JP5690719B2 - Moisture content reduction method and moisture content reduction device for leafy vegetables - Google Patents

Description

  The present invention relates to a method for reducing the moisture content of leafy vegetables that can instantaneously reduce leaf vegetables such as fresh tea leaves to a required moisture content, and a moisture content reducing apparatus for performing the method.

Green tea is produced by, for example, steaming the picked tea leaves, squeezing the steamed tea leaves while drying them, drying the tea leaves that have been squeezed to produce crude tea, and subjecting the crude tea to finishing processing such as burning. be able to. In addition, it is necessary to apply various types of squeezing, such as leaf punching, rough culling, spraining, intermediate culling, and fine scouring.
Thus, in order to manufacture green tea, since it passes through the above-mentioned various processes, it takes about 3 to 4 hours to make rough tea from the picked tea leaves.

  Therefore, in order to shorten the time for green tea production, an apparatus has been developed that can instantly dry the tea leaves by moving them while sandwiching them between the heated belt and drum, thereby reducing the production time. (See Patent Document 1 below).

  In addition, an apparatus has been developed in which tea leaves are heated between two rollers and dried instantaneously to form powdered tea (see Patent Documents 2 and 3 below).

JP-A-11-169076 Japanese Patent Publication No. 5-70410 JP-A-8-173038

However, in the production of green tea, not only evaporating the moisture of the tea leaves and drying, but also an important process for raising the flavor, the flavor is adjusted by performing various mashing Is.
Although the apparatus described in Patent Document 1 can produce green tea by instantly drying tea leaves, it produces green tea without squeezing, and thus cannot produce green tea with excellent flavor. .
Furthermore, since hard and thick parts such as tea stems are difficult to dry, the above apparatus causes unevenness in the drying of tea leaves and adversely affects flavor and color. It was.
In addition, the devices described in Patent Documents 2 and 3 are for producing powdered tea, and are instantly dried to a state where the water content is close to 0%, and thus produce green tea. Was not used for.

If the moisture content of tea leaves can be lowered to a moisture content suitable for instantly and evenly squeezing, green tea production time and green tea with excellent flavor can be produced.
Accordingly, an object of the present invention is to provide a method for reducing the moisture content of leafy vegetables such as fresh tea leaves, which can instantaneously achieve the required moisture content, and an apparatus for performing the method.

The method for reducing the moisture content of tea leaves according to the present invention comprises crushing at least a difficultly dried portion of the unraveled tea leaves with a pressing body of parallel rollers having a gap width of 0.1 mm to 0.4 mm, and heating the crushed tea leaves to a heating body Conductive heating in the range of 100 ° C. to 160 ° C. for 5 seconds to 30 seconds .

  The method for reducing the moisture content of leafy vegetables of the present invention crushes the difficult-to-dry parts of leafy vegetables to easily evaporate water, and conductively heats the leafy vegetables. it can.

It is the perspective view which showed an example of the apparatus for enforcing the moisture content fall method of this invention. It is the side view which showed typically the operation state of the apparatus of FIG. It is the perspective view which showed an example of the vibration conveyor which can be used for the moisture content fall method of this invention. It is a side view of the vibration conveyor of FIG.

  Hereinafter, an embodiment of the method for reducing the moisture content of leafy vegetables of the present invention will be described. However, the present invention is not limited to this embodiment.

  This water content reduction method is characterized by crushing at least a difficultly dried portion of the unraveled leaf vegetables with a pressing body, and conductively heating the crushed leaf vegetables with a heating body.

As leaf vegetables, vegetables such as perilla, spinach, baby leaf, moroheiya and kale can be used in addition to fresh tea leaves. Leafy vegetables may be steamed in advance.
The difficult-to-dry portion of leafy vegetables refers to a portion that is hard and thick and difficult to dry, such as a stem portion and a core portion.

  In this moisture content lowering method, first, the tangled leafy vegetables are unraveled. In order to unravel the leafy vegetables, manual work may be used, but it is preferable to use a vibrating conveyor. By using a vibration conveyor, leaf vegetables can be conveyed while being automatically unwound. At this time, it is preferable that the vibration of the vibration conveyor has an amplitude in the vertical direction of 5 mm to 20 mm, preferably 7 mm to 15 mm, and this vibration is given 450 to 700 times / minute.

  Next, at least the difficultly dried portion of the leaf vegetable is crushed with a pressing body to such an extent that the leaf vegetable is not shattered. Thereby, the part which a water | moisture content cannot evaporate easily is lost, and it can make it easy to reduce a moisture content. As the pressing body, for example, a parallel roll or two metal plates having a gap width of 0.1 mm to 0.4 mm, preferably 0.2 mm to 0.3 mm can be used.

