JP2011125330A - Method for producing green tea - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing green tea having flavor comparable with the green tea produced in conventional method, in a simpler method than conventional method. <P>SOLUTION: The method includes the step of deactivating enzyme of green tea by heat treating the green leaves; the step of passing the leaves after the heating treatment through a space across a pair of heated rollers each rotating toward inside in the opposite direction for rolling and pressing; and the step of drying the tea leaves after the steps. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  Green tea such as sencha, kabusecha, and gyokuro is produced through the process of steaming fresh leaves with a steamer → coarse with a roughing machine → twisting with a twisting machine → medium with a centering machine → sewing with a milling machine → drying with a dryer (Hereinafter, it is also referred to as “conventional method”). In order to simplify the said process, patent document 1 discloses manufacturing powdered tea by processing fresh leaves of tea with a double drum dryer having a surface temperature of 130 to 250 ° C. and then pulverizing. Patent Document 2 discloses that olive leaves are treated with a double drum dryer having a surface temperature of 120 to 150 ° C. and dried to a moisture content of 4 to 10%.

  The raw tea of Matcha is steamed shallowly and dried in a tea machine without drying it. After roughly separating the stems and leaves, the main tea (leaves) and the rough stems (stems) are separately ventilated. Repeated sieving and cutting to adjust the size, and make stem tea by carefully separating the mesophyll part, stem and leaf vein part using electrostatic foliage separator and color sorter, carefully finishing and drying It is known. A tea-tea machine is a drying furnace unique to tea-tea production. In a brick furnace heated to about 200 ° C in the lower stage and about 100 ° C in the upper stage, a net conveyor that operates a three-stage or four-stage wire mesh is installed. The tea leaves dries without being sown while passing through the upper and middle stages. The raw leaf processing capacity of this tea machine is as small as about 100 kg / Hr per machine, and the installation price of the tea machine itself is very high, so the production cost of tea tea is very high. Therefore, there is a demand for improvement of the production capacity of the tea machine and reduction of the tea production cost.

  In addition, green tea drink raw tea is required to have high extraction efficiency per weight in order to reduce raw material costs. Further, tea leaves that are easy to use with respect to leaves are required to have tea leaves that can be extracted as quickly as possible. In addition, cold tea suitable for summer drinking is required to have a high extraction efficiency in which many soluble components are extracted even at low temperatures in the refrigerator.

  In addition, traditional green tea stem and leaf separation is performed by combining wind sorting, electrostatic sorting, and color sorting according to tea type and separation accuracy. Higher separation accuracy requires an expensive color sorter and requires a long selection time. There was a problem that the finishing cost also increased. Therefore, it is required to easily separate the foliage in a short time in the fine finishing process.

JP-A-2-128649 JP 2006-304753 A

  As disclosed in Patent Document 1, the present inventors processed fresh tea leaves with a double drum dryer, and the green tea produced through this processing step has problems of a blue odor, stuffy smell and stuffy taste. I found out.

  The above-mentioned conventional method requires a plurality of steps of rough koji → spinning → middle mushroom → serious koji in order to produce green tea having an excellent flavor. This causes problems with the flavor of green tea. Therefore, an object of the present invention is to provide a method for producing green tea, which is a simpler method than the above-described conventional method, but can produce a green tea with a flavor comparable to the conventional method.

  In order to solve the above-mentioned problems, the present inventor has studied and found that by performing steaming heat treatment before the treatment of the double drum dryer, it is possible to reduce the blue smell, the odor, and the odor, and the present invention is completed. It came.

  That is, the present invention provides the following means.

[1] a step of heat-treating fresh tea leaves to inactivate tea leaf enzymes;
Passing the tea leaves after the step while rolling and pressing between a pair of heated rollers rotating inward in opposite directions; and
And a step of drying the tea leaves after the step.
[2] The method for producing green tea according to [1] above, wherein the tea leaves after the drying step are sieved and cut to a size according to the use, and then thinned to be easily charged with static electricity. The method further comprises a selective finishing step of separating the stem and the leaf vein portion by an electrostatic type leaf and leaf separator, and separating the main tea from the stem and the leaf vein.
[3] The method for producing green tea according to [1] above, wherein in the step of passing tea leaves between a pair of rollers, the input amount of tea leaves, the gap between the rollers, the surface temperature of the rollers, and the number of rotations of the rollers However, the method is characterized in that the green leaves of the tea leaves after passing through the roller are suppressed from being changed, and the tea leaves after passing through the roller are adjusted so as to become small thin slices.
[4] The method for producing green tea according to [1] above, wherein the roller has a surface temperature of 100 ° C. or higher and lower than 130 ° C.
[5] A green tea produced by the method according to any one of [1] to [4] above.

