JPH05308901A - How to make green tea - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain green tea that can extract many tea components in hot water or cold water in a short time and can infuse tea excellent in flavor and color. [Composition] After steaming or roasting process, tea leaves are sprayed with an aqueous solution of cell wall digestive enzymes such as pectinase, cellulase, and plant tissue-disintegrating enzyme, and by the enzymatic action, the cell wall of the tea leaves is processed by the enzyme action. To facilitate the exudation of cell contents.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing green tea (non-fermented tea) from fresh tea leaves, and more particularly to a method for producing green tea having good extractability in hot and cold water.

[0002]

2. Description of the Related Art Green tea is classified according to its tea making method.
It is classified into steamed green tea and kettle roasted green tea. Of these, steamed green tea, such as green tea and gyokuro, is usually produced by the steps of steaming → coarse kneading → rubbing → medium kneading → refining → drying. In addition, bancha or the like can be made into a product by a simpler method, that is, by steaming raw tea leaves, then roughly kneading them, then scouring them and drying them. On the other hand, pot-roasted green tea is produced by the steps of pot roasting → kneading → water drying → closing roasting → drying (finish roasting). Further, as a treatment for inactivating the oxidase of tea leaves (blue-killing treatment), a method of heating tea leaves by irradiating microwaves instead of steam heat treatment or roasting in a kettle is also used.

By the way, commercially available brewed green tea and brewed gyokuro, which are used to infuse tea components with water, are powdered tea and green tea leaves (deep-steamed tea) that have been steamed for a long time during the production and reprocessing of green tea. ) Is used alone or is a blend of them. When the water-extracted green tea is extracted with water, it takes about 1 to 8 hours to obtain an appropriate taste,
The convenience of tea is lost, and since the steaming time is long during tea making, the refreshing aroma component in the tea leaves dissipates during steaming, resulting in a tea with a low aroma. Also,
Powdered tea used in automatic tea dispensers and tea bags has a poor flavor and is problematic in terms of palatability.
It is also inferior in extractability.

Therefore, various methods have been proposed for treating tea leaves with a specific enzyme to enhance the extractability of tea components with water. For example, JP-A-51-11599
No. 9, gazette discloses that raw tea leaves are subjected to microwave blue-killing treatment, then the tea leaves are subdivided by passing through a meat grinder, then tannase is added to the subdivided tea leaves, and water-added tea leaves are re-ground. A method is disclosed in which, after passing through a machine, after enzymatic treatment at room temperature, the tea leaves are dried until the water content becomes 5% to obtain dry green tea having an enhanced cold water extraction degree.
Further, in Japanese Patent Laid-Open No. 1-300848, 25 tea leaves are
There is disclosed a method of treating a cellulase, a pectinase and a phospholipase in water at -60 ° C to improve the extractability of a tea component to obtain a tea extract excellent in aroma, taste and appearance. In the 2-203743 publication,
A method is disclosed in which the concentrated tea extract is frozen and the frozen product is film-packaged to prevent alteration during storage.

[0005]

However, according to the method disclosed in Japanese Patent Laid-Open No. 51-115999, the extractability of the tea component is not directly enhanced by the enzymatic treatment with tannase, but rather the tea leaves are fleshed. The tea ingredients are physically exuded by passing through a grinder and then the gallate-bound catechins that are insoluble in water are enzymatically decomposed by tannase to increase the soluble ingredients in the tea ingredients and to extract cold water. It is designed to increase Therefore, by this method, it is not possible to obtain the green tea of the appearance and shape that we usually see, in which each tea leaf is twisted into a slender shape or finished into a unique round shape. Further, in this method, since the tea leaves are passed through a meat grinder to be subdivided, the original flavor of green tea is partially impaired.

