CN111122729B - Application of tea product in stabilizing blood sugar, quality grading method and screening method - Google Patents
Application of tea product in stabilizing blood sugar, quality grading method and screening method Download PDFInfo
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Abstract
The invention relates to the field of health-care food, and discloses an application of a tea product in stabilizing blood sugar, a quality grading method and a screening method. The concentration of each component contained in the tea product of the invention meets the following characteristics: the content of tea polyphenol is more than or equal to 10 percent; thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2(ii) a Caffeine is more than or equal to 4 percent; theaflavin is more than or equal to 0.9% and less than or equal to 1.2%; (thearubigin x caffeine/theabrownin) is not less than 0.035; and (theaflavin x caffeine)/(catechin x theabrownin) is not more than 0.28 and not more than 0.6. The tea product has good effects of inhibiting alpha-glucosidase, slowing down starch digestion, reducing glucose absorption and stabilizing postprandial blood sugar.
Description
Technical Field
The invention relates to the field of health-care food, in particular to application of a tea product in stabilizing blood sugar, a quality grading method and a screening method of the tea product.
Background
With the development of modern fast-paced lifestyles, the diet is becoming exceedingly fine and the population with dysglycolipid metabolism is growing at an alarming rate. Researches show that long-term diet and life style intervention can reduce abnormal glycolipid metabolism risk and achieve the effect of preventing diseases. The functional food is used for stabilizing the postprandial blood sugar, is beneficial to delaying the development of diabetes, reducing the risk of cardiovascular diseases and improving the life quality of residents in China. The study at home and abroad considers that the tea has the function of stabilizing the postprandial blood sugar. However, due to the influence of factors such as tea varieties and processes, the action characteristics and the activity intensity of the tea are different. At present, no simple and effective means for judging the blood sugar stabilizing effect of the tea leaves exists.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide an application of a tea product in stabilizing blood sugar, a quality grading method and a screening method of the tea product, wherein the tea product meeting the requirements of the invention has good effects of inhibiting alpha-glucosidase, slowing down starch digestion, reducing glucose absorption and stabilizing postprandial blood sugar.
In order to achieve the above object, the present invention provides a tea product for stabilizing blood sugar, wherein the tea product comprises the following components in concentration:
the content of tea polyphenol is more than or equal to 10 percent;
thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2；
Caffeine is more than or equal to 4 percent;
theaflavin is more than or equal to 0.9% and less than or equal to 1.2%;
Preferably, the concentration of each component contained in the tea product satisfies the following characteristics:
16% or more of tea polyphenol is 10% or more;
12% or more than or equal to 5% of thearubigin;
3(％)2not less than theaflavin x catechin not less than 1.2 (%)2；
5% or more than 4% of caffeine;
theaflavin is more than or equal to 0.96% and less than or equal to 1.2%;
Preferably, the tea product inhibits alpha-glucosidase IC50Not more than 0.01mg/mL and the maximum inhibition rate on alpha-amylase>50％。
The second aspect of the present invention provides a quality classification method of a tea product, which comprises measuring the concentrations of tea polyphenol, thearubigin, theaflavin, catechin, caffeine and theabrownin in the tea product, and sequentially judging whether the concentrations satisfy the following relational expression groups (1), (2) and (3):
(1) the content of tea polyphenol is more than or equal to 10 percent;
thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2；
Caffeine is more than or equal to 4 percent;
theaflavin is more than or equal to 0.9% and less than or equal to 1.2%;
(2) The content of tea polyphenol is more than or equal to 10 percent;
catechin is more than or equal to 1 percent; and is
Theaflavin is more than or equal to 0.2;
(3) the content of tea polyphenol is more than or equal to 10 percent; and is
Catechin is more than or equal to 10 percent;
tea products satisfying the relational expression group (1) are classified into 1 grade, tea products satisfying the relational expression group (2) and not satisfying the relational expression group (1) are classified into 2 grades, tea products satisfying the relational expression group (3) and not satisfying the relational expression groups (1) and (2) are classified into 3 grades, and tea products not satisfying the relational expression groups (1), (2) and (3) are classified into 4 grades.
Preferably, the grade 1 tea product inhibits alpha-glucosidase IC50Less than or equal to 0.01mg/mL and the maximum inhibition rate to alpha-amylase is more than 50 percent.
Preferably, the grade 2 tea product inhibits alpha-glucosidase IC50Less than or equal to 0.1mg/mL or the maximum inhibition rate to alpha-amylase is more than 50 percent.
Preferably, the 3-grade tea product inhibits alpha-glucosidase IC50 to be less than or equal to 1.0mg/mL or has the maximum inhibition rate on alpha-amylase to be more than or equal to 10%.
In a third aspect, the present invention provides a method of screening tea products, the method comprising: the quality classification method of the tea product of the present invention is used for classification.
