Preparation process and application of cold-soluble mulberry leaf extract

Abstract

The invention discloses a preparation process and application of a cold-soluble mulberry leaf extract, and relates to the technical field of mulberry leaf extract. The preparation process comprises the following steps: washing mulberry leaf blades, naturally air-drying them, freezing them in a freezing chamber, taking them out and performing vacuum sublimation to obtain mulberry leaf skeletons; placing the mulberry leaf skeletons in a vacuum impregnation box filled with ethanol and hydroxypropyl beta-cyclodextrin, introducing carbon dioxide gas into the impregnation box, adjusting the pressure of the impregnation box to 8-10MPa and the temperature to 35 DEG C, maintaining the pressure and heat, adjusting the pressure to below 5MPa, and obtaining slurry and mulberry leaf residual skeletons after ultrasonic oscillation; filtering, freeze-drying and sterilizing the slurry after collection to obtain the cold-soluble mulberry leaf extract; the mulberry leaf extract prepared by the method has high extraction rate of active components, high activity and good solubility, and can be applied to beverages as a nutritional additive.

Description

Technical Field

[0001] The invention relates to the technical field of mulberry leaf extracts, and in particular to a preparation process and application of a cold-soluble mulberry leaf extract. Background Art

[0002] Mulberry leaf extract is a natural substance obtained from the leaves of mulberry trees through a series of extraction and separation technologies. Mulberry leaf extract is rich in a variety of physiologically active ingredients, which give mulberry leaf extract a variety of pharmacological and biological activities, making it widely used in medicine, food, health products and cosmetics. For example, the flavonoids in it have multiple biological activities such as antioxidant, anti-inflammatory and antibacterial, which can protect the cardiovascular system and prevent arteriosclerosis and heart disease; DNJ (1-deoxynojirimycin) can inhibit the activity of disaccharide degrading enzymes, thereby inhibiting the absorption of disaccharides by the small intestine, which helps to lower postprandial blood sugar levels; polyphenol compounds also have antioxidant effects, can neutralize free radicals, slow down the cell aging process, and have anti-aging effects. Based on this, adding mulberry leaf extract as a nutritional additive to beverages has also become an important development.

[0003] The preparation process of mulberry leaf extract has a decisive influence on the quality of mulberry leaf extract. In the prior art, there are many types of mulberry leaf extract extraction, but basically all of them are to dissolve and extract after the mulberry leaves are crushed. Extraction after the mulberry leaves are crushed may not only damage the structure of the effective ingredients in the extract, but also be unfavorable for solid-liquid separation, resulting in a limited extraction rate of the mulberry leaf extract. At the same time, the water solubility of DNJ in the effective ingredient is poor, resulting in poor solubility of the mulberry leaf extract, which is not conducive to adding it to liquid beverages for use. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation process and application of a cold-soluble mulberry leaf extract to solve the following technical problems:

[0005] How to improve the extraction rate and water solubility of mulberry leaf extract.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] In a first aspect, the present invention discloses a preparation process and application of a cold-soluble mulberry leaf extract, comprising the following steps:

[0008] The first step is to select fresh mulberry leaves, wash the leaves, air-dry them naturally, and then place them in a freezer at -24°C to -10°C for 4-5 hours. After taking them out, place them in a sealed container, evacuate the sealed container with a vacuum pump, and then let them stand for 1-1.5 hours. During this process, the moisture in the mulberry leaves is completely sublimated to obtain a mulberry leaf skeleton with moisture removed.

[0009] During this process, the water in the mulberry leaf skeleton is extracted, leaving internal water channels empty and presenting gaps at multiple locations; the active ingredients in the mulberry leaf blade remain in the mulberry leaf cells in the mulberry leaf skeleton to be extracted.

[0010] The second step is to place the mulberry leaf skeleton in a vacuum impregnation box filled with ethanol and hydroxypropyl-beta-cyclodextrin, and introduce carbon dioxide gas into the impregnation box at a rate of 80-120L / min. At the same time, adjust the pressure of the impregnation box to 8-10MPa and the temperature to 35°C, and maintain the pressure and temperature for 25-35min. After the end, adjust the pressure to below 5MPa to release carbon dioxide, and then transfer it to an ultrasonic water bath oscillator and oscillate ultrasonically at 5MHz-10MHz for 5-10min. After the end, obtain a slurry and a residual mulberry leaf skeleton.

