Fermented tea helpful for maintaining healthy levels of blood sugar and blood fat and preparation method of fermented tea

Abstract

The invention relates to the technical field of functional food, and provides a fermented tea helpful for maintaining blood sugar and blood fat health level and a preparation method thereof, and the fermented tea is prepared by taking low-value tea as a raw material through solid state fermentation of grifola frondosa bacteria. The preparation method comprises the following steps: activating and culturing strains; inoculating and fermenting; and drying. The preparation method disclosed by the invention is simple and convenient to operate, the prepared fermented tea has good sensory quality and has a remarkable dose inhibition effect on alpha-glucosidase and pancreatic lipase, and high-value utilization of low-value tea leaves is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of tea processing, and particularly relates to a fermented tea helpful for maintaining healthy blood sugar and blood lipid levels and a preparation method thereof. Background Art

[0003] According to the growth and development characteristics of tea leaves and different picking times, tea leaves are divided into spring tea, summer tea and autumn tea. Among them, spring tea has fresh tea leaves and is rich in various flavor substances, with high quality. While in summer and autumn tea, the polyphenol components are relatively high, but the contents of amino acids and aromatic substances are relatively low, resulting in a bitter taste and poor aroma, and the quality is far inferior to that of spring tea. The low-quality summer and autumn tea has a low market price and poor profit, resulting in a large amount of summer and autumn tea being abandoned, causing great waste of resources and economic losses.

[0004] Statistics show that low-value tea leaves represented by summer and autumn tea account for about 20% of the total tea production in China. Most of them are overstocked and difficult to sell until they are discarded, causing waste of resources, environmental pollution and direct economic losses, which has become a major problem restricting the sustainable development of the tea industry. In addition, a large number of by-products such as tea waste, tea powder and tea stalks are also generated during the processing of fresh tea leaves, which are landfilled and discarded, also causing waste of resources, environmental pollution and direct economic losses. Therefore, how to deeply process and highly utilize these low-value tea leaves has become an urgent problem to be solved.

[0005] Edible fungi secrete various enzymes (such as cellulase, laccase, etc.) during the fermentation process, decomposing complex organic compounds into small molecule substances. Utilizing the enzyme-producing characteristics of edible fungi for deep processing of low-value tea leaves such as summer and autumn tea can significantly affect the sensory quality and functional characteristics of tea leaves.

[0006] Grifola frondosa is an edible and medicinal fungus, rich in active ingredients such as active polysaccharides, flavonoids and polyphenols, and has biological activities such as enhancing immunity, anti-inflammation, lowering blood sugar and lowering blood lipid. Summary of the Invention

[0007] The purpose of the present invention is to provide a fermented tea helpful for maintaining healthy blood sugar and blood lipid levels and a preparation method thereof. The fermented tea helpful for maintaining healthy blood sugar and blood lipid levels provided by the present invention is prepared by solid-state fermentation with Grifola frondosa using low-value tea leaves as raw materials. The fermented tea helpful for maintaining healthy blood sugar and blood lipid levels prepared by the method of the present invention has good sensory quality and has a significant dose inhibitory effect on α-glucosidase and pancreatic lipase.

[0008] The purpose of the present invention is achieved by the following technical solutions:

[0009] A method for preparing a fermented tea that helps maintain healthy levels of blood sugar and blood lipids, characterized in that distilled water is added to low-value tea leaves to make a tea soup, and after sterilization, a Grifola frondosa seed liquid is inoculated, and after culturing and fermenting, it is dried to obtain the fermented tea;

[0010] The addition amount of the distilled water is 30% - 70% of the dry weight of the low-value tea leaves;

[0011] The inoculation amount of the Grifola frondosa seed liquid is 10% - 40% of the tea soup of the low-value tea leaves;

[0012] The culturing and fermenting time is 60h - 96h, and the temperature is 25°C - 35°C.

[0013] Preferably, the Grifola frondosa seed liquid is prepared by the following method: Take Grifola frondosa mycelium to a PDA plate medium for constant temperature culture at 30°C. After culturing for 3 - 6 days, liquid spawn propagation is carried out; Pick 5mm square mycelium blocks at the edge of 3 PDA plate colonies and inoculate them into a PDB liquid medium, and place them in a constant temperature shaker at 25°C - 35°C and 120r / min for light-avoiding culture for 3 - 6 days to obtain the Grifola frondosa seed liquid.

[0014] Preferably, the culturing and fermenting conditions are: relative humidity 55% - 65%, and turning the materials once every 12h.

[0015] Preferably, the drying conditions are: 50°C - 60°C, 12h - 24h.

[0016] Preferably, the Grifola frondosa is purchased from the Guangdong Provincial Microbial Culture Collection Center, and the preservation number is GDMCC5.463.

[0017] Preferably, the low-value tea leaves refer to low-value tea leaves represented by low-quality summer and autumn tea, as well as by-products such as tea waste, tea powder, and tea stalks generated during the processing of fresh tea leaves.

[0018] Preferably, the low-value tea leaves refer to Gougunao green tea in summer and autumn.

