Method for extracting theabrownin from tea leaves

Abstract

The invention discloses a method for preparing tea leaf extract theabrownin, which comprises the following steps: weighing tea leaves, and grinding the tea leaves to form broken tea; soaking with absolute ethyl alcohol, and filtering to leave tea residues; the tea residues are extracted and filtered, and the tea residues are filtered out; performing vacuum concentration on the filtrate; performing vacuum concentration, extracting, and taking supernatant; concentrating the extracted supernatant under reduced pressure; concentrating under reduced pressure, continuously extracting, and taking subnatant; adding absolute ethyl alcohol into subnatant, carrying out alcohol precipitation and standing; centrifuging, collecting precipitates, and freeze-drying to obtain an extracted theabrownin sample. According to the method, soaking solutions can be efficiently formed for different tea leaves, tea brown in the corresponding tea leaves can be fully released, and the yield of theabrownin can be effectively increased. According to the method, many impurities are removed through multiple times of organic solvent extraction, the content of theabrownin can be effectively increased, and the content of theabrownin extracted under the condition can reach 47.235%.

Description

Technical Field

[0001] The invention relates to the field of theabrownin, in particular to a method for extracting theabrownin from tea leaves. Background Art

[0002] Theabrownin is an important pigment component in tea, which gives tea its unique color and flavor. Theabrownin is mainly found in partially fermented oolong tea, as well as fully fermented black tea and dark tea. During the fermentation process, catechins, epicatechins, and gallic acid ester derivatives are oxidized into complex theaflavins and thearubigins, which are further oxidized and polymerized into brown theaflavins, which contain functional groups such as carboxyl and hydroxyl groups. These functional groups give theabrownin a variety of biological activities. The molecular weight of most theabrownins is greater than 25,000 Da.

[0003] The commonly used method for extracting theabrownin from tea is solvent extraction, which uses the fact that theabrownin is easily soluble in water but insoluble in organic solvents such as dichloromethane, ethyl acetate, and n-butanol. However, this extraction method cannot fully extract theabrownin from tea leaves, and at the same time, the purity of theabrownin is not high, and the extraction effect is poor. Therefore, in view of the above problems, an improved method for extracting theabrownin from tea leaves is proposed. Summary of the invention

[0004] Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a method for extracting theabrownin from tea leaves. The method of the present invention effectively solves the problems in the prior art that theabrownin in tea leaves cannot be fully extracted, and at the same time, the purity of theabrownin is not high and the extraction effect is poor.

[0005] Technical solution: In order to achieve the above-mentioned purpose, the method of producing theabrownin from tea extract of the present invention comprises the following steps:

[0006] (1) weighing tea leaves and grinding the tea leaves to form broken tea leaves;

[0007] (2) soaking with anhydrous ethanol, filtering, and leaving the tea residue;

[0008] (3) extracting and filtering the tea dregs to remove the tea dregs;

[0009] (4) concentrating the filtrate under reduced pressure;

[0010] (5) extracting after concentration under reduced pressure and taking the upper layer;

[0011] (6) concentrating the upper layer liquid after extraction under reduced pressure;

[0012] (7) After step (6), the extraction is continued after reduced pressure concentration, and the lower layer liquid is taken;

[0013] (8) adding anhydrous ethanol to the lower liquid and allowing the alcohol to precipitate and stand;

[0014] (9) Centrifuge and collect the precipitate, freeze-dry it, and obtain the extracted theabrownin product.

[0015] Wherein, in step (1), the tea leaves are weighed, and the weighed tea leaves are dry and clean tea leaves samples. The tea leaves are quantitatively weighed, and the symmetrically taken tea leaves are ground using a mortar to form broken tea.

[0016] In step (2), the broken tea is soaked in a measuring cup for 8 to 12 hours in 95% anhydrous ethanol, 5 to 10 grams of broken tea is soaked in 300 to 500 milliliters of 95% anhydrous ethanol, and then filtered with an absorbent cotton filter to leave tea residue.

[0017] In step (3), a constant temperature water bath is used to extract the tea residues once or twice with water at an extraction temperature of 60 to 100° C., an extraction time of 30 to 150 min, and a solid-liquid ratio of 1:15 to 1:55 g / mL, and the tea residues are filtered after cooling to remove the tea residues.

