JP2019170356A - Manufacturing method of green tea having refreshing green leaf aroma - Google Patents

Abstract

To provide a manufacturing method of green tea having a refreshing green leaf aroma, remaining in a green tea percolate after retort sterilization, even though the refreshing green leaf aroma in green tea is notably reduced and lost in a retort sterilization treatment in manufacturing a drink.SOLUTION: A manufacturing method includes: a wilt treatment of reducing a wet amount reference moisture content of an unseasoned tea leaf to 70% or less under a room temperature and a ventilation environment; a parching treatment of parching the tea leaf after the wilt treatment within 20 seconds; and a hot-blast dehydration treatment of reducing the wet amount reference moisture content of the tea leaf after the parching treatment by hot blast to 5% or less. This invention can provide green tea having a refreshing green leaf aroma.

Description

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

  Green tea is produced by drying fresh leaves (including some stems) after inactivating the oxidase in the tea leaves by steaming or roasting the pot (this process is referred to as blue-killing). In Japan, there are sencha, bancha, strawberry tea, and tama green tea. Of these, sencha, which has the highest production volume, is generally used for steaming, rough koji, cocoon twisting, medium brewing, brewing, and drying processes. It is manufactured after. In addition, strawberry tea, which is a raw material for matcha tea, is produced through steaming, cooling powdered tea, drying in a strawberry tea furnace, separation of stems, and finish drying.

  Green leaves include (2E) -hexenal, (3Z) -hexenol, 3-methyl nonane-2, 4-dione, (E, E) -2, 4-nonadienal, (E) -2-nonenal, etc. In particular, (2E) -hexenal and (3Z) -hexenol are called green leaf aldehyde and green leaf alcohol, respectively, and are known as typical components of green scent. Yes. Both components are rapidly produced in tea leaves when the tea leaves are damaged by plucking or the like using free fatty acids such as linoleic acid and linolenic acid as precursors. It has also been shown that both components increase markedly during the wilting and fermentation stages in black tea production. These aromatic components are components constituting the refreshing green leaf fragrance felt in green tea, but are highly volatile and are significantly reduced in the heating process, particularly the steaming process, in green tea production.

  In green tea drinks, the refreshing scent of green leaves is used as one of useful flavor elements in order to improve drinking comfort and drinkability. However, since it volatilizes by heating as described above, it is significantly reduced and lost in the retort sterilization process. In order to leave an exhilarating green leaf scent after retort sterilization, it is necessary that the green tea scent component is sufficiently contained in the raw tea leaves.

  Generally, in order to produce green tea having a refreshing green leafy scent, a method of producing shallow steaming in which the steaming time is shortened to about 30 seconds is taken. In addition, in order to keep the tea leaves bluish, the steaming time is further shortened by using a steamer with a large stirring axis, a short barrel and a more inclined angle than the steaming machine used to make tea leaves. Manufactured in time. These green teas can feel the scent of green leaves stronger than normal sencha, but the scent remains little in the leachate after the retort sterilization process.

  Patent Document 1 discloses a green tea production method obtained by inactivating endogenous enzymes by pulverizing arbitrarily dried tea leaves under aerobic conditions sufficient to cause discoloration, followed by drying. . The production method of this document does not require a process such as steaming or roasting in order to inactivate endogenous enzymes, and thus it is considered that the reduction of green leaf fragrance components during blueprinting can be avoided. However, in order to completely inactivate endogenous enzymes by drying, it takes longer time to inactivate compared to inactivation methods such as steaming and cooking in a kettle, and the moisture content and dryness of leaves, stems, etc. When different parts are mixed, the inactivation of the endogenous enzyme is not enough depending on the part, and when it is transferred to the drying process, the fermentation may progress and may affect the quality of the final product. From these facts, it is necessary to develop a production method using a conventional blue killing method in order to produce green tea having a green leaf fragrance more efficiently and stably.

  In patent document 2, from the viewpoint of cost saving and labor saving, as a manufacturing method that suppresses the heat load on green tea, the moisture contained in fresh tea leaves is reduced to 100% or less of the dry standard moisture content by air-permeable drying. The method is disclosed in which tea is pulverized and then killed depending on the purpose of use, followed by heat treatment to produce tea. However, this document aims to produce a large amount of dried tea leaves at low cost, and discloses a wilt method intended to increase the green leaf scent component due to wilt and a blue killing method for suppressing the decrease in the green leaf scent component. Not.

  As described above, there is no method for producing green tea having a refreshing green leaf scent remaining in the green tea infusion even after retort sterilization.