Further, the method disclosed in Japanese Patent Laid-Open No. 1-300848 uses a brewed green tea or the like as a raw material and adds a cellulase, a pectinase and a phospholipase to water when extracting a tea component with water, This is a method for obtaining a concentrated extract by treating the water with an enzyme for a long time (about 1 hour) while stirring, and the extract obtained by this method is diluted with hot water or cold water to obtain a normal extract. It is consumed as tea or used as a raw material for natural drinks, sports drinks, carbonated drinks, health drinks and the like. Further, the method disclosed in JP-A-2-203743 is intended to prevent deterioration of tea components during storage by freezing the tea extract obtained by the above-mentioned method and packaging the frozen product in a film. It is what Therefore, according to the methods disclosed in these publications, it is not possible to obtain dry green tea which has the convenience of being able to extract in a short time with hot water or cold water.

The present invention has been made in view of the above circumstances, and many tea components can be extracted in a short time by hot water or cold water, and it is possible to brew tea having excellent flavor and color. The main object of the present invention is to provide a tea manufacturing method capable of obtaining a dry green tea having the appearance and form of. Further, the present invention has an additional object of reducing bitterness and astringency in a water infusion of green tea, and preventing browning of tea leaves of green tea.

[0008]

According to the present invention, in a method for producing green tea including a step of steam-drying or heating microwave tea leaves to perform a blue-killing treatment, green tea leaves before the rough kneading step (in the blue-killing step Later) or later, in the method for making green tea in a kettle roasting, after the roasting step in the kettle (after the blue-killing step), and in the method for shredding tea, the cell wall after the above-mentioned time point or after the shredding step, respectively. A digestive enzyme such as pectinase, cellulase, hemicellulase or plant tissue-disintegrating enzyme, or an enzyme aqueous solution obtained by dissolving a mixture of two or more kinds of these enzymes in water is supplied to tea leaves, for example, by spraying. I chose

As described above, when the aqueous solution of the cell wall digesting enzyme is brought into contact with tea leaves, the cell walls of the tea leaves are decomposed by the action of the enzyme, and the cell contents are easily leached. Therefore, when the produced green tea is extracted with hot water or cold water, many soluble components are leached into water in a short time.

Further, an enzyme aqueous solution prepared by dissolving tannase together with cell wall digesting enzyme in water can be supplied to tea leaves. In this case, the tannase enzyme reacts with epicatechin gallate and epigallocatechin gallate, which have strong bitterness and astringency among the catechins contained in the tea leaves, to hydrolyze their ester bonds, thereby Is converted into gallic acid and epicatechin and epigallocatechin which have a light bitterness.

The kneading process may be performed under anaerobic conditions. Furthermore, the drying of the tea leaves, which is the final stage of the tea making process, may be performed at a low temperature using a vacuum dryer. In these cases, the oxidation of catechin in the tea leaves, which causes browning of the tea leaves, is prevented.

[0012]

The preferred embodiments of the present invention will be described below.

In the tea making method according to the present invention, an enzyme aqueous solution prepared by dissolving a cell wall digesting enzyme in water is sprayed onto tea leaves at an appropriate time after the completion of the blue-killing step and before the start of the final drying step. And so on.
At the time of supplying the enzyme aqueous solution, after the step of slaughtering (steaming, microwave heating, roasting in a pot) or after the rough kneading step,
When making shredded tea, it is at the above-mentioned time point or after the shredding step. As the cell wall digesting enzyme, for example, pectinase, cellulase, hemicellulase or plant tissue-disintegrating enzyme, or a mixture of two or more of them is used.

For example, when sencha is produced by steaming, green tea leaves, steaming, enzyme solution spraying → rough kneading (coarse kneading → enzyme aqueous solution spraying) → kneading → middle kneading → refinement → drying. In addition, kettle-roasted green tea is produced through the steps of green tea fresh leaves → kettle roast → enzyme solution spray → rubbing → water drying → close roasting → drying. When sencha is to be shredded by steaming, green tea leaves → steaming → enzyme solution spraying → rough kneading (coarse kneading → enzyme aqueous solution spraying) → mechanical cutting → sieving → cutting large pieces → kneading → middle kneading → Process of refining → drying. Furthermore, shredded green tea made from kettle is green tea leaves →
It is carried out through the steps of roasting in a kettle, spraying an enzyme aqueous solution, mechanical cutting, sieving, cutting large pieces, kneading, water drying, and drying.