Through the technical scheme, the invention provides the application of the tea product in stabilizing blood sugar, the quality grading method and the screening method of the tea product through deep research on the tea product, and the tea product and the extract which meet the requirements of the invention have stronger activities of inhibiting alpha-glucosidase and alpha-amylase, can slow down starch digestion and glucose absorption, can be directly drunk or used as a functional food formula, and play a role in stabilizing postprandial blood sugar. The tea product meeting the requirements of the invention is very suitable for people who are habitually intake a large amount of carbohydrate foods, such as pre-diabetes, type 2 diabetes and the like and have requirements of stabilizing postprandial blood sugar. By combining measures such as diet intervention and lifestyle adjustment, the method is beneficial to reducing the peak value of postprandial blood sugar and reducing the volatility of blood sugar, and finally plays roles in delaying the progress of diabetes and reducing the risk of cardiovascular end events.
Furthermore, the raw materials, the process and the drinking mode of the tea product are controlled, so that the functional components entering the human body meet the requirements of specific content and proportion, and the health effect of preventing and improving the sugar metabolism, particularly stabilizing the postprandial blood sugar is stably exerted.
According to the invention, through component and activity analysis, reference of the tea leaf auxiliary blood sugar reducing grading standard is provided; and identifying the functional component group of the tea for stabilizing the blood sugar; in combination with the activity-ingredient associations, ingredient content criteria related to activity grading are established within each tea category. The quality grading method and the screening method are suggested as production control indexes, are an operation guide for the tea and the extract thereof to inhibit the activity of alpha-glucosidase and alpha-amylase, and provide raw material selection, quality control standards and propaganda basis with controllable quality and stable effect for preparing functional food with reduced glycemic index.
Based on the tea component and activity evaluation and grading technology disclosed by the invention, the tea component and activity evaluation and grading technology is associated with the production of standardized tea, and tea products with unstable quality and uncontrollable quality among batches can be upgraded into tea which can stably control characteristic components, clearly express functional characteristics and play a role in the efficacy under specific use modes and application scenes.
The invention provides referential scientific basis and production guidance for developing tea and tea products with definite effects, and provides basis for obtaining health claims related to sugar metabolism at home and abroad for the tea and the tea products.
Drawings
Figure 1 is a graph showing the effect of different tea extracts on starch hydrolysis rate.
Fig. 2 is a graph showing blood glucose concentrations measured in a mouse glucose load experiment.
FIG. 3 is a graph showing the postprandial blood glucose of an experimenter.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein. Unless otherwise specified, the concentration in the present invention is a weight concentration, and "%" represents "% by weight".
The invention provides an application of a tea product in stabilizing blood sugar, wherein the concentration of each component in the tea product meets the following characteristics:
the content of tea polyphenol is more than or equal to 10 percent;
thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2；
Caffeine is more than or equal to 4 percent;
theaflavin is more than or equal to 0.9% and less than or equal to 1.2%;
According to the invention, the tea product can inhibit alpha-glucosidase IC50 to be less than or equal to 0.01mg/mL and the maximum inhibition rate to alpha-amylase is more than 50% by enabling the components in the tea product to meet the proportion, and has very good effects of inhibiting alpha-glucosidase, slowing down starch digestion, reducing glucose absorption and stabilizing postprandial blood sugar.
According to the present invention, preferably, the concentration of each component contained in the tea leaf product satisfies the following characteristics:
the content of tea polyphenols is 10-16%, preferably 10.1-15.97%;
thearubigin 5-12%, preferably 6-9%, more preferably 6-8.31%;
"theaflavin x catechin" is 1.2-3 (%)2Preferably 1.22 to 2.72 (%)2；
Coffee is 4-5%, preferably 4.02-4.95%;
theaflavin 0.96-1.2%;
In the present invention, the concentration of catechin is preferably 1 to 5%, preferably 1 to 3%; the concentration of theaflavin is 0.5-1.5%, preferably 0.8-1.2%; the concentration of theabrownin is 6-9%, preferably 6.26-8.8%.
According to a preferred embodiment of the present invention, the tea leaf product comprises the following components in concentrations which satisfy the following characteristics: 11.9% of tea polyphenol; thearubigin is 6.1%; coffee is 4.8%; theaflavin 1.2%;
is 0.037; and is
Is 0.40.
According to a preferred embodiment of the present invention, the tea leaf product comprises the following components in concentrations which satisfy the following characteristics: the content of tea polyphenols is 10.1%; thearubigin is 6%; coffee is 4.8%; theaflavin 1.2%;
is 0.038; and is
Is 0.40.
According to a preferred embodiment of the present invention, the tea leaf product comprises the following components in concentrations which satisfy the following characteristics: 11.9% of tea polyphenol; thearubigin is 6.1%; coffee is 4.5%; theaflavin 1.2%;
is 0.06; and is
Is 0.34.
