WO2014196587A1

WO2014196587A1 - Process for producing tea leaves for green tea

Info

Publication number: WO2014196587A1
Application number: PCT/JP2014/064922
Authority: WO
Inventors: 憲典田中
Original assignee: サントリー食品インターナショナル株式会社; サントリーホールディングス株式会社
Priority date: 2013-06-05
Filing date: 2014-06-05
Publication date: 2014-12-11
Also published as: JP6364003B2; CN105263332A; CN105263332B; JPWO2014196587A1

Abstract

The present invention reduces the odor of hardened leaves contained in tea leaves for green tea, by adding water to dry tea leaves for green tea and thereafter drying the tea leaves under such conditions that the temperature of the tea leaves does not exceed 85°C.

Description

Method for producing green tea leaves

The present invention relates to a method for producing green tea leaves with reduced hard leaf odor.

Green tea leaves are usually manufactured through 1) rough tea processing and 2) finishing. Tea leaves from the third or later tea period (ie, third, fourth, and autumn / winter tea), or fresh leaves that have become hardened after the best harvesting time in the first or second tea (hard leaves) Has a peculiar unpleasant odor called hard leaf odor. When this hard leaf is used as the raw material, the hard leaf odor remains even after the rough tea processing process and the finishing processing process, and the green tea drink obtained by extracting this finished tea (green tea brewed in a teapot or filled in a container) It is handed over to the container-packed green tea drinks in circulation.

Therefore, various methods for reducing the hard leaf odor of tea leaves have been proposed. For example, in the rough tea processing process, instead of the conventional steaming process, a method using superheated steam or humidified hot air (Non-Patent Document 1), a method of repeatedly performing steaming heat treatment (Patent Document 1), or a fresh leaf before the steaming process A method (Non-patent Document 2) for cutting or immersing in hot water has been proposed.

On the other hand, for the purpose of facilitating the brewing of active ingredients such as catechins and amino acids in tea leaves, the extract extracted from tea leaves separately from the tea leaves brewed in the crude tea production process ( For example, the ratio of 1000 cc of extract to 28 kg of tea leaves) is distributed, and the tea leaves are subjected to a roasting temperature of 55 ° C. to 220 ° C. and a roasting time of about 3 to 100 minutes (92 ° C., 25 minutes in the example). A method of drying has been proposed (Patent Document 2). In addition, for the purpose of obtaining tea leaves having an unprecedented aroma and taste, raw material tea leaves such as crude tea are impregnated in an aqueous amino acid solution containing at least one amino acid selected from the group consisting of leucine, valine and isoleucine. And a method for producing tea leaves including a step of heating and drying at a temperature of 100 to 200 ° C. has been reported (Patent Document 3).

JP 2001-54354 A JP 2005-204527 A JP 2012-183064 A

As described above, various methods for reducing hard leaf odor in the rough tea processing step have been proposed, but the reduction degree of hard leaf odor of rough tea obtained by these methods is not necessarily satisfactory. Development of a new method has been desired.

The present invention is to provide a method for producing tea leaves with reduced hard leaf odor.

As a result of intensive studies to solve the above-mentioned problems, the present inventor made water uniformly adhere to the entire tea leaf during the production of the dried tea leaf (hydration treatment), and then the substantially the same before the hydration treatment. It has been found that the hard leaf odor of tea leaves can be effectively reduced by performing a drying treatment at a low temperature until it becomes moisture.

That is, the present invention relates to the following.
1. (A) adding water to green tea leaves, and
(B) drying the tea leaves to which the water has been added under conditions where the tea leaf product temperature does not exceed 85 ° C;
A method for producing tea leaves.
2. (A) The method according to 1 above, wherein the tea leaves of green tea in the step are crude tea.
3. Furthermore, (C) a step of subjecting the dried tea leaves to a firing process,
The method according to 1 or 2 above, comprising:
4). 4. The method according to any one of 1 to 3 above, wherein the tea leaves of the green tea in the step (A) are rough tea and drying is performed until the water content of the tea leaves becomes 4 to 5% in the step (B).
5. 5. The method according to any one of 1 to 4 above, wherein the amount of water added in the step (A) is 5 to 120% by weight based on the tea leaves.
6). 6. The method according to any one of 1 to 5 above, wherein the hydration in step (A) is carried out in two or more steps.
7). 7. The method according to any one of 1 to 6 above, wherein the hydration in the step (A) is performed under stirring of tea leaves.
8). 8. The method according to any one of 1 to 7 above, wherein the water in step (A) is tap water, deionized water, distilled water, or natural water.