[0011] In this process, under a pressure of 8-10MPa, ethanol first enters the gaps in the mulberry leaf skeleton, and with the action of pressure, the cell walls of the mulberry leaf cells are squeezed, thereby releasing the active substances inside. At the same time, carbon dioxide is converted into a supercritical state under this temperature and pressure. At this time, the role of ethanol is transformed into an entrainer, which is beneficial for the supercritical carbon dioxide to capture and dissolve the released active substances. In the process of cell wall squeezing, the hydroxypropyl-beta-cyclodextrin in ethanol moves to the rupture of the cell wall, keeps the rupture open, and continuously releases the active substances, which is beneficial to improve the extraction rate of the active substances.

[0012] When the active substance is almost completely released, ultrasonic oscillation is performed. On the one hand, the vibration trapped in the cell wall crack can be separated and enter the ethanol solution. On the other hand, the active substance contains an important sugar-inhibiting component DNJ (1-deoxynojirimycin). Hydroxypropyl beta-cyclodextrin can be used as an inclusion agent for DNJ. During the ultrasonic vibration process, DNJ enters into hydroxypropyl beta-cyclodextrin, achieving an inclusion effect, which is beneficial to improving the water solubility of DNJ.

[0013] Furthermore, the dosage ratio of the mulberry leaf blade, ethanol and hydroxypropyl beta-cyclodextrin is 1g:(100-200)mL:(0.01-0.03)g, preferably 1g:150mL:0.2g.

[0014] Furthermore, the mass fraction of the ethanol is 50%-65%, preferably 60%.

[0015] The third step is to collect the slurry obtained in step S2, and repeat the process of step S2 1-2 times for the residual skeleton of mulberry leaves. Hydroxypropyl beta-cyclodextrin is not added during the repeated process, and the slurry obtained each time is combined as a crude liquid.

[0016] The residual skeleton of the mulberry leaf still retains the overall structure of the mulberry leaf. The fiber and other impurity components are retained on a large scale on the residual skeleton and can be completely separated from the slurry, which is beneficial to improve the purity of the active substances in the slurry.

[0017] After one separation, a small amount of active substance still remains in the residual skeleton of the mulberry leaf, so repeated extraction is required. After many experiments, the active substance almost no longer appears after 1-2 extractions of the residual skeleton of the mulberry leaf obtained in step S2. Only a small amount of active substance appears when repeated for the second time. Considering the operation time and operation cost, the optimal number of repeated extractions is determined to be 1 time.

[0018] The fourth step is to filter the crude liquid using a nanofiltration membrane with a pore size of 5000D, and then transfer the filter material to a freezer and freeze it at -30°C to -20°C for 0.5-1h, and then transfer it to a freeze dryer for freeze drying. After completion, sterilize it by radiation sterilization to obtain a cold-soluble mulberry leaf extract.

[0019] Furthermore, the specific steps of freeze drying in a freeze dryer are: first freeze drying at -20°C to -10°C for 1-2h, then heating to 10-20°C and drying for 30-60min.

[0020] In a second aspect, the present invention also discloses an application of the cold-soluble mulberry leaf extract as described above, wherein the cold-soluble mulberry leaf extract is used in beverages, including liquid beverages, solid beverages, etc. Adding the cold-soluble mulberry leaf extract as a nutrient to the beverage can enhance the sugar-suppressing effect of the beverage, making it healthier and safer.

[0021] The active substances in the cold-soluble mulberry leaf extract include DNJ, total brass, polyphenols, etc., which have health benefits such as lowering blood pressure and blood sugar, delaying aging, etc.; the DNJ therein is generally poorly soluble, while the DNJ in the cold-soluble mulberry leaf extract of the present invention is externally encapsulated with hydroxypropyl beta-cyclodextrin, which is easily soluble in water and can be used as a food additive, thus helping to dissolve DNJ in various beverages and achieve better application effects.

[0022] Beneficial effects of the present invention:

[0023] 1. In the preparation process of the cold-soluble mulberry leaf extract of the present invention, the water in the mulberry leaf is sublimated and separated, and the complete mulberry leaf skeleton is retained. Due to the extraction of water in the mulberry leaf skeleton, the internal water channels are emptied, presenting gaps at multiple sites; the active ingredients in the mulberry leaf blade are retained in the mulberry leaf cells in the mulberry leaf skeleton to be extracted; then the cell wall is squeezed by pressure to release the active substances, and dissolved in combination with supercritical carbon dioxide. The whole process does not require the mulberry leaf to be crushed, and the overall skeleton fiber of the mulberry leaf can be retained to the greatest extent, which is convenient for the subsequent separation of the extract and the mulberry leaf, and prevents the inactive components from being mixed into the extract during the extraction process, thereby improving the extraction rate of the effective ingredients in the extract.