[0019] Preferably, the addition amount of the distilled water is 50 ± 5% of the dry weight of the low-value tea leaves; the inoculation amount of the Grifola frondosa seed liquid is 25 ± 2% of the tea soup of the low-value tea leaves; the culturing and fermenting time is 88 ± 5h, and the temperature is 30 ± 5°C.

[0020] The fermented tea prepared by the method of the present invention that helps maintain healthy levels of blood sugar and blood lipids.

[0021] Preferably, the fermented tea has an inhibitory effect on α-glucosidase and pancreatic lipase.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The present invention prepares a fermented tea that helps maintain healthy blood sugar and blood lipid levels by solid-state fermenting low-value tea leaves with Grifola frondosa. Grifola frondosa is an edible and medicinal fungus rich in active ingredients such as active polysaccharides, flavonoids, and polyphenols, and has biological activities such as enhancing immunity, anti-inflammation, lowering blood sugar, and lowering blood lipid. At the same time, various enzymes are produced during the fermentation of Grifola frondosa. For example, cellulase can catalyze the degradation of insoluble dietary fiber in tea leaves into soluble dietary fiber and soluble sugars, and polyphenol oxidase can promote the oxidation of tea polyphenols to transform into tea pigments (theaflavins, thearubigins, and tea brown pigments), resulting in corresponding changes in the composition and content of the substances contained in the tea leaves. Eventually, the sensory quality and biological activity of the tea leaves are also changed, so that the fermented tea of the present invention has good sensory quality and has a significant dose-dependent inhibitory effect on α-glucosidase and pancreatic lipase, significantly improving the sensory quality and physiological efficacy of low-value tea leaves, thereby realizing the high-value utilization of low-value tea leaves. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments.

[0025] Figure 1 It is a radar chart of sensory scores for Example 1 and Example 7.

[0026] Figure 2 It is a comparison chart of the inhibitory effects of α-glucosidase activity for Example 1, Example 7, and acarbose.

[0027] Figure 3 It is a comparison chart of the inhibitory effects of pancreatic lipase activity for Example 1, Example 7, and orlistat. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following further elaborates the present invention in conjunction with specific embodiments, but these embodiments are not to be construed as limiting the present invention. The instruments, reagents, materials, etc. involved in the following embodiments, unless otherwise specified, are all conventional instruments, reagents, materials, etc. existing in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following embodiments, unless otherwise specified, are all conventional experimental methods, detection methods, etc. existing in the prior art.

[0029] The Grifola frondosa used in the following embodiments was purchased from the Guangdong Provincial Microbial Culture Collection Center, and the preservation number is GDMCC 5.463.

[0030] Example 1

[0031] Selecting summer and autumn Gougunao green tea as the raw material, a method for preparing Gougunao fermented tea with blood sugar and blood lipid lowering effects specifically includes the following steps:

[0032] (1) Activation of Grifola frondosa strain: Under aseptic conditions, carefully pick a piece of mycelium from the slant and transfer it to the center of a PDA plate, then culture it in a constant temperature incubator at 30 °C for 4 days;

[0033] (2) Preparation of Grifola frondosa seed liquid: Under aseptic conditions, evenly pick 5 mm square mycelium blocks from the edges of 3 PDA plate colonies and inoculate them into 100 mL of PDB liquid medium, then place it in a constant temperature shaker and culture it in the dark at 30 °C and 120 r / min for 3.5 days.

[0034] (3) Put Gonggunao green tea into a tissue culture bottle, add distilled water accounting for 50% of the dry tea weight of the tea leaves, sterilize it at 121 °C for 45 min, after cooling, inoculate the seed liquid under aseptic conditions at an inoculation amount of 25%, mix well and then statically culture it in an incubator at 30 °C, maintain a relative humidity of 60%, turn the material once every 12 h, and ferment for 88 h to obtain a fermented tea sample. Dry the fermented tea sample at 55 °C for 20 h to obtain the fermented tea.

[0035] Example 2: The difference from Example 1 is that the water addition amount is 60%, the inoculation amount of the seed liquid is 20%, and the fermentation time is 84 h.

[0036] Example 3: The difference from Example 1 is that the water addition amount is 70%, the inoculation amount of the seed liquid is 10%, and the fermentation time is 84 h.

[0037] Example 4: The difference from Example 1 is that the water addition amount is 60%, the inoculation amount of the seed liquid is 30%, and the fermentation time is 72 h.

[0038] Example 5: The difference from Example 1 is that the water addition amount is 60%, the inoculation amount of the seed liquid is 30%, and the fermentation time is 96 h.

[0039] Example 6: The difference from Example 1 is that the water addition amount is 50%, the inoculation amount of the seed liquid is 20%, and the fermentation time is 72 h.

[0040] Determine the contents of internal substances such as total phenols, total soluble sugars, free amino acids, theaflavins, and water extracts in the tea leaves, and conduct a comprehensive score. The results are as follows:

[0041]

[0042] Example 7: Use summer and autumn Gonggunao green tea as a control.

