Foporus cyanobacteria extracting solution, preparation method thereof and black tea capable of reducing blood sugar

Abstract

The invention relates to the technical field of health-care products, in particular to a fossilia cyanobacteria extracting solution, a preparation method thereof and black tea capable of reducing blood sugar. The preparation method of the foramen crayfish extracting solution comprises the following steps: (1) mixing foramen crayfish sporocarp with water to obtain a mixture, extracting the mixture for 2-3 times at the temperature of 60-70 DEG C, and combining extracting solutions to obtain an intermediate solution; and (2) concentrating the intermediate liquid to 1 / 3-1 / 5 of the volume of the intermediate liquid to obtain the fossilia cyanobacteria extracting solution. The black tea is prepared by using the fosfoporus cyanobacteria extracting solution disclosed by the invention, and the obtained black tea has the effects of resisting oxidation and reducing blood sugar. And a basis is provided for development of black tea functional food.

Description

Technical Field

[0001] The present invention relates to the technical field of health care products, and particularly relates to an extract of Fomitiporia incarnata, a preparation method thereof, and black tea with blood sugar lowering effect. Background Art

[0002] Black tea has won the love of many consumers with its mellow taste, deep red soup color, and unique aroma. With the improvement of people's living standards and the enhancement of health awareness, more and more consumers pay more attention to the health care effects of black tea.

[0003] Fomitiporia incarnata (scientific name: Fomitiporia) is a genus of fungi belonging to the family Hymenochaetaceae. The latest research found that the fruiting body of Fomitiporia incarnata isolated from Hippophae rhamnoides in the northern part of Shanxi contains 16.10% of protein, 2.14% of crude polysaccharide, and also contains beneficial functional components such as crude fat, amino acids, and triterpenoids.

[0004] There is no prior art report on extracting the beneficial components of Fomitiporia incarnata and adding them to black tea to obtain a tea drink with health care effects.

[0005] In order to better meet the needs of consumers, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide an extract of Fomitiporia incarnata, a preparation method thereof, and black tea with blood sugar lowering effect.

[0007] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a preparation method of an extract of Fomitiporia incarnata, comprising the following steps:

[0009] (1) Mix the fruiting body of Fomitiporia incarnata with water to obtain a mixture, and extract the mixture 2 - 3 times at 60 - 70°C, and combine the extracts to obtain an intermediate liquid;

[0010] (2) Concentrate the intermediate liquid to 1 / 3 - 1 / 5 of the volume of the intermediate liquid to obtain an extract of Fomitiporia incarnata.

[0011] Preferably, the mass ratio of the fruiting body of Fomitiporia incarnata to water in step (1) is 1:5 - 10;

[0012] The vacuum degree during extraction is 50 - 60 kPa, and the extraction time for each time is 30 - 40 min.

[0013] Preferably, the concentration in step (2) is rotary evaporation concentration, the temperature of the concentration is 60 - 70°C, and the vacuum degree of the concentration is 50 - 60 kPa.

[0014] The present invention also provides an Inonotus cyaneus extract prepared by the described preparation method.

[0015] The present invention also provides a hypoglycemic black tea, comprising the following components in parts by mass:

[0016] 3 - 8 parts of Inonotus cyaneus extract and 15 - 20 parts of fresh tea leaves;

[0017] The Inonotus cyaneus extract is the Inonotus cyaneus extract prepared by the described preparation method or the described Inonotus cyaneus extract.

[0018] The present invention also provides a preparation method of a hypoglycemic black tea, comprising the following steps:

[0019] (1) Mix fresh tea leaves with 8 - 10% of the total mass of fresh tea leaves of Inonotus cyaneus extract, and wither for 6 - 8 h to obtain withered tea;

[0020] (2) Mix the withered tea with the remaining Inonotus cyaneus extract, and roll for 40 - 50 min to obtain rolled tea;

[0021] (3) Ferment the rolled tea at a temperature of 26 - 28 °C for 3 - 4 h to obtain fermented tea;

[0022] (4) Dry the fermented tea to obtain the hypoglycemic black tea.

[0023] Preferably, the withering temperature is 30 - 33 °C; the spreading thickness of the tea leaves during withering is 4 - 5 cm;

[0024] The rolling temperature is 30 - 33 °C.

[0025] Preferably, the humidity during fermentation is 90 - 95%; the spreading thickness of the tea leaves during fermentation is 16 - 18 cm.