  According to the method for producing green tea of the present invention, it is possible to produce green tea having a flavor comparable to that of the conventional method by a simpler method than the conventional method.

  Moreover, the green tea made by the method of the present invention has the advantages of higher extraction efficiency and higher cold water solubility than the green tea made by the conventional method.

  In addition, the green tea stems and veins made by the method of the present invention are lightened because they are rolled and thinned between rollers, and are adsorbed by electrostatic foliage separators compared to green tea stems made by conventional methods. It has the advantage that it can be easily separated from the main tea of the mesophyll part. As a result, when the green tea made by the method of the present invention is carefully selected, it can be milled in the same manner as koji tea made by carefully selecting the conventional method, and high-quality powdered tea can be produced.

The flowchart which shows an example of the manufacturing method of the green tea of this invention. The figure which shows the one aspect | mode of the apparatus used with the manufacturing method of the green tea of this invention.

  Hereinafter, the present invention will be described in detail. The following description is intended to illustrate the present invention and is not intended to limit the present invention.

The method for producing green tea of the present invention includes the following steps (1) to (3):
(1) a process of heat-treating tea leaves to inactivate tea leaf enzymes;
(2) The step of passing the tea leaves after the step of (1) while rolling and pressing between a pair of heated rollers rotating inward in opposite directions, and (3) of (2) The process of drying the tea leaves after the process.

  FIG. 1 is a flowchart showing an example of the method for producing green tea of the present invention. Fig. 1 shows heat treatment of fresh tea leaves to inactivate the enzyme; rolling and squeezing by roller heating and drying; further drying (ventilation drying and / or heat ray drying); Cutting and electrostatic foliage separation); each step of drying and burning is shown.

  Hereinafter, each step will be described.

Step (1) In the present invention, the raw “green tea leaves” may be raw leaves that are raw materials for any green tea such as sencha, kabuse tea, gyokuro, strawberry tea, bancha, and the like.

  In the heat treatment step (1), a known method for inactivating the tea leaf enzyme can be used, and for example, steaming heat treatment, kettle roasting method, microwave heating method, roasting steaming method can be used.

  The heat treatment step can be performed according to a known method. For example, in the case of steaming heat treatment, steaming time emphasizes the green color of green tea, and can be performed at 100 ° C. in a short time of about 10 to 40 seconds.

  If the green tea leaves are shredded to the same length and size before the heat treatment, and then made easier to enter between the rollers in the subsequent step (2), the drying efficiency will increase, but if shredded too much The product has higher extraction efficiency at the time of extraction, but the bitterness and miscellaneous taste becomes stronger and the palatability becomes worse. Therefore, it is preferable to adjust the size of shredding according to the use. Prior to the heat treatment, the fresh tea leaves can be shredded, preferably to a length of 3-5 cm.

In the step (2) of (2), the tea leaves after the step (1) are passed between a pair of heated rollers that rotate inward in opposite directions while being rolled.

  The step (2) can be performed using, for example, a commercially available double drum dryer. The double drum dryer supplies the processed material between two steam-heated rollers (see reference numeral 1 in FIG. 2) that rotate inward, and passes the processed material between the rollers. As a result, the processed material is made into a thin film by the pressure between the rollers, and heating, evaporation and drying of the processed material are performed in several tens of seconds. The thin film-like processed material adhering on the roller is scraped off by a scraper (see reference numeral 2 in FIG. 2).

  In the step (2), the pair of rollers may be heated by high-pressure steam, or may be heated by any other means such as a gas furnace combustion, an infrared gas burner, a heavy oil burner, or the like.

  Hereinafter, although the case where the process of (2) is performed using a double drum dryer is demonstrated to an example, the process of (2) of this invention is not limited to the following description.

