JP6629707B2 - Method for producing green tea extract - Google Patents

Description

  The present invention relates to a method for producing a green tea extract.

  As the main components of the non-polymer catechins contained in tea leaves, free non-polymer catechins composed of epigallocatechin, gallocatechin, epicatechin and catechin, and epigallocatechin gallate, gallocatechin gallate, epicatechin gallate and catechin Gallate-type non-polymer catechins composed of gallate are known. In addition, it has been reported that gallate-type non-polymer catechins have stronger antioxidant effects, blood cholesterol lowering effects, and the like of non-polymer catechins than free non-polymer catechins.

  In order to express such a physiological effect, it is advantageous to ingest high-purity non-polymer catechins rich in gallate-type non-polymer catechins. However, since tea leaves contain not only non-polymer catechins but also contaminants such as caffeine, sugar, amino acids, etc., non-polymer catechins rich in gallate-type non-polymer catechins can be highly purified from tea leaves. It is difficult to extract with purity.

  Conventionally, as a technique for recovering gallate-type non-polymer catechins from a tea extract extracted from tea leaves, for example, a gallate-type catechin is prepared by contacting a tea extract with a weakly acidic cation exchange resin containing a carboxylic acid functional group. A method of recovering gallate-type catechin by adsorbing and then contacting an eluent with a weakly acidic cation exchange resin to elute gallate-type catechin from the resin has been proposed (Patent Document 1).

  Further, as a method for producing a green tea extract in which non-polymer catechins are efficiently recovered and impurities such as caffeine are reduced, for example, fresh tea leaves are extracted with water at 70 to 100 ° C., and the extract is separated. Thus, a method has been proposed in which an extraction residue is obtained by immersing the extraction residue in water at 105 to 150 ° C. for extraction (Patent Document 2).

JP 2012-140401 A JP-A-2015-84726

  An object of the present invention is to provide a method for producing a green tea extract containing non-polymer catechins rich in gallate-type non-polymer catechins with high purity.

  The present inventors have examined in view of the above problems, as a result, contacting fresh tea leaves with water at a predetermined temperature, then cutting the tea leaves, then contacting again with water at a predetermined temperature, and extracting with water at a predetermined temperature. Thus, the present inventors have found that a green tea extract containing non-polymer catechins rich in gallate-type non-polymer catechins with high purity can be obtained.

That is, the present invention provides a method for producing a green tea extract, comprising the following steps (A) to (D).
(A) Step of contacting fresh tea leaves with water at 80 to 100 ° C (B) Step of cutting tea leaves after step (A) (C) Contacting tea leaves after step (B) with water at 0 to 40 ° C Step (D) Step of extracting tea leaves after step (C) with water at 50 to 100 ° C

  According to the present invention, a green tea extract containing non-polymer catechins rich in gallate-type non-polymer catechins with high purity can be efficiently produced.

  The method for producing a green tea extract of the present invention includes the steps (A) to (D). Hereinafter, each step will be described in detail.

Step (A)
Step (A) is a step of bringing fresh tea leaves into contact with water at 80 to 100 ° C. Thereby, caffeine can be selectively removed while suppressing fermentation of fresh tea leaves. Here, in the present specification, `` raw tea leaves '', after plucking, tea leaves before heat treatment, or after plucking, refers to tea leaves refrigerated or frozen before heat treatment, from the viewpoint of fermentation suppression, as raw tea leaves, after plucking It is preferable to use one within 24 hours, or one refrigerated or frozen within 24 hours after plucking.

  From the viewpoint of improving the recovery rate of gallate-type non-polymer catechins, improving the purity of non-polymer catechins, and removing impurities, fresh tea leaves (full leaf) are preferably used as raw tea leaves. The picking method includes hand picking, scissor picking, and mechanical picking. Hand picking is usually performed by two leaf picking or three leaf picking. The mechanical picking can be of a portable type, a portable type, a self-propelled type, a riding type, a rail type, or the like, depending on the size and use method of the machine. Tea leaves plucked by these methods can be used without cutting. The timing of collecting the tea leaves is not particularly limited.

