JP7136584B2 - tea production method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing tea that can efficiently remove burnt tea leaves.

General tea is steamed with steam to inactivate the oxidizing enzymes contained in the fresh tea leaves. It is normal to manufacture through a series of steps to make the polymer (see Non-Patent Document 1). When the tea leaves are sterilized by the steaming method of steaming the fresh leaves in this way, the entire tea leaves are softened by the steaming heat, so that the elution of the ingredients in the tea leaves can be enhanced, and strong tea can be brewed.

In the case of Chinese tea and Japanese pot-roasted tea (Kamairi-sei Tamaryokucha), instead of steaming, the tea leaves are roasted in a heated pot to inactivate the oxidizing enzymes. See Patent Document 1). Heating the tea leaves directly over an open flame brings out the unique flavor of roasting, and at the same time, the tea leaves have a refreshing taste. ing.
In addition, the roasted steaming used in Ureshino tea, etc., and the method of heat treatment by applying high-humidity hot air with a humidity of 60 to 90% and a temperature of about 250 to 390 ° C (see Patent Documents 1 and 2) are also known. It is

On the other hand, the manufacturing method of tencha, which is used as a raw material for matcha, uses steam to kill the raw tea leaves (steaming), then removes the steamed dew on the tea leaves, and after dispersing the leaves so that they do not overlap ( cooling/dispersion), drying at high temperature for a short period of time using radiant heat in a kiln (drying), and then removing the leaf veins and stems to leave only the mesophyll (vine-cutting). .
Also in the method for producing tencha, in recent years, instead of steaming, hot air killing has been proposed (see, for example, Patent Document 3).

By the way, in the various tea production methods as described above, when fresh tea leaves are heated and killed or dried, young and small leaves, buds, leaf scraps, and even lesions are burnt, resulting in aroma and light blue color. was lost. Especially in the case of tencha, the effect was great.

As a technique for removing such burnt tea leaves, for example, Patent Document 4 discloses a technique for removing whole fine leaves including burnt leaves.
In addition, Patent Document 5 discloses a process of roasting raw tea leaves, a powder removing process of removing contaminants from the crushed tea leaves, a removing process of removing easily crushable tea leaves from the tea leaves after the powder removal process, and the easily crushable tea leaves. Disclosed is a tea-making method for improving the quality of crude tea by completely removing easily crushable tea leaves including burnt leaves by a tea-making method including a kneading step of rubbing tea leaves from which tea leaves have been removed.

JP-A-9-233997 JP-A-2001-136908 JP 2013-34405 A Japanese Patent No. 3689404 JP 2007-159510 A

Edited by Shizuoka Chamber of Tea Industry, 1988, "New Tea Industry Complete Book", Shizuoka Chamber of Tea Industry, p275-276

The method disclosed in Patent Document 4 is a process in which raw tea leaves are roasted at a high temperature to remove the charred parts by sieving the treated tea leaves through a rotary drum device after the treatment. be. However, in methods other than the method of killing the tea leaves, such as roasting in an iron pot, which drastically reduces the moisture content of the tea leaves, such as hot air drying, the tea leaves after the killing process contain a certain amount of moisture and become burnt. Since the leaves tend to adhere to normal leaves, simply applying the burnt part removal treatment disclosed in Patent Document 4 cannot efficiently separate the burnt parts, or even normal fine leaves are removed, resulting in a low yield. It has become clear that it is declining. In addition, when a lesion or a wound with less moisture than normal tea leaves or its portion (referred to as a “normal portion”) has a large area and is burnt, a large burnt leaf is produced, as described above. It could not be removed by the technique of sieving through a rotary drum device.

The present invention can efficiently remove a burnt part, especially a large area burnt part, while maintaining a normal yield of leaves even when a method other than roasting in a kettle is used. We propose a manufacturing method for

The present invention heats the tea leaves to adjust the moisture content of the tea leaves to 50 to 70% (W.B.), and then applies force to the tea leaves to separate the burnt portion from the normal portion. A method for producing tea is proposed, characterized by performing a separation treatment and performing a burnt part removal treatment for removing the burnt part.

In the tea production method proposed by the present invention, in the heat treatment, the tea leaves are heated to adjust the moisture content of the tea leaves to 50 to 70% (W.B.), so that the part that will be burnt in the subsequent process is removed. Including, it is possible to obtain a burnt portion of a large area while it is large. At this time, if the water content is too small, these portions will turn into powder. Therefore, in the heat treatment, by heating the tea leaves and adjusting the moisture content of the tea leaves to 50 to 70% (W.B.), the generation of fine scorched leaf pieces is suppressed, and fine scorched leaves adhere to the normal part. Insufficient separation due to this can be suppressed.
Then, after performing the heat treatment, a burnt part separation process is performed to separate the burnt part from the normal part by applying force to the tea leaves, and a burnt part removal process is performed to remove the burnt part, thereby removing the large burnt part. It can be separated and removed as it is.
Thus, according to the method for producing tea proposed by the present invention, it is possible to efficiently remove burnt portions, especially large-area burnt portions, while maintaining a normal yield of leaves.