According to a preferred embodiment of the present invention, the tea leaf product comprises the following components in concentrations which satisfy the following characteristics: the content of tea polyphenol is 15.97%; thearubigin 7.85%; coffee is 4.95%; theaflavin 1.05%;
is 0.06; and is
Is 0.3.
According to a preferred embodiment of the present invention, the tea leaf product comprises the following components in concentrations which satisfy the following characteristics: the content of tea polyphenol is 13.93%; thearubigin 8.31%; coffee is 4.68%; theaflavin is 0.99%;
is 0.06; and is
Is 0.3.
According to a preferred embodiment of the present invention, the tea leaf product comprises the following components in concentrations which satisfy the following characteristics: the content of tea polyphenol is 11.38%; thearubigin is 6.44%; coffee is 4.02%; theaflavin 0.96%;
is 0.04; and is
Is 0.5.
According to a preferred embodiment of the present invention, the tea leaf product comprises the following components in concentrations which satisfy the following characteristics: 11.9% of tea polyphenol; thearubigin is 6.1%; coffee is 4.5%; theaflavin 1.2%;
is 0.06; and is
Is 0.34.
The tea leaf product in the present invention may be a tea leaf raw material, tea leaf, a tea leaf product or an extract thereof. In the present invention, the concentration of each component contained in the tea product refers to the weight concentration relative to the dry weight of the tea product, and is expressed as wt%.
The preparation method of the tea product of the present invention may comprise subjecting the tea raw material to withering, rolling, fermentation and drying in sequence. Specifically, the tea product of the invention can be prepared by properly selecting tea raw materials and setting processing parameters.
According to the invention, the tea leaves can be raw materials of black tea, white tea, raw tea and the like, such as raw materials of Jiangxi black tea, raw Yunnan Pu' er tea and raw Fujian white tea. The conditions for the withering may be, for example, 20 to 30 ℃ and preferably 22 to 25 ℃ for 9 to 12 hours. The rolling time may be 20-40 min. As the conditions for the above fermentation, the temperature may be 20 to 30 ℃ and the relative humidity may be 95%, for example, 25 ℃ for 2.5 to 6.5 hours. The drying conditions may include a temperature of 80 to 100 ℃ and a time of 20min or more, for example, 30 to 50 min.
Through the operation, the raw tea can be prepared from the fresh tea leaves. The raw tea is preferably further refined through one or more of screening, winnowing, picking, drying and stacking, and preferably refined through screening, winnowing, picking, drying and stacking in sequence.
The pore size for the sieving may be 12 meshes, for example. The conditions for the air separation may include: the fan speed is 350-1200 r/min. As the conditions of the pick, there may be included: removing non-tea impurities. The color of the tea leaves is blended to meet the requirements of national standard or local standard on sensory grade of tea leaves. The existing arbitrary piecing and stacking color forming method can be adopted.
The preparation method of the tea product extract (such as tea instant powder) comprises the steps of removing impurities from tea raw materials, crushing, leaching, solid-liquid separation, concentrating and drying. Specifically, the method for removing impurities, crushing, leaching, solid-liquid separation, concentration and drying can use the existing method for preparing the instant tea powder.
The impurity removal is used for removing impurities such as dust in the tea raw materials.
The comminution is advantageous for extraction of the tea raw material and the like, and the particle size of the tea raw material after comminution may be, for example, 0.5 to 2 mm.
The extraction is used to extract the active ingredients from the tea leaf material, and as the means of extraction, for example, water extraction, such as extraction with water at 70 ℃, 80 ℃ or 90 ℃ or more, preferably boiling water extraction, can be used. The leaching time is, for example, 30-50min, specifically 15min for the first extraction and 10min for the second extraction; or leaching for more than 30min at a time. The amount of water is 10 parts by weight or more, preferably 12 to 15 parts by weight, based on 1 part by weight of the tea product.
The solid-liquid separation is used for separating the leaching liquor from the tea raw material residues, and is preferably carried out in a centrifugal mode. In order to further satisfy the requirements of the processes such as desalting, sterilization, concentration, purification, etc., it is preferable to further filter the liquid phase obtained by solid-liquid separation, preferably by ceramic membrane filtration.
The concentration is used for increasing the content of the active ingredients in the obtained product, the concentration mode is not particularly limited, and reverse osmosis concentration is preferably adopted. As conditions for the reverse osmosis concentration, for example, there may be included: a semipermeable membrane of cellulose acetate and its derivatives was used at a pressure of 6 MPa.
The drying is used for preparing tea powder, and the freeze drying is preferred in a drying mode so as to retain the color, the fragrance, the taste, the nutrition and the functional characteristics of the tea to the maximum extent. As conditions for freeze-drying, for example, there may be included: freezing the concentrated tea juice at-35 deg.C, vacuum drying under 609Pa to obtain scale-like instant tea with water content less than 3%, and making into tea powder with particle size of 0.2-0.5 μm.