[0024] 2. In the preparation process of the cold-soluble mulberry leaf extract of the present invention, an appropriate amount of hydroxypropyl-beta-cyclodextrin is added in the process of dissolving the effective ingredients. In the process of bursting the mulberry leaf cell wall, the hydroxypropyl-beta-cyclodextrin in the ethanol moves to the rupture of the cell wall and keeps the rupture open, so that the active substance is continuously released, which is beneficial to improve the extraction rate of the active substance; at the same time, hydroxypropyl-beta-cyclodextrin can form an inclusion effect with the released effective ingredient DNJ, thereby improving the solubility performance of the extract, so that it can be better used for adding to beverages.

[0025] 3. In the preparation process of the cold-soluble mulberry leaf extract of the present invention, low-temperature extraction is adopted throughout the process, which will not destroy the activity of the effective ingredients in the mulberry leaf extract. In addition, supercritical carbon dioxide dissolution and ethanol as an entrainer are adopted, which is more environmentally friendly and will not produce pollutants and impurities. Green preparation can be achieved, and the preparation process is simple to operate, which is conducive to batch extraction. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The experimental methods in the following examples, unless otherwise specified, are conventional methods, and are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources. For example, the following mulberry leaves are purchased from Yanda Market, hydroxypropyl beta-cyclodextrin is purchased from Shanghai Yihe Biotechnology Co., Ltd., and ethanol solutions of different mass fractions are prepared by themselves.

[0028] Example 1

[0029] Preparation of cold-soluble mulberry leaf extract:

[0030] Step 1. Weigh 5g of fresh mulberry leaves, wash them, air-dry them naturally, and then place them in a freezer at -18°C for 4.5 hours. Take them out and place them in a sealed glass cup. Use a vacuum pump to evacuate the sealed glass cup and let it stand for 1.2 hours. After completion, the mulberry leaf skeleton with moisture removed is obtained.

[0031] Step 2: Add 750 mL of 60% ethanol solution into the vacuum impregnation box, add 0.1 g of hydroxypropyl beta-cyclodextrin, and then immerse the mulberry leaf skeleton. After vacuum sealing, introduce carbon dioxide gas into the impregnation box at 100 L / min. At the same time, adjust the pressure of the impregnation box to 9 MPa and the temperature to 35°C. Maintain the pressure and heat for 30 minutes. After the end, adjust the pressure to 4 MPa to release carbon dioxide. Then transfer the solution and mulberry leaf skeleton in the vacuum impregnation box to an ultrasonic water bath oscillator and ultrasonically oscillate at 8 MHz for 8 minutes. After the end, obtain a slurry and a residual mulberry leaf skeleton.

[0032] Step three, collect the slurry in step two into a bottle, repeat the operation of step two on the residual skeleton of mulberry leaves, but do not add hydroxypropyl beta-cyclodextrin during the repeating process, combine the obtained slurry into a bottle as a crude liquid, and discard the obtained residual skeleton of mulberry leaves.

[0033] Step 4: Filter the crude liquid using a nanofiltration membrane with a pore size of 5000D, then transfer the filter material to a freezer and freeze it at minus 25°C for 40 minutes, then transfer it to a freeze dryer, first freeze-dry it at minus 15°C for 1.5 hours, then heat it to 15°C and dry it for 40 minutes, then transfer it to an electron beam radiation sterilization device for sterilization for 30 minutes to obtain 0.46 g of cold-soluble mulberry leaf extract.

[0034] Example 2

[0035] Preparation of cold-soluble mulberry leaf extract:

[0036] Step 1. Weigh 5g of fresh mulberry leaves, wash them, air-dry them naturally, and then place them in a freezer at -10°C for 5 hours. Take them out and place them in a sealed glass cup. Use a vacuum pump to evacuate the sealed glass cup and let it stand for 1 hour. After completion, you will get a mulberry leaf skeleton with moisture removed.

