean the mulberry leaves, kudzu root and cinnamon, and wash away the dust and other dirt on the surface. Then put the mulberry leaves, kudzu root and cinnamon into the grinder and grind them into 1-5mm.

[0059] The mass ratio of mulberry leaves, kudzu vine and cinnamon is 8:2:0.5.

[0060] In the present embodiment, the amount of mulberry leaves is 8 kg, the amount of kudzu root is 2 kg, and the amount of cinnamon bark is 0.5 kg.

[0061] The crushed mulberry leaves, kudzu vine root and cinnamon bark are mixed with water in a ratio of 1:3 to obtain a material to be fermented.

[0062] Step 2: Cook the fermented material at 130° C. for 25 min to obtain a cooking mixture.

[0063] Step 3: Cool the cooked mixture to 25°C.

[0064] Then, Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum are added into the cooking mixture, the mixture is kept at 25° C., stirred and mixed, and soaked and fermented for 10 days to obtain a fermentation mixture.

[0065] The total mass of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 0.01% of the total mass of mulberry leaves, Pueraria lobata and cinnamon bark.

[0066] The mass ratio of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 1:0.1:0.3.

[0067] Step 4: Sterilize the fermentation mixture at 85°C for 5 min.

[0068] The sterilized fermentation mixture is centrifuged, and the supernatant is collected to obtain a composite plant fermentation extract. Example 4

[0069] A method for preparing a composite plant fermentation extract comprises the following steps: Step 1: Use clean water to clean the mulberry leaves, kudzu root and cinnamon, and wash away the dust and other dirt on the surface. Then put the mulberry leaves, kudzu root and cinnamon into the grinder and grind them into 1-5mm.

[0070] The mass ratio of mulberry leaves, kudzu vine and cinnamon is 1:7:3.

[0071] In the present embodiment, the amount of mulberry leaves is 1 kg, the amount of kudzu root is 7 kg, and the amount of cinnamon bark is 3 kg.

[0072] The crushed mulberry leaves, kudzu vine root and cinnamon bark are mixed with water in a ratio of 1:2 to obtain a material to be fermented.

[0073] Step 2: Cook the fermented material at 120° C. for 30 min to obtain a cooking mixture.

[0074] Step 3: Cool the cooked mixture to 28°C.

[0075] Then, Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum are added into the cooking mixture, the mixture is kept at 28° C., stirred and mixed, and soaked and fermented for 7 days to obtain a fermentation mixture.

[0076] The total mass of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 0.03% of the total mass of mulberry leaves, Pueraria lobata and cinnamon bark.

[0077] The mass ratio of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 1:0.2:0.2.

[0078] Step 4: Sterilize the fermentation mixture at 80°C for 8 minutes.

[0079] The sterilized fermentation mixture is centrifuged, and the supernatant is collected to obtain a composite plant fermentation extract. Example 5

[0080] A method for preparing a composite plant fermentation extract comprises the following steps: Step 1: Use clean water to clean the mulberry leaves, kudzu root and cinnamon, and wash away the dust and other dirt on the surface. Then put the mulberry leaves, kudzu root and cinnamon into the grinder and grind them into 1-5mm.

[0081] The mass ratio of mulberry leaves, kudzu vine and cinnamon is 7:3:1.

[0082] In the present embodiment, the amount of mulberry leaves is 7 kg, the amount of kudzu root is 3 kg, and the amount of cinnamon bark is 1 kg.

[0083] The crushed mulberry leaves, kudzu vine root and cinnamon bark are mixed with water in a ratio of 1:2 to obtain a material to be fermented.

[0084] Step 2: Cook the fermented material at 120° C. for 30 min to obtain a cooking mixture.

[0085] Step 3: Cool the cooked mixture to 28°C.

[0086] Then, Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum are added into the cooking mixture, the mixture is kept at 28° C., stirred and mixed, and soaked and fermented for 7 days to obtain a fermentation mixture.

[0087] The total mass of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 0.03% of the total mass of mulberry leaves, Pueraria lobata and cinnamon bark.

