Method for identifying oolong tea

Abstract

The invention provides a method for distinguishing the year of aged oolong tea. The method comprises the steps that an aged oolong tea extract is prepared; the content of a compound in the extract isdetected by HPLC, wherein the compound is selected from one or more of catechin monomers, gallic acid (GA), ester catechin content, phenotypic catechin content and total catechin content; and the yearof the aged oolong tea is determined compared with the content standard. The invention further provides comprehensive detection and differentiation by using biological activity test assisted by chemical component detection. Since biological activity test reflects the synergistic and combined effect of all components of the extract, artificially adding a certain component leads to a huge activitydifference, which deviates significantly from the standard. Accurate year distinguishing is realized.

Description

technical field

[0001] The invention relates to the field of food, in particular to an identification method for oolong tea. Background technique

[0002] "Drinking tea should be new, drinking should be old", this is a long-term summary of tea drinking life. However, not all teas are new teas that are better than old teas. In recent years, aged oolong teas have set off a wave of upsurge, and corresponding medical research has also been carried out. Osteoporosis in women over 65 years old found that although tea contains caffeine, the rate of osteoporosis is higher in those who do not drink tea. Doctors believe that aged oolong tea contains plant hormones, catechins It can counteract the negative effects of caffeine. Gout is a disease caused by excess uric acid in the blood. Aged old tea has the functions of diuresis, preventing stones, sterilizing and anti-virus, anti-cancer, anti-oxidation, anti-radiation, removing greasy, helping to reduce fat, lowering blood pressure, ...

Examples

Embodiment 1

[0038] Embodiment 1: the preparation of oolong tea extract

[0039] The preparation flow chart is attached figure 1 , including the following steps:

[0040] S1 Extraction: The raw material oolong tea is extracted 3-5 times with hot water, the water temperature is 80-90°C, and the extraction time is 0.5-1h.

[0041] S2 Filtration while hot: quickly filter the extracted tea soup with filter paper or cotton.

[0042] S3 Concentration by Rotary Evaporation: Concentrate the obtained extract by rotary evaporation between 40-60°C.

[0043] S4 freeze-drying: import the concentrate obtained from step S3 into a suitable container, store at -80°C for 6-10 hours, and then put it into a freeze dryer for freeze-drying.

[0044] S5 storage: put the freeze-dried powder into a ziplock bag, put it in a desiccator and store it at room temperature until use.

Embodiment 2

[0045] Embodiment 2: detection and experimental method:

[0046] 1. Content detection of main biochemical components of tea samples

[0047] Moisture determination: 103°C constant weight method; water extract determination: GB / T8305-2002; tea polyphenol content: ferrous tartrate method GB / T8313-2002; amino acid content: ninhydrin colorimetric method GB / T8314-2002 ; Soluble sugar content: anthrone-sulfuric acid colorimetric method;

[0048] 2. HPLC method to detect the content of catechin monomers in tea soup

[0049] Chromatographic column: Agilent ZORBAX Eclipse XDB-C18 column, 150mm×4.6mm; detection wavelength 280nm, detection temperature 28°C; mobile phase A: aqueous solution containing 0.5% acetic acid, 1% acetonitrile and 2% methanol, mobile phase B: containing 0.5 Aqueous solution of % acetic acid, 10% acetonitrile and 20% methanol; elution steps: within 30min, phase A from 72.5% to 20%, phase B from 27.5% to 80%, after 30min within 5min, phase A from 20% Recovery to ...

Embodiment 6

[0059] Embodiment 6: experimental result

[0060] 1. Table 1 Biochemical component content of aged oolong tea in different years / %

[0061]

[0062] Note: * p** p<0.01, with 2016 oolong tea as the control.

