JPH09121770A - Production of paste tea and powder tea - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce paste tea and powder tea having excellent dispersibility and also sweetness by eliminating bitter taste and astringent taste in a tea drink. SOLUTION: A tea leaf raw material is preliminarily crushed to have a granular diameter of <=1mm and resultant powder tea obtained by the preliminary crushing is suspended in a liquid and wet crushed to a superfine powder tea having about <=10μm average granular diameter by a high-pressure homogenizer. A paste tea is produced by freeze-dewatering the suspension containing the resultant powder tea, and a powder tea is produced by freeze-drying the suspension instead of the freeze-dewatering.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing paste tea and powdered tea which are excellent in dispersibility in hot and cold water, have less roughness and bitterness, can be obtained as a sweet tea beverage, and can be added to foods. Regarding

[0002]

2. Description of the Related Art Tea is roughly classified into non-fermented tea such as green tea, semi-fermented tea such as oolong tea and fermented tea such as black tea according to its manufacturing method. Green tea includes sencha, gyokuro, matcha tea, kamaicha and hojicha. There are various types such as tea leaf raw materials and manufacturing methods. In these teas, the extract obtained by immersing the product tea leaves in warm water or hot water for a predetermined time is usually provided for drinking. In the case of matcha, hot water at a predetermined temperature is added to fine powder of tea leaves, and the tea powder is stirred with a tea whisk and whipped to be consumed.

When drinking sencha or black tea, an apparatus such as a tea strainer is required to extract tea with hot water, and the extraction work is troublesome. Even for tea bags to simplify the extraction work, it takes time to prepare and discard used tea bags after extraction, so it has the advantage of taste and aroma, but the taste in canned tea, etc. Recently, canned green tea and black tea have been favored by consumers, coupled with the improvement in quality such as reduction of aroma and retort odor.

According to recent studies, tea leaves contain catechins (tannins), xanthines, flavonoids, theanine, vitamins, amino acids, etc., and have an anti-cancer effect and an antioxidant that suppresses the oxidation of intracellular fat. It has been revealed that it has effects such as an action, a blood pressure lowering action, an antibacterial action, and a dental caries preventive action, and powdered tea and paste tea have come to be reviewed as a type of tea that ingests whole tea leaves.

As a type of tea in which whole tea leaves are ingested, there is matcha which is a powder obtained by steaming and drying the tea leaves.
However, matcha is not only widely accepted as a beverage because of its "astringency", but also has a drawback that it is difficult to prevent oxidation of the various components during pulverization.
In addition, matcha is made by grinding tencha with a stone mill to make a fine powder with a particle size of 20 μm or less, and a large amount of air is included between the fine powder particles. Since it did not disperse, it was necessary to thoroughly stir the hot water. When the particle size is 20 μm or less, the dispersibility is further deteriorated. Therefore, it has been found that it is necessary to set the particle size to 20 μm or more in order to improve the dispersibility.

[0006] In the case of producing a fine powder tea using a stone mill, it takes time to make fine powder, and the product becomes expensive. In order to produce low-cost powdered tea, for example, as described in JP-A-60-160844, a technique has been developed in which a rough tea material such as green tea is dried and then crushed with a mixer. There is.

When crushing rough tea material with a mixer, the tea may deteriorate due to frictional heat generated during crushing. Therefore, Japanese Patent Application Laid-Open No. 6-78674 discloses that when green tea is cooled, the tea is crushed by 150- A technique for producing powdered tea of about 200 mesh is described. In Japanese Patent Laid-Open No. 53-62897, crude tea is cooled to 0 ° C. or below and then cooled by a low temperature pulverizer to 50
A technique is disclosed in which powdered tea having a mesh or less is produced and granulated with a granulator.

[0008] The powdered tea having a mesh of the extent described in these publications has a disadvantage that the texture is unfavorable and the bitterness is strong because the mesh is coarse.

Japanese Unexamined Patent Publication (Kokai) No. 6-62737 discloses that raw tea is 5 to 7
Disclosed is a technique in which powdered tea having a particle size of about 3 to 100 μm and a rounded grain shape is produced by impact crushing using a hammer while keeping the temperature at ℃. The powdered tea obtained by this method has a particle size of 20 μm or less,
Although it is suitable for tea bags to extract over time, it is not practical to drink it by putting this powdered tea directly in the hot water, as it will make the powder tea "dama". The bitterness was strong like other dry ground tea.