Then, the leaf vegetables are brought into contact with the heating body and conductively heated. Thereby, a moisture content can be reduced instantaneously. This heating depends on the type of leaf vegetable, but the leaf vegetable is heated at 100 ° C. to 160 ° C., preferably 110 ° C. to 150 ° C., particularly preferably 120 ° C. to 140 ° C. for 5 seconds to 30 seconds, preferably 10 seconds. Heat for ~ 20 seconds. When leaf vegetables are made from fresh tea leaves, the water content is preferably 30 to 70%, particularly 40 to 60%. As a heating body, a heated roll, a heated metal plate, etc. can be used, for example.
In addition, the moisture content of leafy vegetables can be measured by the atmospheric pressure drying method.

  The water content reduction method can be performed using, for example, the water content reduction device 1 shown in FIG. 1. A method for lowering the moisture content of the liquid is described.

  As shown in FIG. 1 or 2, the moisture content lowering device 1 can crush the unraveled tea steamed leaves 2 with two rolls 3 and reduce the moisture content by conducting heating on the peripheral surface 31. Is.

The apparatus 1 has two rolls 3 arranged in parallel, and the roll 3 is formed to have a diameter of 300 mm to 1500 mm, preferably 1000 mm to 1500 mm, and a gap width of 0.1 mm to 0.4 mm, preferably Are arranged in parallel so as to be 0.2 mm to 0.3 mm, and are rotated inward at a rotation speed of 1 rpm to 10 rpm.
The peripheral surface 31 of the roll 3 is heated in the range of 100 ° C. to 160 ° C., preferably 110 ° C. to 150 ° C., particularly preferably 120 ° C. to 140 ° C. by supplying steam or the like into the roll 3.
The peripheral surface 31 of the roll 3 is preferably a smooth surface. By setting the surface roughness (Ra) to about 0.01 μm to 4 μm, the tea steamed leaves 2 are easily attached and the degree of drying is uniform. .

  As shown in FIG. 2, the tip of a scraper 4 having a sharp tip is in contact with the peripheral surface 31 of the roll 3 so that the tea steamed leaves 2 attached to the peripheral surface 31 can be peeled off. .

In order to reduce the water content of the tea steamed leaves 2 using the apparatus 1, first, the tea steamed leaves 2 are often entangled, so that they are unraveled. For unraveling, it is preferable to use a vibrating conveyor 5 shown in FIG. 3 or FIG.
The vibration conveyor 5 has a plurality of leaf springs 52 arranged obliquely and in parallel on a gantry 51, and a conveying plate 53 having a length of 1 m to 10 m is fixed thereon, and a tea plate is placed on the upper surface of the conveying plate 53. The leaves 2 can be placed. As shown in FIG. 4, one end of a crank 54 is fixed to the lower surface side of the transport plate 53, and a pulley 55 fixed to the other end is rotated by a motor 56 and a belt 57, whereby the crank 54 is The reciprocating motion is applied to the conveying plate 53 by the movement of the crank and the leaf spring 52 so that the tea steamed leaves 2 placed thereon can be conveyed while being unwound. At this time, it is preferable that the vibration of the vibration conveyor 5 has an amplitude in the vertical direction of 5 mm to 20 mm, preferably 7 mm to 15 mm, and this vibration is applied 450 to 700 times / minute.
Moreover, it is preferable that a plurality of dimples are formed on the upper surface of the transport plate 53 so that the tea steamed leaves 2 are not attached due to their own moisture.

The tea steamed leaves 2 unraveled in this way are put into the gap between the rolls 3 from above, and the hard-to-dry parts such as the stems of the tea steamed leaves 2 are pressed and crushed by the gaps between the rolls 3 as shown in FIG. The degree of crushing can be adjusted by the diameter of the roll 3, the gap width, the rotation speed, and the like.
The crushed tea steamed leaves 2 are discharged from below the gap, and stick to the peripheral surface 31 to move. At this time, since the tea steamed leaves 2 are in direct contact with the peripheral surface 31, they are conductively heated and moisture is evaporated. The tea steamed leaves 2 attached to the peripheral surface 31 are peeled off by the scraper 4 and fall downward.

  At this time, the tea steamed leaves 2 are preferably conductively heated by contacting the peripheral surface 31 for 5 to 30 seconds, particularly 10 to 20 seconds. This heating time can be adjusted by the position of the scraper 4, the rotational speed of the roller 3, and the like. Thereby, the moisture content of the tea steamed leaf 2 can be 30 to 70%, preferably 40 to 60%.

