JPH07112404B2 - How to make green tea - Google Patents

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 water 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 sencha 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, kettle roasting green tea is manufactured by the steps of roasting kettle → kneading → water drying → tight roasting → drying (finish roasting). Further, as a treatment for inactivating the oxidase of tea leaves (blue-killing treatment), a method of heating the tea leaves by irradiating microwaves instead of steaming heat treatment or roasting in a kettle is also used.

[0003] 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,
The 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 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 with enhanced cold water extraction.
In addition, Japanese Patent Application Laid-Open No. 1-300848 discloses 25 tea leaves.
There is disclosed a method of treating a cellulase, a pectinase and a phospholipase in water at -60 ° C to improve the extractability of tea components to obtain a tea extract excellent in aroma, taste and appearance. No. 2-203743 discloses that
A method is disclosed in which the concentrated tea extract is frozen and the frozen product is film-wrapped 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 treated with meat. The tea component is physically exuded by slicing through a grinder, and then the gallate-bound catechins that are insoluble in water are enzymatically decomposed by tannase to increase the soluble components in the tea component and extract the cold water. It is intended to increase the. 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 of 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 beverages, sports beverages, carbonated beverages, health beverages, and the like. Further, the method disclosed in Japanese Patent Application Laid-Open No. 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 a dry green tea having the convenience that it can be extracted with hot water or cold water in a short time.

The present invention has been made in view of the above circumstances, and a large amount of tea components can be extracted in a short time by hot water or cold water, and tea having an excellent flavor and color can be brewed normally. 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-irradiated green tea leaves to perform blue-killing treatment, before the rough mashing step (of the blue-killing step) Later) or later, in the tea making method of kettle roasting green tea, after the kettle roasting step (after the blue-killing step), and in the shredding tea making method, at the above-mentioned time point or after the shredding step, the cell wall, 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 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 to gallic acid and epicatechin and epigallocatechin which have a light bitterness.

The kneading process may be performed under anaerobic conditions. Furthermore, it is advisable to dry the tea leaves, which is the final stage of the tea making process, 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.
The enzyme aqueous solution is supplied at the end of 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 in combination 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, and drying are performed. In addition, kettle-roasted green tea is produced through the steps of green tea raw leaf-roasting-kettle roasting-spraying enzyme solution-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 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 aqueous enzyme solution are conventionally known steps and can be carried out according to the conventional method 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 after spraying the aqueous enzyme solution on the tea leaves until the tea leaves are inactivated by drying the tea leaves at a temperature of about 65 ° C. or higher. 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 likely to be leached out when the prepared green tea is poured with hot or cold water.

Alternatively, tannase may be dissolved in water together with the above cell wall-disintegrating enzyme to prepare an aqueous enzyme solution, and the aqueous enzyme 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 enzyme action, and the bitterness is improved.

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. Further, 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 Corp.) 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) ÷ 5,000U. Therefore, by using the amount of tannase enzyme calculated as described above, it is possible to obtain a 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. A large amount of tea leaves undergo 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 farmers. Therefore,
In order to solve such problems from the aspect of tea making technology, the rubbing process can be performed under such conditions by replacing the air in the closed chamber with nitrogen gas to create an anaerobic atmosphere, or drying the tea leaves after the rubbing process. The treatment can be carried out at a low temperature by using a vacuum dryer, or the shredded tea method can be used to quickly dry the tea leaves without the refining process to shorten 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 Method 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 in accordance with a conventional sencha manufacturing method using a 2 kg machine (experimental machine) 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 conducted by three expert judges.

[0026]

[Table 2]

As can be seen from the results shown in Table 2, as compared with the sencha produced when the tea was made without adding the enzyme (No. 1), the tea was produced with the enzyme added (No. 2, No. 1). Three
And No. The sencha of 4) had a lot 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 rating is high. In addition, the sencha produced by adding enzymes does not show the stiff leaf odor peculiar to Nibancha,
The bitterness and astringency was also small.