[0037] Step 2: Add 500 mL of 50% ethanol solution into the vacuum impregnation box, add 0.05 g of hydroxypropyl beta-cyclodextrin, and then immerse the mulberry leaf skeleton. After vacuum sealing, introduce carbon dioxide gas into the impregnation box at 80 L / min. At the same time, adjust the pressure of the impregnation box to 8 MPa and the temperature to 35°C. Maintain the pressure and heat for 35 minutes. After the end, adjust the pressure to 4 MPa to release carbon dioxide. Then transfer the solution and mulberry leaf skeleton in the vacuum impregnation box to an ultrasonic water bath oscillator and oscillate at 5 MHz for 10 minutes. After the end, obtain a slurry and a residual mulberry leaf skeleton.

[0038] Step three, collect the slurry in step two into a bottle, repeat the operation of step two on the residual skeleton of mulberry leaves, but do not add hydroxypropyl beta-cyclodextrin during the repeating process, combine the obtained slurry into a bottle as a crude liquid, and discard the obtained residual skeleton of mulberry leaves.

[0039] Step 4: Filter the crude liquid using a nanofiltration membrane with a pore size of 5000D, then transfer the filter material to a freezer and freeze it at minus 20°C for 1 hour, then transfer it to a freeze dryer, first freeze-dry it at minus 10°C for 2 hours, then heat it to 10°C and dry it for 60 minutes, then transfer it to an electron beam radiation sterilization device for sterilization for 30 minutes to obtain 0.45g of cold-soluble mulberry leaf extract.

[0040] Example 3

[0041] Preparation of cold-soluble mulberry leaf extract:

[0042] Step 1: Weigh 5g of fresh mulberry leaves, wash them, air-dry them naturally, and then place them in a freezer at -24°C for 4 hours. Take them out and place them in a sealed glass cup. Use a vacuum pump to evacuate the sealed glass cup and let it stand for 1 hour. After completion, you will get a mulberry leaf skeleton with moisture removed.

[0043] Step 2: Add 1000 mL of 70% ethanol solution into the vacuum impregnation box, add 0.15 g of hydroxypropyl beta-cyclodextrin, and then immerse the mulberry leaf skeleton. After vacuum sealing, introduce carbon dioxide gas into the impregnation box at a rate of 120 L / min. At the same time, adjust the pressure of the impregnation box to 10 MPa and the temperature to 35°C. Maintain the pressure and heat for 25 minutes. After the end, adjust the pressure to 4 MPa to release carbon dioxide. Subsequently, transfer the solution and the mulberry leaf skeleton in the vacuum impregnation box to an ultrasonic water bath oscillator and ultrasonically oscillate at 10 MHz for 5 minutes. After the end, obtain a slurry and a residual mulberry leaf skeleton.

[0044] Step three, collect the slurry in step two into a bottle, repeat the operation of step two on the residual skeleton of mulberry leaves, but do not add hydroxypropyl beta-cyclodextrin during the repeating process, combine the obtained slurry into a bottle as a crude liquid, and discard the obtained residual skeleton of mulberry leaves.

[0045] Step 4: Filter the crude liquid using a nanofiltration membrane with a pore size of 5000D, then transfer the filter material to a freezer and freeze it at minus 30°C for 30 minutes, then transfer it to a freeze dryer, first freeze-dry it at minus 20°C for 1 hour, then heat it to 20°C and dry it for 30 minutes, then transfer it to an electron beam radiation sterilization device for sterilization for 30 minutes to obtain 0.44 g of cold-soluble mulberry leaf extract.

[0046] Comparative Example 1

[0047] Compared with Example 1, the only difference is that in step 1, the mulberry leaves are washed and naturally air-dried without subsequent operations and step 2 is directly performed. Other conditions are exactly the same, and finally 0.35 g of cold-soluble mulberry leaf extract is obtained.

[0048] Comparative Example 2

[0049] Compared with Example 1, the only difference is that hydroxypropyl-beta-cyclodextrin is not added in step 2, and other conditions are exactly the same, and finally 0.31 g of cold-soluble mulberry leaf extract is obtained.

[0050] Comparative Example 3

[0051] Compared with Example 1, the only difference is that no ultrasonic oscillation is performed after releasing carbon dioxide in step 2, and other conditions are exactly the same, and finally 0.29 g of cold-soluble mulberry leaf extract is obtained.