According to a preferred embodiment of the invention, the preparation method comprises the steps of sequentially removing impurities, crushing, leaching, centrifuging, filtering by a ceramic membrane, concentrating by reverse osmosis, freezing and drying in vacuum, packaging and detecting the tea raw materials.
The tea product of the invention can also be packaged and subjected to component detection according to the requirements. As a detection method, the content of components such as tea polyphenol, catechin, theaflavin, caffeine and the like can be measured according to the requirements of national standards.
As the use method of the tea product, the tea product can be drunk after being brewed or directly drunk, wherein the tea needs to be soaked, for example, the tea is soaked in hot water with the temperature of more than 95 ℃ for 2min, and the using amount of the tea is 2-10g/200mL of water; the tea extract (instant tea powder) can be drunk by brewing with a concentration of 0.5-2g/200 mL. The infusion is generally taken within 90 min. By using the method, the functional components entering the human body meet the requirements of specific content and proportion, thereby stably playing the health role of preventing and improving glycometabolism, particularly stabilizing postprandial blood sugar, and further achieving the effects of inhibiting alpha-glucosidase, slowing down starch digestion, reducing glucose absorption and stabilizing postprandial blood sugar.
The tea product of the present invention can be used as a food material in combination with other foods, for example, as an additive component of a staple food, and can also provide excellent effects of inhibiting α -glucosidase, slowing down starch digestion, reducing glucose absorption, and stabilizing postprandial blood glucose.
The invention also provides a quality grading method of the tea product, wherein the method comprises the steps of measuring the contents of tea polyphenol, thearubigin, theaflavin, catechin, caffeine and theabrownin in the tea product, and sequentially judging whether the contents satisfy the following relational expression groups (1), (2) and (3):
(1) the content of tea polyphenol is more than or equal to 10 percent;
thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2；
Caffeine is more than or equal to 4 percent;
theaflavin is more than or equal to 0.9% and less than or equal to 1.2%;
(2) The content of tea polyphenol is more than or equal to 10 percent;
catechin is more than or equal to 1 percent; and is
Theaflavin is more than or equal to 0.2;
(3) the content of tea polyphenol is more than or equal to 10 percent; and is
Catechin is more than or equal to 10 percent;
tea products satisfying the relational expression group (1) are classified into 1 grade, tea products satisfying the relational expression group (2) and not satisfying the relational expression group (1) are classified into 2 grades, tea products satisfying the relational expression group (3) and not satisfying the relational expression groups (1) and (2) are classified into 3 grades, and tea products not satisfying the relational expression groups (1), (2) and (3) are classified into 4 grades.
By the classification method of the present invention, the blood sugar stabilizing effect of the tea product can be estimated without specific experiments. The above grade 1-4 tea products have successively lower postprandial blood glucose stabilizing effects.
In the above relational expression group (1), preferably, the tea polyphenol is 10 to 16%, preferably 10.1 to 15.97%;
thearubigin 5-12%, preferably 6-9%, more preferably 6-8.31%;
"theaflavin x catechin" is 1.2-3 (%)2Preferably 1.22 to 2.72 (%)2；
Coffee is 4-5%, preferably 4.02-4.95%;
theaflavin 0.96-1.2%;
In the present invention, the concentration of catechin is preferably 1 to 5%, preferably 1 to 3%; the concentration of theaflavin is 0.5-1.5%, preferably 0.8-1.2%; the concentration of theabrownin is 6-9%, preferably 6.26-8.8%.
After the grading method is used for grading, the maximum inhibition rates of the tea products at all levels for inhibiting alpha-glucosidase and alpha-amylase respectively satisfy the following relations:
as the grade 1 tea product, alpha-glucosidase IC is inhibited50Less than or equal to 0.01mg/mL and the maximum inhibition rate to alpha-amylase is more than 50 percent.
As the grade 2 tea product, alpha-glucosidase IC is inhibited50Less than or equal to 0.1mg/mL or the maximum inhibition rate to alpha-amylase is more than 50 percent.
As the 3-grade tea product, alpha-glucosidase IC is inhibited50Not more than 1.0mg/mL or not less than 10% of the maximum inhibition rate of alpha-amylase.
The present invention also provides a method for screening tea products for preventing and improving health of sugar metabolism, wherein the tea products are classified using the method for classifying quality of tea products according to the present invention.
The screening method of the tea product can be used for screening the tea product for preventing sugar metabolism diseases and/or improving sugar metabolism health. By using the quality grading method of the tea product to grade, the tea product with smaller grade number can bring better effects of inhibiting alpha-glucosidase, slowing down starch digestion, reducing glucose absorption and stabilizing postprandial blood sugar, thereby having greater application prospect.
The present invention will be described in detail below by way of examples. In the following examples, the concentration of tea polyphenols was determined according to GB/T8313-2018.
