Tea leaf steaming treatment apparatus and its steaming treatment method

Abstract

To provide a steaming apparatus of tea leaves capable of, readily and with precision, rendering tea leaves in a steaming chamber to a desired tea temperature, can suppress loss of a flavor component of a low boiling temperature and can deactivate a sufficient oxidizing enzyme.SOLUTION: A steaming apparatus 1 comprises: a loading unit 2 having a steam chamber S1 into which raw tea leaves are loaded and steam for heat-treating the raw tea leaves is supplied; a rotary drum 3 made of a rotatable cylindrical wire mesh member, and can transfer the tea leaves heat-treated in the steam chamber S1 while housing; and stirring means 4 capable of stirring the tea leaves in the rotary drum 3, air generating means 5 capable of generating air at a predetermined temperature, blowing means 6 capable of blowing air of a predetermined temperature generated by the air generating means 5 to mix it with the steam; and control means 7 for controlling a blow amount by the blowing means 6, based on a mixing ratio of vapor capable of making the tea leaves in the steaming chamber S1 to a desired tea leaf surface temperature and an air of a predetermined temperature.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a tea steaming and heat treatment apparatus capable of supplying steam to heat-treat fresh tea leaves and a method for steaming and heat-treating the same.

Background Art

[0002] Green tea is manufactured through various processing steps such as a steaming step, a rough rolling step, a rolling step, a medium rolling step, and a finishing step. Among these, the steaming step is a step of obtaining steamed leaves by steaming fresh tea leaves with the latent heat of vaporization of the steam supplied to a steam chamber capable of supplying steam generated by a boiler, as disclosed in, for example, Patent Document 1. Such a steaming step rapidly loses the activity of oxidase in fresh tea leaves, eliminates the green odor, develops the unique fragrance of green tea, softens the tea leaves, and has a function of creating a base that allows the subsequent rough rolling step to be smoothly processed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above prior art, since fresh tea leaves are steamed exclusively with steam at 100°C, there is a risk that aroma components such as low-boiling-point green leaf alcohols and terpene alcohols are lost and the quality deteriorates. On the other hand, when steaming fresh tea leaves using steam at 80°C or lower, the inactivation of the oxidase in the tea leaves may be insufficient. Therefore, it is necessary to control the steam temperature at a temperature of 80°C or higher at which the aroma components are not lost, but such delicate control of the steam temperature is considered extremely difficult.

[0005] However, the applicant of the present application noticed that the fresh tea leaves introduced into the steam chamber contain a large amount of moisture and the surface temperature of the tea leaves in the steam chamber (hereinafter referred to as the tea leaf temperature) can be approximated by the wet-bulb temperature. By mixing air with the supplied steam at a predetermined mixing ratio, it was found that the tea leaf temperature based on the wet-bulb temperature can be accurately estimated. That is, by keeping the temperature of the supplied steam constant and controlling the amount of air (dry air amount) mixed into the steam, it is possible to adjust the temperature to a desired tea leaf temperature (a temperature that does not cause loss of flavor components and enables sufficient inactivation of oxidase). The wet-bulb temperature is, for example, the temperature obtained by a wet-bulb thermometer with the measuring part wrapped in wet gauze. Such a wet-bulb temperature is lower than the dry-bulb temperature because water evaporates from the gauze at the measuring part and heat is taken away.

[0006] The present invention has been made in view of such circumstances, and provides a tea leaf steam heat treatment apparatus and a steam heat treatment method thereof that can easily and accurately set the tea temperature of the tea leaves in the steam chamber to a desired temperature, and can suppress the disappearance of low-boiling flavor components and achieve sufficient inactivation of oxidase.

Means for Solving the Problems

[0007] The invention according to claim 1 has an input section having a steam chamber into which fresh tea leaves are introduced and steam for heat-treating the fresh tea leaves is supplied, a rotatable cylindrical wire mesh member, and a rotary drum capable of accommodating and conveying the tea leaves heat-treated in the steam chamber, and a stirring means capable of stirring the tea leaves in the rotary drum. In the tea leaf steam heat treatment apparatus, there are provided an air generating means capable of generating air at a predetermined temperature, a blowing means capable of blowing the air at the predetermined temperature generated by the air generating means and mixing it with the steam, and a control means for controlling the blowing amount by the blowing means based on the mixing ratio of the steam and the air at the predetermined temperature that can make the tea leaf temperature in the steam chamber Based on the wet-bulb temperature a desired tea leaf temperature.