Japanese Unexamined Patent Publication (Kokai) No. 1-269451 discloses a method of slowly roasting tea leaves at low temperature for a long period of time and then using a pulverizer to produce fine powdered tea having a particle size of 30 to 40 μm. . The pulverization method is considered to be dry pulverization because the tea leaves are roasted and then pulverized.

Japanese Unexamined Patent Publication No. 7-67532 discloses a method for producing a green tea paste in which dried green tea leaves are finely pulverized to 200 mesh or more and mixed with a solvent containing substantially no water. According to this publication, a coarse powder of 150 mesh or less has a bad texture to the green tea paste, and a crushed powder of 200 mesh or more gives a paste having a smooth feel.
It is described that the graininess and foreign-body sensation peculiar to the powder made into ultra fine powder of 00 mesh or more are not felt at all, and a powder having a fine texture can be obtained.

The crusher in this manufacturing method is considered to be a dry crusher such as a pin mill type. When the tea leaves are pulverized to an ultrafine size, the dispersibility in water is poor, so that they should be mixed with a solvent other than water. ing.

However, since green tea is mixed with a solvent such as ethanol, propylene glycol, and glycerin, substances other than green tea that have a taste and aroma are mixed in, and the original taste, aroma, body, bitterness, etc. of green tea can be absorbed. The texture will change. Therefore, this paste tea may not be preferable in that it changes the taste of green tea.

[0014]

As described above, all the techniques for pulverizing tea leaves to produce finely powdered tea are dry, and even if the dry leaves are finely pulverized, they can be used for drinking. However, since a large amount of air is included between the fine particles of powdered tea, it is difficult to disperse it in hot water.

According to the present invention, when tea leaves are made into ultrafine powder tea by wet pulverization and the water used in wet pulverization is used to freeze-dry or freeze-dry the suspension, not only dispersibility but also conventional This is based on the finding that a tea beverage having sweetness can be obtained by eliminating the bitterness and astringency that are inevitable with tea.

[0016] An object of the present invention is to eliminate the bitterness and astringency in tea beverages and to produce a tea beverage that also has sweetness.

Another object of the present invention is to make it possible to produce paste tea and powder tea having excellent dispersibility in hot and cold water.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0019]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, according to the present invention, the tea leaf raw material is pulverized by wet pulverization, which has hardly been conventionally considered, and the suspension containing the powdered tea obtained by pulverization is freeze-dehydrated to produce paste tea. Further, in the present invention, the tea leaf raw material is preliminarily pulverized by dry pulverization so that the particle diameter is 1 mm or less, preferably 300 μm or less, and the powder tea obtained by preliminary pulverization is suspended in a liquid and averaged by a high pressure homogenizer. Powdered tea having a particle size of about 10 μm or less, that is, ultrafine powdered tea is pulverized, and the suspension containing the finely powdered tea obtained by this wet pulverization is freeze-dehydrated to produce paste tea. Furthermore, the present invention produces powdered tea by freeze-drying a suspension containing powdered tea obtained by wet grinding to remove water. Wet grinding can also be performed using a high-pressure homogenizer when producing fine powdered tea.

As the tea leaf raw material used in the present invention, green tea such as sencha and bancha is suitable, but it can be applied to tea leaves other than green tea such as oolong tea and black tea. As the tea leaf raw material, raw tea before drying, rough tea after natural drying or mechanical drying, and finish tea sold as a product can be used.