[0026] Preferably, the drying method is as follows: first, dry the water content of the tea leaves to 28 - 32% at 90 - 100 °C; then, dry the water content of the tea leaves to 10 - 15% at 70 - 80 °C; finally, dry the water content of the tea leaves to less than 8% at 60 - 65 °C.

[0027] The present invention also provides the application of the described hypoglycemic black tea or the hypoglycemic black tea prepared by the described preparation method in the preparation of a health product with hypoglycemic efficacy.

[0028] The present invention provides a Phellinus iguarius extract, a preparation method thereof, and black tea with blood sugar lowering effect. The preparation method of the Phellinus iguarius extract of the present invention comprises the following steps: (1) mixing the fruiting body of Phellinus iguarius with water to obtain a mixture, subjecting the mixture to extraction 2 - 3 times under the condition of 60 - 70 °C, and combining the extraction liquids to obtain an intermediate liquid; (2) concentrating the intermediate liquid to 1 / 3 - 1 / 5 of the volume of the intermediate liquid to obtain the Phellinus iguarius extract. In the present invention, when extracting the effective component content in Phellinus iguarius, it is carried out under the condition of 60 - 70 °C. Under this condition, the effective components in Phellinus iguarius can be retained to the greatest extent, and the efficacy of the extract is guaranteed to the greatest extent. Using the Phellinus iguarius extract of the present invention to prepare black tea, the obtained black tea has the effects of antioxidant and blood sugar lowering. In the preparation process of the black tea with blood sugar lowering effect of the present invention, segmented drying is used. The black tea obtained by this drying method has a rich fragrance, a mellow taste, and excellent sensory effects. Detailed Embodiments

[0029] The present invention provides a preparation method of a Phellinus iguarius extract, comprising the following steps:

[0030] (1) Mixing the fruiting body of Phellinus iguarius with water to obtain a mixture, subjecting the mixture to extraction 2 - 3 times under the condition of 60 - 70 °C, and combining the extraction liquids to obtain an intermediate liquid;

[0031] (2) Concentrating the intermediate liquid to 1 / 3 - 1 / 5 of the volume of the intermediate liquid to obtain the Phellinus iguarius extract.

[0032] In the present invention, the mass ratio of the fruiting body of Phellinus iguarius to water in step (1) is 1:5 - 10, preferably 1:8; in the present invention, the fruiting body of Phellinus iguarius is collected from Hippophae rhamnoides in the Yanbei area, preserved in the General Microbiological Center of the China Committee for Culture Collection of Microorganisms, the preservation address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, the preservation date is December 28, 2016, and the preservation number is CGMCC No. 13380, which has been disclosed in the Chinese patent with the application number 201710040810.3 "New Strain of Phellinus iguarius and Its Domestication Method".

[0033] In the present invention, the temperature of the extraction in step (1) is preferably 62 °C, and the number of extractions is preferably 3 times; the vacuum degree during extraction is 50 - 60 kpa, preferably 55 kpa; the time for each extraction is 30 - 40 min, preferably 35 min.

[0034] In the present invention, the concentration in step (2) is rotary evaporation concentration, the temperature of the concentration is 60 - 70 °C, preferably 65 °C, and the vacuum degree of the concentration is 50 - 60 kpa, preferably 55 kpa.

[0035] The present invention also provides a Phellinus caesius extract prepared by the described preparation method.

[0036] The present invention also provides a hypoglycemic black tea, comprising the following components in parts by mass:

[0037] 3 - 8 parts of Phellinus caesius extract, preferably 5 parts;

[0038] 15 - 20 parts of fresh tea leaves, preferably 18 parts;

[0039] The Phellinus caesius extract is the Phellinus caesius extract prepared by the described preparation method or the described Phellinus caesius extract.

[0040] The present invention also provides a preparation method of a hypoglycemic black tea, comprising the following steps:

[0041] (1) Mix fresh tea leaves with 8 - 10% of the total mass of fresh tea leaves of Phellinus caesius extract, and wither for 6 - 8 h to obtain withered tea;

[0042] (2) Mix the withered tea with the remaining Phellinus caesius extract, and knead for 40 - 50 min to obtain kneaded tea;

[0043] (3) Ferment the kneaded tea at a temperature of 26 - 28 °C for 3 - 4 h to obtain fermented tea;

[0044] (4) Dry the fermented tea to obtain hypoglycemic black tea.