  The tea leaves after the heat treatment step of (1) are thrown uniformly so as not to be stored in the upper part of the drum of the double drum dryer. When stored in the upper part of the drum, heat denaturation occurs at a high temperature here, and the green color becomes reddish, resulting in a scent and a savory taste. The tea leaves are put into a double drum dryer, rolled and squeezed between the drums, and the tea leaves and the tea leaf pressing liquid are rapidly dried at the drum surface temperature to make the tea leaves into a thin film.

  The amount of tea leaves, drum gap, drum surface temperature, and drum rotation speed were adjusted so that the green color of the tea leaves after the treatment was suppressed and the tea leaves after the treatment became small slices. The

  That is, the amount of tea leaves to be introduced is thin and even so as not to be stored in the upper part of the drum.

  If the gap between the drums is a minute gap (for example, 0.05 to 0.5 mm), it is easy to make a thin film section. The narrower the gap, the smaller the section, and the drying progresses but becomes powdery. Conversely, the wider the gap, the less the rolling, the insufficient extraction of the tea leaf pressing liquid, and the drying does not proceed.

  The vapor pressure is set so that the drum surface temperature is generally 100 to 140 ° C., preferably 100 ° C. or higher and lower than 130 ° C., desirably 125 ° C. The higher the drum temperature, the higher the drying efficiency, but it is susceptible to thermal denaturation, leading to a reduction in quality. Conversely, if it is too low, the drying efficiency is low, and a load is applied in the subsequent drying step. Patent Document 1 (Japanese Patent Laid-Open No. 2-128649) does not perform the heat treatment step (1) and the drying step (3), but performs a high-temperature double drum dryer treatment at 130 to 250 ° C. In the invention, since the flavor of green tea is emphasized, treatment at a high temperature is not preferable.

  In order to avoid processing at a high drum (roller) surface temperature, as shown in FIG. 2, a heat ray irradiator 3 is provided below the roller 1, and the tea leaves are rolled between the rollers and dried on the roller surface. Until it is scraped off in step 2, the tea leaves may be irradiated with heat rays from the outside to further promote the drying of the tea leaves. In FIG. 2, the heat ray irradiator 3 arrange | positions the reflecting plate 4 on the opposite side to the roller 1, and irradiates a tea leaf efficiently with a heat ray. By arranging the heat ray irradiator 3 in this way, sufficient drying of the tea leaves can be achieved even at a low roller surface temperature (for example, less than 130 ° C.), prevention of stuffy aroma by heating, generation of aroma by heat ray irradiation. The effect that can be obtained.

  The rotation speed of the drum is the contact time between the tea leaves and the drum, and if it is slow, the contact time becomes long and the drying proceeds, but it is susceptible to thermal denaturation, causing deterioration, and if it is early, the contact time is shortened and drying does not proceed. It is discharged and the subsequent drying process is overloaded, and tea juice adheres to the drum surface and cannot be scraped off with a scrubber, resulting in quality degradation and failure. The range of drum rotation speed is generally 3 to 13 rpm, preferably 5 to 6 rpm.

In the step (3) of (3), the tea leaves made into a thin film by passing between rollers in the step (2) are dried. This drying step can be performed according to a known method. For example, after discharging the roller, a continuous drying process, or a drying process and a heat ray irradiation and drying process are performed to make green tea with a water content of 5% or less. The tea temperature at this time should be as low as about 60-80 ° C in the early stage when there is a lot of moisture, and the temperature can be changed according to the product application in the later stage when the moisture is low, Dry and add fire incense and fire taste.

  By the steps (1) to (3) described above, it is possible to produce green tea without the conventional method of rough koji, twisting, middle mushroom, and refinement.

  A fine finishing step may be performed after the drying step (3).

  In other words, green tea (green tea that was rolled on a drum and dried into thin-film slices) made as described above was sieved and cut to a size appropriate for the application, and it became thin and easily charged with static electricity. The stem / leaf vein portion may be separated by an electrostatic type leaf / leaf separator to separate the tea from the stem / leaf vein. By repeating these operations, the shape and size may be aligned, and the accuracy of separation between the main tea and the stem / leaf vein may be improved.

  In this case, the stems and veins of green tea made by this method are light in weight because they are thin, and are more easily adsorbed by electrostatic foliage separators compared to gyokuro, sencha and strawberry tea stems made by conventional methods, Separation of mesocha from the main tea can be easily performed.