[0052] Comparative Example 4

[0053] Compared with Example 1, the only difference is that in step 2, the pressure of the impregnation box is changed from 9 MPa to 7 MPa, and other conditions are exactly the same, and finally 0.25 g of cold-soluble mulberry leaf extract is obtained.

[0054] Comparative Example 5

[0055] Compared with Example 1, the only difference is that in step 2, the pressure of the impregnation box is changed from 9 MPa to 11 MPa, and other conditions are exactly the same, and finally 0.42 g of cold-soluble mulberry leaf extract is obtained.

[0056] The contents of active substance DNJ, total flavonoids and polyphenols in the cold-soluble mulberry leaf extracts prepared in Examples 1-3 and Comparative Examples 1-5 were tested, and the test results are listed in Table 1. Table 1 is as follows:

[0057]

[0058] By analyzing the data in Table 1, it can be seen that in the cold-soluble mulberry leaf extracts prepared in Examples 1-3, the contents of DNJ, total flavonoids and polyphenols are all at a high level, and the contents are significantly higher than those in Comparative Examples 1-5, which indicates that the preparation method of the cold-soluble mulberry leaf extract of the present invention has a higher extraction rate for these active components.

[0059] Specifically:

[0060] Compared with Example 1, the content of each active substance in Comparative Example 1 is significantly reduced. The reason may be that the water in the mulberry leaves is not vacuum sublimated, resulting in water remaining in the water channel, which affects the supercritical carbon dioxide, ethanol and hydroxypropyl beta-cyclodextrin entering the channel in the subsequent extraction process to deeply contact and dissolve the released active components;

[0061] Compared with Example 1, the content of each active substance in Comparative Example 2 was significantly reduced. The reason may be that hydroxypropyl-beta-cyclodextrin was not used to support the cracked cell wall, resulting in partial cell wall closure after cracking, thus affecting the release of the active substance.

[0062] Compared with Example 1, the content of each active substance in Comparative Example 3 was significantly reduced, which may be due to the lack of ultrasonic vibration, resulting in some active substances remaining in the mulberry leaf skeleton;

[0063] Compared with Example 1, the content of each active substance in Comparative Example 4 is significantly reduced. The reason may be that the pressure in the impregnation box is too low, resulting in insufficient pressure to break the cell wall of the mulberry leaves, and some cell walls are not completely broken, so the active substances therein cannot be released.

[0064] Compared with Example 1, the content of each active substance in Comparative Example 5 is significantly reduced. The reason may be that the pressure in the impregnation box is too high, which causes the structure of hydroxypropyl-beta-cyclodextrin to be destroyed, so it cannot play a supporting role at the rupture of the mulberry leaf cell wall.

[0065] The glucose inhibition ability of the cold-soluble mulberry leaf extracts prepared in Examples 1-3 and Comparative Examples 1-5 was tested, and the test methods included enzyme inhibition test and antioxidant activity test, as follows:

[0066] Enzyme inhibition experiment: maltase was selected as the experimental object, and a mixed reaction of mulberry leaf extract solution and enzyme solution was set up. The concentration change of substrate or product before and after the reaction was measured to calculate the enzyme activity inhibition rate.

[0067] Antioxidant activity experiment: ABTS+ free radicals were mixed with mulberry leaf extract solution to react, and the free radical scavenging rate was calculated by measuring the change in free radical concentration before and after the reaction.

[0068] The test results are listed in Table 2, which is as follows:

[0069]

[0070] By analyzing the data in Table 2, it can be seen that the cold-soluble mulberry leaf extracts prepared in Examples 1-3 have significantly higher sugar inhibition rates and free radical scavenging rates than those in Comparative Examples 1-5, which indicates that the active ingredients in the cold-soluble mulberry leaf extracts prepared by the method of the present invention have higher activity.

[0071] By comparing the data in Table 2 with the data in Table 1, it can be seen that the test results of Examples 1-3 and Comparative Examples 1-4 correspond to each other, which indicates that the activity of the active ingredients in the cold-soluble mulberry leaf extract is affected by the content of the active ingredients. However, the activity of the cold-soluble mulberry leaf extract obtained in Comparative Example 5 is significantly worse than the test results of the active component content. This may be because the pressure in the impregnation box is too high, which causes the structure of hydroxypropyl-beta-cyclodextrin to be destroyed and the activity of some active substances is adversely affected.