[0018] The cooled soaking liquid is filtered using an absorbent cotton filter. After filtering once, check whether there are tea particle impurities in the filtrate. If there are, filter multiple times to completely filter out the tea particles to form an extract.

[0019] In step (4), the whole extract is concentrated to 60-90 ml by using a rotary evaporator under reduced pressure to form a concentrated solution, so as to facilitate sufficient extraction in the following extraction step.

[0020] In step (5), the concentrated solution is injected into a separatory funnel, and dichloromethane is added to the separatory funnel, the volume ratio of the concentrated solution to dichloromethane is 3-4:1, the separatory funnel is fully shaken for 1-3 minutes, and then allowed to stand for 10-30 minutes, and the water layer and the dichloromethane layer are separated after standing, and this step is performed two to three times.

[0021] Further, dichloromethane was added to the separatory funnel, and the volume ratio of the two was 3:1. The volume ratio of the concentrate to dichloromethane was 3:1.

[0022] In step (6), a rotary evaporator is used to reduce the pressure and concentrate the entire upper layer liquid to 20-30 mL, so as to facilitate sufficient extraction in the following extraction step.

[0023] Wherein, in step (7), the concentrated solution is injected into a separatory funnel, an equal volume of ethyl acetate is added to the separatory funnel, the separatory funnel is fully shaken for 1-3 minutes, the separatory funnel is allowed to stand for 10-30 minutes, the water layer and the ethyl acetate layer are separated after standing, and the lower water layer is separated from the ethyl acetate layer, and this step is performed three to four times; then, an equal volume of n-butanol is added to the separatory funnel as the water layer, the separatory funnel is fully shaken for 1-3 minutes, the separatory funnel is allowed to stand for 10-30 minutes, the water layer and the n-butanol layer are separated after standing, and the lower water layer is separated from the n-butanol layer, and this step is performed three to four times.

[0024] In step (8), anhydrous ethanol is added to the lower layer liquid to make the volume of the lower layer ethanol solution reach 85-90% of the final volume, and the alcohol precipitation is allowed to stand for 8-12 hours.

[0025] In step (9), a centrifuge is used at 8000 r / min. -1 The mixture was centrifuged for 15 min and the precipitate was collected. After pre-freezing, the precipitate was freeze-dried for 24 h to obtain the extracted theabrownin sample.

[0026] During the extraction of the present invention, in step (5), an aqueous phase and a dichloromethane organic phase are used, and the volume ratio of the two is ensured to be 3:1, which effectively reduces the loss of theabrownin. When the volume ratio of the aqueous phase to the dichloromethane organic phase is 1:1, the yield of theabrownin will be significantly reduced. When an organic phase such as ethyl acetate or n-butanol is used, the ratio of the aqueous phase to the organic phase is adjusted according to the method of the present invention, and the yield of theabrownin does not change significantly.

[0027] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0028] (1) The present invention can efficiently form soaking liquid for different tea leaves, fully release the brown color in the corresponding tea leaves, and effectively increase the yield of theabrownin.

[0029] (2) The present invention removes more impurities through multiple organic solvent extractions, which can effectively increase the content of theabrownin. The theabrownin content extracted under this condition can reach 47.235%.

[0030] (3) The present invention reduces the loss of theabrownin and effectively increases the yield of theabrownin by changing the volume ratio of the aqueous phase to the dichloromethane organic phase in step (5). BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Flowchart for improving the extraction method;

[0032] Figure 2This is a flow chart of the original unmodified method;

[0033] Figure 3 This is the extraction effect diagram when the volume ratio of water phase to dichloromethane organic phase is 1:1 and 1:3. Figure 3 A is the extraction effect when the volume ratio of water phase to dichloromethane organic phase is 1:1, Figure 3 B is the extraction effect when the volume ratio of water phase to dichloromethane organic phase is 1:3;

[0034] Figure 4 It is a comparison diagram of the extraction results of the solvent extraction method and the present invention;

[0035] Figure 5 The effect of solid-liquid ratio on the content of theabrownin;

[0036] Figure 6 The effect of extraction temperature on the content of theabrownin;

[0037] Figure 7 Effect of extraction time on theabrownin content. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0039] Unless otherwise specified, the materials and reagents used in the examples of the present invention can be obtained from commercial sources. Experimental methods without specific conditions in the examples are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0040] Example 1

[0041] like Figure 1 As shown, an improvement of a method for producing theabrownin from tea extract comprises the following steps:

[0042] (1) Weigh the tea leaves. Select dry and clean tea leaves as the weighed tea leaves. Weigh the tea leaves quantitatively. The weighed weight is 10 grams. Grind the symmetrically taken tea leaves using a mortar to form broken tea leaves, so that the brown color in the tea leaves can be fully extracted for subsequent testing.