According to the present invention, the hard leaf odor contained in green tea leaves can be reduced, and the hard leaf odor in finished tea and green tea beverages can be reduced.

The present invention relates to a method for producing tea leaves with less hard leaf odor. In the production method of the present invention, when water is added to crude tea and / or finished tea and then dried until it has substantially the same water content as before adding water, hard leaves that are aroma components in the water-soluble category This is based on the knowledge that odor can be reduced efficiently. In green tea beverages, where the aroma is an important factor in quality and the idea of leaching the aroma of tea leaves into the water as much as possible to enjoy the aroma, water is added to the tea leaves to reduce or eliminate the water-soluble category This is thought to be something that those skilled in the art usually do not recall.

Here, “hard leaf odor” as used in the present specification is a kind of green tea fragrance, and is a fragrance that is often contained in low-grade products of a certain level or lower, and has an unpleasant odor with a unique blue nose. In addition, the term “raw tea” as used in the present invention refers to a processed tea product obtained by subjecting fresh leaves picked from tea tree (scientific name: Camellia sinensis) to a rough tea processing step, and “finished tea” refers to the above rough tea. Tea leaves obtained by finishing processing such as burning and sorting tea.

Hereinafter, embodiments of the present invention will be described in more detail.

(Hydrolysis and drying process)
In the production method of the present invention, a process of adding an appropriate amount of water (hydrolysis process) to tea leaves having a hard leaf odor (hereinafter referred to as “target tea leaves”), and the added water is removed by drying. Including a process (drying process). Even if a known aroma component separation / removal technique (for example, reduced pressure treatment by an evaporator) is simply applied to the target tea leaves, the hard leaf odor does not change at all, and the hard leaf odor cannot be reduced from the target tea leaves. In the invention, by adding an appropriate amount of water to the target tea leaf having a hard leaf odor, the affinity between the causative component of the hard leaf odor (hereinafter also referred to as the hard leaf odor component) and water is utilized. Thus, the hard leaf odor can be easily separated and removed (see Examples described later).

The water added in the present invention refers to mere tap water, deionized water, distilled water, natural water, etc., and means water that does not contain components other than water such as amino acids and tea leaf extract. The present invention is expected to remove the hard leaf odor component which is a water-soluble category at the same time as the water added in the drying treatment is lost. By including a component other than water, an unexpected reaction may occur, such as changing the affinity of hard leaf odor to water or changing the preferred aroma balance of tea leaves. As long as the effect of the present invention is not impaired, sugars, emulsifiers, acids such as hydrochloric acid and acetic acid, alkalis such as sodium bicarbonate, antioxidants such as ascorbic acid, and water are easily mixed. These liquids (for example, acetic acid, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, glycerin, etc.) may be added as appropriate.

If the temperature of the water to be added is too high, the soluble components in the tea leaves are likely to elute, and the preferred aroma components of the tea leaves other than the hard leaf odor components are likely to scatter, so the water added in the water treatment step is , 40 ° C. or lower, preferably 30 ° C. or lower.

In the present invention, after adding water to the tea leaves, the water is dried to remove the hard leaf odor component which is a water-soluble category, but it is necessary to add water to the extent that the entire tea leaves are moistened. It is. For this purpose, an appropriate amount of water is 5 to 120% by weight, preferably about 10 to 110% by weight, more preferably 20 to 100% by weight, based on the target tea leaves. When the amount of water is less than 5% by weight with respect to the target tea leaf, the hard leaf odor component may not be effectively removed. In addition, when the amount of water exceeds 120% by weight with respect to the target tea leaf, a soluble component contained in the target tea leaf may be dissolved in water or may cause a flavor loss, so that the desired tea leaf flavor may not be obtained.

Although the addition method is not particularly limited, for example, a method of spraying, mixing, and absorbing water while dripping water using a spray or watering means such as spray, funnel, and dropper on the target tea leaves can be considered. As a means for mixing the target tea leaves and the added water, various stirring devices such as a container rotating mixer, a stirring mixer, and a drum mixer can be used.