[0072] The solubility of the cold-soluble mulberry leaf extracts prepared in Examples 1-3 and Comparative Examples 1-5 was tested. The test method was as follows: 8 test tubes were numbered according to Examples 1-3 and Comparative Examples 1-5, 50 mL of water was added to the corresponding test tubes, and then 0.1 g of the prepared cold-soluble mulberry leaf extract was added. After stirring evenly, the solution was allowed to stand for observation, and the solution state was recorded every 5 hours. The recorded results are listed in Table 3. Table 3 is as follows:

[0073]

[0074] By analyzing the observation results in the table, it can be found that, except for Comparative Example 2 and Comparative Example 5, the cold-soluble mulberry leaf extracts prepared in other groups showed good solubility within 25 hours, while Comparative Example 2 and Comparative Example 5 showed incomplete dissolution at 20 hours and 25 hours, respectively. This may be due to the lack of addition of hydroxypropyl beta-cyclodextrin and the inactivation of hydroxypropyl beta-cyclodextrin, resulting in the failure of DNJ to form inclusion complex and insufficient inclusion complex.

[0075] In summary, the cold-soluble mulberry leaf extract prepared by the present invention has a high extraction rate for active ingredients, high activity, and excellent solubility, and can be used as a nutritional additive for beverages.

[0076] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A preparation process of a cold-soluble mulberry leaf extract, characterized in that: The following steps are involved: S1. Wash the mulberry leaves and air-dry them naturally, then place them in a freezer at -24°C to -5°C for 4-5 hours, take them out and perform vacuum sublimation to obtain a mulberry leaf skeleton with water removed; S2, placing the mulberry leaf skeleton in a vacuum impregnation box filled with ethanol and hydroxypropyl beta-cyclodextrin, introducing carbon dioxide gas into the impregnation box, and adjusting the pressure of the impregnation box to 8-10MPa and the temperature to 35°C, maintaining the pressure and temperature for 25-35min, and after the end, adjusting the pressure to below 5MPa to release carbon dioxide, and then ultrasonically oscillating for 5-10min, after the end, obtaining a slurry and a residual mulberry leaf skeleton; S3, collecting the slurry obtained in step S2, repeating the process of step S2 1-2 times for the residual skeleton of mulberry leaves, without adding hydroxypropyl beta-cyclodextrin during the repetition process, and combining the slurry obtained each time as a crude liquid; S4, filtering, freeze-drying and sterilizing the crude liquid to obtain a cold-soluble mulberry leaf extract; In step S1-S2, the ratio of mulberry leaf leaf, ethanol and hydroxypropyl beta-cyclodextrin is 1 g: (100-200) mL: (0.01-0.03) g; In step S1, the method for performing vacuum sublimation is: placing the mulberry leaves taken out from the freezer in a sealed container, evacuating the sealed container using a vacuum pump, and then leaving it to stand for 1-1.5 hours to complete the vacuum sublimation.

2. The preparation process of the cold-soluble mulberry leaf extract according to claim 1, characterized in that: The mass fraction of the ethanol is 50-65%.

3. The preparation process of the cold-soluble mulberry leaf extract according to claim 1, characterized in that: In step S2, the frequency range of the ultrasonic oscillation is 5 MHz-10 MHz.

4. The preparation process of the cold-soluble mulberry leaf extract according to claim 1, characterized in that: In step S4, filtration is performed using a nanofiltration membrane, the pore size of the nanofiltration membrane is 5000D.

5. The preparation process of the cold-soluble mulberry leaf extract according to claim 1, characterized in that: In step S4, freeze drying is performed using a freeze dryer, and the freeze drying steps are: first freeze drying at -20°C - -10°C for 1-2h, then heating to 10°C -20°C and drying for 30min -60min; and pre-cooling and drying is performed before freeze drying, and the pre-cooling and drying temperature is -30°C - -20°C, and the time is 0.5-1h.

6. The preparation process of the cold-soluble mulberry leaf extract according to claim 5, characterized in that: The operation method of the pre-cooling and drying is: freezing the filtered filter material at minus 30° C. to minus 20° C. for 0.5 to 1 hour.

7. The preparation process of the cold-soluble mulberry leaf extract according to claim 1, characterized in that: In step S4, sterilization is performed by radiation sterilization.

8. An application of the cold-soluble mulberry leaf extract according to any one of claims 1 to 7, characterized in that: For beverages.

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