[0043] (2) Soak the broken tea leaves in a measuring cup for 8 hours using 95% anhydrous ethanol (500 ml of 95% anhydrous ethanol), and then filter using an absorbent cotton filter to leave the tea residue.

[0044] (3) Use a constant temperature water bath, extract the tea residue once at an extraction temperature of 90°C, an extraction time of 90 min, and a solid-liquid ratio of 1:35 g / mL, and filter with an absorbent cotton filter to remove the tea residue to form an extract. After filtration, check whether there are tea particle impurities in the filtrate. If there are, filter it multiple times to completely remove the tea particles to form an extract.

[0045] (4) Use a rotary evaporator to reduce the pressure and concentrate the entire extract to about 60-90 mL to form a concentrated solution, so that it can be fully extracted in the following extraction step.

[0046] (5) The concentrate was injected into a separatory funnel, and dichloromethane was added into the separatory funnel. The volume of the concentrate and dichloromethane was 3:1. The separatory funnel was fully shaken for 2 minutes. After shaking, the funnel was allowed to stand for 15 minutes. After standing, the water layer and the dichloromethane layer were separated. This step was performed twice, and the upper organic phase was combined.

[0047] (6) Use a rotary evaporator to reduce the volume of the upper layer solution after extraction to 20-30 mL.

[0048] (7) The concentrate was injected into a separatory funnel, and an equal volume of ethyl acetate was added to the separatory funnel. The separatory funnel was shaken thoroughly for 2 minutes. After shaking, the funnel was allowed to stand for 15 minutes. After standing, the aqueous layer and the ethyl acetate layer were separated. This step was repeated three times, and the aqueous layers were combined.

[0049] (8) Pour the lower aqueous layer into a separatory funnel, add an equal volume of n-butanol to the aqueous layer into the separatory funnel, and shake the separatory funnel thoroughly for 2 minutes. After shaking, let it stand for 15 minutes to separate the aqueous layer and the n-butanol layer. This step is repeated three times, and the aqueous layers are combined.

[0050] (9) Add 95% anhydrous ethanol to the aqueous layer to make the ethanol volume reach 85% of the final volume, and let the alcohol precipitation stand for 12 hours.

[0051] (10) The mixture was centrifuged at 8000 r / min for 15 min and the precipitate was collected. After pre-freezing, the precipitate was freeze-dried for 24 h to obtain the extracted theabrownin product. The theabrownin content was as high as 47.235%.

[0052] Example 2

[0053] like Figure 2 As shown, the method of Example 2 is the same as that of Example 1, except that in step (5), equal volumes of dichloromethane are used for extraction twice.

[0054] By comparing the extraction effect diagram of the improved method of Example 1 with the original unimproved method of Example 2 in dichloromethane extraction (such as Figure 3 It was found that the improved method had better extraction effect, reduced the loss of theabrownin, and effectively increased the content of theabrownin.

[0055] By comparing the tea brown book content obtained by the improved method of Example 1 with the original unimproved method of Example 2 under the same treatment conditions (such as Figure 4 It was found that the theabrownin content of the product obtained by the improved method was significantly increased, indicating that the improved method can effectively increase the yield of theabrownin.

[0056] Meanwhile, if the same method as in Example 1 is used, except that the volume ratio of the aqueous phase to the dichloromethane organic phase in step (5) is 5:1, the yield of theabrownin will also be significantly reduced, and the theabrownin content is only about 35%.

[0057] Example 3

[0058] On the basis of Example 1, the effects of different extraction parameters on the content of theabrownin in the improved method were explored by controlling variables through single factor experiments. Different extraction parameters include: solid-liquid ratio (1:15, 1:25, 1:35, 1:45, 1:55 g / mL), extraction temperature (60°C, 70°C, 80°C, 90°C, 100°C), extraction time (30min, 60min, 90min, 120min, 150min), and each experimental treatment was repeated three times.