  Since the stems and leaves can be easily separated, the green tea that has been carefully selected after the method of the present invention can be ground with a mortar, and can produce high-quality powdered tea, similar to the tea that has been carefully selected by the conventional method. .

  After the fine finishing process, it may be ignited according to a known method.

  Green tea made by the method of the present invention has the following advantages.

  1. The green tea made by the method of the present invention differs greatly from the green tea made by the traditional tea making method (sencha, kabusecha, gyokuro, etc.), and the conventional tea (steamed and dried without drying) Green tea) in the form of a thin film with a soft feel.

  In addition, the green tea made by the method of the present invention maintains the green color and light blue, aroma, taste, and palatability suitable for each type of sencha, kabuse tea, gyokuro, and mochi tea made by the conventional method, and has a blue odor. It has a refreshing and rich light blue color and flavor.

  When heat irradiation irradiation such as infrared rays or far-infrared rays was performed on a low heat, the flavor disappeared, the aroma was increased, and a flavor equivalent to a commercially available tea was obtained.

  2. Simplified traditional methods for producing crude tea such as sencha and gyokuro, and reduced process production of green tea has become possible. In the method for producing crude tea according to the method of the present invention, the process is mainly completed in three steps: a steamer, a double drum dryer, and a dryer. It was possible to omit the five processes of the roughing machine (leaf cutter, roughing machine), dredging machine, centering machine and precision milling machine used in the conventional method.

  3. We were able to develop a method for producing green tea with the quality of conventional tea without using a conventional tea machine.

  4). Green tea made by the method of the present invention has higher extraction efficiency than green tea made by the conventional brewed tea and brewed tea methods, can be extracted in a short time, is highly soluble in cold water, is a drink raw material tea, tea bag The improvement of extraction efficiency as raw tea and cold tea raw tea was solved.

  5. The stems and veins of green tea made by the method of the present invention are light in specific gravity because they are rolled with a drum dryer and made into a thin film. It was easily adsorbed and could be easily separated from the mesocha tea leaves.

  6). Since the leaves and leaves can be separated easily using an electrostatic foliage separator, green tea that has been finely selected by this method can be ground with a mortar, and can be used to produce high-quality powdered tea. Can be produced.

Example 1: Sensory test (1) As raw raw tea leaves, freshly-grown sencha green leaves in the 1st tea season and covered green tea leaves under cover cultivation (direct covering 75% light shielding degree 13 days) were used. Conventional method, 2. Raw leaf DD, 3. Three test sections of this method steamed leaf DD were set up to produce crude tea.

(2) Test categories and manufacturing processes are as follows. In the conventional method, a 2 kg machine was used and manufactured according to the standard tea manufacturing method. 2. 2. Raw leaf DD and 3. In this method, green tea was produced using a double drum dryer (John Milder JM-D1 manufactured by Johnson Boiler).

(3) Steaming in the test section 1.3.4.6 was performed using a band-type steamer and the steaming time was 30 seconds.

(4) The setting of the double drum dryer used in the test section 2.3.5.6 was as follows.

1. Steam pressure: 0.25MPa (Drum surface temperature: 125 ℃)
2. Drum rotation speed: 5.0 rpm (circumferential speed 12 seconds)
3. Drum gap: Slightly present 4. Cutting green tea leaves: None (5) In the conventional technique, the test section of “Natural Leaf DD” treats the set temperature of the double drum dryer at a high temperature of 130 ° C. to 250 ° C. Therefore, in order to compare the quality with this method in this test, the method of using a double drum dryer was made common with this method. For this reason, drying was insufficient, and ventilation drying was performed in a subsequent process. In the final step, drying was performed with hot air at 80 ° C. so that the moisture content of the crude tea was 5% or less.

(6) The quality of the produced crude tea was performed using a sensory examination method. As the inspection items, four skilled inspectors conducted four items of Aozawa, aroma, light blue, and taste. Since the shape is significantly different from the conventional method, it was removed from the examination. The “conventional method” test zone was standard, with 10 points for each item.

(7) The following table shows the results of the crude tea sensory examination between the conventional method, the fresh leaf DD method and this method.