Next, in order to see how the degree of atomization in the particle size of 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 increases as the amount of added macerozyme 2S increases, and when cellulase onozuka 3S is used in combination, the amount of soluble component is further increased due to 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 the cell wall digesting enzyme, as in the case of the above Production Example 1, macerozyme 2S and cellulase onozuka 3S (both Yakult Co., Ltd. trade name) were used, and each enzyme was added in a small amount of 0.1% with respect to the amount of fresh leaves. An enzyme aqueous solution was prepared by dissolving in water. For tea manufacture, after steam-heat treating raw tea leaves, the 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 content of the tea, 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, and the shredded tea leaves are cut. After rubbing for 30 minutes to promote the cell wall degrading action by the enzyme during that, after undergoing a medium rubbing step, at 30 ° C. for 30 minutes.
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 conducted by three expert judges.

[0038]

[Table 6]

From the results shown in Table 6, the sencha produced by the enzyme treatment and the shredding treatment (No. 4) was excellent in color balance, had a good aroma and a light blue color, and had a strong 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 (No. 1) without performing any enzyme treatment or shredding treatment was 100%.

[0041]

[Table 7]

From the results shown in Table 7, the sencha prepared by enzymatically treating and shredding (No. 4) has a significantly increased amount of soluble components and is a tea that is very easily brewed. I understand. On the other hand, in the case of sencha produced by shredding without the enzyme treatment (No. 2), the leaching of soluble components was reduced. This is because the shredding process was not performed on shredded tea leaves, and it was revealed from this result that the leaching of soluble components does 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 are Yakult Co., Ltd. trade names), tannase manufactured by Kikkoman Co., Ltd. is used, and each enzyme is used in an amount of 0.1% based on 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 steam-heated, an aqueous enzyme solution is evenly sprayed onto the tea leaves, and the tea leaves are taken out from the coarse kneader at the time of 50% / WB water content in the rough kneading step, and the tea leaves are shredded by a food processor. , # 7 sieve, the tea leaves remaining above the sieve are shredded again, and the shredded tea leaves are kneaded for 30 minutes to accelerate the cell wall degrading action by the enzyme, and then the medium kneading. 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 the user does not feel the bitterness and 1 for the degree of bitterness when the user feels a strong bitterness.
This is when 0 is set.

[0049]

[Table 10]

From the results shown in Table 10, the bitterness and astringency of each of the green teas when tannase was added to produce tea (Nos. 3 to 7) were 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 the tea leaves was promoted by destroying the cell wall of the tea leaves by the cell wall digestive enzyme.

Further, 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 g and leaching for 30 minutes, and each tea infusion 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 with the addition of tannase (No. 3 to 7) was prepared without the addition of 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 different flavors 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 morphology that we normally see, has the convenience that many tea ingredients can be extracted 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 the 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 final process of drying the tea leaves is performed by vacuum drying at a 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 through at least a steaming step, a rough kneading step, a finely kneading 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 green 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, 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 made from kettle roast from green tea leaves through at least a kettle roasting step, a kneading step, a water drying step, a closing roasting step and a drying step, wherein a cell wall digestive enzyme is added after the kettle roasting step. A method for producing green tea, which comprises supplying an aqueous enzyme solution in which is dissolved in water to tea leaves. 5. A method for shred-making steamed green tea from green tea leaves through at least a steaming step, a rough-rubbing step, a shredding step and a drying step, which is before or after the rough-rubbing 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 fresh tea leaves through at least a microwave-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, 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 in a kettle roasting process from green tea leaves through at least a kettle roasting step, shredding step, kneading step, water drying step and drying step, 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 claim 1. How to make green tea. 10. The method for producing green tea according to claim 1, wherein the enzyme aqueous 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 the 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 carried out under anaerobic conditions. 13. The method for producing green tea according to claim 1, wherein the drying step is performed by a method of vacuum drying at a low temperature.