[0008] The invention according to claim 2 is the apparatus for steam heat treatment of tea leaves according to claim 1, further comprising a boiler for generating the steam, and a steam pipe connecting the boiler and the input section for supplying the steam generated in the boiler to the steam chamber, and having an air pipe connecting the air blowing means and the steam pipe for introducing the air at the predetermined temperature blown by the air blowing means into the steam pipe to mix with the steam.

[0009] The invention according to claim 3 is the apparatus for steam heat treatment of tea leaves according to claim 1 or 2, wherein the air at the predetermined temperature generated by the air generating means is set to 100°C or higher.

[0010] The invention according to claim 4 is the apparatus for steam heat treatment of tea leaves according to any one of claims 1 to 3, wherein the air generating means has heating means for heating air to a predetermined temperature, and detection means for detecting the temperature and humidity of the heated air, and calculates the amount of dry air and the amount of water vapor contained in the air based on the temperature and humidity detected by the detection means, and determines the mixing ratio based on the calculated amount of dry air and the amount of water vapor contained in the air.

[0011] The invention according to claim 5 is the apparatus for steam heat treatment of tea leaves according to claim 4, wherein the mixing ratio is determined by adding the calculated amount of water vapor to the supply amount of the steam.

[0012] The invention according to claim 6 is the apparatus for steam heat treatment of tea leaves according to any one of claims 1 to 5, wherein the air blowing amount of the air at the predetermined temperature is determined according to the set target tea leaf temperature to control the air blowing means.

[0013] The invention according to claim 7 is the apparatus for steam heat treatment of tea leaves according to any one of claims 1 to 6, wherein the control means controls the air blowing amount of the air blowing means based on an approximate formula showing the relationship between the tea leaf temperature and the mixing ratio.

[0014] The invention according to claim 8 is the tea leaf steaming and heat treatment apparatus according to any one of claims 1 to 7, wherein the control means controls the temperature of the air by the air generating means.

[0015] The invention according to claim 9 is the tea leaf steaming and heat treatment apparatus according to any one of claims 1 to 8, wherein the desired tea leaf temperature is 80 to 100°C.

[0016] The invention according to claim 10 is a tea leaf steaming and heat treatment method using a tea leaf steaming and heat treatment apparatus having an input section having a steam chamber into which raw tea leaves are introduced and steam for heat-treating the raw tea leaves is supplied, a rotatable cylindrical wire mesh member, a rotating cylinder capable of accommodating and transporting the tea leaves heat-treated in the steam chamber, stirring means capable of stirring the tea leaves in the rotating cylinder, air generating means capable of generating air at a predetermined temperature, and blowing means capable of blowing the air at the predetermined temperature generated by the air generating means to mix it with the steam. The method includes Based on the wet-bulb temperature controlling the blowing amount by the blowing means based on the mixing ratio of the steam capable of achieving the desired tea leaf temperature and the air at the predetermined temperature.

Advantages of the Invention

[0017] According to the inventions of claims 1 and 10, since the blowing amount by the blowing means is controlled based on the mixing ratio of the steam capable of achieving the desired tea leaf temperature and the air at the predetermined temperature in the steam chamber, the tea leaves in the steam chamber can be easily and accurately set to the desired tea leaf temperature, suppressing the disappearance of low-boiling flavor components and achieving sufficient inactivation of oxidase. Further, by treating the desired tea leaf temperature at a lower temperature than in the prior art, less destruction of chlorophyll due to heat can be achieved, and thus improvement in the color of the tea leaves can also be achieved. Based on the wet-bulb temperature

[0018] According to the invention of claim 2, since the blowing means and the steam pipe are connected and an air pipe capable of introducing the air at the predetermined temperature blown by the blowing means into the steam pipe and mixing it with the steam is provided, the air at the predetermined temperature can be mixed into the steam before it is supplied to the steam chamber, and a more uniform steaming process in the steaming and heat treatment step can be performed.​

[0019] According to the invention of claim 3, since the air at a predetermined temperature generated by the air generating means is set to 100°C or higher, liquefaction of the steam can be avoided, and generation of steamed dew or the like in the steaming process can be suppressed.