[0045] In the present invention, the withering temperature is 30 - 33 °C, preferably 32 °C; the spreading thickness of tea leaves during withering is 4 - 5 cm, preferably 4.5 cm;

[0046] The kneading temperature is 30 - 33 °C, preferably 32 °C.

[0047] In the present invention, the humidity during fermentation is 90 - 95%, preferably 92%; the spreading thickness of tea leaves during fermentation is 16 - 18 cm, preferably 17 cm.

[0048] In the present invention, the drying method is as follows: first, under the condition of 90 - 100 °C, dry the water content of tea leaves to 28 - 32%; then, under the condition of 70 - 80 °C, dry the water content of tea leaves to 10 - 15%; finally, under the condition of 60 - 65 °C, dry the water content of tea leaves to less than 8%. In the present invention, the preferred temperature for the first drying is 95 °C, the preferred temperature for the second drying is 75 °C, and the preferred temperature for the final drying is 63 °C.

[0049] The present invention also provides the use of the black tea with blood sugar lowering effect or the black tea with blood sugar lowering effect prepared by the preparation method in the preparation of a health product with blood sugar lowering effect.

[0050] The following examples are used to illustrate the solutions provided by the present invention in detail, but they should not be construed as limiting the protection scope of the present invention.

[0051] In the embodiment of the present invention, the fruiting body of Fomitiporia cyanescens is collected from Hippophae rhamnoides in the Yanbei area, preserved in the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, the preservation address is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, the preservation date is December 28, 2016, and the preservation number is CGMCC No. 13380, which has been disclosed in the Chinese patent with the application number 201710040810.3 "New Strain of Fomitiporia cyanescens and Its Domestication Method".

[0052] Example 1

[0053] The fruiting body of Fomitiporia cyanescens is ground and sieved through a 20-mesh sieve to obtain the fruiting body powder of Fomitiporia cyanescens. The fruiting body powder of Fomitiporia cyanescens is mixed with distilled water according to a mass ratio of 1:8, placed under the conditions of a vacuum degree of 55 kPa and a temperature of 62 °C for extraction 3 times, each extraction for 30 min, and the extraction liquids are combined to obtain an intermediate liquid. The intermediate liquid is placed in a rotary evaporator and concentrated to 1 / 3 of the volume of the intermediate liquid under the conditions of a vacuum degree of 55 kPa and a temperature of 62 °C to obtain the extraction liquid of Fomitiporia cyanescens.

[0054] 15 kg of fresh tea leaves are mixed with 1.5 kg of the extraction liquid of Fomitiporia cyanescens, spread on a withering curtain with a thickness of 4 cm, and withered at a temperature of 32 °C for 8 h to obtain withered tea. The withered tea is mixed with 2 kg of the extraction liquid of Fomitiporia cyanescens and kneaded at a temperature of 32 °C for 45 min to obtain kneaded tea. The kneaded tea is spread in a dustpan with a thickness of 16 cm and fermented at a temperature of 27 °C and a humidity of 90% for 3.5 h (stirred once every 1 hour), and when the tea leaves emit a strong fragrance, the fermentation is stopped to obtain fermented tea. The fermented tea is first dried at 100 °C until the water content of the tea leaves is 30%, then dried at 75 °C until the water content of the tea leaves is 15%, and finally dried at 60 °C until the water content of the tea leaves is 6% to obtain the black tea with blood sugar lowering effect.

[0055] Example 2

[0056] Mix 20 kg of fresh tea leaves with 1.6 kg of the Fomitiporia cyanescens extract prepared in Example 1, spread them out on a withering curtain with a thickness of 5 cm, and wither for 8 h at a temperature of 30 °C to obtain withered tea. Mix the withered tea with 1.4 kg of the Fomitiporia cyanescens extract, and knead for 50 min at a temperature of 30 °C to obtain kneaded tea. Spread the kneaded tea in a winnowing basket with a thickness of 18 cm, ferment for 3 h (stir and mix once every hour) at a temperature of 28 °C and a humidity of 95%, stop fermentation when the tea gives off a strong fragrance to obtain fermented tea. First, dry the fermented tea at 90 °C until the water content of the tea leaves reaches 32%, then dry at 80 °C until the water content reaches 12%, and finally dry the tea leaves at 65 °C until the water content is 6% to obtain hypoglycemic black tea.