The above-mentioned steps other than the step of spraying the tea leaves with the enzyme aqueous solution are conventionally known steps and can be carried out according to the conventional method by using a conventionally used machine. Therefore, the description will be given in this specification. Omit it. The reaction by the cell wall-disintegrating enzyme is continued for about 0.3 to 2.0 hours from spraying the enzyme aqueous solution on the tea leaves to drying the tea leaves at a temperature of, for example, about 65 ° C. to inactivate the enzyme. The reaction temperature at this time is about 15 to 55 ° C. The amount of enzyme is, for example, about 0.01 to 0.5% with respect to the amount of fresh leaves, and the water content of tea leaves during the enzyme reaction is 75 to 2
It is set to about 0% / WB (wet base). And
The enzyme action during this time decomposes the cell wall of the tea leaves, and the contents of the cells are easily leached when hot or cold water is poured into the green tea produced.

Alternatively, tannase may be dissolved in water together with the above cell wall-disintegrating enzyme to prepare an enzyme aqueous solution, and the enzyme aqueous solution may be sprayed onto tea leaves. The mechanism of action of tannase on tea leaves in this case will be described.

The tea leaves contain 15 to 20% of catechins, and these catechins are the main components that give the bitter and astringent taste of tea. Of these catechins, 5 to 10% is epicatechin, 20 to 30% is epigallocatechin, 10 to 15% is epicatechin gallate, and 50 to 60%.
% Is epigallocatechin gallate. Among these catechins, epicatechin and epigallocatechin have a light bitterness, and epicatechin gallate and epigallocatechin gallate exhibit a strong bitter and astringent taste of tea. The tannase enzyme has a function of reacting with epicatechin gallate and epigallocatechin gallate among these catechins, and hydrolyzing the ester bond to convert gallic acid into epicatechin and epigallocatechin. Therefore, by spraying an enzyme aqueous solution containing tannase on tea leaves, the strong bitterness and astringency due to epicatechin gallate or epigallocatechin gallate disappears due to the enzymatic action, and the bitterness is improved to light.

The tannase enzyme has an optimum pH at which the activity is 5.5, and has an activity of 80% at pH 4.5 to 6.0. The optimum temperature at which the tannase enzyme exhibits activity is 40 ° C, and it is known that it has 75% activity at 30 to 50 ° C. Therefore, tannase exhibits a sufficient enzymatic activity within the range of conventional tea-making conditions.

The amount of tannase enzyme used is determined as follows. That is, the content A (mol) of the gallate catechins in the tea leaves is A = the amount of green tea leaves × solid content ratio × the content ratio of catechins × the content ratio of gallate catechins / the molecular weight of epigallocatechin = the green tea leaves × (20 / 1
00) × (20/100) × (70/100) ÷ 446
Is. Here, the product standard of tannase (Kikkoman Corporation) is 5,000 units (U) / g (tannase 1
The unit (1 U) is the amount of enzyme capable of hydrolyzing the ester bond of 1 μmol of tannic acid in 1 minute under the conditions of 30 ° C. and pH 5.5), and therefore the required addition amount of tannase T (g) Is T = A ÷ (1 / 1,000,0
00) ÷ processing time (minutes) ÷ 5,000 U. Therefore, by using the tannase enzyme in the amount calculated as described above, it is possible to obtain green tea capable of brewing tea having a light bitterness without a strong bitterness and astringency.

In the process of producing green tea, the catechins in the tea leaves are oxidized and the brown color of the color of the tea leaves changes. Especially, the catechin content such as mill bud tea and second tea in the new tea season is high. A large amount of tea leaves undergo a remarkable browning, which deteriorates the quality of green tea in terms of appearance. At present, the measures for preventing such browning of tea leaves have been entrusted to the improvement of cultivation and production techniques by tea producers. Therefore,
In order to solve such problems from the aspect of tea making technology, the rubbing process is performed under the conditions by creating an anaerobic atmosphere by replacing the air in the closed chamber with nitrogen gas, or drying the tea leaves after the rubbing process. The treatment can be carried out at a low temperature using a vacuum dryer, or the shredded tea method can be used to quickly dry the tea leaves without the refining process, thereby shortening the oxidation time.