[0020] According to the invention of claim 4, the air generating means has heating means for heating the air to a predetermined temperature, and is provided with detecting means capable of detecting the temperature and humidity of the heated air. Based on the temperature and humidity detected by the detecting means, the dry air amount and the amount of water vapor contained in the air are calculated, and the mixing ratio is obtained based on the calculated dry air amount and the amount of water vapor contained. Therefore, the tea leaf temperature can be accurately adjusted in consideration of the moisture state of the air mixed with the steam.

[0021] According to the invention of claim 5, since the mixing ratio is obtained by adding the calculated amount of water vapor to the supply amount of the steam, the tea leaf temperature can be adjusted more accurately.

[0022] According to the invention of claim 6, the target tea leaf temperature is set as the steaming time elapses, and the blowing amount of the air at a predetermined temperature is obtained according to the target tea leaf temperature to control the blowing means. Therefore, the desired tea leaf temperature can be smoothly obtained, and variations in the finish of the steaming process can be reduced.

[0023] According to the invention of claim 7, since the control means controls the blowing amount of the blowing means based on an approximate formula showing the relationship between the tea leaf temperature and the mixing ratio, the blowing amount by the blowing means can be quickly obtained and controlled by calculation using the approximate formula.

[0024] According to the invention of claim 8, since the control means controls the temperature of the air by the air generating means, the steaming temperature in the steaming process can be arbitrarily adjusted.

[0025] According to the invention of claim 9, since the desired tea leaf temperature is set to 80 to 100°C, in addition to suppressing the disappearance of low-boiling flavor components, the destruction of chlorophyll by heat is small, so the color of the tea leaves can be improved.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0027] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The tea leaf steam heat treatment apparatus 1 according to the present embodiment applies steam to raw tea leaves and performs a steam heat treatment process using the latent heat of vaporization. As shown in FIGS. 1 to 3, it includes a charging section 2, a rotating cylinder 3, a stirring means 4, a boiler B, an air generating means 5, a blowing means 6, a control means 7, and a detecting means 8.

[0028] The charging section 2 has a steam chamber S1 into which raw tea leaves are charged and steam for heat-treating the raw tea leaves is supplied. An inlet 2a through which raw tea leaves can be charged is formed at a predetermined position. Such a charging section 2 is fixed to a frame F fixed to the floor surface and includes pipes Ha and Hb, and a mixed gas obtained by mixing steam and air at a predetermined temperature can be supplied to the internal steam chamber S1.

[0029] One end of the input section 2 is connected to a rotary drum 3. Such a rotary drum 3 is composed of a cylindrical wire mesh member rotatable with respect to the frame F and has an accommodation space S2 communicating with the steam chamber S1. Then, the tea leaves heat-treated in the steam chamber S1 reach the accommodation space S2 in the rotary drum 3, and the tea leaves can be conveyed toward the discharge port on the right side in FIG. 1 as the rotary drum 3 rotates.

[0030] Furthermore, as shown in FIGS. 2 and 3, a shaft member L extending in the longitudinal direction of the rotary drum 3 is attached to the steam chamber S1 of the input section 2 and the accommodation space S2 of the rotary drum 3. Such a shaft member L can be rotationally driven by a drive source (not shown) and has a plurality of stirring means 4 formed thereon. Then, as the plurality of stirring means 4 rotate with the rotation of the shaft member L, the tea leaves moving in the steam chamber S1 and the accommodation space S2 can be stirred and pressed.

[0031] Note that a ring gear Ga is formed on the outer peripheral surface of the rotary drum 3 according to the present embodiment over the circumferential direction, and a drive gear Gb is disposed in a state of meshing with the ring gear Ga. Such a drive gear Ga can be rotationally driven by a drive source (not shown), and its rotational force is transmitted to the rotary drum 3 via the ring gear Ga, and it can rotate about the central axis.