  The tea varieties of the raw tea leaves are not particularly limited as long as they are generally cultivated. For example, the genus Camellia, for example, C. sinensis var. Sinensis (including the yabu-kita species), C. sinensis var. And tea leaves (Camellia sinensis) selected from hybrids. As specific examples of varieties, in Japanese tea leaves, for example, benifuuki, benihodori, benifuji, benihikari, yabukita, asatsuyu, yamatomidori, makinohara, kanayamidori, yaeho Gase, Yutaka Midori, Okumusashi, Okumidori, Oishase, Okuhikari, Meiryoku, Samidori, Komakage, Yamanami, Minekaori, Hatsumomi, Yamakai, Karabe, etc. Other than tea leaves, for example, Darjeeling, Uba, Keyman, Assam, Kenya and the like can be mentioned. One or more kinds of fresh tea leaves can be appropriately selected and used, and not only tea leaves but also stems can be used.

The type of water used in the step (A) is not particularly limited, and for example, tap water, distilled water, ion-exchanged water, natural water, and the like can be appropriately selected and used.
The temperature of the water is 80 to 100 ° C., preferably 83 ° C. or higher, more preferably 85 ° C. or higher, still more preferably 87 ° C. or higher, from the viewpoint of selective removal of caffeine, and further from the viewpoint of temperature control. , 99 ° C or less, more preferably 98 ° C or less, and even more preferably 97 ° C or less. Such a temperature range is preferably 83 to 99 ° C, more preferably 85 to 98 ° C, and still more preferably 87 to 97 ° C.

  The contact method is not particularly limited as long as the surface of the raw tea leaves can be brought into contact with water, and examples thereof include a method of immersing the raw tea leaves in water, a method of supplying water to the raw tea leaves in a shower, and the like. .

  The amount of water used for the contact can be appropriately selected depending on the contact method and scale, but from the viewpoint of selective removal of caffeine, the amount is preferably 3 times by mass or more, more preferably 5% by mass with respect to the raw tea leaves. And more preferably 10 times or more, more preferably 100 times or less, more preferably 75 times or less, even more preferably 50 times or less. The range of the amount of water is preferably 3 to 100 times by mass, more preferably 5 to 75 times by mass, and still more preferably 10 to 50 times by mass with respect to fresh tea leaves.

  The contact time with water is preferably 2 minutes or more, more preferably 2.5 minutes or more, still more preferably 3 minutes or more, and preferably 10 minutes or less, from the viewpoint of suppressing fermentation and selectively removing caffeine. Minutes or less, more preferably 7 minutes or less. The range of the contact time is preferably 2 to 10 minutes, more preferably 2.5 to 9 minutes, and still more preferably 3 to 7 minutes.

  Before the step (B), the water attached to the surface of the tea leaves after the step (A) can be removed. As a removing method, the material may be removed by shaking or the like, or may be lightly wiped with a rag, paper, or the like. Further, the tea leaves after the step (A) can be dried.

Step (B)
The step (B) is a step of cutting the tea leaves after the step (A). This makes it easier to remove water-soluble contaminants such as sugars and amino acids in the step (C), and can increase the extraction efficiency of gallate-type non-polymer catechins in the step (D). Here, the term "non-polymer catechins" as used herein means epigallocatechin gallate, gallocatechin gallate, gallate-type non-polymer catechins composed of epicatechin gallate and catechin gallate, and epigallocatechin, gallocatechin, epigallocatechin, It is a collective term for catechin and free non-polymer catechins composed of catechin. The concentration of the non-polymer catechins is defined based on the total amount of the above eight kinds.
Although the cutting method is not particularly limited, for example, the cutting can be performed using a cutter or the like, or using a kneader, a rotor vane, or a CTC machine. The size of the tea leaves after cutting is usually 1 to 20 mm, preferably 2 to 15 mm.