The tea steamed leaves 2 that have fallen from the peripheral surface 31 are collected, and the tea steamed leaves 2 can be further subjected to squeezing, drying, and the like such as twisting, middle twisting, and sperm to make a green tea product. In this case, leaf punching and rough kneading can be omitted, and it can be done in less time, such as cramping, mid-twisting, sperm kneading, etc., so that green tea can be produced in a shorter time than conventional, Nevertheless, green tea with excellent flavor can be produced.
Moreover, when leaf punching or rough culling is performed, small pieces of tea steamed leaves are scattered and fall around the machine that performs them, but the apparatus 1 hardly has such a thing.

  When collecting the tea leaves 2 that have fallen from the peripheral surface 31, as shown in FIG. 1 or FIG. This conveyor 6 is divided into three parts, and tea steamed leaves 2 with a short heating time are gathered at the center, and appropriately heated tea steamed leaves 2 are gathered on both sides. It is preferable that the short tea steamed leaves 2 are again put into the gap between the rollers 3 and heated again.

  Examples of the present invention will be described below. However, the present invention is not limited to this embodiment.

<Test 1>
Crude teas 1 to 5 were prepared, the moisture content was measured, and sensory evaluation of color and flavor was performed.

(Tea steamed leaves)
The fresh tea leaves were steamed with non-pressure steam for 30 seconds in a band-type steamer, then blown to the fresh tea leaves and cooled to room temperature to prepare tea steamed leaves. In addition, the moisture content of this tea steamed leaf was measured by the atmospheric pressure drying method, and the average value measured 5 times was 79.6%.

(Rough tea 1)
The tea steamed leaves are placed on a vibration conveyor having the same configuration as that of the vibration conveyor shown in FIG. 3 or FIG. 4 to unravel the tea steamed leaves. The water content of the tea steamed leaves was lowered by inserting into the gap. This tea steamed leaf was further sprinkled, twisted, and refined, and then dried at 80 ° C. until the heart water in the steamed tea leaf (water at the center of the leaf) was removed to produce crude tea. .
The vibratory conveyor used has a conveying plate length of 2 m and vibration of 10 mm amplitude is applied 600 times / min. The roll of the apparatus used has a diameter of 1000 mm, a gap width of 0.3 mm, and a circumferential surface. The temperature was 120 ° C., and rotation was performed at 2.2 rpm. When the heating time was measured, it was about 20 seconds.

(Rough tea 2)
The tea steamed leaves are placed on a vibration conveyor having the same structure as the vibration conveyor shown in FIG. 3 or FIG. 4 to unravel the tea leaves, and the unraveled tea leaves are placed on a metal plate heated to 120 ° C. for 20 seconds. Reduced leaf moisture content. This tea steamed leaf was further sprinkled, twisted, and refined, and then dried at 80 ° C. until the heart water in the steamed tea leaf (water at the center of the leaf) was removed to produce crude tea. .
In addition, the used vibration conveyor set the length of the conveyance plate to 2 m, and applied vibration with an amplitude of 10 mm to 600 times / minute.

(Aracha 3)
The tea steamed leaves were put into a gap between rolls of an apparatus having the same configuration as the apparatus shown in FIG. 1 without unraveling, and the moisture content of the tea steamed leaves was lowered. This tea steamed leaf was further sprinkled, twisted, and refined, and then dried at 80 ° C. until the heart water in the steamed tea leaf (water at the center of the leaf) was removed to produce crude tea. .
The roll of the apparatus used had a diameter of 1000 mm, a gap width of 0.3 mm, a peripheral surface temperature of 120 ° C., and was rotated at a rotational speed of 2.2 rpm. When the heating time was measured, it was about 20 seconds.

(Rough tea 4)
The tea steamed leaves were placed on a metal plate heated to 120 ° C. for 20 seconds without unraveling to reduce the moisture content of the tea steamed leaves. Using this tea steamed leaves, after twisting, curling, and brewing, the tea was dried at 80 ° C. until the heart water (water at the center of the leaves) in the tea steamed leaves was removed, thereby producing crude tea.

(Rough tea 5)
The above tea steamed leaves are crushed and coarsely kneaded, and further subjected to twisting, curling, and koji, and then dried at 80 ° C. until the heart water in the steamed tea leaves (water at the center of the leaves) is removed. To give crude tea.