The dried tea leaf raw material is pre-pulverized and then pulverized by a wet pulverizer into ultrafine powder. A high-pressure homogenizer can be used as this wet pulverizer. A high-pressure homogenizer is, for example, a device that atomizes liquid droplets or suspended particles under high pressure by ejecting the liquid from the pores and causing them to collide with each other. Emulsion or suspended particles are generated by the combined action of cavitation caused by sudden pressure drop when ejected from jets and colliding with each other, shearing force when passing through pores reaching supersonic velocity, impact due to collision, etc. It is a kind of line-type emulsification, dispersion, and pulverization device for refining oil, manufactured by Nimizer Co., Ltd., trade name "Nanomizer LA33"
Alternatively, a product name “Microfluitizer M110-E / E” manufactured by Mizuho Industry Co., Ltd. can be used. In addition, a Gorin homogenizer (trade name) of a type in which the suspension is divided into two directions, that is, the upper and lower sides of the wall, is passed through a narrow gap, and cavitation is generated by using a tearing force can be used. Up to now, no example of using this for crushing tea leaves has been known, and this wet crusher crushes the tea leaf raw material into ultrafine powdered tea with particles of 10 μm or less.

The wet pulverizer is not particularly limited as long as it can wet pulverize particles to 10 μm or less in addition to a high pressure homogenizer. For example, a planetary ball mill,
A vibrating ball mill, an ultrasonic ball mill, a colloid mill, etc. can be used.

In the preliminary pulverization before treating the tea leaves with the high-pressure homogenizer, the tea leaves are pulverized in advance to a particle size of 1 mm or less, preferably 0.2 mm or less. The method of this preliminary crushing is not particularly limited, and for example, a conventionally used dry crushing device can be used. To the high-pressure homogenizer, the pre-milled tea leaves are suspended in water or a liquid containing water as a main component and introduced. The concentration of tea leaves in the suspension is 0.1 to 50% by weight, preferably 0.5.
10 to 10% by weight. The operating conditions of the high-pressure homogenizer vary depending on the model, so it cannot be said at once, but it is better to treat at a pressure of 300 kg / cm ² or more, and if sufficient treatment cannot be obtained by one treatment, Repeat several times to dozens of times.

Powdered tea can be obtained by freeze-drying a suspension containing powdered tea that has become ultrafine powdered tea particles having a particle size of 10 μm or less by wet pulverization, and pace tea can be obtained by freeze-drying.

Freeze-drying is performed by using ice at 0 ° C. with a water vapor pressure of 4.5 mmHg.
It is intended to sublimate and dehydrate the water of the condensate that has become ice by maintaining the following reduced pressure conditions, and theoretically 4.5
If it is less than mmHg (5.9 × 10 ⁻³ atm), it is possible to remove water in the frozen condensate to produce powdered tea.

Without freeze-drying until it becomes powdered tea,
If the process is stopped during freeze-drying, paste tea having a predetermined water content can be obtained. In this specification, the operation of stopping the freeze-drying process in the middle of the process is called "freeze dehydration".

To freeze-dry a suspension containing powdered tea,
For example, this suspension is poured into a container, and the container is carried into a preliminary freezing tank provided in association with the freeze-drying device to be pre-frozen. In the preliminary freezing tank, for example, antifreeze methanol cooled to about -50 ° C is stored, whereby the suspension in the container is prefrozen.

When the condensed liquid frozen by the preliminary freezing process is connected to the freeze-drying device, the indicated pressure in the container drops to 0.12 mmHg (1.6 × 10 ⁻⁴ atm) and settles down. At this time, the sublimation of water starts, the sublimated water stays in the apparatus and the pressure rises, while the sublimated water freezes due to the cold trap and the pressure drops to 0.
Maintain equilibrium at 12 mmHg.

However, as the dehydration progresses, the amount of sublimated water decreases, and the equilibrium state collapses. Therefore, the inside of the apparatus approaches a vacuum, and when the equilibrium is almost completed, the indicated pressure is 0.04 mmHg. It is thought that it will decrease to near.

Whether or not the dehydration is completed can be determined by whether or not the pressure in the container reaches the minimum ultimate vacuum degree, but completion of the dehydration is determined by whether or not the temperature in the container is room temperature. Alternatively, the latter determination method has an advantage that the determination can be performed in a shorter time than the determination based on the minimum ultimate vacuum degree.

When the freeze-drying process is performed, the water content is 1
An ultrafine powdered tea is obtained which is dried to a level of 0% by weight or less, preferably 1 to 5% by weight. For example, when it is dried up to about 3% by weight, powdered tea is obtained by only removing the lumps of dried material.