[0057] Example 3

[0058] Mix 20 kg of fresh tea leaves with 2 kg of the Fomitiporia cyanescens extract prepared in Example 1, spread them out on a withering curtain with a thickness of 4 cm, and wither for 6 h at a temperature of 33 °C to obtain withered tea. Mix the withered tea with 5 kg of the Fomitiporia cyanescens extract, and knead for 40 min at a temperature of 33 °C to obtain kneaded tea. Spread the kneaded tea in a winnowing basket with a thickness of 16 cm, ferment for 4 h (stir and mix once every hour) at a temperature of 26 °C and a humidity of 92%, stop fermentation when the tea gives off a strong fragrance to obtain fermented tea. First, dry the fermented tea at 95 °C until the water content of the tea leaves reaches 30%, then dry at 80 °C until the water content reaches 15%, and finally dry the tea leaves at 60 °C until the water content is 6% to obtain hypoglycemic black tea.

[0059] Comparative Example 1

[0060] Set up the scheme of Comparative Example 1 according to the method of Example 1. Different from Example 1, no Fomitiporia cyanescens extract is added in this Comparative Example 1.

[0061] Experimental Example 1

[0062] Respectively take 1 g of the hypoglycemic black tea obtained in Examples 1 to 3 and Comparative Example 1, add 50 mL of boiling water for brewing, observe the color and aroma of the tea soup of the hypoglycemic black tea after 5 min, and record the taste of the hypoglycemic black tea obtained by different methods. The results are shown in Table 1.

[0063] Detect the polysaccharide content and protein content in the hypoglycemic black tea obtained by different methods. The results are shown in Table 2. The detection method for polysaccharide content is the phenol-sulfuric acid method, and the detection method for protein content is the Coomassie brilliant blue method.

[0064] Table 1 Sensory qualities of the hypoglycemic black tea obtained by different methods

[0065] Group Color and luster Aroma Taste Example 1 Dark red, translucent Sweet fragrance Fresh and sweet Example 2 Dark red, translucent Sweet fragrance Fresh and sweet Example 3 Dark red, translucent Sweet fragrance Fresh and sweet Comparative example 1 Dark red, translucent Light fragrance Fresh, slightly bitter

[0066] It can be seen that the hypoglycemic black tea obtained by the methods of Examples 1 to 3 has a sweet taste and no bitter taste.

[0067] Table 2 Contents of active substances in the tea soup of hypoglycemic black tea obtained by different methods

[0068] Group Polysaccharide content % Protein content % Example 1 3.12±0.34 28.16±1.08 Example 2 2.88±0.26 27.94±0.89 Example 3 3.46±0.42 29.21±0.93 Comparative example 1 1.92±0.17 20.17±0.82

[0069] It can be seen that the polysaccharide content and protein content in the hypoglycemic black tea added with the extract of Fomitiporia cyanescens are higher than those in Comparative Example 1 without adding this extract. This shows that the active ingredients in the black tea obtained after adding Fomitiporia cyanescens are higher.

[0070] Experimental Example 2

[0071] Respectively take 1 g of the hypoglycemic black tea of Example 1 and Comparative Example 1, add 50 mL of boiling water for brewing, and detect the scavenging rate of the tea soup on DPPH after cooling. The specific steps are as follows:

[0072] Experimental group: Take 2 mL of the tea soup and mix it evenly with 2 mL of 95% ethanol solution containing 0.5 mmol / L DPPH, and let it stand for 30 min.

[0073] Blank group: Mix 2 mL of sterile deionized water evenly with 2 mL of 95% ethanol solution containing 0.5 mmol / L DPPH, and let it stand for 30 min.

[0074] Control group: Mix 2 mL of the tea soup evenly with 2 mL of 95% ethanol solution, and let it stand for 30 min.

[0075] Place the experimental group, blank group and control group at a wavelength of 519 nm to detect the absorbance value, and calculate the scavenging rate of the tea soup of the hypoglycemic black tea obtained by different methods according to the formula. The results are shown in Table 3.

[0076] Scavenging rate of DPPH = [1 - (A 1 - A 2 ) / A 3 × 100%;

[0077] A 1 represents the absorbance value of the experimental group, A 2 represents the absorbance value of the control group, and A 3 represents the absorbance value of the blank group.