In the hydration process of the present invention, if a large amount of water is added at one time, soluble components contained in the target tea leaves may be dissolved in water. In addition, the added water may adhere to the drum wall surface and reduce the temperature of the drum without fully fulfilling the originally expected role of adhering to the tea leaves and evaporating to remove the hard leaf odor. . Also, the surface becomes dry with the target tea leaves sticking to each other, causing unevenness in quality due to the partial distribution of water, which causes the added water to adhere to the walls of the device during drying, leading to a decrease in yield and burning. There is a possibility that moisture may be trapped inside, resulting in corruption. The appropriate amount of water added at one time is about 5 to 20% with respect to the target tea leaf, and the more preferable amount of water added at once is about 5 to 15% by weight with respect to the target tea leaf. That is, 5 to 20% by weight (preferably 5 to 15% by weight) of water with respect to the target tea leaf is divided into multiple times so that the total amount of water is about 10 to 120% by weight with respect to the target tea leaf. In order to uniformly add water to the entire target tea leaf, it is preferable to add while repeating hydration and mixing, or to perform hydration with stirring.

In the present invention, the moisture added to the target tea leaves is removed by a drying process, so that the hard leaf odor is separated and removed from the target tea leaves simultaneously with the moisture. Hard leaf odor can be reduced and removed effectively by performing a gentle drying process at a low temperature rather than under high temperature conditions such as roasting (heating). After the treatment of the present invention, an arbitrary finishing process can be performed, and an arbitrary firing strength can be obtained.

As the drying treatment apparatus, any of a reduced pressure drying apparatus, a freeze drying apparatus, a drum type food drying apparatus, and the like may be used. In particular, when a drum type food drying apparatus is used, it is preferable because the hydrated target tea leaves are easily brought into contact with hot air by rotation, and the entire tea leaves are uniformly dried in a relatively short time. In addition, a drum-type burning device provided with a nozzle for spraying or spraying a predetermined amount of water that has already been put into practical use can be substituted for the drying treatment device of the present invention.

The drying treatment is preferably performed at a low temperature in order to maintain a good quality aroma and color tone contained in the tea leaves. Specifically, it is preferable that the drying conditions are such that the temperature of the target tea leaves is 85 ° C. or lower, preferably 80 ° C. or lower. Here, when the product temperature of the tea leaf is referred to in the present specification, it represents the surface temperature of the tea leaf. For example, when a vacuum drying apparatus such as an evaporator is used, the temperature of the hot water bath for heating the container containing the sample varies depending on the degree of vacuum, but is heated to about 40 to 80 ° C., preferably about 50 ± 10 ° C. Increasing the temperature of the hot water bath generally increases the drying rate. However, if the degree of vacuum is low, the temperature of the tea leaves increases, which causes browning of the tea leaves, deterioration of the fragrance, and the like. When using a device that dries by heating, such as a hot air type, such as a drum-type drying device, in the drum so that the product temperature of the target tea leaves reaches 85 ° C, preferably 80 ° C. It is preferable to set the temperature or the surface temperature of the drum hook.

The drying treatment in the present invention is performed until the water content in the target tea leaves becomes the same water content as before the water treatment. Here, the moisture content of the same level as before the water treatment is such that the difference between the tea leaf weight after the drying treatment and the target tea leaf weight before the water treatment is less than 2% (preferably less than 1.5%). A state that is a difference. For example, when general rough tea having a water content of about 5% is used as the target tea leaf, the drying treatment is performed until the water content becomes about 3 to 7%, preferably about 3.5 to 6.5%. . In this case, the water content is most preferably 5% or less, more specifically about 4 to 5%.

As described in the examples described later, the hard leaf odor can be effectively removed by repeating the drying treatment. In the present invention, it is preferable to carry out the water treatment and the drying treatment as a series of treatments a plurality of times. That is, the step 1 of adding 5 to 20% by weight (preferably 5 to 15% by weight) of water to the target tea leaf and the step 2 of drying treatment are performed in a total amount of 10% of the target tea leaf. An embodiment in which the series of treatments in Steps 1 and 2 are repeated until about 120 wt% (preferably 20 to 100 wt%) is one of the preferred embodiments of the present invention.