Next, the present invention will be described based on embodiments. However, the present invention is not limited to the embodiments described below.

<Honcha production method>
The method for producing tea proposed by the present invention (also referred to as "this method for producing tea") involves heating tea leaves to adjust the moisture content of the tea leaves to 50 to 70% (W.B.). 1. A method for producing tea, characterized by performing a burnt portion separation treatment of applying force to tea leaves to separate the burnt portion from the normal portion, and performing a burnt portion removal treatment of removing the burnt portion.

(Heat treatment)
The heat treatment in this tea production method can be performed by direct fire heating such as roasting in a kettle, roasting steam, hot air sterilization or drying, etc., if the moisture content of the tea leaves can be adjusted to 50 to 70% (W.B.). , any heating means can be employed. A combination of these is also possible.

In the heat treatment in this tea production method, by adjusting the moisture content of the tea leaves to 50 to 70% (W.B.), it is possible to suppress the generation of fine burnt leaf pieces, and the portion that will be burnt in the subsequent process Since it is possible to obtain a large-area burnt portion including the , it is possible to efficiently remove the burnt-out portion, especially the large-area burnt-out portion, in the post-process.
From this point of view, in the heat treatment, it is preferable to adjust the moisture content of the tea leaves to 50 to 70% (W.B.), especially 52% (W.B.) or more or 68% (W.B.) or less. Among them, it is more preferable to adjust to 55% (W.B.) or more or 65% (W.B.) or less.

In addition, in the heat treatment, from the same viewpoint as above, it is preferable to adjust the treatment conditions so that the moisture content of the tea leaves can be reduced at a rate of 7 to 20% (W.B.), especially 8% (W. .B.) or more or 18% (W.B.) or less, and the heat treatment conditions are adjusted so that the reduction can be made at a rate of 9% (W.B.) or more or 17% (W.B.) or less. Adjusting is even more preferable.

Furthermore, in the heat treatment, the moisture content (B) of the tea leaves to be separated and removed (also referred to as the “separated burnt portion”) relative to the moisture content (A) of the tea leaves not separated and removed in the burnt portion separation process (also referred to as the “normal portion”) It is preferable to carry out so that the ratio (B/A) of 0.2 to 0.7.
Most of the tea leaves (separated burnt portions) separated and removed in the burnt portion separation process are burnt tea leaves or tea leaves that are highly likely to be burnt in a post-process, and contain many lesions. Therefore, by performing the heat treatment so that the above ratio (B / A) is achieved, abnormal tea leaf parts such as lesions that are likely to be burnt while maintaining flexibility in normal tea leaf parts can be made brittle, so that burnt tea leaves or tea leaves that are likely to be scorched in the post-process can be easily separated in the burnt portion separation treatment in the post-process.
Furthermore, by suppressing excessive drying of the lesion, it is possible to prevent the scorched portion from becoming too brittle and to obtain the lesion as a scorched portion with a large area. In addition, by maintaining the flexibility of the normal part, even when force is applied to the tea leaves in the process of separating the burnt part, it is possible to suppress the occurrence of fine leaves such as broken leaves and spilled leaves from the normal part. The burnt portion can be separated selectively and efficiently, and the yield of the normal portion can be improved.
Therefore, in the heat treatment, the ratio (B/A) of the moisture content (B) of the tea leaves (separated burnt portion) to be separated and removed to the moisture content (A) of the tea leaves (normal portion) not separated and removed in the burnt portion separation treatment. is preferably 0.2 to 0.7, more preferably 0.22 or more or 0.60 or less, more preferably 0.25 or more or 0.50 or less. .

The “normal portion” and the “lesioned portion” can be distinguished mainly by visual observation, for example, by color, shape, pattern, withered buds, and the like.
In the present invention, the term “normal portion” refers to tea leaves and such portions that can be used as a product, and the term “lesioned portion” refers to diseased tea leaves or part of tea leaves, as well as factors other than disease, such as trauma and pests. It is meant to include a portion that has been damaged by such influences and has a lower moisture content than a normal portion.

(Burned part separation processing)
In the burnt part separation treatment in this tea production method, the method of applying force to the tea leaves to separate the burnt parts includes a method of applying a striking force to the tea leaves, a method of applying frictional force to the tea leaves, and pinching or pressing the tea leaves. Any method, such as a method of applying pressure, can be employed as long as the burnt portion can be separated from the normal portion. It should be noted that the normal portion in this case means a portion that is not a burnt portion.