[0078] Table 3 Scavenging rate of the tea soup of the hypoglycemic black tea obtained by different methods

[0079] Group Example 1 Comparative example 1 DPPH scavenging rate % 82.13±1.24 64.71±1.06

[0080] As can be seen from Table 3, the clearance rate of the black tea with hypoglycemic effect in Example 1 on DPPH is higher than that of the black tea in Comparative Example 1. This indicates that the black tea prepared by adding the extract of Fomitiporia cyanescens improves its antioxidant activity.

[0081] Experimental Example 3

[0082] Take 1 g of the black tea with hypoglycemic effect in Example 1 and Comparative Example 1 respectively, add 50 mL of boiling water for brewing, and measure the clearance rate of the tea soup on hydroxyl radicals after cooling.

[0083] Experimental group: Add 2 mL of 9 mmol / L ferrous sulfate solution, 2 mL of 9 mmol / L salicylic acid solution and 2 mL of 8.8 mmol / L H 2 O 2 to 2 mL of the tea soup, shake well, and keep it in a water bath at 38 °C for 25 min for later use.

[0084] Control group: Mix 2 mL of 9 mmol / L ferrous sulfate solution, 2 mL of 9 mmol / L salicylic acid solution, 2 mL of 8.8 mmol / L H 2 O 2 and 2 mL of sterile distilled water, shake well, and keep it in a water bath at 38 °C for 25 min for later use.

[0085] Measure the absorbance values of the experimental group and the control group at a wavelength of 510 nm respectively. Calculate the clearance rate of the black tea soup with hypoglycemic effect obtained in Example 1 and Comparative Example 1 on hydroxyl radicals according to the formula. The results are shown in Table 4.

[0086] Hydroxyl radical clearance rate = (A 0 - A 1 ) / A 0 × 100%;

[0087] A 0 represents the absorbance value of the control group, and A 1 represents the absorbance value of the experimental group.

[0088] Table 4 Clearance rate of black tea soup with hypoglycemic effect obtained by different methods on hydroxyl radicals

[0089] Group Example 1 Comparative example 1 Hydroxyl radical scavenging rate % 76.15±1.20 58.67±0.96

[0090] As can be seen from Table 4, the clearance rate of the black tea with hypoglycemic effect in Example 1 on hydroxyl radicals is higher than that of the black tea in Comparative Example 1. This indicates that the black tea prepared by adding the extract of Fomitiporia cyanescens improves its ability to scavenge hydroxyl radicals.

[0091] Experimental Example 4

[0092] Healthy Kunming mice with an average weight of 20 ± 1.2 g were used for the experiment. Five mice were taken as the blank control group. The remaining mice were injected with 0.7% alloxan at a dose of 0.12 g / kg, and then injected again 24 h later. 12 h after the injection, blood was taken from the tail vein of the mice to detect the blood glucose concentration. Mice with a blood glucose value > 13.8 mmol / L were selected for the experiment to obtain the experimental group mice.

[0093] The experimental group mice were randomly divided into 3 groups: the Example 1 group, the Comparative Example 1 group, and the model control group, with 8 mice in each group. The drinking water for the mice in the Example 1 group was the hypoglycemic black tea tea soup prepared in Example 1, the drinking water for the mice in the Comparative Example 1 group was the hypoglycemic black tea tea soup prepared in Comparative Example 1, and the drinking water for the mice in the model control group and the blank control group was distilled water. The remaining feeding methods were carried out according to the conventional methods. Blood was taken from the tail vein of each group of mice after fasting for 12 h on the 14th and 28th days of feeding, and the blood glucose values of each group of mice were measured by the o-toluidine method. The results are shown in Table 5.

[0094] Method for preparing black tea tea soup using the hypoglycemic black tea of Example 1: Take 1 g of the hypoglycemic black tea of Example 1, add 50 mL of boiling water, and let it cool to obtain the hypoglycemic black tea tea soup.

[0095] Method for preparing black tea tea soup using the hypoglycemic black tea of Comparative Example 1: Take 1 g of the hypoglycemic black tea of Comparative Example 1, add 50 mL of boiling water, and let it cool to obtain the hypoglycemic black tea tea soup.