The production process of tea leaves for tea beverages used for extraction usually includes 1) rough tea processing step and 2) finishing processing step. 1) In the manufacturing process of crude tea, (i) plucking of fresh tea, (ii) blowing, (iii) steaming, (iv) cooling, (v) leaf punching, (vi) crude koji, (vii) koji, Crude tea is obtained through processes such as (viii) medium mash, (ix) medium mash, (x) refined mash, and (xi) drying. Here, (ii) in the air blowing process, air of high humidity is sent to prevent the deterioration of fresh tea quality and maintain freshness, to keep moisture and lower the heat of breathing. (Iii) In the steaming process, tea leaves Steaming the tea leaves the oxidase that oxidizes the tea leaves, keeping the tea leaves green and removing the blue odor. (Iv) The cooling step is a step of maintaining the color and flavor of tea leaves by sending wind to the hot tea leaves and rapidly cooling them to room temperature without any unevenness. The process is a process to improve the drying effect by removing hot steam from the dried hot air and removing steam dew on the tea leaves in order to improve the color and flavor of the tea leaves and shorten the time of the next rough koji process. . (Vi) In the coarse koji process, the tea leaves are softened by squeezing them, and in order to reduce the water content inside, the hot leaves are sent in while blowing dry air, and the tea leaves are gently rubbed with friction and pressure, (vii) In the cocoon process, the tea leaves are made into a lump and mixed with high pressure without heating (this breaks down the tea leaf tissue and makes it easier to produce components such as tea taste, while at the same time making the moisture uniform) Plan). Further, (viii) in the middle kneading process, the tea leaves that have become clumps in the twisting process are crushed while sending hot air that has been dried. (X) In the sperm process, dry the whole tea leaf while removing the water by transferring the water from the stem to the leaf, and rub it with human hands. The tea leaves are kneaded only in a certain direction, and the tea leaves are arranged in a narrow and elongated shape unique to green tea. Finally, the water content (about 10-13%) of the tea leaves obtained in the refinement process in (xi) drying process is dried with hot air. To about 5%. In addition, 2) the finishing process includes a pre-ignition method (method of separating and shaping after burning and drying) or a post-fire method (method of separating and shaping and then burning and drying). Through the process, “finished tea” is obtained.

The tea leaves (target tea leaves) to be subjected to the water treatment and drying treatment steps of the present invention may be crude tea or finished tea. Moreover, the tea leaf of the arbitrary timings of a rough tea processing process may be sufficient. From the viewpoint of reducing flavor loss in the drying process, that is, selectively removing hard leaf odors while leaving the high quality aroma of tea leaves, and ease of quality control, crude tea that has undergone step (xi) (Water content: about 5%) should be used as the target tea leaves.

In the following, one of the preferred embodiments of the present invention, a method for subjecting crude tea produced through the rough tea processing step to water treatment and drying treatment, and then subjecting it to a finishing processing step to produce tea leaves will be described in detail. As described above, the present invention is not limited to this as described above.

(Rough tea processing process)
As long as the raw leaves used for the production of crude tea are raw leaves of tea, their varieties and production areas are not limited. Examples of varieties include Yabukita, Yutaka Midori, Okumidori, Sayaka Kaori, Kanaya Midori, Samidori and Asatsuyu. Examples of production areas include Shizuoka Prefecture, Kagoshima Prefecture, Mie Prefecture, Kumamoto Prefecture, Fukuoka Prefecture, Kyoto Prefecture, Miyazaki Prefecture, Saitama Prefecture, and the like.

An object of the present invention is to efficiently remove a hard leaf odor from a tea leaf having a hard leaf odor to obtain a tea leaf having an excellent aroma. From this point of view, the present invention includes tea leaves that have a late harvest time, such as Sanbancha, Sanbancha, and fall / winter bancha, or tea leaves that have been harvested after the shoots have grown to some extent among the first and second teas. (So-called “hard leaves”) are used. Specifically, the content of total nitrogen (total amount of nitrogen derived from amino acids, amides, proteins, caffeine, and nucleic acids), which is a component of tea leaves obtained by near infrared spectroscopy, is 4.5% by weight or less, preferably Is less than 4.4% by weight, more preferably less than 4.3% by weight.

The picking method is not particularly limited, and customary methods such as hand picking, picking, and mechanical picking can be used.