Examples of the method of applying impact force to the tea leaves include a method of stirring the tea leaves with a stirring blade or a stirring rod, hitting with a stick, or colliding the tea leaves with each other or with an obstacle using wind power or the like. can be done.

(Burned part removal processing)
As a method for removing the burnt portion separated from the normal portion as described above, known sorting methods such as sieving, wind sorting, and color sorting can be employed. Specifically, it is passed through a rotating drum made of a mesh such as a wire mesh to be separated and removed under the sieve, or is placed in a sieve made of a mesh such as a wire mesh and vibrated to be separated and removed under the sieve. can be done.

Further, the burnt portion separation processing and the burnt portion removal processing may be performed simultaneously. By performing the burnt portion separation process and the burnt part removal process at the same time, it is possible to suppress adhesion of the burnt part to the normal part, and increase the removal rate of the burnt part.

(Separation of small tea leaves)
In the present tea production method, after the heat treatment and before the burnt portion separation treatment, a small tea leaf separation treatment for removing fine leaves may be performed.
By introducing this small tea leaf separation process and removing small tea leaf pieces in advance before the burnt part separation process, small dried leaves are not mixed in the burnt part separation process. When adding, it is possible to suppress the occurrence of fine scorched leaves caused by crushing of small leaves, and to suppress poor separation due to adhesion of fine scorched leaves to normal parts.
As a guideline for the above-mentioned "small tea leaf pieces", the size corresponds to 5 mm square to 10 mm square, and as a guideline for the above "fine tea leaf pieces", the size is smaller than the size corresponding to 5 mm square. belongs to.

As a specific means of small tea leaf separation treatment, a known sorting machine such as sieving, wind selection, color sorting, etc. may be used to separate small tea leaf pieces, or a net-like or mesh-like basket or It may be placed in a belt or the like to separate and remove small tea leaf pieces while being conveyed.

(Utilization of this tea manufacturing method)
This tea production method can be used as long as it is a tea production method that performs heat treatment such as sterilization treatment and drying treatment.

For example, in the production of crude tea used for sencha and packaged green tea beverages, tea leaves are heated to adjust the moisture content of tea leaves to 50 to 70% (WB). After applying force to the tea leaves to separate the burnt portions, and then performing the burnt portion removal processing to remove the burnt portions, crude tea can be produced through rolling, drying, and the like.

In addition, in the production of tencha, after heating the tea leaves and adjusting the moisture content of the tea leaves to 50 to 70% (W.B.), a heat treatment is performed, and then force is applied to the tea leaves to remove the burnt parts. After performing a burnt part separation treatment to separate the burnt part and performing a burnt part removal treatment to remove the burnt part, tencha can be produced through drying in a kiln, cutting, etc.

Next, an embodiment in which the present tea production method is applied to a tencha production method will be specifically described.

<Method of producing real tencha>
A production method according to an example of the embodiment of the present invention (referred to as "this tencha production method") is to heat raw tea leaves to perform a blue killing treatment for killing tea leaves, and then remove small leaves as necessary. A small tea leaf separation process is performed, then a burnt part separation process is performed and a burnt part removal process is performed. It is a method for producing tencha, characterized in that it is carried out, and then a vine cutting process is carried out.

When producing tencha, it is common to adopt a production method that does not apply pressure. Therefore, since the drying process is performed with the fine leaves exposed on the tencha surface, scorching is likely to occur. Therefore, it can be said that the present invention is more effective when used in the production of tencha than in sencha, in which the powder on the surface of tea leaves is entangled inside by applying kneading pressure.

It should be noted that the tencha manufacturing method can add other processes as long as the processes described above are provided. For example, crushing treatment, drying treatment, cooling treatment, and other treatments can be added as appropriate.

In the present invention, "tencha" refers to tea obtained by killing fresh tea leaves and drying without rubbing.

(Raw tea leaves)
Raw tea leaves, which are the raw material tea leaves for the tencha production method, are not limited in terms of tea variety, tea cultivation method, and plucking time. For example, it is possible to use oishita tea leaves that have been harvested after covered cultivation for a certain period of time before harvesting, or to use tea leaves that have not been covered and cultivated. In addition, first-grade tea, second-grade tea, third-grade tea, fourth-grade tea, autumn-winter-grade tea, etc. can also be used.
It is also possible to use a combination of two or more types of tea leaves with different tea varieties, tea cultivation methods, plucking times, and the like.
The term “raw tea leaves” used in the present invention refers to tea leaves that have not undergone an enzyme deactivation treatment (depletion).