[0096] Table 5 Blood glucose values of different mice at different stages

[0097] Group 0d (mmol / L) 14d (mmol / L) 28d (mmol / L) Blank control group 5.28±0.38 5.34±0.52 5.16±0.34 Model control group 5.19±0.37 17.19±1.86 19.24±2.33 Example 1 group 5.31±0.42 10.59±1.25 7.14±0.92 Comparative example 1 group 5.24±0.29 15.86±1.41 14.67±1.20

[0098] As can be seen from Table 5, the blood glucose value in the mice drinking the tea soup of Example 1 decreased significantly after 28 d. It shows that the black tea of the present invention has the effect of lowering blood glucose.

[0099] As can be seen from the above examples, the present invention provides a Fomitiporia cyanescens extract, its preparation method, and hypoglycemic black tea. The preparation method of the Fomitiporia cyanescens extract of the present invention includes the following steps:

[0100] (1) Mix the fruiting body of Fomitiporia cyanescens with water to obtain a mixture, and extract the mixture 2 - 3 times at 60 - 70 °C. Combine the extracts to obtain an intermediate liquid. (2) Concentrate the intermediate liquid to 1 / 3 - 1 / 5 of its original volume to obtain an extract of Fomitiporia cyanescens. In the present invention, the extraction of the active components from Fomitiporia cyanescens is carried out at 60 - 70 °C. Under this condition, the active components in Fomitiporia cyanescens can be retained to the greatest extent, and the efficacy of the extract is maximally ensured. Using the extract of Fomitiporia cyanescens of the present invention to prepare black tea, the obtained black tea has the effects of antioxidation and blood sugar reduction. In the preparation process of the blood sugar - reducing black tea of the present invention, the drying step is segmented drying. The black tea obtained by this drying method has a rich fragrance, a mellow taste, and excellent sensory effects.

[0101] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a Cyanosporium extract, characterized in that: The steps include: (1) mixing the fruiting body of the blue spore fungus with water to obtain a mixture, extracting the mixture 2 to 3 times at 60 to 70° C., combining the extracts to obtain an intermediate solution; (2) Concentrating the intermediate solution to 1 / 3 to 1 / 5 of the volume of the intermediate solution to obtain a Cyanosporium extract.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the mixture of the blue spore fungus fruiting body and water in step (1) is 1:5-10; The vacuum degree during the leaching is 50-60 kPa, and the time of each leaching is 30-40 minutes.

3. The preparation method according to claim 2, characterized in that: The concentration in step (2) is rotary evaporation concentration, the concentration temperature is 60-70° C., and the concentration vacuum degree is 50-60 kPa.

4. The cyanobacterium extract prepared by the preparation method according to any one of claims 1 to 3.

5. A black tea for lowering blood sugar, characterized in that: The composition includes the following components in parts by weight: 3-8 parts of Cyanosporium cyanobacteria extract and 15-20 parts of fresh tea leaves; The cyanobacterium extract is the cyanobacterium extract prepared by the preparation method according to any one of claims 1 to 3 or the cyanobacterium extract according to claim 4.

6. A method for preparing black tea for lowering blood sugar, characterized in that: The steps include: (1) mixing fresh tea leaves with 8-10% of the total weight of the fresh tea leaves by a Cyanosporium extract, and withering for 6-8 hours to obtain withered tea; (2) mixing the withered tea with the remaining cyanobacteria extract, and rolling for 40 to 50 minutes to obtain rolled tea; (3) fermenting the rolled tea at a temperature of 26 to 28° C. for 3 to 4 hours to obtain fermented tea; (4) Drying the fermented tea to obtain blood sugar lowering black tea.

7. The preparation method according to claim 6, characterized in that: The withering temperature is 30-33°C; the thickness of the tea leaves during withering is 4-5 cm; The temperature of the kneading is 30-33°C.

8. The preparation method according to claim 7, characterized in that: The humidity of the fermentation is 90-95%; the thickness of the tea leaves spread during the fermentation is 16-18 cm.

9. The preparation method according to claim 8, characterized in that: The drying method comprises the following steps: firstly drying the tea leaves to a moisture content of 28-32% at 90-100°C; then drying the tea leaves to a moisture content of 10-15% at 70-80°C; and finally drying the tea leaves to a moisture content of less than 8% at 60-65°C.

10. Use of the blood sugar lowering black tea according to claim 5 or the blood sugar lowering black tea prepared by the preparation method according to any one of claims 6 to 9 in preparing a health product with blood sugar lowering effect.