Next, a specific example of the method for producing green tea according to the present invention and the result of the quality inspection of green tea produced by the method will be described.

[Production Example 1]

Senba leaves from the second tea stage were used as raw tea leaves, and 2 kg each of the tea leaves were treated with a 2 kg machine (experimental machine) according to the conventional sencha manufacturing method to produce tea. As the cell wall digestive enzyme, macerozyme 2S (Yakult Co., Ltd. plant tissue degrading enzyme) and cellulase onozuka 3S (Yakult Co., Ltd. cellulase enzyme) were used, and an enzyme aqueous solution prepared by dissolving the enzyme in a small amount of water was used. It was added into the coarse kneader. Tea making was performed twice for each. Table 1 shows the amount of enzyme added to the inside of the rough kneader, the amount of water when the tea leaves were taken out of the rough kneader, and the kneading time.

[0024]

[Table 1]

Table 2 shows the results of the sensory evaluation by three expert judges.

[0026]

[Table 2]

As can be seen from the results shown in Table 2, compared with the sencha prepared without adding enzyme (No. 1), the case prepared with added enzyme (No. 2, No. 1). Three
And No. The sencha of 4) had a large amount of powder in appearance due to the decomposition of the cell wall of the tea leaves, and the evaluation was degraded, but as for the internal quality, a rich infusion was obtained and the flavor was improved,
The overall evaluation is high. In addition, the sencha produced by adding enzymes does not show the stiff leaf odor peculiar to Nibancha,
There was also little bitterness.

Next, in order to see how the degree of atomization in the particle size of the tea leaves changes due to the cell wall-decomposing action of the tea leaves by the enzyme, the particle size distribution was examined using a low tap type shaking sieving machine. The measurement conditions are as follows:
760 μm, 2,830 μm, 1,680 μm, 1,1
Centrifugal effect K with 5 types of 90 μm and 1,000 μm
= 1.31, shaking time 300 seconds, tea amount 100 g.
The results are shown in Table 3.

[0029]

[Table 3]

From the results shown in Table 3, Macero Team 2S
As the amount of the enzyme was increased, the decomposition of the cell wall of the tea leaf was promoted, and the grain size of 1,000 μm or less was remarkably recognized. In addition, when both macerozyme 2S and cellulase onozuka 3S were added, the cell wall decomposition of tea leaves was advanced compared to the case where macerozyme 2S was used alone, but the effect of cellulase was notable in terms of particle size. Did not appear.

In addition, the ingredients of each green tea were mixed with cold water (2
The amount of soluble components after leaching at 5 ° C.) for 30 minutes was measured. The results are shown in Table 4.

[0032]

[Table 4]

From the results shown in Table 4, the amount of soluble component increased as the amount of macerozyme 2S added increased, and when cellulase onozuka 3S was used in combination, the amount of soluble component was further increased by the synergistic action of the cell wall decomposing ability of tea leaves. You can see that it will increase.

[Production Example 2]

Sencha leaves of the second tea stage were used as raw tea leaves, and 2 kg of fresh tea leaves were used for making tea. As cell wall digestive enzymes, as in the case of the above Production Example 1, macerozyme 2S and cellulase onozuka 3S (both are Yakult Co., Ltd. trade names) were used, and each enzyme was added in a small amount of 0.1% to the amount of fresh leaves. An enzyme aqueous solution was prepared by dissolving it in water. For tea production, raw tea leaves are steamed and heat treated, and then an aqueous enzyme solution is uniformly sprayed onto the tea leaves, and 50% / WB is applied in the rough kneading process.
At the time of the amount of water of, the tea leaves are shredded with a food processor, passed through a # 7 sieve, and then the tea leaves remaining above the sieve are shredded again. After rubbing for 30 minutes to promote the cell wall degrading action by the enzyme during that, through a middle rubbing process, at 30 ° C at 30 ° C.
It was carried out by drying the tea leaves for a minute. In addition, tea making without shredding was performed according to a conventional sencha manufacturing method. Table 5 shows the ward system.