The plucked tea leaves can be washed, dried, and cooled, if necessary, and then subjected to the sterilization treatment described below.

(killing treatment)
In the blue killing treatment of the present tencha production method, it is preferable to adjust the moisture content of tea leaves to 50 to 70% (W.B.) for the reasons described above, especially 52% (W.B.) or more or 68% ( W.B.) or less, more preferably 55% (W.B.) or more or 65% (W.B.) or less.

In the blue killing treatment, from the same viewpoint as above, it is preferable to adjust the treatment conditions so that the moisture content of the tea leaves can be reduced by 7 to 20% (W.B.), that is, by 8%. (W.B.) or more or 18% (W.B.) or less, among which the treatment conditions are such that the ratio can be reduced by 9% (W.B.) or more or 17% (W.B.) or less. is more preferably adjusted.

Furthermore, in the blue killing treatment, for the reasons described above, the moisture content (A) of the tea leaves that are not separated and removed in the burnt part separation treatment (also referred to as "normal parts") is separated and removed (also referred to as "separated burnt parts"). It is preferable to carry out so that the ratio (B/A) of the water content (B) is 0.2 to 0.7, especially 0.22 or more or 0.60 or less, especially 0.25 or more or 0.25 or more. It is more preferable to implement it so that it becomes 50 or less.

In the method for producing tencha, it is preferable to carry out drying at the same time as the killing using hot air. By using hot air to kill the blue at the same time as drying in this way, it is possible to increase the degree of greenness compared to the conventional case of drying after killing the blue by steam heat. Furthermore, since the drying temperature in this blue-killing treatment is lower than the conventional drying temperature, it is possible to obtain the effect that the color is less likely to fade.
Hereinafter, the conditions for drying with hot air will be described.

In order to adjust the moisture content of tea leaves after the killing process, the temperature of the hot air, the time of contact between the fresh tea leaves and the hot air, the amount of tea leaves supplied to the device for the killing process, and the time of the hot air. It is sufficient to adjust the supply amount per unit. However, it is not limited to these.

In the blue killing treatment, it is preferable to prepare hot air adjusted to a temperature of 180° C. or higher, and supply the hot air to the fresh tea leaves to bring them into contact.
If hot air with a temperature of 180° C. or higher is produced and supplied to the fresh tea leaves, the fresh tea leaves can be sufficiently killed and the moisture content of the tea leaves can be adjusted to a preferable range. However, if it is brought into contact with hot air of too high a temperature, it may scorch.
From this point of view, in the blue killing treatment, hot air adjusted to a temperature of 180 ° C. or higher, especially 190 ° C. or higher or 350 ° C. or lower, especially 200 ° C. or higher or 335 ° C. or lower is produced, and the hot air is supplied to the raw tea leaves and brought into contact. It is even more preferable to let

In the blue-killing treatment, the time for which the hot air is brought into contact with the fresh tea leaves is preferably 90 to 300 seconds for each fresh tea leaf, especially 120 seconds or more or 250 seconds or less, especially 150 seconds or more or 200 seconds or less. More preferred.

In the aericide treatment, the ratio of the flow rate of fresh tea leaves (kg/min) to the flow rate of hot air (m ³ /min) (flow rate of tea leaves/flow rate of hot air×100) is preferably 10-17.
By adjusting the ratio between the flow rate of fresh tea leaves (kg/min) and the air flow rate of hot air (m ³ /min) in the killing process (flow rate of tea leaves/hot air flow rate × 100) to 10 to 17, while accurately killing the green leaves. , can increase the greenness of tencha.
From this point of view, the ratio between the flow rate of fresh tea leaves (kg/min) and the flow rate of hot air (m ³ /min) (flow rate of tea leaves/flow rate of hot air × 100) in the aeralization treatment is set to 10 to 17 (unit: kg/m ³ ). It is preferable to adjust, especially 11 or more or 16 or less, more preferably 12 or more or 15 or less.
The flow rate of fresh tea leaves means the amount of fresh tea leaves supplied to the aeralization treatment apparatus per unit time, and the hot air flow rate means the amount of hot air supplied per unit time.

It is preferable not to knead the tea leaves or apply pressure to the tea leaves before the blue killing treatment and the drying treatment, from the viewpoint of drying the tea leaves without causing overlapping of the tea leaves and enhancing the color tone of the product.

Any device can be adopted as the device for carrying out the sterilization treatment, as long as it has a structure capable of bringing hot air into contact with the fresh tea leaves. One example is a device comprising a rotating processing cylinder capable of moving tea leaves in a fixed direction, and a hot air supply pipe arranged in the axial direction in the rotating processing cylinder and having a large number of hot air ejection ports. can be done.