[0032] Moreover, in the present embodiment, it includes a boiler B for generating steam and a steam pipe D1 connecting the boiler B and the input section 2 and capable of supplying the steam generated in the boiler B to the steam chamber S1. The steam pipe D1 is connected to a pipe Ha, and the steam generated in the boiler B can be supplied to the steam chamber S1 in the input section 2 via the steam pipe D1, the pipe Ha, and a pipe Hb.

[0033] Here, the steam heat treatment apparatus 1 for tea leaves according to the present embodiment includes air generating means 5 capable of generating air at a predetermined temperature, blowing means 6 for blowing the air at the predetermined temperature generated by the air generating means 5 into the steam chamber S1, and control means 7 capable of controlling the blowing amount of the blowing means 6. Thereby, a mixed gas in which the steam generated by the boiler B and the air generated by the air generating means 5 are mixed at a predetermined ratio is produced, and the mixed gas can be supplied to the charging section 2.

[0034] The air generating means 5 is capable of generating air at a predetermined temperature, and is configured to have heating means 5a for heating the air to the predetermined temperature. Since the amount of air used in the examples is about 5 m 3 / min, an electric heater is used as the heating means 5a. However, it is not limited thereto, and a so-called gas burner or other heating means may be used.

[0035] Furthermore, in the present embodiment, the air at the predetermined temperature generated by the air generating means 5 is set so as to be adjustable to 100°C or higher, and is configured to be higher than the temperature of the steam generated by the boiler B. In addition, the air generating means 5 according to the present embodiment includes detection means 8 capable of detecting the temperature, humidity, and atmospheric pressure of the heated air, and is capable of calculating the dry air amount (volume) and the amount of water vapor contained in the air based on the temperature and humidity detected by the detection means 8.

[0036] The blowing means 6 is composed of a blower, a fan, etc. capable of blowing the air at the predetermined temperature generated by the air generating means 5 and mixing it with the steam. For example, the rotational speed of the fan can be controlled by the control means 7, and the blowing amount can be arbitrarily adjusted. Such blowing means 6 is connected to a predetermined portion of the steam pipe D1 via the air pipe D2. Thereby, the air at the predetermined temperature blown by the blowing means 6 can be introduced into the steam pipe D1 via the air pipe D2 and mixed with the steam. A check valve 9 is attached in the middle of the air pipe D2 to prevent the steam flowing through the steam pipe D1 from flowing into the air generating means 5.

[0037] The control means 7 consists of a control box or the like, and controls the air volume blown by the blowing means 6 based on the mixing ratio of steam (steam supplied from the boiler B) that can achieve a desired tea leaf temperature for the tea leaves in the steam chamber S1 and air at a predetermined temperature (air generated by the air generating means 5). That is, the raw tea leaves put into the steam chamber S1 have a high moisture content of about 80% (WB), and since the surface temperature of the tea leaves in the steam chamber S1 can be approximated by the wet-bulb temperature, by mixing the steam supplied from the boiler B with the air at a predetermined temperature generated by the air generating means 5 at a predetermined mixing ratio and applying it to the tea leaves, the tea leaf temperature equivalent to the wet-bulb temperature can be accurately estimated. The desired tea leaf temperature is a temperature that does not cause loss of the aforementioned flavor components and enables sufficient inactivation of oxidase, specifically 80°C or higher and 100°C or lower.

[0038] Here, the wet-bulb temperature corresponding to the tea leaf temperature generally refers to the temperature indicating the physical characteristics of a gas and steam (usually a system mixed with air and water vapor). As a simple correlation formula, assuming atmospheric pressure (P), dry-bulb temperature (t), wet-bulb temperature (t'), and water vapor pressure (e), the following formula is known to hold. e = E(t') - constant (0.0008)*P*(t - t') ····(1) (However, E(t') is the saturated water vapor pressure at that wet-bulb temperature)

[0039] Also, it is known that there are the following correlations among the water vapor mass in the air, the mass of the air, the water vapor pressure, and the mixing ratio. Here, the mixing ratio is one expression of the amount of water vapor contained in the atmosphere and is the ratio of the mass of water vapor to the mass of dry air in an air parcel containing moist air. When the pressure of the air is p and the water vapor pressure is e, the mixing ratio m is expressed by the following formula. m = constant (0.622)*e / (p - e) ····(2)

[0040] Regarding the calculation of the saturated water vapor pressure at the wet-bulb temperature of the above formula (1), for example, if Sonntag's formula (see the following formula (3) of Japanese Industrial Standard JIS Z 8806) is used, since this formula is a function of only the dry-bulb temperature, the above formula (1) can be expressed by a correlation formula of water vapor pressure (e), atmospheric pressure, dry-bulb temperature, and wet-bulb temperature.