[0036]

[Table 5]

Table 6 shows the results of the sensory evaluation by three expert judges.

[0038]

[Table 6]

From the results shown in Table 6, the sencha produced by the enzyme treatment and shredded treatment (No. 4) is excellent in color tone, good in aroma and light blue, and has a rich taste. It turns out that it is a high quality tea.

Next, the ingredients of each green tea were mixed with cold water (25
The amount of soluble components after leaching for 30 minutes was measured. The results are shown in Table 7 as numerical values when the amount of the soluble component of sencha in the case of making tea without performing any enzyme treatment or shredding treatment (No. 1) was 100%.

[0041]

[Table 7]

From the results shown in Table 7, the sencha produced by the enzyme treatment and the shredding treatment (No. 4) has a significantly increased amount of soluble components and is a tea which is very easily brewed. I understand. On the other hand, in the case of sencha produced by shredding without the enzyme treatment (No. 2), leaching of soluble components was less. This is because the shredding process was not performed for shredded tea leaves, and it was revealed from this result that the leaching of soluble components did not increase only by shredding.

[Production Example 3]

Sencha leaves of the second tea stage were used as raw tea leaves, and 2 kg of fresh tea leaves were used for tea making. As the enzyme, in addition to the above-mentioned macerozyme 2S and cellulase onozuka 3S (both Yakult Co., Ltd. trade name), tannase manufactured by Kikkoman Co., Ltd. is used, and each enzyme is used in an amount of 0.1% with respect to the amount of fresh leaves. Alternatively, it was dissolved in a small amount of 0.05% water to prepare an enzyme aqueous solution. For tea production, raw tea leaves are steamed and heat-treated, and then an aqueous enzyme solution is uniformly sprayed on the tea leaves, taken out from the coarse kneader at a moisture content of 50% / WB in the rough kneading step, and the tea leaves are shredded by a food processor. , # 7 sieve, and then shred the tea leaves remaining above the sieve again, and knead the shredded tea leaves for 30 minutes to promote the cell wall-degrading action by the enzyme during the Through the steps, the tea leaves were dried at 60 ° C. for 30 minutes. In addition, tea making without shredding was performed according to a conventional sencha manufacturing method. Table 8 shows the ward system.

[0045]

[Table 8]

Table 9 shows the results of the sensory evaluation conducted by three expert judges.

[0047]

[Table 9]

Table 10 shows the results of sensory evaluation of bitterness and astringency. The values in the table are 0 for the bitterness and astringency when no bitterness is felt, and 1 for the bitterness and astringency when strongly felt.
This is when 0 is set.

[0049]

[Table 10]

From the results shown in Table 10, the bitterness and astringency of each sencha when tannase was added to produce tea (Nos. 3 to 7) was reduced. Especially when using both macerozyme 2S and cellulase onozuka 3S (especially N
o. 5 and No. It can be seen that the bitterness and astringency of the green tea of 7) is significantly reduced. It is considered that this is because the contact between catechin and tannase in tea leaves was promoted by the destruction of the cell wall of tea leaves by the cell wall digestive enzyme.

Furthermore, changes in the amount of catechins contained in the infusions of each green tea were examined. Leachate is Sencha 1
It was obtained by adding 100 cc of hot water of 80 ° C. to gram and leaching for 30 minutes, and each tea leaching solution was subjected to liquid chromatographic analysis. The results are shown in Table 11.

[0052]

[Table 11]

From the results shown in Table 11, each sencha prepared by adding tannase (No. 3 to 7) was prepared without adding tannase (No. 1 and No. 2). Compared to Sencha, the amount of ester catechins such as epigallocatechin gallate and epicatechin gallate decreased, and the amount of free catechins such as epigallocatechin and epicatechin increased, and the action of tannase caused ester type catechins to increase. It can be seen that catechin was converted to free catechin.