The catechin, the theaflavin and the caffeine are determined according to the GB/T30483 and 2013 optimization method, and the specific operation is as follows:
weighing 0.100g of uniformly crushed tea powder in a 10mL centrifuge tube, adding 5mL of 70% methanol at 70 ℃, uniformly mixing, immediately transferring into 70 ℃ water bath, leaching for 10min, uniformly mixing once every 5min, centrifuging at 3000rpm for 5min, taking supernate in the 10mL centrifuge tube, leaching residues once with 5mL of 70% methanol, combining the supernate, cooling to room temperature, and fixing the volume with 70% methanol. Adding 0.25mL of stable solution into 0.75mL of alcohol extract sample extract, uniformly mixing in a 1.5mL centrifuge tube by vortex, passing through a 0.45-micron membrane, putting into a sample bottle (the sample can be stored for 48h at 4 ℃), and detecting by a high performance liquid chromatograph under the following conditions:
a chromatographic column: c18Column, column length 250mm, inner diameter 4.6mm, particle size 5 μm, column temperature: 35 ℃; fluorescence detector, detection wavelength: 372. 278 nm; sample introduction amount: 10 μ L.
Mobile phase A: 2% acetic acid (9% acetonitrile in water), mobile phase B: 2% acetic acid (80% acetonitrile in water) and eluted in a gradient.
| Time (min) | Flow rate (mL/min) | A(％) | B(％) |
| 0 | 1 | 100 | 0 |
| 10 | 1 | 100 | 0 |
| 25 | 1 | 68 | 32 |
| 35 | 1 | 68 | 32 |
| 40 | 1 | 100 | 0 |
Thearubigin, theabrownin were measured by the following standardized procedure.
Weighing 2.00g of tea product in a 100mL conical flask with a plug, adding 85mL of boiling water, boiling for 10min (shaking the flask once in the middle), taking out about 35mL of tea product in a 50mL centrifuge tube, cooling in ice bath, and centrifuging at 3000rpm for 5min to obtain supernatant as a solution to be tested.
Adding 15mL of ethyl acetate into 15mL of to-be-detected solution, horizontally shaking at 200rpm for 5min, standing for layering, adding 4.2mL of ethanol (95 vol%) into 0.8mL of the layered upper layer to obtain solution A, and adding 0.4mL of saturated oxalic acid, 1.2mL of water and 3mL of ethanol (95 vol%) into 0.4mL of the layered lower layer to obtain solution D;
adding 5mL of sodium carbonate solution (2.5%) into 5mL of solution to be detected, rapidly shaking for 30s, standing for layering, and adding 4.2mL of ethanol (95 vol%) into 0.8mL of the upper layer to obtain solution C;
adding 5mL of the solution to be detected into 5mL of the solution to be detected, adding 5mL of n-butanol into the solution to be detected, horizontally shaking the solution at 200rpm for 5min, standing the solution for layering, and adding 0.4mL of saturated oxalic acid, 1.2mL of water and 3mL of ethanol (95 vol%) into 0.4mL of the lower layer to obtain a solution B.
And (3) respectively measuring the absorbance values of the solution A, the solution B, the solution C and the solution D at 380nm by using a spectrophotometer, respectively recording the results as A, B, C and D, and calculating the contents of thearubigin and theabrownin according to the following formulas:
in the above formula, m represents the mass (g) of the sample, and m represents the dry matter content (%) of the sample.
In the following examples, inhibition of alpha-glucosidase IC50And the maximum inhibition of alpha-amylase were determined by the following standardization procedure.
(1) α -glucosidase: adding the following components in a 96-hole enzyme label plate in sequence: 60 μ l of sample to be tested or buffer (solution 1), 50 μ l of enzyme solution or buffer (solution 2), incubating at 37 ℃ for 20 min; then 50. mu.l of 5mM p-nitrophenyl-alpha-D-glucopyranoside (solution 3) was added. Incubate at 37 ℃ for 10 min. The absorbance values were read at 405nm using a microplate reader (Synergy2, Bio-Tek, USA). The enzyme inhibition was calculated as follows:
wherein A: both solutions 1 and 2 are buffer solutions; b: the solution 1 is a buffer solution, and the solution 2 is an enzyme solution; c: the solution 1 is a sample to be detected, and the solution 2 is a buffer solution; d: the solution 1 is a sample to be detected, and the solution 2 is an enzyme solution.