[0041] Such Sonntag's formula (E (hPa)) is a calculation formula for obtaining the saturated water vapor partial pressure, and specifically consists of the following formula. However, let T = 273.15 + T3, where T3 is the dry-bulb temperature. E (hPa) = (exp (-6096.9385T-1 + 21.240942 - 2.711193 * 10-2T + 1.673852 * 10-5T2 + 2.433502In (T))) / 100 ····(3)

[0042] Also, in formula (2), since it is expressed by a correlation formula of mixing ratio, water vapor pressure (e), and atmospheric pressure, if the parameter of water vapor pressure (e) is eliminated from formulas (1) and (2), a correlation formula of mixing ratio, atmospheric pressure, dry-bulb temperature, and wet-bulb temperature can be obtained. Regarding atmospheric pressure and dry-bulb temperature, since they are obtained from the measured values of the mixed gas measured by the detection means 8, as a result, it can be said that the wet-bulb temperature is a function of the mixing ratio of the mixed gas (vapor and air) (see FIGS. 4 to 6).

[0043] Furthermore, if the amount and temperature of the steam supplied from the boiler B are controlled to be constant, the steam part of the above mixing ratio becomes a constant, and only the air part to be mixed becomes a variable. Therefore, as a result, the wet-bulb temperature corresponding to the tea leaf temperature becomes a function of only the amount of air to be mixed. Therefore, by controlling the amount of air to be mixed, which is the air flow rate by the air blowing means 6, by the control means 7, it is possible to adjust the wet-bulb temperature regarded as the tea leaf temperature.

[0044] Specifically, the air flow rate (air flow rate of dry air) by the control means 7 is set in terms of volume per minute (m 3 / min). And the volume per minute (m 3The mass per minute (kg / min) is obtained from the ( ) / min, and the amount of steam (kg / min) from the boiler B is grasped, whereby the mixing ratio (mass of dry air (kg) / mass of water vapor (kg), or mass of water vapor (kg) / mass of dry air (kg)) can be calculated.

[0045] Furthermore, the amount of dry air and the amount of water vapor contained in the air are calculated based on the temperature and humidity detected by the detection means 8, and the mixing ratio may be obtained based on the calculated amount of dry air and the amount of water vapor contained. Specifically, the calculated amount of water vapor may be added to the supply amount of steam to obtain the mixing ratio. That is, since the volume of air varies depending on the temperature, and by obtaining the volume of dry air and the amount of water vapor contained from the temperature and humidity state of the air in advance and reflecting it in the control, more accurate adjustment of the tea leaf temperature can be achieved.

[0046] Figures 4 and 5 are graphs showing the relationship between the wet-bulb temperature and the mixing ratio of the mixed gas described above. The horizontal axis shows the ratio (mixing ratio) of the amount of steam from the boiler to the amount of air to be mixed, and the vertical axis shows the wet-bulb temperature corresponding to the tea leaf temperature. By setting the horizontal axis as the mixing ratio and the vertical axis as the tea leaf temperature, the relationship between the amount of air to be mixed with the steam, which is the control parameter, and the tea leaf temperature (wet-bulb temperature) is clear at a glance. As shown in Figure 6 for the horizontal axis, a similar relational expression can be obtained using the mixing ratio of water vapor mass (kg) / dry air mass (kg). As a specific method for plotting these graphs, the wet-bulb temperature (tea leaf temperature) with respect to the mixing ratio of air and steam (air (kg) / steam (kg)) was plotted at regular intervals, and the correlation line of the plotted points was created and obtained as the approximate expressions of graphs α and β. When the tea leaf temperature is y and the mixing ratio is x, graphs α and β can be approximated by the following cubic equation as the approximate expression. Graph α y = -0.6379x3 + 4.2651x2 - 16.003x + 99.312 Graph β y = -0.6429x3 + 4.2584x2 - 15.586x + 100.2

[0047] In this embodiment, the air volume of the air blowing means 6 is controlled using the approximate expressions of graph α and graph β. By using such an approximate expression as a control value, there is an advantage that the calculation of the air volume becomes rapid.