In addition, as a method of killing blue in the present tencha manufacturing method, a method of performing drying simultaneously with killing blue using hot air was described above. However, if the moisture content of the tea leaves can be adjusted to 50-70% (W.B.), any heating means such as direct fire heating such as kettle roasting, roasting steam, hot air blowing or drying can be used. It can be adopted as a method for killing blue tea in tencha production methods. It is also possible to combine these.

(Separation of small tea leaves)
In the present tencha production method, it is preferable to perform a small tea leaf separation treatment for removing small leaves after the ablation treatment and before the burnt part separation treatment. However, small tea leaf separation treatment may be performed as necessary, and is not always required.

As a specific means of the small tea leaf separation treatment in the present tencha production method, it is preferable to separate and remove small tea leaves while conveying the tea leaves after sterilization with a net-like or mesh-like basket or belt.

(Burned part separation process and burnt part removal process)
By performing burnt part separation treatment and burnt part removal treatment before drying treatment, the amount of burnt leaves derived from lesions and leaves burnt due to low moisture content to be subjected to drying treatment can be reduced. be able to. As a result, the lesions are less likely to be scorched during the drying process, and the lesions that become brittle when the tea leaves move through the furnace separate from the normal part and fall into the furnace and be scorched. It is possible to suppress the adhesion of the burnt smell to the tencha.
Furthermore, in each of the heat treatment before the drying treatment, the small tea leaf separation treatment, the burnt part separation treatment, and the burnt part removal treatment, it is possible to suppress the adhesion of fine burnt leaves to normal tea leaves. It is possible to suppress the occurrence of scorching on the surface of the tea leaves, and it is possible to suppress the adhesion of the scorched smell to the tencha.

In the present tencha production method, the burnt part separation process of applying force to the tea leaves to separate the burnt part from the normal part and the burnt part removal process of removing the burnt part may be performed by separate machines or devices. , may be performed simultaneously on the same machine or apparatus.

As a method of simultaneously performing the burnt portion separation treatment and the burnt portion removal treatment with the same machine or device, for example, a device equipped with a rotating shaft and a large number of stirring blades in a rotating wire mesh barrel that can move the tea leaves in a certain direction is used. It is preferable to remove the scorched portions while applying pressure to the tea leaves to separate the scorched portions by supplying the tea leaves after the sterilization treatment into the rotating wire mesh cylinder.
If tea leaves are processed using such a device, that is, a device having a rotating shaft and a large number of stirring blades in a rotating wire mesh barrel, the large number of stirring blades can apply pressure to the tea leaves, removing the burnt portion. , not only can the tea leaves be separated from the unburned portion, but also friction pressure can be applied to the tea leaves in the gap between the tip of the rotating blade and the inner circumference of the rotating wire mesh barrel, and the separation of the burnt portion can be promoted. can.

In the above apparatus, it is also preferable to provide a difference between the rotation speed of the rotating wire mesh cylinder and the rotation speed of the rotating shaft. At this time, it is preferable that the rotating speed of the rotating shaft is faster than the rotating speed of the rotating wire mesh cylinder.
The shape of the mesh of the rotating wire mesh cylinder may be square, rectangle, rhombus, circle, ellipse, or any other shape. or 8 mm or less, more preferably 2 mm or more or 6 mm or less, preferably 0.5 to 8 mm in short diameter, especially 1 mm or more or 7 mm or less, especially 2 mm or more or 5 mm or less. is more preferred.

(Snow tea processing)
After the burnt portion removing treatment, it is preferable to perform a tea dispersing treatment for cooling the tea leaves and dispersing the tea leaves by stirring the tea leaves using a tea dispersing machine or the like.
In this way, by cooling the tea leaves and dispersing the tea leaves to prevent the tea leaves from overlapping and sticking to each other, not only can the effect of the drying treatment be uniformly imparted, but also the color and luster of the tea leaves can be blackened. can be prevented from becoming

Stirring in the cooling treatment can be performed using a known tea-sprinkling machine. However, the device is not limited to the tea-scattering machine as long as it can cool the tea leaves and at the same time eliminate the state in which the tea leaves are overlapping and sticking to each other.

(drying process)
In the drying process, it is preferable to heat the tea leaves to dry them to a moisture content of 3 to 50% (W.B.).
In the present tencha production method, the method of drying the tea leaves is preferably indirect heating using a heat medium, more preferably a method of contacting with air, steam, heated inorganic solids or organic solids, and further infrared rays or far infrared rays. A method using hot air, a method using heated steam, and a method in which the tea leaves are brought into contact with a heated container are preferable. is preferred. By heating the tea leaves using radiant heat, the tea leaves can be given a unique roasted aroma.
A kiln is surrounded by bricks and utilizes the radiant heat of the bricks, i.e. far-infrared heat.