Further, comprehensively evaluated from the results shown in Table 9, Table 10 and Table 11, when three kinds of enzymes were used and shredded to make tea (No. 5), it was very excellent. It was found that sencha with a strong flavor was obtained.

[0055]

Since the present invention is constructed and operates as described above, according to the tea manufacturing method of the present invention,
A dry green tea that has the appearance and form that we normally see, has the convenience of being able to extract many tea ingredients in a short time with hot or cold water, and can infuse tea with excellent flavor and color. can get.

When an enzyme aqueous solution is prepared by dissolving tannase in water together with a cell wall digestive enzyme and the enzyme aqueous solution is supplied to the tea leaves for enzyme treatment, tea with reduced bitterness and astringency is obtained. A green tea is obtained which can be infused. Furthermore, when the rubbing process in the tea making process is performed under anaerobic conditions, or when the tea leaf drying process in the final process is performed by vacuum drying at low temperature, green tea without browning of the tea leaves is seen. Can be obtained.

Claims (13)

[Claims] 1. A method for producing steamed green tea from fresh tea leaves at least through a steaming step, a rough kneading step, a scouring step and a drying step, wherein a cell wall digestive enzyme is dissolved in water before or after the rough kneading step. A method for producing green tea, which comprises supplying the thus-obtained enzyme aqueous solution to tea leaves. 2. A method for producing green tea from fresh tea leaves through at least a microwave blue-killing step, a rough kneading step, a finely kneading step and a drying step, wherein a cell wall digestive enzyme is added to water before or after the rough kneading step. A method for producing green tea, which comprises supplying a dissolved enzyme aqueous solution to tea leaves. 3. The method for producing green tea according to claim 1 or 2, wherein a kneading step and a middle kneading step are performed in order between the rough kneading step and the fine kneading step. 4. A method for producing green tea produced by kettle roasting from green tea leaves at least through a roasting step, a roasting step, a water drying step, a closing roasting step and a drying step, wherein after the kettle roasting step, a cell wall digestive enzyme is produced. A method for producing green tea, which comprises supplying an aqueous solution of an enzyme in which is dissolved in water to tea leaves. 5. A method for chopping steamed green tea from fresh tea leaves through at least a steaming step, a rough kneading step, a shredding step and a drying step, before or after the rough kneading step, or in the shredding step. After that, a method for producing green tea is characterized in that an enzyme aqueous solution in which a cell wall digestive enzyme is dissolved in water is supplied to tea leaves. 6. A method for producing shredded green tea from green tea leaves through at least a microwave blue-killing step, a rough rubbing step, a shredding step and a drying step, before or after the rough rubbing step, or the shredding step. After that, a method for producing green tea is characterized in that an enzyme aqueous solution in which a cell wall digesting enzyme is dissolved in water is supplied to tea leaves. 7. The method for producing green tea according to claim 5 or 6, wherein a kneading step and a middle kneading step are performed in order between the shredding step and the drying step. 8. A method for producing shredded green tea made from kettle in the order of at least a kettle roasting step, shredding step, kneading step, water drying step and drying step from fresh tea leaves, after or after the kettle roasting step or After the shredding step, an enzyme aqueous solution in which a cell wall digestive enzyme is dissolved in water is supplied to tea leaves, and a method for producing green tea. 9. The cell wall digestive enzyme is one or two or more enzymes selected from the group consisting of pectinase, cellulase, hemicellulase and plant tissue-disintegrating enzyme, according to any one of claims 1 to 8. How to make green tea. 10. The method for producing green tea according to claim 1, wherein the aqueous enzyme solution is sprayed and brought into contact with tea leaves. 11. The method for producing green tea according to claim 1, wherein tannase is dissolved in water together with a cell wall digesting enzyme to prepare an aqueous enzyme solution. 12. The method for producing green tea according to claim 3, 4, or 7 to 11, wherein the kneading step is performed under anaerobic conditions. 13. The method for producing green tea according to claim 1, wherein the drying step is performed by a vacuum drying method at a low temperature.