[0059] The results of the single factor test are as follows Figures 5 to 7 The results of the single factor test showed that the solid-liquid ratio was 1:35 g / mL (such as Figure 5 When the extraction temperature is 90°C (as shown in Figure 6 As shown), the extraction time is 90min (as shown Figure 7 When the theabrownin content is high (as shown in FIG.

Claims

1. A method for extracting theabrownin from tea leaves, characterized in that: The steps include: (1) weighing tea leaves and grinding the tea leaves to form broken tea leaves; (2) soaking with anhydrous ethanol, filtering, and leaving the tea residue; (3) extracting and filtering the tea dregs to remove the tea dregs; (4) concentrating the filtrate under reduced pressure; (5) extracting after concentration under reduced pressure and taking the upper liquid; (6) concentrating the upper layer liquid after extraction under reduced pressure; (7) After step (6), the extraction is continued after reduced pressure concentration, and the lower layer liquid is taken; (8) adding anhydrous ethanol to the lower liquid and allowing the alcohol to precipitate; (9) Centrifuge and collect the precipitate, freeze-dry it, and obtain the extracted theabrownin product.

2. The method for extracting theabrownin from tea leaves according to claim 1, characterized in that: In step (1), the tea leaves are weighed, and the weighed tea leaves are selected from dry and clean tea leaves samples. The tea leaves are weighed quantitatively, and the symmetrically taken tea leaves are ground using a mortar to form broken tea.

3. The method for extracting theabrownin from tea leaves according to claim 1, characterized in that: In step (2), the broken tea is soaked in a measuring cup for 8 to 12 hours in 95% anhydrous ethanol, 5 to 10 grams of broken tea is soaked in 300 to 500 milliliters of 95% anhydrous ethanol, and then filtered with an absorbent cotton filter to leave tea residue.

4. The method for extracting theabrownin from tea leaves according to claim 1, characterized in that: In step (3), a constant temperature water bath is used to extract the tea residues once or twice with water at an extraction temperature of 60 to 100° C., an extraction time of 30 to 150 min, and a solid-liquid ratio of 1:15 to 1:55 g / mL. After cooling, the tea residues are filtered to remove the tea residues.

5. The method for extracting theabrownin from tea leaves according to claim 4, characterized in that: The cooled soaking liquid is filtered using an absorbent cotton filter. After filtering once, check whether there are tea particle impurities in the filtrate. If there are, filter multiple times to completely filter out the tea particle impurities to form an extract.

6. The method for extracting theabrownin from tea leaves according to claim 1, characterized in that: In step (4), the entire extract is concentrated to 60-90 ml under reduced pressure using a rotary evaporator to form a concentrated solution.

7. The method for extracting theabrownin from tea leaves according to claim 1, characterized in that: In step (5), the concentrated solution is injected into a separatory funnel, and dichloromethane is added to the separatory funnel. The volume ratio of the two is preferably 3-4:

1. The separatory funnel is fully shaken for 1-3 minutes. After shaking, the mixture is allowed to stand for 10-30 minutes. After standing, the water layer and the dichloromethane layer are separated. The water layer and the dichloromethane layer are separated. This step is performed two to three times.

8. The method for extracting theabrownin from tea leaves according to claim 1, characterized in that: In step (6), the entire upper layer liquid is concentrated to 20-30 mL under reduced pressure using a rotary evaporator to form a concentrated solution.

9. The method for extracting theabrownin from tea leaves according to claim 1, characterized in that: In step (7), the concentrated solution is injected into a separatory funnel, an equal volume of ethyl acetate is added to the separatory funnel, and the separatory funnel is fully shaken for 1-3 minutes. After shaking, the separatory funnel is allowed to stand for 10-30 minutes. After standing, the water layer and the ethyl acetate layer are separated, and the lower water layer and the ethyl acetate layer are separated. This step is repeated three to four times; then, an equal volume of n-butanol is added to the separatory funnel as the water layer, and the separatory funnel is fully shaken for 1-3 minutes. After shaking, the separatory funnel is allowed to stand for 10-30 minutes. After standing, the water layer and the n-butanol layer are separated, and the lower water layer and the n-butanol layer are separated. This step is repeated three to four times.

10. The method for extracting theabrownin from tea leaves according to claim 1, characterized in that: In step (8), anhydrous ethanol is added to the lower layer liquid to make the volume of the lower layer ethanol solution reach 85-90% of the final volume, and the alcohol precipitation is allowed to stand for 8-12 hours.

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