[0063] It can be seen from Table 1 that the contents of tea polyphenols and soluble sugars in the three kinds of oolong teas of different years do not have a universally applicable rule, but the contents of amino acids in the three kinds of oolong teas have a general rule. The content is generally lower than that of oolong tea in 2016. There are large differences in the content of flavonoids. In Huang Jinrong and Daye Qilan, the content of flavonoids in 1990 oolong tea is significantly lower than that of 2016 oolong tea. In Lingtou Dancong, the flavonoid content of 1990 oolong tea was higher than that of 2016 oolong tea. Therefore, according to the results, it can be seen that except for amino acids, other indicators are not universal indicators, and cannot be speci...

technical field

[0001] The invention relates to the field of food, in particular to an identification method for oolong tea. Background technique

[0002] "Drinking tea should be new, drinking should be old", this is a long-term summary of tea drinking life. However, not all teas are new teas that are better than old teas. In recent years, aged oolong teas have set off a wave of upsurge, and corresponding medical research has also been carried out. Osteoporosis in women over 65 years old found that although tea contains caffeine, the rate of osteoporosis is higher in those who do not drink tea. Doctors believe that aged oolong tea contains plant hormones, catechins It can counteract the negative effects of caffeine. Gout is a disease caused by excess uric acid in the blood. Aged old tea has the functions of diuresis, preventing stones, sterilizing and anti-virus, anti-cancer, anti-oxidation, anti-radiation, removing greasy, helping to reduce fat, lowering blood pressure, ...

Examples

Embodiment 1

[0038] Embodiment 1: the preparation of oolong tea extract

[0039] The preparation flow chart is attached figure 1 , including the following steps:

[0040] S1 Extraction: The raw material oolong tea is extracted 3-5 times with hot water, the water temperature is 80-90°C, and the extraction time is 0.5-1h.

[0041] S2 Filtration while hot: quickly filter the extracted tea soup with filter paper or cotton.

[0042] S3 Concentration by Rotary Evaporation: Concentrate the obtained extract by rotary evaporation between 40-60°C.

[0043] S4 freeze-drying: import the concentrate obtained from step S3 into a suitable container, store at -80°C for 6-10 hours, and then put it into a freeze dryer for freeze-drying.

[0044] S5 storage: put the freeze-dried powder into a ziplock bag, put it in a desiccator and store it at room temperature until use.

Embodiment 2

[0045] Embodiment 2: detection and experimental method:

[0046] 1. Content detection of main biochemical components of tea samples

[0047] Moisture determination: 103°C constant weight method; water extract determination: GB / T8305-2002; tea polyphenol content: ferrous tartrate method GB / T8313-2002; amino acid content: ninhydrin colorimetric method GB / T8314-2002 ; Soluble sugar content: anthrone-sulfuric acid colorimetric method;

[0048] 2. HPLC method to detect the content of catechin monomers in tea soup

[0049] Chromatographic column: Agilent ZORBAX Eclipse XDB-C18 column, 150mm×4.6mm; detection wavelength 280nm, detection temperature 28°C; mobile phase A: aqueous solution containing 0.5% acetic acid, 1% acetonitrile and 2% methanol, mobile phase B: containing 0.5 Aqueous solution of % acetic acid, 10% acetonitrile and 20% methanol; elution steps: within 30min, phase A from 72.5% to 20%, phase B from 27.5% to 80%, after 30min within 5min, phase A from 20% Recovery to ...

Embodiment 6

[0059] Embodiment 6: experimental result

[0060] 1. Table 1 Biochemical component content of aged oolong tea in different years / %

[0061]

[0062] Note: * p** p<0.01, with 2016 oolong tea as the control.

[0063] It can be seen from Table 1 that the contents of tea polyphenols and soluble sugars in the three kinds of oolong teas of different years do not have a universally applicable rule, but the contents of amino acids in the three kinds of oolong teas have a general rule. The content is generally lower than that of oolong tea in 2016. There are large differences in the content of flavonoids. In Huang Jinrong and Daye Qilan, the content of flavonoids in 1990 oolong tea is significantly lower than that of 2016 oolong tea. In Lingtou Dancong, the flavonoid content of 1990 oolong tea was higher than that of 2016 oolong tea. Therefore, according to the results, it can be seen that except for amino acids, other indicators are not universal indicators, and cannot be speci...

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