[0048] Furthermore, FIGS. 4 and 5 show that the temperatures of the mixed gas of steam and air at a predetermined temperature (100° C. in FIG. 4 and 150° C. in FIG. 5) are different. For example, when the desired tea leaf temperature is 90° C., the mixing ratio obtained from graph α in FIG. 4 is 0.77, whereas the mixing ratio obtained from graph β in FIG. 5 is 0.81. Further, although not shown in the drawings, when the temperature of the mixed gas is set to 200° C. and the drawing is made in the same manner, the mixing ratio obtained from the graph is 0.94. This indicates that by increasing the temperature of the mixed gas, the amount of air in the mixed gas also increases, which means that the drying ability of the tea leaves in the drying chamber S1 of the steam dryer increases.

[0049] For example, in the case of tea leaves with a high moisture content such as rain tea leaves, it is convenient that the drying ability is high because the steamed dew can be effectively removed. Therefore, as the control device 7, it is also possible to have a plurality of air volume control maps (graph α, graph β, etc.) of the air blowing means 6 with different temperatures of the mixed gas shown in FIGS. 4 and 5, and appropriately select and use the control map according to the variety and state of the tea leaves. As an example of the control maps with different temperatures, it is sufficient to have them every 50° C. in the temperature range of about 100° C. to 300° C.

[0050] Furthermore, the control means 7 is configured to obtain the air volume of the air at a predetermined temperature according to the target tea leaf temperature and control the air blowing means 6. As a set value, by setting it to 80° C. to 100° C. (preferably, the lower 80° C. to 90° C.), which is a temperature lower than the conventional 100° C., the destruction of chlorophyll by heat is less compared to the conventional case, and the color tone of the tea leaves can be improved.

[0051] Such setting of the target tea leaf temperature may be set as the optimum value by default, but it is also possible to give a command to the control means 7 by the user instructing the desired temperature on an operation panel (not shown) or the like. Also, on this operation panel, the user may be able to select and instruct the temperature of the aforementioned mixed gas. By allowing the user to freely set the target tea leaf temperature and the temperature of the mixed gas, it becomes possible to perform the steaming heat treatment desired by the user that is suitable for the tea variety and the state of the tea leaves. At that time, regarding the temperature of the mixed gas, it is advisable to link it to the tea variety or the state of the tea leaves and allow the user to select the tea variety or the state of the tea leaves as a selection item.

[0052] According to the steaming heat treatment apparatus or method according to this embodiment, since the air volume blown by the blowing means 6 is controlled based on the mixing ratio of the steam that can achieve the desired tea leaf temperature and the air at a predetermined temperature in the steam chamber S1, the tea leaves in the steam chamber S1 can be easily and accurately set to the desired tea leaf temperature, and it is possible to suppress the disappearance of low-boiling flavor components and achieve sufficient inactivation of oxidase. Also, by treating the desired tea leaf temperature at a lower temperature than before, the destruction of chlorophyll by heat is reduced, so that the color and luster of the tea leaves can also be improved.

[0053] Further, according to this embodiment, since the blowing means 6 and the steam pipe D1 are connected and the air pipe D2 for introducing the air at a predetermined temperature blown by the blowing means 6 into the steam pipe D1 and mixing it with the steam is provided, it is possible to mix the air at a predetermined temperature into the steam before it is supplied to the steam chamber S1, and a more uniform steaming process in the steaming heat treatment process can be performed.

[0054] Furthermore, since the air at a predetermined temperature generated by the air generating means 5 is set to 100°C or higher, it is possible to avoid the liquefaction of the steam and suppress the occurrence of steamed dew or the like in the steaming heat treatment process. In particular, by setting the temperature of the air generated by the air generating means 5 higher, it is possible to cause the evaporation of the tea leaf moisture, and the efficiency and quality of the tea manufacturing operation can be improved.