In the drying process, an example can be given in which the inside of the furnace is divided into a plurality of stages such as an upper stage, a middle stage, and a lower stage, and the tea leaves are dried while moving the tea leaves in order through each stage.
At this time, the atmosphere temperature of the highest temperature region among the plurality of stages is 170 to 220° C., especially 180° C. or more or 210° C. or less, and the time for passing through that region is 90 to 210 seconds, especially 100 seconds or more or 200 seconds. seconds or less, preferably 150 seconds or more or 190 seconds or less.
Further, the total stage moving time for moving all the stages is preferably 10 to 21 minutes, more preferably 12 minutes or more or 19 minutes or less, more preferably 13 minutes or more or 19 minutes or less.

(Vine cutting process)
In the pickling process, it is preferable to select only the mesophyll by removing the leaf veins and stems after drying.

(Pulverization and sorting)
Furthermore, if necessary, the diameter of the tea leaves (the width of the longest part × length) when the mesophyll is sorted is 25 × 35 mm, especially the width is 2 mm or more or 15 mm or less, and the length is 2 mm or more and 30 mm or less. , preferably crushed and screened.

<Tencha obtained by this tencha manufacturing method>
Tencha obtained by the present tencha manufacturing method is tencha having an excellent degree of greenness, and can be ground into powder and used as matcha.
Furthermore, according to the present tencha production method, it is possible to effectively increase the degree of greenness by using less expensive raw material tea such as autumn and winter bancha, so it is possible to provide an inexpensive raw material for processed foods.

<Explanation of terms>
In this specification, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, "X or more and Y or less" and "preferably larger than X" or "preferably Y It also includes the meaning of "less than".
In addition, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), "preferably larger than X" or "preferably less than Y" It also includes intent.

Hereinafter, the present invention will be described in further detail based on the following examples and comparative examples. However, the present invention is not limited to the following examples.

<Example 1>
As raw material tea leaves, Yabukita variety produced in Nara Prefecture (1st tea, covered, plucked on May 30) was used. The water content of this raw tea leaf (fresh leaf) was 80.4% (W.B.).
The moisture content of the tea leaves was measured by normal pressure drying at 105° C. using a moisture meter (Shimadzu Corporation Moisture Meter “MOC63u”) (the same applies thereafter).

After subjecting the above-mentioned raw tea leaves to hot air contact with raw tea leaves as described below to subject them to decubitus treatment, the tea leaves are passed through a rotating wire mesh cylinder equipped with rotating stirring blades, and pressure is applied to the tea leaves in the rotating wire mesh cylinder. , The burnt part is separated from the normal part through the wire mesh and the burnt part is removed, and then the tea leaves are treated by using a tea dispersing machine, and then supplied to the kiln to heat the tea leaves. A drying treatment was performed, followed by slicing, pulverization and sorting to obtain tencha (sample).

In the aquatic treatment, a device equipped with a rotating processing cylinder capable of moving tea leaves in a fixed direction and a hot air supply pipe having a large number of hot air blowing holes arranged in the axial direction in the rotating processing cylinder is used. A hot air of 280° C. was produced by the hot air, and the hot air was brought into contact with the raw tea leaves in the rotary treatment drum through the hot air supply pipe and the hot air jet port.
At this time, the killing time, that is, the time during which the hot air is brought into contact with the fresh tea leaves, that is, the time during which the raw tea leaves pass through the rotary treatment drum is 3 minutes, and the flow rate of the raw tea leaves is 280 kg/h (4.7 kg/min). , the hot air flow rate (m ³ /min) was 33.9, and the tea leaf flow rate/hot air flow rate×100 was 13.8 (kg/m ³ ).
The moisture content of the tea leaves (D) after the sterilization treatment was 64.8% (W.B.).

The rotating wire mesh cylinder with rotating stirring blades is a device equipped with a rotating shaft and a large number of stirring blades in a rotating wire mesh cylinder having a length of 1.2 m, a diameter of 21 cm, and a mesh size of 3 mm in major diameter and 3 mm in minor diameter. Cylinder rotation speed 42r. p. m, the rotational speed of the rotating shaft is 320 r.m. p. set to m. Also, the inclination angle of the rotating wire mesh cylinder was set to 2°. Furthermore, the gap between the rotating wire mesh cylinder and the stirring blade was set to 8 mm.
Tea leaves can be moved while the rotating wire mesh cylinder rotates, the tea leaves are beaten by a large number of stirring blades, and finely divided tea leaf pieces are sieved downward from the mesh of the rotating wire mesh cylinder.
At this time, tea leaves corresponding to 0.94% by mass of the raw material tea leaves (fresh leaves) were sieved downward from the mesh and removed. That is, the removal rate of the separated scorched portion relative to the raw material fresh leaves was 0.94% by mass (shown as "removal rate" in the table). Then, arbitrarily extract 20 g from each of the tea leaves on the sieve (“normal part”) and the tea leaves separated and removed under the sieve (“separated burnt part”), and the water content (A) of the normal part and the separated burnt The water content (B) of each portion was measured, and the ratio (B/A) of the water content (B) of the separated burnt portion to the water content (A) of the normal portion was calculated.
When the separated scorched portion of the tea leaves was observed, it was found to be a scorched portion or a lesion portion that would become a scorched portion in a post-process. This point was the same for other examples.