Step (C)
Step (C) is a step of bringing the tea leaves after step (B) into contact with water at 0 to 40 ° C. Thereby, water-soluble impurities such as sugars and amino acids, and free non-polymer catechins can be efficiently removed.
The temperature of the water is from 0 to 40 ° C, preferably from 10 ° C or more, more preferably from 15 ° C or more, still more preferably from 20 ° C or more, and preferably from 35 ° C or less, from the viewpoint of removing water-soluble impurities. The temperature is more preferably at most 30 ° C. Such a temperature range is preferably from 10 to 35 ° C, more preferably from 15 to 33 ° C, and still more preferably from 20 to 30 ° C.

The type of water is not particularly limited, and for example, tap water, distilled water, ion-exchanged water, natural water, and the like can be appropriately selected and used as in step (A).
Examples of the contact method include, as in the step (A), a method of dipping fresh tea leaves in water, a method of supplying water to the fresh tea leaves in a shower, and the like, and bringing the surface of the fresh tea leaves into contact with water. There is no particular limitation as long as it is possible.

  The amount of water used for the contact can be appropriately selected depending on the contact method and scale, but from the viewpoint of removing water-soluble contaminants, the amount is preferably 3 times by mass or more, more preferably 5 times by mass with respect to the raw tea leaves. The above is more preferable, 10 times by mass or more is further preferable, and 100 times by mass or less is preferable, 75 times by mass or less is more preferable, and 50 times by mass or less is further preferable. The range of the amount of water is preferably 3 to 100 times by mass, more preferably 5 to 75 times by mass, and still more preferably 10 to 50 times by mass with respect to fresh tea leaves.

  The contact time with water is preferably 10 minutes or more, more preferably 15 minutes or more, still more preferably 20 minutes or more, and is preferably 120 minutes or less, preferably 90 minutes or less, from the viewpoint of removing water-soluble impurities. Minutes or less is more preferred. The range of the contact time is preferably 10 to 120 minutes, more preferably 15 to 90 minutes, and still more preferably 20 to 60 minutes.

Step (D)
The step (D) is a step of extracting the tea leaves after the step (C) with water at 50 to 100 ° C. As a result, a green tea extract containing non-polymer catechins rich in gallate-type non-polymer catechins with high purity can be obtained.

As the extraction method, known methods such as stirring extraction, column extraction, and drip extraction can be adopted.
The temperature of water used for extraction is 50 to 100 ° C., but from the viewpoint of the extraction efficiency of gallate-type non-polymer catechins, is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, still more preferably 80 ° C. or higher, In addition, from the viewpoint of temperature control, the temperature is preferably 98 ° C or lower, more preferably 95 ° C or lower. The temperature range of the water is preferably 60 to 98 ° C, more preferably 70 to 98 ° C, and still more preferably 80 to 95 ° C.

  As the water, the same water as described above can be used. Among them, ion-exchanged water is preferable from the viewpoint of taste. To the water used for the extraction, an organic acid such as ascorbin sodium or a salt thereof, or an inorganic acid such as sodium hydrogen carbonate or a salt thereof may be added.

  The amount of water used for the extraction can be appropriately selected depending on the extraction method, but from the viewpoint of the extraction efficiency of the non-polymer catechins, is preferably at least 1 mass times, more preferably at least 1.5 mass times with respect to the raw tea leaves. Is more preferably 2 times by mass or more, and from the viewpoint of flavor, is preferably 20 times by mass or less, more preferably 15 times by mass or less, and even more preferably 10 times by mass or less. The range of the amount of water is preferably 1 to 20 times by mass, more preferably 1.5 to 15 times by mass, and still more preferably 2 to 10 times by mass relative to fresh tea leaves.

  The extraction time is not uniform depending on the scale or the like, but, for example, is preferably 5 minutes or more, more preferably 8 minutes or more, still more preferably 10 minutes or more, from the viewpoint of the extraction efficiency of the non-polymer catechins. From the viewpoint of reducing unpleasant taste, the time is preferably 120 minutes or less, more preferably 90 minutes or less, and still more preferably 60 minutes or less. The range of the extraction time is preferably 5 to 120 minutes, more preferably 8 to 90 minutes, and still more preferably 10 to 60 minutes.