And setting samples to be detected with different concentrations, and respectively calculating inhibition rates. The solution concentration at which the inhibition ratio was 50%, i.e., the half-inhibitory concentration IC, was calculated by a computer program (Sigmaplot)50。
(2) Alpha-amylase: to a 2mL deep well plate were added in the order: 50. mu.l of sample to be tested or buffer (solution 1), 50. mu.l of enzyme solution or buffer (solution 2), incubated at 37 ℃ for 10 min; 100. mu.l of a 1.7% by weight starch solution (solution 3) were added. Incubate at 37 ℃ for 3min, develop color at 100 ℃ for 5min, and cool on ice for 5 min. Take 50. mu.l reaction + 100. mu.l ddH2O in 96 well plates and absorbance values were read at 540nm using a microplate reader (supra). The enzyme inhibition was calculated as follows:
wherein A: both solutions 1 and 2 are buffer solutions; b: the solution 1 is a buffer solution, and the solution 2 is an enzyme solution; c: the solution 1 is a sample to be detected, and the solution 2 is a buffer solution; d: the solution 1 is a sample to be detected, and the solution 2 is an enzyme solution. And taking the maximum inhibition rate.
Example 1: preparation of black tea product with alpha-glucosidase and alpha-amylase activity inhibition
Picking up tea raw materials of a first bud, a second bud and a third leaf in a floating girder in the west of the river, storing the leaves and preparing the tea according to the following processes:
primary preparation: fresh leaves-withering (temperature 25 ℃, duration: 10h) -rolling (duration 30min) -fermenting (25 ℃, 5h) -drying (90 ℃) -raw tea.
Refining: the production process comprises the steps of raw tea screening (aperture: 12 meshes), air separation, picking (removing non-tea inclusions), stacking and color forming (meeting the requirement of more than three grades of DB 36/T1028).
The content of the ingredients was measured as a percentage of the dry weight of the tea leaves according to the above method, as shown in table 1.
TABLE 1
The classification method of the present invention is used for classification, and the black tea product meets the requirements of the following relational expression group (1), and is classified as a grade 1 tea product.
(1) The content of tea polyphenol is more than or equal to 10 percent;
thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2；
Caffeine is more than or equal to 4 percent;
theaflavin is more than or equal to 0.9% and less than or equal to 1.2%;
The black tea product can inhibit alpha-glucosidase IC500.009mg/ml, and the maximum inhibition of alpha-amylase was 51%.
The black tea product is brewed for 1-2min according to 2-5g/200mL, is brewed for 2 times repeatedly, is drunk within 90min, and has the effects of inhibiting alpha-glucosidase, slowing down starch digestion, reducing glucose absorption and stabilizing postprandial blood sugar.
Example 2: preparation of crude extract of black tea water (instant tea powder) with activity of inhibiting alpha-glucosidase and alpha-amylase
The same Jiangxi black tea material as in example 1 was subjected to the following tea extract extraction and drying process to prepare an aqueous extract.
(1) Removing impurities: further removing non-tea impurities.
(2) Crushing: the particle size of the crushed tea is 0.5-2 mm.
(3) Leaching: leaching with water of 90 deg.C or higher at a ratio of 10 times for 40 min.
(4) Centrifuging: and carrying out solid-liquid separation by centrifugation at 800 r/min.
(5) Ceramic membrane filtration: with Al2O3Ceramic membrane process (Shijie membrane Co., 0.3 μm ceramic membrane tube)
The contents of the components contained in the above tea extract, in terms of dry weight of the raw materials, are shown in table 2 below. As can be seen from the results in table 2, the tea extract meets the requirements of the relational expression set (1), and is classified into a grade 1 tea product.
TABLE 2
| Composition (I) | Content (wt%) |
| Tea polyphenols | 10.1 |
| Catechin | 1.8 |
| Theaflavins | 1.1 |
| Thearubigin | 6.0 |
| Theabrownin | 7.5 |
| Caffeine | 4.8 |
| Inhibition of alpha-glucosidase IC50 | 0.007mg/ml |
| Of alpha-amylasesMaximum rate of inhibition | 51％ |
The extract is infused with 1g/200mL, and can be drunk within 90min, and has effects of reducing glucose absorption and stabilizing postprandial blood sugar.
The test was performed using the post-prandial blood glucose load test (OGTT test) of C57 mice, as follows: mice were acclimatized for 5 days and then gavaged with soluble starch (6 g/kg). The extract water solution (200mg/kg) is administered by intragastric administration at 200mg/kg 1d and 30min before sugar load, which is equivalent to 1.5g black tea powder per day. Blood glucose was measured from the tail vein of the mouse at 6 time points, 0, 20, 40, 60, 80 and 100min after gavage. The 7-day recovery period was given during which gavage was continued and after 7 days the sugar loading experiment was repeated and intestinal α -glucosidase activity was measured and the results are shown in figure 2. The results in fig. 2 show that the area under the postprandial blood glucose curve of the mice of the experimental group with continuous gavage of aqueous solution of black tea extract was reduced by 15.3% and, in addition, the intestinal α -glucosidase activity of the mice of the experimental group with aqueous solution of gavage of black tea extract was reduced by 25%, compared to the control group of mice without aqueous solution of gavage of black tea extract.