The tea leaves discharged from the rotating wire mesh drum as described above are placed in a box made of wire mesh, dried, and transported to a tea dispersing machine. After dispersing, it is then supplied to the furnace described below to heat the tea leaves to dry the tea leaves, and then the leaves and stems are separated by vine cutting. The water content of the tea leaves (the back leaves of the vine cut into the tea leaves) was set to 4.4% (W.B.).
The kiln used at this time had a side wall made of refractory bricks with excellent heat insulation performance. is equipped with a heavy oil combustion type burner, and the high temperature gas heated by the flame of the burner is folded back from the lower stage to other stages along multiple flues branching from the furnace, and is installed on the side of the tencha machine. It was configured to be exhausted to the outside from a chimney that was installed. Then, the inside of this kiln is placed on a belt conveyor type conveying means, and the tea leaves are dried while moving in the order of the lower stage, the upper stage, the second stage, and the take-out stage, and pass through the lower area with the atmospheric temperature of the lower area being 211 ° C. The time is 1 minute and 50 seconds, the atmospheric temperature in the upper region is 118°C, the time to pass through the upper region is 3 minutes and 50 seconds, the atmospheric temperature in the second region is 104°C, and the time to pass through the second region is 4 minutes. 57 seconds, the ambient temperature in the unloading stage area was 101° C., the time to pass through the unloading stage area was 5 minutes and 23 seconds, and the total stage movement time was 16 minutes.

After the above-mentioned drying treatment, the leaf veins and stems of the tea leaves coming out of the kiln are separated from the pulp by vine cutting, and only the pulp is selected, and the diameter of the tea leaves (width of the longest part x length) is 25 x 35 mm. Tencha (sample) was obtained by pulverizing and sorting so that

<Example 2>
Tencha (sample) was obtained in the same manner as in Example 1, except that small tea leaf separation treatment was added. That is, tencha (sample) was obtained in the same manner as in Example 1, except that after the sterilization treatment, small tea leaves were separated while being transported to a rotating wire mesh cylinder with a rotating stirring blade.
At this time, the small tea leaf separation treatment is carried out by placing the tea leaves that have been subjected to the aereptic treatment on a wire net conveyor (mesh: major diameter 8 mm × minor diameter 6 mm), conveying at a conveying speed of 25 cm / sec and a conveying time of 10 seconds. processed.
Tea leaves corresponding to 0.22% by mass of raw tea leaves (fresh leaves) were removed under the sieve. That is, the removal rate of the separated small tea leaves relative to the raw material fresh leaves was 0.22% by mass (shown as "removal rate" in the table). The water content (E) of the removed small tea leaves was 38.4% (W.B.).

When the small tea leaves removed under the sieve by the above small tea leaf separation treatment were observed, they were burnt portions, lesions or small tea leaf pieces that would be burnt portions in a later step. This point was the same for other examples in which small tea leaf separation treatment was performed.

<Example 3>
Tencha in the same manner as in Example 1, except that Yabukita variety produced in Nara Prefecture (first tea, covered, plucked May 30, moisture content 78.3% (W.B.)) was used as the raw material tea leaves. (sample) was obtained.

<Example 4>
Tencha in the same manner as in Example 2, except that Yabukita variety produced in Nara Prefecture (Second-grade tea, covered, harvested on July 18, moisture content 79.3% (W.B.)) was used as the raw material tea leaves. (sample) was obtained.

<Example 5>
Tencha in the same manner as in Example 2, except that Yabukita from Nara Prefecture (Autumn/Winter Bancha, uncoated, picked on October 26, moisture content 69.6% (W.B.)) was used as the raw material tea leaves. (sample) was obtained.

<Example 6>
Tencha in the same manner as in Example 1, except that Yabukita variety produced in Nara Prefecture (Autumn/Winter Bancha, uncoated, plucked on October 26, moisture content 69.6% (W.B.)) was used as the raw material tea leaves. (sample) was obtained.