(8) The shape is very different from conventional sencha and gyokuro, and in the “Namaha DD” and “This method” test sections, the mesophyll portion is rolled into thin, unshaped sections of about 1 to 2 cm in size. It has a shape similar to that of high-quality tea with thin mesophyll, but it is thinner and lighter than the crude tea of the high-quality tea, and the stem has a fiber shape that is rolled into a thin film.

(9) In the “Namaha DD” and “This method” test plots, Irozawa has a bright green color because both green tea leaves and green tea leaves are less discolored by heat and are rolled into a thin film. It had a bright dark green color similar to 碾 茶, and the evaluation was good.

(10) The fragrance was scored in the test section of “Namaha DD”, because the green odor derived from the navy leaves was felt strongly and the taste was poor. In the test zone of "this method", the blue odor is diffused by steaming heat, so the blue odor is small and improved, and there is no fragrant fire incense generated in the refinement process of the "conventional method" test zone, Although it feels a little fragrant, this is not a problem because it is raised in the subsequent dry drying process.

(11) For the light blue color, the green leaves DD and the present method test plots have a higher green and darker score than the “conventional method” test plots, indicating a high extraction efficiency.

(12) As for the taste, the green odor derived from fresh leaves was strongly felt in the test section of “Namayo DD”, and the bitterness and astringency were also felt. In the test zone of "this method", the blue odor is dissipated by steaming, so the blue odor is reduced and improved, and there is a rich taste, the score is the same as the test zone of "conventional method" The effect of the present invention was recognized.

(13) In this way, when the fresh leaves are directly dried with a drum dryer, the blue odor and blue odor are strong and the palatability is poor. However, in this method, the fresh leaves are first steamed to disperse the blue odor. The taste and blue odor were significantly reduced.

(14) This method simplifies conventional methods for producing crude tea such as sencha and gyokuro, and enables process-saving production. The rough tea production method by this method is mainly completed in three steps: steamer, double dryer, and dryer, and the roughing machine (leaf cutter, roughing machine) and dredging machine used in the conventional green tea rough tea manufacturing method. , 5 processes of the intermediate machine and the precision machine could be omitted.

(15) According to this method, the shape is similar to that of premium tea with thin mesophyll, and green tea with the quality of conventional tea can be produced without using a conventional tea machine.

Example 2: Extraction test (1) In order to confirm the effect of improving the extraction efficiency, an extraction experiment was performed using the crude tea prepared in Example 1 while changing the extraction temperature, and the concentration was measured using a densitometer. The extraction temperature was classified into three categories of 100 ° C., 40 ° C., and 7 ° C.

(2) Crude tea from each test section was classified into No. 7 sieve, and No. 7 was cut on the sieve, and this was repeated twice to make the size uniform. For hot water and 40 ° C extraction, 2 g of tea was placed in a 200 ml test tea bowl, 200 ml of hot water was poured, allowed to stand for 5 minutes, filtered through filter paper, and measured using a densitometer (Atago RX7α-Tea). The 7 ° C. extraction was performed for 60 minutes.

(3) The following table shows a comparison of the extraction rate (contrast%) between the conventional method, the fresh leaf DD method and this method.

(4) The extraction rate improvement effect by this method was improved over the conventional method regardless of sencha, coated tea and extraction temperature. In particular, in the extraction at 40 ° C. for 5 minutes, the elution of tea leaf components was worse in the conventional method, but in this method, the extraction rate was improved by 158% for fresh green tea leaves and 179% for fresh green tea leaves.

(5) From the above, the green tea made by this method has higher extraction efficiency than green tea made by the conventional method, can be extracted in a short time, has high cold water solubility, and drink tea and tea bag ingredients. The problem of improving the extraction efficiency as tea and cold tea was solved.

Example 3: Electrostatic foliage separation test (1) About the tea leaf selection method of tea leaves manufactured by this method, it was confirmed that an electrostatic foliage separator works effectively as a foliage separation method.

  This method Kabusecha made in test section 6 of Example 1 was dried by ventilation, and immediately after that, it was passed through a Nakamura-type small total finishing machine (Nakamura Wagoen) and sieved with No. 7 sieve. Cut and repeated to align the shape and size. At that time, the electrostatic stem separator attached to the Aircraft was operated, and the mesophyll part and the stem / leaf vein were electrostatically separated. It is strongly adsorbed and falls to the product storage part, and the mesophyll part is also thin, but it is hard to be adsorbed by static electricity, and it falls to the wind sorting part and can easily separate the foliage with high accuracy using static electricity. It was.