[0088] The mass ratio of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 0.3:1:0.1.

[0089] Step 4: Sterilize the fermentation mixture at 80°C for 8 minutes.

[0090] The sterilized fermentation mixture is centrifuged, and the supernatant is collected to obtain a composite plant fermentation extract.

[0091] Comparative Example 1 A method for preparing a composite plant fermentation extract, which is different from Example 1 in that mulberry leaves are replaced by liquorice.

[0092] Comparative Example 2 A method for preparing a composite plant fermentation extract, which is different from Example 1 in that Pueraria lobata is replaced by Chinese yam.

[0093] Comparative Example 3 A method for preparing a composite plant fermentation extract, which is different from Example 1 in that cinnamon is replaced by hawthorn.

[0094] Comparative Example 4 A method for preparing a composite plant fermentation extract, which is different from Example 1 in that Pueraria lobata and cinnamon bark are replaced by mulberry leaves.

[0095] Comparative Example 5 A method for preparing a composite plant fermentation extract, which is different from that of Example 1 in that Aspergillus niger is replaced by Eurotium cristatum.

[0096] Comparative Example 6 A method for preparing a composite plant fermentation extract, which is different from that of Example 1 in that Lactobacillus acidophilus is replaced by Lactobacillus plantarum.

[0097] Comparative Example 7 A method for preparing a composite plant fermentation extract, which is different from Example 1 in that Geotrichum candidum is replaced by cellulase.

[0098] Comparative Example 8 A method for preparing a composite plant fermentation extract, which is different from that of Example 1 in that Lactobacillus acidophilus and Geotrichum candidum are replaced by Eurotium cristatum.

[0099] Comparative Example 9 A method for preparing a composite plant fermentation extract, which is different from that of Example 1 in that Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum are replaced by Lactobacillus plantarum.

[0100] 1. Total flavonoids content: Accurately weigh 20 mg of rutin reference substance dried to constant weight at 105°C, dissolve it in 60% ethanol, and dilute to 100 mL as the reference substance stock solution. According to the NaNO2-Al(NO3)3-NaOH system complex chemical method, with the reagent blank as the reference, draw a rutin standard curve at 510 nm, and the linear equation is: A=0.0109C-0.012 (C: concentration, mg·mL -1 ; A: absorbance value), R=0.9997.

[0101] 1.0 mL of the composite plant fermentation extracts of Examples 1-5 and Comparative Examples 1-9 were taken respectively, diluted to 10 mL, and the absorbance was measured at 510 nm according to the working curve method to calculate the total flavonoid yield. The total flavonoid yield was recorded in Table 1.

[0102]

[0103] Where: C is the mass concentration of flavonoids in the extract, mg·mL -1; V is the total volume of the extract, mL; M is the dry mass of the substance to be tested, g 2. Antioxidant performance: DPPH free radical inhibition rate test Weigh 0.5 g of the composite plant fermentation extracts of Examples 1-5 and Comparative Examples 1-9, respectively, dissolve them in pure water, and transfer them to a 100 mL volumetric flask to make up to volume. Prepare a 5.00 × 10 -3 g / mL of sample solution.

[0104] Pipette 3 mL of the sample solution to be tested into a 10 mL volumetric flask, then add 3 mL of a 2×10 -4 g / mL DPPH solution. Cover the stopper, shake well, react for 30 minutes, and measure the absorbance A at 517nm i ; Determine the absorbance A of 3mL sample solution and 3mL ethanol mixture j ; The concentration of 3mL was determined to be 2×10 -4 The absorbance A0 after mixing DPPH solution of 0.05 g / mL with 3 mL of pure water.

[0105] According to the formula P = [1-(A i -A j ) / A0]×100%, and the measured absorbance was substituted into the inhibitory rate of the test solution on DPPH· free radicals.

[0106] The inhibition rates are recorded in Table 1.