Mice are fed with high-fat and high-sugar feed to form a glucose metabolism disorder model, and the extract aqueous solution is respectively administered with 100 mg/kg, 200mg/kg and 400mg/kg per day, which is equivalent to drinking 0.75 g, 1.5g and 3g of black tea powder per day by people. After 6 weeks of intervention, gavage was given with glucose (6 g/kg). The elution was stopped 1d before sugar loading by the above extract. Blood glucose was measured from vein blood taken from the tail of the mouse at 6 time points 0, 20, 40, 60, 80 and 100min after gastric lavage with glucose. As a result, it was found that the area under the postprandial blood glucose curve of the mice of the test group continuously gabled with 100, 200, 400mg/kg aqueous solution of black tea extract was reduced by 5%, 7%, 9%, respectively, as compared with the mice of the test group not gabled with the aqueous solution of black tea extract. Meanwhile, compared with the control group, the high-fat feed causes the weight of the animals in the model group to be additionally increased by 17.8%, and the weight of the mice is averagely reduced by 0%, 5.5% and 12.7% by the black tea extract aqueous solution in the three-dose intragastric administration groups, which shows that the intervention of the black tea extract with medium and high doses also has the effect of helping to maintain healthy weight.
The results of blood glucose measurements of 30 pre-diabetic subjects recruited and drunk an aqueous solution containing 1g of the above extract daily for 30 consecutive days without changing the dietary pattern are shown in fig. 3. Wherein the baseline is day 0, the middle is day 15, and the end is day 30. The results in figure 3 show a significant improvement in postprandial glycemic response with a 78.75mmol/L min reduction from baseline.
Example 3: black tea activity grading and ingredient characteristics
The concentrations of the respective components were measured using the teas shown in table 4, and the results of the amounts of tea polyphenol, theaflavin, thearubigin, caffeine, (thearubigin × caffeine)/theabrownin, (theaflavin × caffeine)/(catechin × theabrownin) contained therein were calculated as shown in table 3.
TABLE 3
Judging whether the content satisfies the following relational expression groups (1), (2) and (3) in sequence:
(1) the content of tea polyphenol is more than or equal to 10 percent;
thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2；
Caffeine is more than or equal to 4 percent;
theaflavin is more than or equal to 0.9% and less than or equal to 1.2%;
(2) The content of tea polyphenol is more than or equal to 10 percent;
catechin is more than or equal to 1 percent; and is
Theaflavin is more than or equal to 0.2;
(3) the content of tea polyphenol is more than or equal to 10 percent; and is
Catechin is more than or equal to 10 percent;
tea products satisfying the relational expression group (1) are classified into 1 grade, tea products satisfying the relational expression group (2) and not satisfying the relational expression group (1) are classified into 2 grades, tea products satisfying the relational expression group (3) and not satisfying the relational expression groups (1) and (2) are classified into 3 grades, and tea products not satisfying the relational expression groups (1), (2) and (3) are classified into 4 grades. The results of the fractionation are shown in Table 4.
And (3) verifying grading results: determination of inhibition of alpha-glucosidase IC by each tea50And the maximum inhibition of alpha-amylase, the results are shown in table 4. The above fractionation results were compared with the inventive alpha-glucosidase IC for grade 1-4 tea50And the maximum inhibition rate of alpha-amylase.
TABLE 4
Example 4: functional staple food containing tea leaf extract
Extracts of Xiaozhonghong (Zhengshan Tang), Haiyochong (Xiamen tea imports and exports Co., Ltd.), and Yunnan red (Yunnan Red group) were prepared according to the method of example 3.
The three black tea extracts (0.5 g of black tea extract was added to 100g of the dried noodles) were compounded in the dried noodles, and the effect on the starch hydrolysis rate was examined by the following in vitro digestion simulation test, and the results are shown in fig. 1.
(1) The crushed sample is put into a 50mL inlet centrifuge tube, 5mL of 50% saturated benzoic acid is added, 10mL of preheated pepsin solution is added, and the mixture is obliquely shaken in a water bath at 37 ℃ for 30 min.
(2) Taking out, adding 5mL of sodium acetate solution, adjusting the pH to 5.2 by using 2mol/L of sodium hydroxide, adding 5mL of working enzyme solution and 5 glass beads, screwing a bottle cap, and horizontally shaking in a water bath shaking table at 37 ℃.
(3) The reaction was stopped by pipetting 0.2mL into a centrifuge tube containing 2mL of absolute ethanol at 0, 10, 20, 40, 60, and 120min, respectively.
(4) All the glass beads were removed, 10mL of 7M potassium hydroxide was added to each tube, carefully mixed, and shaken in an ice bath for 30 min.