If freeze-drying is stopped during the process of performing freeze-drying, freeze-drying can be performed as described above. However, by stopping freeze-drying at a predetermined time before the completion of freeze-drying, A paste tea having an arbitrary water content can be obtained. Powder tea can also be obtained by freeze-drying the paste tea thus obtained again.

Since paste tea is packed in tubes after being freeze-dehydrated, the moisture content that can be packed in tubes is about 60 to 79% by weight, although it depends on the particle size of the powder tea that has been finely pulverized. It is preferable that the moisture content is When the water content was 79% by weight, the paste tea had a viscosity of 26 Pa · S at 25 ° C. at 25 ° C. and could be packed in a tube.

The optimum range for tube filling is a moisture content range of 65 to 77% by weight and a viscosity of 53 Pa.
・ S or more. For example, when the water content is 85% by weight, the viscosity becomes 5 Pa · S, and finally the paste state can be maintained. These numerical values differ depending on the type of wet pulverizer, the conditions of use, the particle size of the tea leaves, etc., but are not limited as long as the water content can maintain the paste state.

Since the paste tea and powdered tea of the present invention are pulverized by wet method into ultrafine powdered tea, they are less rough, bitter and astringent and more sweet than conventional dry pulverization. An unexpected effect was obtained.

Although it has been considered that when it is made into an ultrafine powder, it is difficult to dissolve it in the conventional common sense, it has excellent dispersibility in water or hot water, that is, is easily soluble, and has an effect that it can be made into a tea beverage without stirring.

Since both paste tea and powdered tea contain not only the tea leaf extract but also the tea leaves, ingestion of the active ingredients contained in the tea leaves can be expected to bring about effects such as catechins and vitamins.

Further, since the tea leaves are finely pulverized, the amount of extraction is increased, and the amount of paste tea or powdered tea is small enough to ingest the same amount of active ingredient, which is economical.

[0040]

【Example】

(Example 1) Yabutaki tea (produced in Shizuoka prefecture) was dried, and then dried with a centrifugal pulverizer to have a particle size of 125 μm or less and a median diameter of 6
Preliminary pulverization to 5 μm produced centrifugally pulverized tea, which was suspended in water at a ratio of 5%. 1000 kg of this suspension was put in a high pressure homogenizer (Nanomizer LA33 manufactured by Nanomizer Co., Ltd.) which is a wet type ultra-fine pulverizer.
The treatment was repeated 10 times at a pressure of / cm ² to obtain a suspension of ultrafine powdered tea, that is, a suspension treated with a high-pressure homogenizer.

The particle size distributions of the ultrafine powdered tea thus obtained and commercially available matcha tea were measured with a laser particle size distribution measuring device (manufactured by Tohnichi Computer Applications Co., Ltd.), as shown in FIGS. 1 and 2. It was The median diameter (D ₅₀ ) of each powder was 3.6 μm for ultrafine powdered tea and 5.9 μm for commercially available matcha.

The suspension containing ultra-fine powdered tea was freeze-dried using a vacuum freeze dryer (manufactured by Ikeda Rika Co., Ltd.) under the conditions of 10 ⁻⁴ atm and cold trap −50 ° C., and the water content was 7.
It was dried to 5% by weight and dehydrated to obtain paste tea. The viscosity of this paste tea was 58 Pa · S at 25 ° C. using a B type viscometer. 2g of this paste tea at 80 ℃
When 250 ml of hot water was added and stirred, the ultrafine powdered tea in the paste tea was almost dispersed and was in a good dispersed state. When this was sampled, the taste was good, as shown in Table 1, in which roughness, bitterness and astringency were suppressed and sweetness was felt. Table 1 shows the results of the flavor test in which 10 panelists (5 males and 5 females) were sampled at the same time and evaluated, and the numbers in the table indicate the number of people.

The manufacturing process of the paste tea thus prepared is shown in FIG. 3 (a).

Example 2 The paste tea of Example 1 was further freeze-dried to obtain a mass of powdered tea. When this lump was loosened, powdered tea was obtained. 105 this powdered tea
When the moisture content was measured by heating loss using a ℃ dryer, it was 2% by weight. However, the powdered tea may be directly produced by freeze-drying the suspension of powdered tea that has been made into an ultrafine powder by a high-pressure homogenizer. The manufacturing process of powdered tea in this case is shown in FIG.
As in (b). When powder tea is produced using paste tea, the paste tea obtained by freeze-drying is again carried into the freeze-drying device.