JP2012-80877

JP-A-6-125708

  The refreshing scent of green leaves in green tea is significantly reduced and lost during the retort sterilization process in beverage production. The subject of this invention is providing the manufacturing method of the green tea which has the refreshing green leaf fragrance which remains in a green tea infusion even after retort sterilization.

  In order to solve the above-mentioned problems, the present inventors have intensively studied a method for producing green tea having an exhilarating green leaf fragrance, so that fresh tea leaves are wilted at room temperature in a ventilated environment, steamed, cooked in a kettle, or The green tea obtained by sterilizing and drying for a short time by microwave heating has a refreshing green leaf fragrance, and the green tea infusion has a similar fragrance after the retort sterilization process. As a result, the present invention has been completed.

  That is, the present invention comprises a step of wilting green tea leaves to enhance green leaf incense, a step of killing fresh tea leaves with wilt in a short time in order to leave sufficient green leaf fragrance, and a tea leaf after blue killing, And a green tea produced by the production method, including a hot air drying step of drying with hot air to a moisture content suitable for storage.

  Specifically, the present invention is [1] a wilt process for reducing the moisture content moisture content of fresh tea leaves to 70% or less at room temperature and in a ventilated environment, and killing tea leaves after the wilt process within 20 seconds. A method for producing green tea, comprising a blue-killing step and a hot-air drying step in which the tea leaves after the blue-killing step are reduced by hot air to a moisture-based moisture content of 5% or less. [2] Moisture-based moisture content of fresh tea leaves after the wilting process [3] The green tea production method according to [1], wherein the tea leaves are harvested during the first tea season and the autumn / winter bancha season [1] or [2] [4] The method for producing green tea according to any one of [1] to [3], wherein the temperature in the wilting step is 10 to 35 ° C., preferably 10 to 20 ° C., [5] ] Blue heat killing process within 20 seconds, preferably within 10 seconds The green tea production method according to any one of [1] to [4], which is a blue-killing step by microwave heating, and [6] the hot-air temperature in the hot-air drying step is 40 to 100 ° C., preferably 70 to 80 ° C. [ It consists of the green tea manufactured by the manufacturing method in any one of [1]-[5], and the manufacturing method in any one of [7] [1]-[6].

  The present invention can provide a green tea having a refreshing green leaf scent remaining in a green tea infusion even after retort sterilization, and a method for producing the same.

  As used herein, “tea fresh leaves” refers to tea leaves that have not been heat-treated after harvesting. That is, the fresh tea leaves include not only the tea leaves immediately after harvesting, but also the tea leaves stored in a fresh leaf management machine or refrigerator after harvesting, and the tea leaves after wilt treatment. The fresh tea leaves may contain any part such as shoots, adult leaves, stems, etc., and the harvesting part and the content ratio of each part are not limited. The fresh tea leaves used in the present invention may be any fresh tea leaves used in any of fermented tea, semi-fermented tea, or non-fermented tea, and are not particularly limited. That is, Camellia sinensisvar. sinensis, Camellia sinensis var. Any leaves harvested from as samica and their related species can be used. In addition, for example, varieties classification based on the seedling method, such as Yabukita, Sayaka Kaori, or Samidori, is not limited, and any varieties can be used, including native species that are not registered as varieties. it can.

  Although tea shoots vary depending on cultivar and production area, they generally enter dormancy from autumn to early winter, awake from dormancy between February and April of the following year, and transition to the budding period. After the budding period, the young leaves open at a rate of about one every five days, and after about five to seven leaves are opened, the state is called fold-out, and the growth of new buds stops. The ratio of the unfolding buds to the total number of shoots within a certain area is called the unfolding degree, but the most tea is picked when the unfolding degree is about 50 to 80%. After the first tea bud is opened and closed, the growth is temporarily stopped, but the growth is started again, and at the same time, the growth of the bud starts, which becomes the second tea bud. As the temperature rises during the summer, the second tea bud opens at a rate of about one every four days. After the second tea bud, the third tea bud and the autumn bud grow as well as the second tea bud. The “first tea season” described in the present specification refers to the period from the bud emergence after dormancy awakening to the second tea bud harvest, and the “autumn / winter ban tea season” described herein refers to the next year from the autumn bud harvest. Refers to the period up to

The method for producing green tea of the present invention includes a wilting step for reducing the moisture content moisture content to 70% or less at room temperature and in a ventilated environment, and a blue-killing step for performing short-term blue-killing by steaming, cooking in a pot, or microwave heating. And a hot air drying step for reducing the moisture content moisture content to 5% or less by hot air.
The details of the wilting step, the blue-killing step, the hot air drying step, and the pulverizing step in the present invention will be described below.