(Moisture content)
In the crude teas 1 to 5, the moisture content of the steamed tea leaves discharged from the roll was measured by an atmospheric drying method, and the average value and standard deviation (STD) measured five times were calculated. The results are shown in Table 1.

(Irozawa evaluation)
Evaluate the appearance of rough teas 1 to 5 with the following five-level evaluation, assuming that bright green ones are very good “5”, reddish ones, dark ones, and uneven ones as bad “1” I did it. The results are shown in Table 1.
5: Very good 4: Good 3: Normal 2: Somewhat bad 1: Bad

(Flavor evaluation)
Using crude tea 1-5, 200 ml of 100 ° C. hot water was added to 3 g of these and extracted for 60 seconds. The extract was tasted and the flavor was evaluated. Very good "10" from which umami and bitter astringency were extracted in a balanced manner. Those having a strange odor such as a stuffy odor, or those with insufficient extraction and thinness were evaluated as a failure “1” on a 10-point scale. The results are shown in Table 1.

(Comprehensive evaluation)
The total score of Irozawa and flavor was calculated and comprehensively evaluated as “◎” for 12 points or more, “◯” for 9 to 11 points, “△” for 6 to 8 points, and “×” for 5 points or less. . The results are shown in Table 1.

(result)
Aracha 1 was good in both color and flavor.
Since Aracha 2 did not crush the tea steamed leaves, the portion that was difficult to dry remained, the moisture content was high, and the color and flavor of the Aracha were inferior.
Since Aracha 3 did not unravel the tea steamed leaves, the variation in moisture content increased and normal results were obtained.
The crude tea 4 had a high moisture content, a large variation in the moisture content, and the color and flavor were poor.
Aracha 5 was relatively good in color and flavor, but took a long time.

<Test 2>
The heating temperature and the heating time were changed, and how the color and flavor sensory evaluation and moisture content were changed were measured.

(Production of rough tea)
The fresh tea leaves were steamed with non-pressure steam for 30 seconds in a band-type steamer, then blown to the fresh tea leaves and cooled to room temperature to prepare tea steamed leaves. In addition, the moisture content of this tea steamed leaf was measured by the atmospheric pressure drying method, and the average value measured 5 times was 79.6%. This tea steamed leaf is placed on a vibration conveyor having the same configuration as that of the vibration conveyor shown in FIG. 3 or FIG. 4 to unravel the tea steamed leaves. The water content of the tea steamed leaves was lowered by inserting into the gap. This tea steamed leaf was further sprinkled, twisted, and refined, and then dried at 80 ° C. until the heart water in the steamed tea leaf (water at the center of the leaf) was removed to produce crude tea. .
The vibratory conveyor used has a conveying plate length of 2 m and a vibration with an amplitude of 10 mm is applied 600 times / minute. The roll of the apparatus used has a diameter of 1000 mm and a gap width of 0.3 mm, The surface temperature was set as shown in Table 2 or 3 below, the number of revolutions was adjusted, and the heating time was adjusted as shown in Table 2 or 3 below.

(Evaluation)
The produced rough tea was subjected to sensory evaluation and comprehensive evaluation of color and flavor in the same manner as in Test 1. In addition, the moisture content of the tea steamed leaves discharged from the roll was measured. The results are shown in Tables 2 and 3.

(result)
It was confirmed that the crude tea obtained by heating the tea steamed leaves in the range of 100 ° C. to 160 ° C. for 5 seconds to 30 seconds has excellent color and flavor.

1 Dryer 2 Tea Steamed Leaves 3 Rolls 31 Circumference 4 Scraper 5 Vibration Conveyor 6 Conveyor

Claims (5)

At least the difficultly dried portion of the unraveled tea leaves is crushed with a pressing body of parallel rollers having a gap width of 0.1 mm to 0.4 mm , and the crushed tea leaves are heated with a heating body in the range of 100 ° C. to 160 ° C. for 5 seconds. A method for reducing the moisture content of tea leaves that is conductively heated for 30 seconds . Water content reduction process of tea according to claim 1, disentangle tea leaves in the vibration conveyor. The method for reducing the moisture content of tea leaves according to claim 1 or 2 , wherein the peripheral surface of the roller is a heating element. Water content of tea leaves provided with parallel rolls having a gap width of 0.1 mm to 0.4 mm, crushing at least difficultly dried portions of the tea leaves with the gaps, and conducting and heating the tea leaves crushed on the peripheral surface Rate reduction device. The apparatus for reducing the moisture content of tea leaves according to claim 4 , wherein the peripheral surface of the roll is smooth.