生 Processing such plucked fresh leaves into rough tea. As described above, the processing steps of crude tea are as follows: (i) plucking of fresh tea, (ii) air blowing, (iii) steaming, (iv) cooling, (v) leaf punching, (vi) rough koji, (vii) koji It includes the steps of cocoon, (viii) medium cocoon, (ix) medium cocoon, (x) fine cocoon, and (xi) drying. If it is the manufacturing method of the rough tea which a person skilled in the art usually performs, in the range which does not impair the effect of the present invention, one or a plurality of processes of these processes may be omitted, for example, stubble is omitted. It may be dried after the middle. Moreover, you may process into tea. In other words, after the picked fresh leaves (hard leaves) are steamed, the tea leaves can be obtained through a powdered tea machine, a coffee tea furnace, and a dryer. After the above-mentioned hydration treatment and drying treatment are performed on the crude tea of this tea, a green tea with reduced hard leaf odor can be produced by pulverizing a millstone or the like.

Thus, the rough tea processing method is not particularly limited in the present invention. The crude tea to be subjected to the water addition and drying treatment of the present invention is used for deeply steamed tea, kettle roasted tea, ball green tea, hand-made tea, etc., as long as it has a hard leaf odor. Contains crude tea.

(Finishing process)
Finished tea can be obtained by processing crude tea. In a preferred embodiment of the present invention, as the pretreatment of the finishing process, the above-mentioned hydration treatment and drying treatment are performed on the crude tea having a water content of about 5%, and then subjected to the finishing process.

The finishing process includes a pre-fire method or a post-fire method, but is not particularly limited in the present invention. The crude tea subjected to the hydration treatment and the drying treatment is subjected to a finishing process consisting of processes such as sieving, cutting large tea, separating powder and tree stalks, firing, and assembling. In the firing process in the finishing process, a stronger heat is given than in the drying process after the water addition of the present invention, and the water content of tea leaves is usually less than 5%, preferably about 1% or less. Is done. In the present invention, the firing temperature is not particularly limited, but may be about 90 to 220 ° C, preferably about 100 to 200 ° C.

火 The burning method is not particularly limited, and for example, any type of burning device such as a direct flame method or a far infrared ray method may be used, and the shape thereof may be a drum type or a plate type. After a predetermined amount of crude tea has been put into a drum-type heating device provided with a nozzle for spraying or spraying a predetermined amount of water, a predetermined ratio of moisture is supplied to the crude tea while appropriately stirring the crude tea. Add water from the nozzle to make the water evenly adhere to the entire surface of the crude tea (hydration treatment), and then supply hot air to the stirred crude tea so that the product temperature does not exceed 85 ° C. If the drying process is performed until the moisture content is almost the same as before the hydration process, and then subjected to the firing process in the finishing process as it is, hard leaf odor can be easily reduced without the need for new equipment or complicated processes. Can produce tea leaves. However, such crude tea is poured into the drum for burning, and then water is sprayed from the nozzle of the burning device, and the final temperature of the tea leaves is 85 ° C. or lower (preferably 80 ° C. or lower). In the method of performing the continuous process of raising the temperature in the drum and performing the `` burning process '' after that, it takes time until it reaches the burning process temperature, Since the tea leaves in the apparatus may be browned, the flavor may be deteriorated, or may be finely pulverized, it may be dried even when a burning drum is used in the drying process of the present invention. From the viewpoint of quality, it is preferable to adopt a method in which tea leaves are once taken out after the treatment is completed, set to a firing temperature, and then introduced again.

(Green tea beverage packed in a container)
In recent years, the market for containerized green tea beverages has expanded, and it is necessary to make full use of various raw materials for the stable supply of tea leaves. According to the present invention, even when it is difficult to stably supply high-quality tea leaves due to bad weather or other external factors, it is possible to suppress the hard leaf odor to a desired level, and to pack containers of a certain quality or higher. Significantly helpful in providing green tea beverages. In addition, the heat treatment process at the time of producing the green tea beverage packed in a container tends to become more conspicuous by promoting the hard leaf odor, but there is an advantage that the hard leaf odor is hardly perceived when the tea leaves obtained by the present invention are used. is there. From such a viewpoint, the tea leaves obtained by the present invention are suitably used as raw tea leaves for container-packed beverages.