(Wilt process)
In the wilting step, the fresh tea leaves are wilted until the moisture content moisture content becomes 70% or less under room temperature and ventilation. The room temperature in this step is 10 to 35 ° C, preferably 10 to 20 ° C. Ventilation may be continuous, intermittent, or a combination of both, and can be adjusted as appropriate to achieve the target moisture content while preventing an increase in tea temperature due to respiratory heat. The fresh leaves used in this step may be appropriately cut using a cutting machine or crusher that cuts fresh tea leaves into a predetermined length, such as fresh leaf cutters, food slicers, and feed cutters. In this step, under the above environment, wilt is performed until the moisture content moisture content of fresh tea leaves is 70% or less, preferably 60% or less. The wilting in this step may be performed using a fresh tea leaf container, a constant temperature ventilation dryer, a shelf dryer, a flat dryer, or a container dryer, and ventilation can be performed from any direction. Further, when the room temperature is low, warm air of 35 ° C. or less may be passed.

(Blue killing process)
The blue-killing step in the present invention is a step intended to stop the fermentation of tea leaves by inactivating the action of oxidase in order to produce green tea. As the blue-killing method, blue-killing by steaming and blue-killing by cooking in a kettle are common, but in this step, a blue-killing method by steaming, cooking in a kettle, or microwave heating can be used. Steam heat is a blue-killing method in which fresh tea leaves are heated by the latent heat of condensation released from saturated water vapor to inactivate oxidase. Steaming is carried out using a steamer, but there are two types of steamers: a zonal-type steamer and a net-cylinder rotary stirring-type steamer, both of which can be used in this process. Common sencha is produced in a steaming time, that is, a steaming time of fresh tea leaves is about 30 to 40 seconds. In order to leave vivid bluish color in Aizawa, it is necessary to produce it with a shallower steam, so it is devised so that it has a short barrel and a more inclined angle than that used for making tea. Boiled with a rotating drum-stirred steamer. When the blue-killing step in the present invention is performed by steaming, the steaming time is 20 seconds or less, preferably 10 seconds or less in order to leave a refreshing green leaf fragrance.
In kettle roasting, fresh tea leaves are roasted at a high temperature and killed, but by heating the tea leaves in a cylindrical kettle heated to 350-400 ° C, moisture in the tea leaves is vaporized and saturated in the cylindrical kettle. Steam is filled. In addition to the heat of conduction from the kettle, the latent heat of condensation released from the saturated water vapor heats the tea leaves and inactivates the oxidase. There are several types of frying leaf machines, such as a continuous type, a single cylinder, two fixed pot type, etc., but any one can be used in this step as long as it is a machine that performs blue killing using the above principle. Although the fried leaf time for enzyme deactivation changes with frying machines to be used, it is generally about 60 to 120 seconds. In the case of performing the blue-killing step in the present invention by roasting the kettle, the roasting time is 20 seconds or less, preferably 10 seconds or less in order to leave a refreshing green leaf fragrance.
Blue killing by microwave heating is a blue killing method that inactivates oxidase by irradiating fresh tea leaves with microwaves and heating the water in fresh tea leaves. When the blue-killing step in the present invention is carried out by microwave heating, the microwave output is 7.2 kW or more and the microwave irradiation time is 20 seconds, preferably 10 seconds or less in order to leave a refreshing green leaf fragrance sufficiently.
Any of the methods described above can be used as the blue killing method in the present invention.

(Hot air drying process)
The hot air drying step is a step of heating the tea leaves after the blue-killing step by exposing them to hot air, and drying the moisture contained in the tea leaves to a moisture content moisture content of 5% or less. The hot air temperature in this step is adjusted to 40 to 100 ° C, preferably 70 to 80 ° C. This process is not limited to a drying method as long as the water in the tea leaves can be dried by heating and evaporating. For example, a constant temperature ventilation dryer, a shelf dryer, a flat dryer, a container It can be carried out using a type dryer, fluidized bed dryer, net-type dryer or the like. Moreover, the ventilation in this process can be performed from arbitrary directions. Alternatively, in this step, a brick stacked type tea ceremony furnace or a stationary type tea ceremony furnace can be used as a drying means. In addition, in order to prevent the generation of stuffy odor, depending on the water content of the tea leaves after the blue-killing process, before this process, using a roughing machine, steamed leaf processing machine, leaf punching machine, or twister, etc. It is possible to adjust the water content and the moisture distribution in each part of the tea leaves.