[0055] For example, when the mixing ratio of the mixed gas of steam and air is 1:1 at 100°C, the tea leaf temperature is about 87°C. However, when the air is heated to 300°C, the temperature of the mixed gas becomes about 170°C, and the tea leaf temperature becomes about 89°C. As a result, the amount of water vapor that can be contained in the air increases, and transpiration occurs from the tea leaves. Also, when the mixing ratio of the air is increased to about 1.2 times, the tea leaf temperature is maintained at about 87°C, and the drying ability increases. Thus, in the case of tea leaves with a high moisture content (high moisture content varieties, first flush tea leaves, rain tea leaves, etc.), the steamed dew can be removed, so that the efficiency and quality of the tea manufacturing process can be improved.

[0056] Furthermore, the air generating means 5 according to the present embodiment has a heating means 5a for heating air to a predetermined temperature, and includes a detecting means 8 capable of detecting the temperature and humidity of the heated air. Based on the temperature and humidity detected by the detecting means 8, the amount of dry air and the amount of water vapor contained in the air are calculated, and the mixing ratio is obtained based on the calculated amount of dry air and the amount of water vapor contained. Therefore, the tea leaf temperature can be adjusted accurately in consideration of the wet state of the air mixed with the steam. In particular, according to the present embodiment, since the mixing ratio is obtained by adding the calculated amount of water vapor to the supply amount of the steam, the tea leaf temperature can be adjusted more accurately.

[0057] In addition, the target tea leaf temperature is set as the steaming time elapses, and the blowing amount of air at a predetermined temperature is obtained according to the target tea leaf temperature to control the blowing means 6. Therefore, the desired tea leaf temperature can be smoothly achieved, and the variation in the finish of the steaming process can be reduced. Further, since the control means 7 according to the present embodiment controls the blowing amount of the blowing means 6 based on an approximate formula showing the relationship between the tea leaf temperature and the mixing ratio, the blowing amount by the blowing means 6 can be quickly obtained and controlled by the calculation using the approximate formula.

[0058] As described above, the present embodiment has been explained. However, the present invention is not limited to this. For example, in addition to controlling the air volume by the blowing means 6, the control means 7 may control the temperature of the air by the air generating means 5. In this way, if the control means 7 controls the temperature of the air by the air generating means 5, the steaming temperature in the steaming process can be arbitrarily adjusted. Further, in the present embodiment, the air pipe D2 is connected to a predetermined portion of the steam pipe D1, and after mixing the steam and the air at a predetermined temperature, the mixed gas is supplied to the steam chamber S1. However, each of the steam pipe D1 and the air pipe D2 may be connected to the steam chamber S1, and the steam and the air at a predetermined temperature may be mixed in the steam chamber S1.

[0059] In addition, the present invention can be applied not only to tea leaves but also to the removal of the astringency of blanching and the prevention of leaf deterioration of soft vegetables such as daikon leaves and high-moisture raw materials such as young barley leaves as long as they are subjected to steaming heat treatment as a blanching process. In this case, since the object regarded as the wet-bulb temperature is not the tea leaf temperature of the above-described embodiment but the surface temperature of the leaves of soft vegetables and young barley leaves, etc., it is necessary to adjust the processing conditions of the steaming heat treatment according to the characteristics of the green leaves. For example, when applying to daikon leaves, since the shape of the petiole and leaf vein parts of daikon leaves is significantly larger in volume and in a lump shape compared to tea leaves, it is necessary to adjust the heating time in consideration of the heat conduction time to the inside. Even if the type of green leaves subjected to the steaming heat treatment is changed in this way, by changing the conditions of the steaming heat treatment so as to suit the characteristics of the green leaves, in addition to the effect on the aroma side such as removing the peculiar astringency of the green leaves, it is possible to obtain the effect of improving the color of the leaves such as preventing the destruction of chlorophyll in the leaves due to heat during the steaming heat treatment and preventing the deterioration of the leaves.