The process for obtaining a green tea beverage packed in a container is generally an extraction process for extracting finished tea with warm water, a coarse filtration process for removing extraction residues from the extract, a cooling process for cooling the extract, and a fine solid content from the extract. Filtration process to remove water, green tea extract, antioxidant, pH adjuster etc. added to the extraction liquid preparation process, sterilization process to sterilize the preparation liquid, sterilized preparation liquid is filled into the container It consists of a container filling process. However, the said process is an example to the last, and is not limited to this, For example, the order of a process can be replaced or another process can be added.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples. Further, unless otherwise specified in the present specification, the concentration and the like are based on weight, and the numerical range is described as including the end points.

(Example 1)
As a target tea leaf, 100 g of rough tea (total nitrogen: 3.1%, water content: 4.6%) of autumn / winter bancha produced in Shizuoka Prefecture produced by a conventional method was used. Using a commercially available spray bottle, water was added little by little while thoroughly stirring the target tea leaves so that the amount of water (ion exchange water) shown in Table 1 uniformly adhered to the whole tea leaves.

Thereafter, vacuum degassing (drying) was performed with an evaporator (R-210 manufactured by BUCHI), and the tea leaves were dried until the water content was about 4 to 5% (degree of vacuum: about 15 to 40 hPa). The conditions of the evaporator were as follows: hot water bath temperature: 50 ° C. or 80 ° C., refrigerant temperature: −5 ° C., and the solvent reservoir was ice-cooled (products 1 to 3 of the present invention).

Moreover, what performed only the vacuum deaeration process, without performing a hydration process as a comparative product was prepared (Comparative product 1). A control product that was not subjected to hydration treatment and vacuum degassing treatment was used, and the reduction degree of hard leaf odor was examined for the inventive products 1 to 3 and the comparative product. Specifically, 2.0 g of each obtained tea leaf (raw tea) was weighed and extracted with 200 g of hot water for 5 minutes to obtain a tea leaf extract, which was subjected to sensory evaluation based on the following criteria.
+++: Hard leaf odor is felt very strongly ++++: Hard leaf odor is felt strongly ++: Hard leaf odor is felt +: Hard leaf odor is slightly felt-: Hard leaf odor is not felt

Table 1 shows the results. The rough leaf odor (control product) that was not subjected to the hydration treatment and the drying treatment felt the hard leaf odor very strongly. Moreover, when only the drying process was performed without performing the water treatment, there was no change in the hard leaf odor even when the pressure was reduced to 20 hPa or less and the process was performed for 120 minutes (Comparative Example 1). On the other hand, the rough tea (invention products 1 to 3) subjected to the hydration treatment and the drying treatment greatly reduced the hard leaf odor compared to the control product. From this, it was suggested that the hard leaf odor can be effectively and efficiently removed by subjecting the tea leaves having a hard leaf odor to a water treatment and a drying treatment to the extent that the water thus dried is dried. The level of hard leaf odor “++” is a desirable quality level.

(Example 2)
As the target tea leaves, 100 g of the same tea leaves as in Example 1 were used, and the drying treatment apparatus was a drum-type drying apparatus (manufactured by Terada Seisakusho, a small-scale flame igniter “Meika”), and the rotation speed of the stirring blade (fan) was set to 20 rpm. The tea leaves were manufactured in place of the device. Specifically, using a commercially available spray bottle, 20 g of water (ion-exchanged water) was added little by little while stirring the target tea leaf in the same manner as in Example 1, and then a drum-type drying apparatus (surface temperature of the kettle: 120 ℃), and dried until the water content of tea leaves reaches about 4-5% (Product 4 of the present invention). Change the sprayer into a dropper and drop 20g of water on the target tea leaves in a stationary state. Then, after the tea leaves have sufficiently absorbed water, they are put into a drum-type drying device (the surface temperature of the kettle: 120 ° C) and dried until the water content of the tea leaves reaches about 4-5% ( Inventive product 5) First, the target tea leaves are put into a drum-type drying apparatus (the surface temperature of the kettle: 120 ° C.), and immediately after dropping 20 g of water with a dropper, the water content of the tea leaves becomes about 4-5%. Each of which was subjected to a drying treatment (Product 6 of the present invention). Moreover, it was made to be the same as that of the present invention product 6 except that the water to be dropped was added in 3 portions of 10 g + 5 g + 5 g (in the second and subsequent additions, the water was added when the tea leaf product temperature rose to about 65 ° C.). A product was also produced (Product 7 of the present invention). In any case, when the temperature of the tea leaves reached 75 ° C., the drying was finished, and the tea leaves were taken out from the drum. For the obtained tea leaves (control product and inventive products 4 to 7), the degree of hard leaf odor was sensory evaluated in the same manner as in Example 1.