(5) Preparing another set of 50mL centrifuge tube, adding 10mL of 0.5M acetic acid into each tube, adding 1mL of ice water shaken sample, adding 0.2mL of amyloglucosidase, reacting at 70 ℃ for 30min, stopping the reaction by boiling water for 10min, cooling to room temperature, adding 30mL of water, mixing uniformly, and centrifuging (1500rpm, 5 min).
(6) Adding 0, 40, 80, 120, 160 and 200 mu L of 1mg/mL glucose into a deep-hole plate, supplementing water to 200 mu L, adding 400 mu L of DNS reagent, carrying out boiling water bath for 5min, taking out, carrying out ice bath, cooling to room temperature, correspondingly absorbing 60 mu L of reaction liquid into an enzyme-labeled plate added with 180 mu L of deionized water through an automatic sampler in advance according to the hole, shaking the plate at a medium speed for 10s, and measuring the absorbance at 540nm to obtain ABlank spaceAnd AControl. The sample (200. mu.L) was used in place of the standard substance in the same manner as above to obtain ASample (I). Determination of the Absorbance A of 20. mu.L sample + 220. mu.L deionized Water1Measuring the absorbance A of deionized water2. Final absorbance of sample: is aSample (I)-A1+A2-ABlank space。
The results in figure 1 show that all three black tea extracts have a starch digestion inhibiting effect.
Example 5: evaluation and grading of representative tea in China
Commercially available 9 kinds of tea leaves including green tea, white tea, black tea, oolong tea, puer tea, dark tea, Liupu tea, etc. of various origins and processes were selected, and the contents of active ingredients required for the method were measured and classified in the same manner as in example 3, and the results are shown in Table 5.
TABLE 5
Separately determining alpha-glucosidase IC of each tea50And the maximum inhibition of alpha-amylase, the results are shown in table 6.
TABLE 6
The above fractionation results were compared with the inventive alpha-glucosidase IC for grade 1-4 tea50And the maximum inhibition rate of alpha-amylase.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (8)
1. The application of the tea product in preparing the composition for stabilizing the blood sugar is characterized in that the concentration of each component contained in the tea product meets the following characteristics:
the content of tea polyphenol is more than or equal to 10 percent;
thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2；
Caffeine is more than or equal to 4 percent;
theaflavin is more than or equal to 0.9% and less than or equal to 1.2%;
2. The use according to claim 1, wherein the tea product comprises the following components in concentrations that satisfy the following characteristics:
16% or more of tea polyphenol is 10% or more;
12% or more than or equal to 5% of thearubigin;
3(％)2not less than theaflavin x catechin not less than 1.2 (%)2；
5% or more than 4% of caffeine;
theaflavin is more than or equal to 0.96% and less than or equal to 1.2%;
3. Use according to claim 1 or 2, wherein the tea product inhibits alpha-glucosidase IC50Not more than 0.01mg/mL and the maximum inhibition rate on alpha-amylase>50％。
4. A quality grading method of a tea product is characterized in that the method comprises the steps of measuring the concentrations of tea polyphenol, thearubigin, theaflavin, catechin, caffeine and theabrownin in the tea product, and sequentially judging whether the concentrations satisfy the following relational expression groups (1), (2) and (3):
(1) the content of tea polyphenol is more than or equal to 10 percent;
thearubigin greater than or equal to 5% or theaflavin x catechin greater than or equal to 1.2 (%)2；
Caffeine is more than or equal to 4 percent;
theaflavin is more than or equal to 0.9% and less than or equal to 1.2%;
(2) The content of tea polyphenol is more than or equal to 10 percent;
catechin is more than or equal to 1 percent; and is
Theaflavin is more than or equal to 0.2%;
(3) the content of tea polyphenol is more than or equal to 10 percent; and is
Catechin is more than or equal to 10 percent;
tea products satisfying the relational expression group (1) are classified into 1 grade, tea products satisfying the relational expression group (2) and not satisfying the relational expression group (1) are classified into 2 grades, tea products satisfying the relational expression group (3) and not satisfying the relational expression groups (1) and (2) are classified into 3 grades, and tea products not satisfying the relational expression groups (1), (2) and (3) are classified into 4 grades.
5. A quality grading process for a tea product according to claim 4 wherein the grade 1 tea product inhibits alpha glucosidase IC50Less than or equal to 0.01mg/mL and the maximum inhibition rate to alpha-amylase is more than 50 percent.
6. A quality grading process for a tea product according to claim 4 wherein the grade 2 tea product inhibits alpha glucosidase IC50Less than or equal to 0.1mg/mL or the maximum inhibition rate to alpha-amylase is more than 50 percent.
7. A quality grading method of a tea product according to claim 4 wherein the grade 3 tea product inhibits alpha-glucosidase IC50 ≤ 1.0mg/mL or has a maximum inhibition rate for alpha-amylase ≥ 10%.
8. A method of screening for a tea product, the method comprising: grading using the method of quality grading of a tea product according to any of claims 4 to 7.
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