Industrial Applicability

[0060] The tea leaves in the steam chamber Based on the wet-bulb temperature A tea leaf steaming treatment apparatus and its steaming treatment method for controlling the air volume by the blowing means based on the mixing ratio of the steam that can achieve the desired tea leaf temperature and the air at a predetermined temperature can be applied to those with different external shapes or those with other functions added.

Explanation of Symbols

[0061] 1 Steam heat treatment apparatus 2 Feed section 2a Feed inlet 3 Rotary drum 4 Stirring means 5 Air generating means 6 Blowing means 7 Control means 8 Detection means 9 Check valve L Shaft member S1 Steam chamber S2 Accommodation space F Frame B Boiler D1 Steam pipe D2 Air pipe

Claims

1. An input section having a steam chamber into which fresh tea leaves are introduced and steam for heat-treating the fresh tea leaves is supplied; A rotatable cylindrical wire mesh member, and a rotating cylinder capable of accommodating and conveying the tea leaves heat-treated in the steam chamber; Stirring means capable of stirring the tea leaves in the rotating cylinder; In a tea leaf steam heat treatment apparatus having the above, Air generation means capable of generating air at a predetermined temperature; Blowing means for blowing the air at a predetermined temperature generated by the air generation means and mixing it with the steam; Control means for controlling the blowing amount by the blowing means based on the mixing ratio of the steam and the air at a predetermined temperature, which can make the tea leaves in the steam chamber reach a desired tea leaf temperature equivalent to the wet-bulb temperature; A tea leaf steam heat treatment apparatus characterized by comprising the above.

2. The tea leaf steam heat treatment apparatus according to claim 1, further comprising a boiler for generating the steam, and a steam pipe connecting the boiler and the input section and capable of supplying the steam generated by the boiler to the steam chamber, and an air pipe connecting the blowing means and the steam pipe and capable of introducing the air at a predetermined temperature blown by the blowing means into the steam pipe and mixing it with the steam.

3. The tea leaf steam heat treatment apparatus according to claim 1 or claim 2, wherein the air at a predetermined temperature generated by the air generation means is set to 100°C or higher.

4. The air generation means has heating means for heating air to a predetermined temperature, and detection means capable of detecting the temperature and humidity of the heated air, calculates the dry air amount and the amount of water vapor contained in the air based on the temperature and humidity detected by the detection means, and the mixing ratio is obtained based on the calculated dry air amount and the amount of water vapor contained therein. The tea leaf steam heat treatment apparatus according to any one of claims 1 to 3.

5. The tea leaf steam heat treatment apparatus according to claim 4, wherein the mixing ratio is obtained by adding the calculated amount of water vapor to the supply amount of the steam.

6. The tea leaf steam heat treatment apparatus according to any one of claims 1 to 5, characterized in that the blowing amount of the air at a predetermined temperature is obtained according to the set target tea leaf temperature and the blowing means is controlled.

7. The tea leaf steam heat treatment apparatus according to any one of claims 1 to 6, wherein the control means controls the blowing amount of the blowing means based on an approximate formula showing the relationship between the tea leaf temperature and the mixing ratio.

8. The tea leaf steam heat treatment apparatus according to any one of claims 1 to 7, wherein the control means controls the temperature of the air by the air generating means.

9. The tea leaf steam heat treatment apparatus according to any one of claims 1 to 8, wherein the desired tea leaf temperature is set to 80 to 100 °C.

10. An input section having a steam chamber into which raw tea leaves are introduced and steam for heat-treating the raw tea leaves is supplied, A rotating cylinder composed of a rotatable cylindrical wire mesh member, which can accommodate and convey the tea leaves heat-treated in the steam chamber, Stirring means capable of stirring the tea leaves in the rotating cylinder, Air generating means capable of generating air at a predetermined temperature, Blowing means capable of blowing the air at a predetermined temperature generated by the air generating means and mixing it with the steam, A steam heat treatment method using a tea leaf steam heat treatment apparatus having: A steam heat treatment method using a tea leaf steam heat treatment apparatus, characterized in that the air volume blown by the blowing means is controlled based on the mixing ratio of the steam and the air at a predetermined temperature, which can set the tea leaves in the steam chamber to a desired tea leaf temperature equivalent to the wet bulb temperature.

Images