  After extraction, filtration can be performed as an operation to separate the tea leaves and the green tea extract. As the filtration, for example, filter separation using filter paper, a metal filter such as stainless steel, or the like, and centrifugal separation can be employed. The mesh size of the metal filter is, for example, 18 to 300 mesh. As a centrifugal separator used for centrifugation, a general device such as a separation plate type, a cylindrical type, and a decanter type can be used.

After the step (D), the green tea extract obtained in the step (D) can be subjected to solid-liquid separation.
As the solid-liquid separation, a method usually used in the food industry can be employed. For example, filter paper filtration, centrifugal separation, membrane treatment and the like can be mentioned, and it can be performed alone or in combination of two or more.

  In the filter paper filtration, for example, a filter aid may be pre-coated on the filter paper. Examples of the filter aid include diatomaceous earth, cellulose, and a combination thereof. The amount of the filter aid can be appropriately selected. Further, filtration methods such as pressure filtration and suction filtration can also be employed.

As the centrifugal separator used in the centrifugation, a common device such as a separation plate type, a cylindrical type, and a decanter type can be used as described above.
The temperature at the time of centrifugation is preferably 5 to 80 ° C, more preferably 10 to 70 ° C, from the viewpoint of improving the recovery of non-polymer catechins and removing impurities. The number of rotations and time can be set as appropriate. For example, in the case of a separation plate type, the number of rotations is preferably 2,000 to 10,000 r / min, more preferably 2,500 to 9000 r / min, and still more preferably 3,000 to 8,000 r / min. min, and the time is preferably 0.2 to 75 minutes, more preferably 0.5 to 60 minutes, and still more preferably 1 to 30 minutes.

As the processing conditions by membrane filtration, processing can be performed under general filtration conditions.
The membrane pore size is preferably 0.1 μm or more, more preferably 0.15 μm or more, still more preferably 0.2 μm or more, and preferably 10 μm or less, from the viewpoint of improving the recovery rate of non-polymer catechins and removing impurities. 5 μm or less is more preferable, and 2 μm or less is further preferable. The range of the membrane pore size is preferably 0.1 to 10 μm, more preferably 0.15 to 5 μm, and further preferably 0.2 to 2 μm. In addition, as a measuring method of the membrane pore size, a general measuring method using a mercury intrusion method, a bubble point test, a bacterial filtration method, or the like can be mentioned, but it is preferable to use a value obtained by a bubble point test.
Examples of the material of the film include a polymer film, a ceramic film, and a stainless steel film.

Thus, the green tea extract of the present invention can be produced, and the green tea extract can have the following characteristics (i) to (iii).
(I) The purity of the non-polymer catechins is usually 30% or more, preferably 33% or more, and more preferably 35% or more. The upper limit of the purity of the non-polymer catechins may be 100%, but is preferably 80% or less, more preferably 70% or less from the viewpoint of production efficiency. Here, the purity of the non-polymer catechins is the content ratio of the non-polymer catechins in the solid content.
(Ii) The gallate ratio is usually 55% or more, preferably 57% or more, and more preferably 60% or more. The upper limit of the gallate body ratio may be 100%, but is preferably 95% or less, more preferably 90% or less, from the viewpoint of production efficiency. Here, the “gallate ratio” is a ratio of gallate-type non-polymer catechins to eight non-polymer catechins.
(Iii) The mass ratio of (a) non-polymer catechins to (b) caffeine [(b) / (a)] is usually 0.00 to 0.10, preferably 0.005 to 0.07. And more preferably 0.01 to 0.05.

  Examples of the form of the green tea extract include various forms such as liquid, slurry, semi-solid, and solid. When a liquid is desirable as the product form of the green tea extract, for example, it is possible to concentrate by vacuum concentration, reverse osmosis membrane concentration and the like, and when a solid is desirable, for example, powder by spray drying or freeze drying It can also be.