Example 1
In Example 1, using green tea leaves harvested in the first tea season, green tea having a sufficient refreshing scent of green leaves is produced, and the green tea drink produced with the leachate has a refreshing green scent after retort. We verified whether we have.

(material)
All the samples shown in Table 1 were produced using “Sami-dori” Ichibancha, which was collected at Fukujuen CHA Yugaku Park.

(Wilt process)
In the wilting process of Samples 2 to 5, fresh tea leaves were cut into a suitable size and then wilted in a fresh leaf container 100K (manufactured by Kawasaki Kiko Co., Ltd.) at room temperature and in a constantly ventilated environment. At that time, hydration was not performed. The average temperature in the fresh leaf container was 22 ° C. The moisture content moisture content of the tea leaves immediately before the blue-killing process was measured using an infrared moisture meter (manufactured by Ketto Science Laboratory Co., Ltd.).

(Blue killing process)
Sample 1 was freshly killed by steaming after cutting the green tea leaves to an appropriate size. Samples 2 to 5 were killed by steaming after the wilting step. Steaming was performed for 5 to 30 seconds using a zonal steamer 2K (manufactured by Kawasaki Kiko Co., Ltd.), and cooled quickly after steaming. The vapor pressure was adjusted to 20-30 kg / h.

(Hot air drying process)
The hot air drying process was performed using a hot air dryer (manufactured by Quana Giken Co., Ltd.). The hot air temperature was set to 80 ° C., and drying was performed until the moisture content moisture content of the tea leaves became 5 to 1%.

(Leaf sensory examination)
2 g of tea leaves were extracted with 200 ml of boiling deionized water for 5 minutes to obtain an extract. Using Sample 1 as a standard, aroma and taste were evaluated. The standard was 5 points, and those who felt the refreshing scent of green leaves were added, while those who felt weak were reduced.

(Drink production method)
10 g of tea leaves were extracted with 1000 ml of deionized water at 70 ° C. for 5 minutes to obtain an extract. During the extraction, stirring was added after 2.5 minutes. Dilution was performed by adding deionized water so that the Brix value of the extract was 0.200%. 0.03 wt% sodium ascorbate and 0.005 wt% sodium bicarbonate were added to the diluted solution. The solution after the addition was filled into a 200 ml capacity beverage steel can and subjected to retort sterilization at 105 ° C. for 10 minutes.

(Sensory evaluation of drinks)
About the flavor of the manufactured tea drink, sensory evaluation was performed by making the drink manufactured using the sample 1 into a standard. The standard was 5 points, and those who felt the refreshing scent of green leaves were added, while those who felt weak were reduced.

  Example 1 revealed the following.

  Sample 1 did not feel the desired Aoba incense, while sample 5 having the same steaming time was weak but could feel the Aoba incense. Therefore, Aoba incense can be strengthened by the wilting process.

  Samples 2 to 5 all had the desired green leaf incense, but the intensity of green leaf incense decreased as the steaming time increased, and in order to leave the green leaf incense sufficiently, the steaming time was within 20 seconds. It is desirable to make it.

  Furthermore, when the sensory evaluation of the drink was made, it was felt weaker than the leaf, but in the samples 2 to 4, it was possible to feel the green leaf incense, and the strength of the green leaf incense decreased as the steaming time increased as in the leaf. .

  Therefore, in order to produce green tea with a sufficient refreshing scent of green leaves, it is preferable that the first tea is wilted at room temperature until the moisture content of the tea leaves reaches 70% or less at room temperature, preferably within 20 seconds. It is desirable to produce a product which is killed within 10 seconds and further dried with hot air.

Example 2
In Example 2, green tea leaves with a refreshing scent of green leaves are produced using fresh tea leaves harvested in the fall / winter banquet season, and the green tea drink produced with the leachate has a refreshing green scent after retort. We verified whether we have.

(Plucking)
All the samples shown in Table 2 were produced using “Goko” autumn / winter bancha from Kyoto Prefecture.

(Wilt process)
In the wilting process of Samples 6 to 15, the fresh tea leaves were cut to an appropriate size and then placed in a fresh leaf container 100K (manufactured by Kawasaki Kiko Co., Ltd.) at room temperature and intermittent ventilation (15 minutes ventilation, 30 minutes pause) With wilt. At that time, hydration was not performed. The average temperature in the fresh leaf container was 10 ° C. The moisture content moisture content of tea leaves immediately before the blue-killing process was measured by the same method as in Example 1.