[0043] Example 8: Performance test

[0044] Compared with summer and autumn Gonggunao green tea (a kind of green tea specialty of Jiangxi), the Gonggunao fermented tea described in the present invention has good sensory quality, and has a significant dose inhibitory effect on α-glucosidase and pancreatic lipase, showing obvious blood sugar lowering and blood lipid lowering effects.

[0045] 1. Sensory evaluation

[0046] The sensory evaluation of tea was carried out according to the "GB / T 23776-2018 Method for Sensory Evaluation of Tea". The evaluation was carried out from factors such as appearance, soup color, aroma, taste, and leaf bottom. The full score was 100 points, and the corresponding weights were 20%, 15%, 25%, 30%, and 10% respectively. The comprehensive score was calculated by weighted calculation. Taking Example 1 as the sample and comparing it with the control group of Example 7, the overall sensory evaluation score of the Gonggulao fermented tea was 86.33 points, higher than 84.56 points of the Gonggulao green tea. Its core advantages were reflected in the soup color and taste of the tea soup. See specifically Figure 1 。

[0047] 2. α-Glucosidase activity inhibition experiment

[0048] Taking Example 1 as the sample and comparing it with the control group of Example 7, both Gonggulao fermented tea and Gonggulao green tea had a certain inhibitory effect on α-glucosidase as a whole and showed a dose-dependent effect. However, the inhibitory effect of Gonggulao fermented tea was significantly better than that of Gonggulao green tea. The half inhibitory concentration (IC50) of Gonggulao fermented tea on α-glucosidase was 0.236 mg / mL, significantly lower than 0.289 mg / mL of Gonggulao green tea (P<0.01). The specific effect is as Figure 2 。

[0049] 3. Pancreatic lipase inhibition experiment

[0050] Taking Example 1 as the sample and comparing it with the control group of Example 7, both Gonggulao fermented tea and Gonggulao green tea had a certain inhibitory effect on pancreatic lipase as a whole and showed a dose-dependent effect. However, the inhibitory effect of Gonggulao fermented tea was significantly better than that of Gonggulao green tea. The half inhibitory concentration (IC50) of Gonggulao fermented tea on pancreatic lipase was 0.524 mg / mL, significantly lower than 0.821 mg / mL of Gonggulao green tea (P<0.01). The specific effect is as Figure 3 。

[0051] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the application of the present invention is limited to these descriptions. For those skilled in the technical field to which the present invention belongs, without departing from the core concept of the present invention, appropriate deductions or substitutions can be made, and these deductions or substitutions still belong to the protection scope of the present invention.

Claims

1. A method for preparing fermented tea that helps maintain healthy levels of blood sugar and blood lipids, characterized in that: Adding distilled water to low-value tea leaves to prepare tea soup, sterilizing, adding Grifola frondosa seed liquid, culturing and fermenting, and drying to obtain fermented tea; The amount of distilled water added is 30% to 70% of the dry weight of the low-value tea leaves; The inoculation amount of the Grifola frondosa seed liquid is 10% to 40% of the low-value tea soup; The culture and fermentation time is 60h to 96h, and the temperature is 25°C to 35°C.

2. The preparation method according to claim 1, characterized in that: The Grifola frondosa seed liquid is prepared by the following method: taking Grifola frondosa mycelium to a PDA plate culture medium for constant temperature culture at 30°C, and after culture for 3 to 6 days, carrying out liquid bacterial seed propagation; picking 3 square mycelium blocks with 5 mm on the edge of the PDA plate colony, inoculating them into a PDB liquid culture medium, placing them in a constant temperature shaker at 25°C to 35°C, 120 r / min, and dark-proof culture for 3 to 6 days to obtain the Grifola frondosa seed liquid.

3. The preparation method according to claim 1, characterized in that: The culture and fermentation conditions are: relative humidity 55% to 65%, and the material is turned over once every 12 hours.

4. The preparation method according to claim 3, characterized in that: The drying conditions are: 50° C. to 60° C., 12 h to 24 h.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The Grifola frondosa was purchased from Guangdong Microbiological Culture Collection Center with a collection number of GDMCC 5.

463.

6. The preparation method according to claim 5, characterized in that: The low-value tea refers to low-value tea represented by low-quality summer and autumn tea, as well as tea scraps, tea powder, tea stems and other by-products produced in the processing of fresh tea leaves.

7. The preparation method according to claim 6, characterized in that: The low-value tea refers to the Gougunnao green tea in summer and autumn.

8. The preparation method according to claim 7, characterized in that: The amount of distilled water added is 50±5% of the dry weight of low-value tea leaves; the inoculation amount of Grifola frondosa seed liquid is 25±2% of the tea soup of low-value tea leaves; the culture and fermentation time is 88±5h, and the temperature is 30±5℃.

9. The fermented tea prepared by the method according to any one of claims 1 to 8, which helps maintain healthy levels of blood sugar and blood lipids.

10. The fermented tea according to claim 9, characterized in that The fermented tea has an inhibitory effect on alpha-glucosidase and pancreatic lipase.

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