  The same method was used for the topped tea produced in the test section 4 of Example 1 by the conventional method, but because the topped stem is thick and heavy, it is not easily affected by static electricity. It was necessary to remove stems that could not be removed by using a color sorter as the second step.

These results are shown in the following table as the effectiveness of the electrostatic foliage separation method between the conventional method and the present method.

  This foliage separation method is preferably performed immediately after drying, and electrostatic separation becomes difficult when wet. Therefore, it is preferable to perform the foliage separation continuously after the crude tea is dried by the present method. When the foliage is packaged separately and stored refrigerated and frozen, the volume is reduced and the packaging storage cost is suppressed.

  When fine finishing is performed later, separation can be easily performed by performing electrostatic foliage separation after a drying step.

Example 4: Quality test (1) After the green tea made by fine selection (sieving, cutting, foliage separation) as described above was lightly infrared-fired and then ground with a stone mill, the specific gravity was too light. Therefore, there is a problem in securing the fluidity in the tea cup receiver at the top of the stone mill, but it can be improved by devising such as reducing the particle size of green tea or changing the shape of the stirring bar to an uneven shape that easily causes friction. It was possible enough to grind.

(2) In order to confirm the quality of the powdered tea by this method, the quality was compared with a commercially available matcha tea corresponding to the market price. (Judging will be done by multiple expert judges)
The following table shows the quality comparison results between commercially available matcha and this method powdered tea.

  From this result, the color is slightly fresh green compared to commercial matcha, the light blue is slightly fresh green, the fragrance is slightly scented with a scent of fire, and the taste is slightly umami and slightly covered. It was evaluated that the quality was better than that.

  Covered directly on raw tea leaves, 75% shading degree Covered tea leaves with a covering period of 13 days are used as raw materials, so they were evaluated as green tea quality equivalent to or higher than the original leaves.

Example 5: Confirmation test of the effect of the present method (1) Using summer tea shoots in an outdoor harvested on September 3, 2009, Conventional method (boiled tea), 2. 2. Conventional method (boiled tea); Raw leaf DD, 4. Manufactured with this method, the advantages of this method were demonstrated.

(2) The test area was set as follows. The fresh leaves tested were 2 kg each.

  This setting clarified the quality difference between the conventional method for making tea and the method for producing only fresh leaf DD that was lacking in the above examples.

(3) The steam used in 1, 2, and 4 districts was steamed for 30 seconds using a 2kg band-type steamer.

(4) The 1st district was manufactured by a standard tea method using a 2kg machine.

(5) The 2nd tea ceremony machine uses a three-stage gas-fired furnace, and the steamed leaves that have passed through the three tea ceremony machines are sown on the lowermost net conveyor in a furnace at 150 ° C in 4 minutes. Passing, blown to the uppermost net conveyor, passed at 100 ° C. for 4 minutes, transferred to the middle net conveyor, and taken out at 100 ° C. for 10 minutes to finish rough drying.

(6) The Johnson drum JM-D1 made by Johnson Boiler was used as the double drum dryer in the 3rd and 4th districts, and the settings were as follows.

(7) The drying of 1, 2 and 4 sections was carried out by setting the ventilation temperature to 60 ° C. with a gas ventilation dryer until the moisture content was 5% or less.

(8) The sensory examination results of the crude tea produced by the above method are shown in the following table.

(9) The rough tea in test areas 1, 2, and 4 is passed through a Nakamura-type compact general finishing machine (Nakamura Wagoen) and sieved with No. 7, and the sieve is cut with No. 7 and the shape is repeated. And the same size.

  At that time, the test sections 1 and 4 operated the electrostatic foliage separator attached to the same machine, and the mesophyll part and the stem / leaf vein were separated by the electrostatic machine.

  Test Zone 2 performed wind sorting using the wind sorting machine attached to the Aircraft.

  In test group 1, since the stem portion was not completely removed by electrostatic separation, the stem portion was further removed using a color sorter.

The weight ratio (%) of the above foliage separation and the number of selections are shown in the following table. Although the raw leaf DD in Section 3 was cut through No. 7 and No. 7, it was not targeted because it did not separate the foliage.