(Blue killing process)
Samples 6 to 9 were subjected to steam-killing by the same method as in Example 1. Samples 10 to 12 were killed by roasting the kettle. The kettle was roasted and steamed for 10 to 30 seconds after the fresh tea leaves were put into a stirrer heated to a temperature of 300 ° C. Samples 13 to 15 were killed by microleaf heating. Microwave heating is performed by irradiating the raw tea leaves for 10 to 30 seconds with a microwave (frequency: 2450 ± 30 MHz) of 7.2 kW using a microwave drying fire for tea leaves (manufactured by New Japan Radio Co., Ltd.). I went.

(Tea making process)
After the blue-killing process, the sample 6 was transferred to the hot air drying process through the tea-making process in the order of coarse koji, cocoon twisting, middle mushroom, and refined koji in the same manner as ordinary sencha. Samples 7 to 15 were transferred to the hot air drying process after the blue-killing process and only through the twisting process.

(Hot air drying process)
All the samples shown in Table 2 were subjected to hot air drying. This step was performed in the same manner as in Example 1.

(Cutting process)
The tea leaves after the hot air drying step were cut using a cutting machine (manufactured by Horai Co., Ltd.). A cutting machine screen having a punch diameter of 5 mm was used.

(Leaf sensory examination)
The sensory examination of the leaf was performed in the same manner as in Example 1 using Sample 6 as a standard.

(Sensory evaluation of drinks)
The sensory examination of the drink was performed in the same manner as in Example 1 using Sample 6 as a standard.

  Example 2 revealed the following.

  Sample 6 had a strong bancha odor, and the desired refreshing green leaf scent could not be felt. On the other hand, in sample 7 having the same steaming time, the desired green leaf fragrance can be felt, and even in autumn / winter bancha, the green leaf fragrance can be strengthened by the wilting process.

  After the wilting step, Samples 7 to 9 which had been boiled by steaming had a strong feeling of the desired green leaf fragrance as the duration of blue killing was shortened. Samples 10-12, which had been killed by roasting the kettle, were samples 11-12, which had a shorter blue killing time, than the sample 10 with a blue killing time of 30 seconds. I felt that Aoba incense was inferior to other methods. In Samples 13 to 15 which were subjected to blue killing by microwave heating, the target Aoba incense could be felt most strongly in Sample 15 having a blue killing time of 10 seconds.

  In addition, when the sensory evaluation of the drink was performed, it was not possible to feel the green leaves incense from the drinks manufactured from the samples 7, 10, and 13, that is, the samples having a blue-killing time of 30 seconds. It was. However, it was possible to feel a green scent from a sample other than the above, that is, a drink produced from a sample having a blue-killing time of 20 seconds or 10 seconds. Furthermore, regarding the intensity of the green leaves of the drink produced from the sample killed with steam or microwave, the one with 10 seconds of blue killing time was stronger than that with 20 seconds.

  Therefore, green tea with sufficient aroma of refreshing green leaves can be produced in autumn / winter bancha as well as Ichibancha, and after wilt until the moisture content moisture content of tea leaves is less than 70% at room temperature, It is desirable to produce the product by killing within 20 seconds, preferably within 10 seconds, and further drying with hot air by any method of steaming, cooking in a pot or microwave heating.

  As described above, the present invention makes it possible to produce green tea having a refreshing green leaf scent remaining in the green tea infusion even after retort sterilization, and to provide the green tea.

Claims (7)

At room temperature and in a ventilated environment, the wilting process to reduce the moisture content of tea leaves to 70% or less, the blueing process to kill the tea leaves after the wilting process within 20 seconds, and the tea leaves after the blueing process to hot air And a hot air drying step for reducing the moisture content moisture content to 5% or less. 2. The method for producing green tea according to 1, wherein the moisture content moisture content of fresh tea leaves after the wilting step is 70% or less, preferably 60% or less. 3. The method for producing green tea according to 1 or 2, wherein the fresh tea leaves use fresh tea leaves harvested in the first tea season and autumn / winter ban tea season. The manufacturing method of the green tea in any one of 1-3 whose temperature in a wilting process is 10-35 degreeC, Preferably it is 10-20 degreeC. 5. The method for producing green tea according to any one of 1 to 4, wherein the blue-killing step is within 20 seconds, preferably 10 seconds or less, and the blue-killing step by microwave heating. The manufacturing method of the green tea in any one of 1-5 whose hot-air temperature in a hot-air drying process is 40-100 degreeC, Preferably it is 70-80 degreeC. Green tea manufactured by the manufacturing method in any one of 1-6.