1. Analysis of non-polymer catechins and caffeine Using a high-performance liquid chromatograph (model SCL-10AVP) manufactured by Shimadzu Corporation, a sample diluted with pure water was packed with an octadecyl group-introduced liquid chromatograph packed column (L-column TM ODS). , 4.6 mmφ × 250 mm: manufactured by Chemicals Evaluation and Research Institute), and measured at a column temperature of 35 ° C. by a gradient method. The mobile phase A solution was a distilled aqueous solution containing 0.1 mol / L of acetic acid, and the B solution was an acetonitrile solution containing 0.1 mol / L of acetic acid. The flow rate was 1 mL / min, the sample injection amount was 10 μL, and the UV detector wavelength was The measurement was performed at 280 nm. The gradient conditions are as follows.

Concentration gradient conditions (vol%)
Time Solution A concentration Solution B concentration 0 minutes 97% 3%
5 minutes 97% 3%
37 minutes 80% 20%
43 minutes 80% 20%
43.5 minutes 0% 100%
48.5 minutes 0% 100%
49 minutes 97% 3%
60 minutes 97% 3%

Example 1
Step (A)
100 g of full leaf fresh tea leaves were immersed in 3000 g of 95 ° C. ion-exchanged water for 7 minutes. Next, the tea leaves were recovered from ion-exchanged water by filtration through a wire mesh.
Step (B)
The collected tea leaves were cut by a food processor for 30 seconds. The size of the tea leaves after cutting was about 3 mm.
Step (C)
The cut tea leaves were immersed in 2500 g of ion-exchanged water at 25 ° C. for 30 minutes. Then, the mixture was filtered through a wire mesh to collect the tea leaves from the ion-exchanged water.
Step (D)
Next, the collected tea leaves were stirred and extracted with 380 g of ion-exchanged water at 90 ° C. for 30 minutes. Thereafter, the mixture was filtered through a wire mesh and centrifuged to obtain a green tea extract. Table 1 shows the analysis results of the obtained green tea extract.

Comparative Example 1
A green tea extract was obtained in the same manner as in Example 1 except that Step (B) was not performed. Table 1 also shows the analysis results of the obtained green tea extract.

Comparative Example 2
A green tea extract was obtained in the same manner as in Example 1 except that Step (C) was not performed. Table 1 also shows the analysis results of the obtained green tea extract.

Comparative Example 3
In Example 1, green tea was produced in the same manner as in Example 1 except that steam heat treatment was performed in which 3000 g of 100 ° C. steam was brought into contact with tea leaves for 30 seconds in place of step (A), and step (C) was not performed. An extract was obtained. Table 1 also shows the analysis results of the obtained green tea extract.

  From Table 1, it can be seen that the green tea extract containing the non-polymer catechins rich in gallate-type non-polymer catechins with high purity can be obtained by performing the steps (A) to (D) according to the present invention. I understand.

Claims (5)

A method for producing a green tea extract, comprising the following steps (A) to (D).
(A) Step of contacting fresh tea leaves with water at 80 to 100 ° C (B) Step of cutting tea leaves after step (A) (C) Contacting tea leaves after step (B) with water at 0 to 40 ° C Step (D) Step of extracting tea leaves after step (C) with water at 50 to 100 ° C   The method for producing a green tea extract according to claim 1, wherein in the step (A), the fresh tea leaves are brought into contact with water in an amount of 3 to 100 times by mass relative to water.   The method for producing a green tea extract according to claim 1 or 2, wherein in the step (A), the contact time is 2 to 10 minutes.   The method for producing a green tea extract according to any one of claims 1 to 3, wherein in the step (C), the raw tea leaves are brought into contact with water in an amount of 3 to 100 times by mass relative to the fresh tea leaves.   The method for producing a green tea extract according to any one of claims 1 to 4, wherein in the step (C), the contact time is 10 to 120 minutes.