<Example 7>
Tencha in the same manner as in Example 2, except that Yabukita (Autumn/Winter Bancha, uncoated, harvested on October 26, moisture content 71.2% (W.B.)) from Nara Prefecture was used as the raw material tea leaves. (sample) was obtained.

<Comparative Example 1>
Tencha (sample) was obtained in the same manner as in Example 1, except that the burnt portion separation treatment was not performed.

<Comparative Example 2>
Tencha in the same manner as in Comparative Example 1, except that Yabukita variety produced in Nara Prefecture (Second-grade tea, covered, harvested on July 18, moisture content 79.3% (W.B.)) was used as the raw material tea leaves. (sample) was obtained.

<Comparative Example 3>
Tencha in the same manner as in Comparative Example 1, except that Yabukita variety produced in Nara Prefecture (Autumn/Winter Bancha, uncoated, harvested on October 26, moisture content 69.6% (W.B.)) was used as the raw material tea leaves. (sample) was obtained.

<Evaluation of tencha production method>
The tencha manufacturing method was evaluated by the following indices.

<Yield of normal leaves>
In the above example, the tea leaves removed by the burnt part removal treatment were visually selected to select normal tea leaves, that is, normal parts that could be used as a product. evaluated with
◎: The removal rate after the burnt part removal treatment is less than 1.5% by mass, and the ratio of normal parts among the removed leaves is less than 10% (each ratio is converted to fresh leaves. The same applies hereinafter).
○: The removal rate after the burnt part removal treatment is less than 1.5% by mass, and the percentage of normal parts in the removed leaves is less than 30% ×: The removal rate after the burnt part removal treatment is 1.5% by mass. 5% by mass or more, or 30% or more of the normal part of the removed leaves

<Removal rate of burnt leaves>
Arbitrarily extract 200 g from the tencha obtained in the above examples and comparative examples (the back leaves of the vine-cut Chinese tea leaves), visually select the burnt leaves, measure the ratio of burnt leaves (% by mass), and burn the leaves according to the following criteria. was evaluated.
◎: The percentage of burnt leaves is less than 0.25% by mass ○: The percentage of burnt leaves is 0.25% by mass or more and less than 0.30% by mass ×: The percentage of burnt leaves is 0.30% by mass or more

<Strength of burnt smell>
The tencha (samples) obtained in the above Examples and Comparative Examples were selected by 10 panelists engaged in the production of tea leaves, evaluated according to the following criteria, and the one with the highest evaluation was adopted.

⊚: No burning smell was felt.
◯: Almost no burnt smell was felt.
x: A burning smell was felt.

(Discussion)
From the above examples and the test results that the present inventor has conducted so far, after performing a heat treatment to adjust the moisture content of the tea leaves to 50 to 70% (WB), force is applied to the tea leaves to burn the part. By performing a burnt part separation process that separates the burnt part and performing a burnt part removal process that removes the burnt part, for example, including the part that becomes a burnt part in the post-process heat drying etc., a large area burnt part remains large It was found that the scorched portions, especially the scorched portions with large areas, could be efficiently removed while maintaining a normal yield of leaves.

Claims (8)

After adjusting the moisture content of the tea leaves to 50 to 70% (W.B.) by heating the raw tea leaves to kill the tea leaves, the tea leaves are passed through a rotating wire mesh cylinder with a rotating stirring blade and the rotating wire mesh. A burning force is applied to the tea leaves in the drum to separate the burnt portions from the normal portions through the wire mesh, and the burnt portions are removed, and heat is applied to the tea leaves to dry them. A method for producing Tencha. 2. The method for producing tencha according to claim 1, wherein the process of applying kneading pressure is not performed. 3. The method for producing tencha according to claim 1 or 2 , characterized in that the ablation treatment is carried out by using hot air and drying at the same time. In the blue killing treatment, the ratio (B/A) of the moisture content (B) of the tea leaves separated and removed to the moisture content (A) of the tea leaves not separated and removed in the burnt part separation treatment is 0.2 to 0.7. The method for producing tencha according to any one of claims 1 to 3 , characterized in that it is carried out as follows. The method for producing tencha according to any one of claims 1 to 4 , characterized in that a small tea leaf separation treatment for removing small leaves is performed after the blue killing treatment and before the burnt part separation treatment. . The method for producing tencha according to any one of claims 1 to 5 , wherein the drying process is performed by applying heat to the tea leaves using a tencha. The method for producing tencha according to any one of claims 1 to 6 , characterized in that after the drying treatment, a pickling treatment is performed. The method for producing tencha according to any one of claims 1 to 7 , characterized in that after performing the burnt portion removal treatment and before the drying treatment, a powdered tea treatment is performed.