  According to this, in the conventional method (boiled tea), the ratio of stems that can be obtained by one electrostatic foliage separation is as low as 3.5%, and the color selection that can be finally selected three times is 16.9% and the specific gravity is high. In contrast, this method can achieve 24.1% separation with only one electrostatic foliage separation, and not only the stems but also the veins can be separated. .

(10) Using the mesophyll parts that were carefully selected in the test sections 1, 2, and 4, infrared firing was performed for about 30 seconds, and the sections 2, 3, and 4 were crushed with a stone mortar. Tables 10 and 11 show the sensory examination results of the tea and powdered tea.

  The shape of the present method is greatly different from that of the conventional method of tea. The taste of the conventional method of tea is made into a soft and thin film.

  The color and light blue of this method are inferior to fresh green compared to fresh leaf DD, but they are more bluish and dark green than traditional methods of umami tea and strawberry tea, and enhance palatability.

  The fragrance of this method is equivalent to the traditional method of umami tea, and the fragrance of sweet and savory bud tea is insufficient, but the green odor is reduced to fresh leaf DD, and there is no stem odor or stuffy odor that occurs during heating, and it is palatable Remarkably improved.

  The taste of this method is richer than the traditional method of umami tea and strawberry tea, and shows a good extraction efficiency, and it reduces the strong blue odor of fresh leaves DD and is remarkable without stalk and stuffiness Improved palatability.

(11)

  The powdered tea of this method is superior to the traditional method of green tea, and is rated as green tea with aroma and aroma that does not have a raw odor, and it is light blue and red water is improved to blue water. There was little miscellaneous taste.

  In the raw leaf DD, the color of the blue sky was very green and very good evaluation, but it had a scent of hay, smell of hay, odor of hay, blue odor, stem odor, mellow odor, odor of stalk, and light taste.

  The raw odor and flavor of strawberry tea are more likely to be produced when grinding tea with thicker mesophyll, but with this method, it has a thin-film shape, which makes it easier to apply heat ray irradiation and reduce the blue odor. Occasionally, the raw odor and flavor generated from the inside of the mesophyll are considered to be small.

  In addition, the fresh leaf DD does not lose the intense blue odor or blue odor held by the fresh leaf when it is heated for a short time with a double drum dryer. The hay-like quality is not preferred, and quality degradation is unavoidable when treated with a double drum dryer alone.

(12) Next, the extraction efficiency of each section was measured by the method shown in Example 2, and the results are shown in the following table.

  According to this method, extraction at 100 ° C for 5 minutes showed a high extraction efficiency of 145% compared to the conventional method, and extraction at 40 ° C for 5 minutes improved the extraction efficiency by 167%.

  There was almost no difference from fresh leaf DD.

  The method in which tea leaves are rolled and squeezed with a double drum dryer and the tea leaves and the tea leaf pressing liquid are rapidly dried to produce a drastic improvement in the extraction rate compared to conventional brewed tea.

Example 6: Drum surface temperature of double drum dryer treatment (DD treatment) (1) As shown in the table below, the drum surface temperature of double drum dryer treatment (DD treatment) was changed and the same method as in Example 1 was used. Produced crude tea. As raw tea leaves, fresh green tea leaves from the first tea season were used, and 500 g was used for each test section.

(2) The steaming of fresh leaves was performed for 30 seconds using a 2 kg band-type steamer. As a double drum dryer, a John Boiler John Milder JM-T type was used. Drying after the double drum dryer treatment was carried out for 30 minutes by setting the ventilation temperature to 80 ° C. with an electric ventilation dryer.

(3) The following table shows the results of sensory examination of crude tea produced according to the above method.

(4) The test section 4 with a drum surface temperature of 125 ° C. was used as a standard, with 10 items for each item. In Test Zones 1, 2, and 3 where the drum surface temperature was lower than 125 ° C., the color was particularly bright green and the taste increased freshness, giving good evaluation. In the test sections 1 and 2 where the drum surface temperature was 110 ° C. and 115 ° C., a lump-like shape was observed, a slight odor was generated in the aroma, and a slight blue odor was generated in the taste. About the point that the shape of the lump shape is recognized, due to the drum surface temperature being low, undried tea leaves within the passage time will not lump into a thin film piece when scraped with a scraper, This could be solved by slowing the drum rotation speed and increasing the drying time on the drum surface. In addition, it was possible to eliminate the slight odor of flavor and the slight blue odor of taste by going through a subsequent firing process for finishing tea.