[0107] Table 1

[0108] Comparative Examples 1-3 are based on Example 1, and any of the mulberry leaves, kudzu vine and cinnamon are replaced with other plants; Comparative Example 4 is based on Example 1, and kudzu vine and cinnamon are replaced with mulberry leaves, that is, flavonoids are only extracted from mulberry leaves. According to the comparison of the test data in Table 1, the total flavonoid content of Comparative Examples 1-4 is not as high as that of Example 1, and the inhibition rate of DPPH free radicals in Comparative Examples 1-4 is also far less than that of Example 1.

[0109] Comparative Examples 5-7 are based on Example 1, and any of them replaces Eurotium guanidinum, Lactobacillus acidophilus, and Geotrichum candidum with other microorganisms; Comparative Example 8 is based on Example 1, and Lactobacillus acidophilus and Geotrichum candidum are replaced by Eurotium guanidinum, that is, only the microorganism of Eurotium guanidinum is contained; Comparative Example 9 is based on Example 1, and Eurotium guanidinum, Lactobacillus acidophilus, and Geotrichum candidum are replaced by Lactobacillus plantarum, that is, only Lactobacillus plantarum is contained. According to the test data in Table 1, after destroying the special combination of Eurotium guanidinum, Lactobacillus acidophilus, and Geotrichum candidum, the total flavonoid content of the obtained composite plant fermentation extract is not as high as that of Example 1, and the antioxidant performance is not as good as that of Example 1.

[0110] This indicates that after destroying the plant raw material combination of mulberry leaves, kudzu vine and cinnamon bark or destroying the microbial combination of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum, the synergistic effect is destroyed, making it impossible to effectively increase the flavonoid content of the prepared composite plant fermentation extract, and the antioxidant property is also poor.

[0111] Example 4 is based on Example 1, and the proportion of mulberry leaves, kudzu vine and cinnamon is changed; Example 5 is based on Example 1, and the proportion of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is changed. According to the test data in Table 1, the total flavonoids content and free radical inhibition rate of Example 4 and Example 5 are reduced. It means that if the proportion of mulberry leaves, kudzu vine and cinnamon can be further limited or the proportion of Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum can be further limited, the synergistic effect between plants and microorganisms can be better, thereby further improving the performance of the composite plant fermentation extract.

[0112] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing a composite plant fermentation extract, characterized in that: The following steps are involved: Step 1: Crush mulberry leaves, kudzu root and cinnamon bark and mix with water to obtain a product to be fermented; Step 2: cooking the fermented material at 110-130° C. for 25-40 minutes to obtain a cooking mixture; Step 3: Cool the cooking mixture to 25-30° C., add Eurotium cristatum, Lactobacillus acidophilus, and Geotrichum candidum into the cooking mixture, stir and mix, and soak and ferment for 5-10 days to obtain a fermentation mixture; Step 4: sterilize and centrifuge the fermentation mixture, collect the supernatant, and obtain the composite plant fermentation extract.

2. The method for preparing the composite plant fermentation extract according to claim 1, characterized in that: The mass ratio of the mulberry leaf, kudzu vine and cinnamon bark is (6-8): (2-4): (0.5-1.5).

3. The method for preparing the composite plant fermentation extract according to claim 1, characterized in that: The mass ratio of the Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 1:(0.1-0.3):(0.1-0.3).

4. The method for preparing the composite plant fermentation extract according to claim 1, characterized in that: The total mass of the Eurotium cristatum, Lactobacillus acidophilus and Geotrichum candidum is 0.01-0.05% of the total mass of the mulberry leaves, Pueraria lobata and cinnamon bark.

5. The method for preparing the composite plant fermentation extract according to claim 1, characterized in that: In the step 1, the total mass of mulberry leaves, kudzu vine and cinnamon bark to the mass of water is 1:(1-3).

6. The method for preparing the composite plant fermentation extract according to claim 1, characterized in that: The sterilization conditions of step 4 are 75-85° C. and 5-10 min.

7. The method for preparing the composite plant fermentation extract according to claim 1, characterized in that: The mulberry leaves, kudzu vine root and cinnamon bark are crushed into 1-5 mm.

8. A composite plant fermentation extract obtained by the preparation method of the composite plant fermentation extract according to any one of claims 1 to 7.

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