Table 2 shows the results. Compared with crude tea (control product) that was not subjected to hydration treatment and drying treatment, the product of the present invention that was subjected to hydration treatment and drying treatment had reduced hard leaf odor. In the case where water was not uniformly adhered to the whole tea leaf (product 5 of the present invention), the degree of reduction in hard leaf odor was small. Moreover, the number of times of hydration (Invention product 6) was also low in the reduction of hard leaf odor. On the other hand, when the target tea leaves rotated (stirred) in the heated drum type drying apparatus were divided and added with water, the hard leaf odor was effectively reduced (Product 7 of the present invention). From this, it was suggested that it is preferable to add water under stirring so that water uniformly adheres to the target tea leaves, and it is preferable to repeat the hydration treatment and the drying treatment.

(Example 3)
Tea leaves were produced using the same target tea leaves, hydration method (dropper) and drying treatment apparatus (drum type drying apparatus) as in Example 2. Specifically, in the same manner as the products 6 and 7 of the present invention of Example 2, the target tea leaves are put into a drum-type drying device (surface temperature of the kettle: 120 ° C.), and immediately after that, a predetermined amount of water is batched with a dropper. Or, it was dropped in a plurality of times and dried until the water content of the tea leaves reached about 4 to 5% (Products 8 to 12 of the present invention). In either case, the temperature of the tea leaves taken out from the drum dryer was 75 ° C. In addition, tea leaves were produced in the same manner as the products 7 and 10 of the present invention except that the surface temperature of the kettle of the drum type drying apparatus was changed to 150 ° C. (products 13 and 14 of the present invention). In any case, when dividing and adding water, about 10 g was added for the first time, and after that, about 5 g was added at the timing when the tea leaf temperature rose to about 65 ° C. Drying was completed when the tea leaf temperature reached 75 ° C. Furthermore, as a comparative product, a product which was heated by a drum-type drying apparatus without adding water until the tea leaf product temperature reached 75 ° C. was manufactured (Comparative product 2). For the obtained tea leaves (control product, comparative product 2 and products 8 to 14 of the present invention), the degree of hard leaf odor was sensory evaluated in the same manner as in Example 1.

Table 3 shows the results. When only the drying treatment was performed without performing the hydration treatment, there was no change in the hard leaf odor even when the tea leaf product temperature reached 75 ° C. (Comparative Example 2). On the other hand, the product of the present invention in which 10 to 100 g (10 to 100% by weight with respect to tea leaves) of the subject tea leaves is subjected to a water treatment and dried, the hard leaf odor is reduced in all treatment areas. It was. As the amount of water increases, the degree of reduction in hard leaf odor increases, but it is more effective to divide and add water than to add water at once, and the total amount of water is divided into multiple times at 80 g or 100 g. When hydrated, the hard leaf odor could be reduced to a slightly felt “+” level.

According to the present invention, hard leaf odor contained in green tea leaves can be reduced. As a result, the hard leaf odor in finish tea and green tea drink can be reduced. Even if various tea leaves are used, it is possible to provide finished tea and green tea beverages with excellent flavor quality.

Claims

(A) adding water to green tea leaves, and
(B) drying the tea leaves to which the water has been added under conditions where the tea leaf product temperature does not exceed 85 ° C;
A method for producing tea leaves.
The method according to claim 1, wherein the tea leaves of green tea in step (A) are crude tea.
Furthermore, (C) a step of subjecting the dried tea leaves to a firing process,
The method according to claim 1, comprising:
The method according to any one of claims 1 to 3, wherein the tea leaves of the green tea in the step (A) are rough tea, and drying is performed until the water content of the tea leaves becomes 4 to 5% in the step (B).
The method according to any one of claims 1 to 4, wherein the amount of water added in the step (A) is 5 to 120% by weight based on the tea leaves.
The method according to any one of claims 1 to 5, wherein the hydration in step (A) is carried out in two or more steps.
The method according to any one of claims 1 to 6, wherein the hydration in step (A) is carried out under stirring of tea leaves.
The method according to any one of claims 1 to 7, wherein the water in step (A) is tap water, deionized water, distilled water, or natural water.