(5) In the test sections 5 and 6 where the drum surface temperature is higher than 125 ° C., the shape is a thin film, but there is no problem, but compared to the standard test section 4, the color is slightly reddish and the light blue is slightly red water The aroma was slightly scented and the taste was slightly scented. These points were not resolved even after the subsequent firing process.

(6) In this way, the drum surface temperature was 125 ° C as a standard, and at lower temperatures (especially 110 ° C and 115 ° C), the production efficiency tended to decrease, but the quality could be maintained. . On the other hand, at temperatures of 130 ° C. or higher (particularly 135 ° C.), there was a tendency for slight deterioration in quality. From these experimental results, it is understood that the drum surface temperature is preferably 100 ° C. or higher and lower than 130 ° C.

Example 7: Test for confirming the effect of external heat ray irradiation (1) Using a heat ray irradiator 3 as shown in FIG. 2, sufficient drying of tea leaves is possible even at a low drum surface temperature, heating It was confirmed that the fragrance caused by the scent could be prevented and that a fragrance was generated by heat ray irradiation.

(2) In this example, crude tea was produced in the same manner as in Example 1. As raw material tea leaves, fresh green tea leaves from the first tea season were used, and 500 g was used for each test section.

(3) The steaming of the fresh leaves was performed for 30 seconds using a 2 kg machine band-type steamer. As a double drum dryer, a John Boiler John Milder JM-T type was used. Drying after the double drum dryer treatment was carried out for 30 minutes by setting the ventilation temperature to 80 ° C. with an electric ventilation dryer.

(4) A heat ray irradiator was installed using an Iwatani Sangyo Electric Heater (IEH-081) at 800 W, separated by about 20 cm below the double drum dryer.

(5) The drum surface temperature was 110 ° C., and a test section 1 where no heat ray irradiation was performed was provided for comparison.

(6) The following table shows the weight immediately after the double drum dryer treatment (weight immediately after the drum) and the moisture content, and the sensory examination results of the crude tea produced according to the above method.

(7) Those not irradiated with heat rays (test section 1) were standard, and 10 items were set for each item. In the case of the heat ray irradiation (test group 2), the weight immediately after the drum and the water content decreased and the drying was promoted by the external heat ray irradiation as compared with the case of no heat ray irradiation (test group 1).

(8) In sensory examination, the effect of reducing raw odor, generating aroma and reducing blue odor was obtained by external heat ray irradiation, and the quality of crude tea was improved.

(9) In this way, by applying heat ray irradiation, the drying of tea leaves can be promoted even at a low drum surface temperature, the raw odor and the blue odor can be reduced, the unique fragrance can be generated, and the quality can be improved. did it.

DESCRIPTION OF SYMBOLS 1 ... Roller 2 ... Scraper 3 ... Heat ray irradiator 4 ... Reflector

Claims (6)

A process of heat-treating tea leaves to inactivate tea leaf enzymes;
Passing the tea leaves after the step while rolling and pressing between a pair of heated rollers rotating inward in opposite directions; and
And a step of drying the tea leaves after the step.   The method for producing green tea according to claim 1, wherein the tea leaves after the drying step are sieved and cut to a size according to the use, and then thinned to become easily charged with static electricity. The method further comprises a selective finishing step of separating the tea from the stem and leaf veins by separating the tea with an electrostatic stem and leaf separator.   It is a manufacturing method of the green tea of Claim 1, Comprising: In the process which passes a tea leaf between a pair of rollers, the input amount of a tea leaf, the gap | interval of a roller, the surface temperature of a roller, and the rotation speed of a roller pass a roller. The method is characterized in that changes in the green color of the subsequent tea leaves are suppressed, and the tea leaves after passing through the roller are adjusted so as to be thin slices.   The method for producing green tea according to claim 1, wherein the roller has a surface temperature of 100 ° C or higher and lower than 130 ° C.   The method for producing green tea according to claim 1, further comprising irradiating the tea leaves on the roller surface with heat rays after passing the tea leaves between the rollers.   Green tea produced by the method according to any one of claims 1 to 5.

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