To 0.5 g of this powdered tea, 250 ° C. hot water 250
When ml was added, the powdered tea was immediately dispersed in hot water and was in a good dispersed state. When it was tasted, as shown in Table 1, the flavor was rough, bitterness and astringency were suppressed, and sweetness was felt.

Example 3 A similar test was carried out using water at 25 ° C. instead of hot water at 80 ° C. for the powdered tea of Example 2, and the powdered tea was almost dispersed in water and had a size of 1 to 2 mm. Only one "sama" floated on the surface of the water, but it was completely dispersed by stirring with a glass rod, and when tasting was done, as shown in Table 1, the flavor was rough, bitterness and astringency were suppressed,
It was a good result that the sweetness was felt.

(Results of Dispersibility Test) The centrifugally ground tea preliminarily ground in Example 1 was suspended in water at a ratio of 5%. Freeze-dried powder tea obtained by freeze-drying this suspension was placed in a beaker, and water at 25 ° C. was poured into it,
"Dama" with a size of 1-2 mm is placed on the bottom of the beaker.
Four of them settled, and one similar "dama" floated on the water surface. The "dama" did not disperse even with stirring. When hot and cold water at 80 ° C. was poured into the same freeze-dried powder tea, it was almost dispersed.

Further, the centrifugally pulverized tea was freeze-dried to produce freeze-dried paste tea having a water content of 75% by weight, which was put in a beaker and water at 25 ° C. was poured. "Dama" settled on the bottom of the beaker,
Many "dama" with a size of 3 to 4 mm were seen. These did not disperse even with stirring. Even when hot water of 80 ° C. was poured into the same freeze-dried paste tea, many “dama” having a size of 4 to 5 mm remained on the bottom surface of the beaker, and the “dama” was not dispersed only by stirring.

As described above, a suspension containing ultrafine powdered tea having an average particle size of 10 μm or less is freeze-dried, and a suspension containing powdered tea having an average particle size of about 65 μm is freeze-dried or freeze-dried. Compared with the case of, the ultra-fine powdered tea has better dispersibility than the powdered tea with a larger particle size than that of freeze-dried powder. Can be said to have better dispersibility.

(Comparative Example 1) The centrifugal powdered tea obtained by the preliminary pulverization of Example 1 was mixed with water until the water content became 75% by weight to obtain paste tea. 80 g for 2 g of this paste tea
When 250 ml of hot and cold water at 0 ° C was added and stirred, it was almost dispersed, and a good dispersion result was obtained. However, when this was sampled, as shown in Table 1, roughness, bitterness and astringency were conspicuous, and no sweetness was felt.

Comparative Example 2 0.25 g of centrifugal powdered tea obtained by the preliminary pulverization of Example 1 was added to 500 ml of hot water at 80 ° C.
Was added, the powder immediately dispersed, but a tea leaf powder having a large particle size was precipitated within 5 minutes. As a result of tasting this, as shown in Table 1, the taste was rough, bitter and astringent, and no sweetness was felt.

(Comparative Example 3) 25 ° C instead of hot water at 80 ° C
When tested in the same manner as in Comparative Example 2 except that the above water was used,
The tea leaves remained on the bottom of the water, and a “dama” having a diameter of 1 mm floated on the water surface when stirred. As a result of tasting this, as shown in the results of Table 1, the flavor had a bad result such that roughness, bitterness and astringency were conspicuous and sweetness was not felt.

(Comparative Example 4) A test was conducted in the same manner as in Comparative Example 2 except that matcha tea was used instead of centrifugally ground tea. As a result, a "dama" having a size of 3 to 4 mm remained at the bottom of the hot water. "Dama" remained even after stirring, and the dispersibility was poor.

(Comparative Example 5) As in Comparative Example 4, except that matcha tea was used and water at 25 ° C was used instead of hot water at 80 ° C,
When the same test as in Comparative Example 4 was carried out, the water bottom was 1-2 mm.
"Dama" with a size of 3 "remained, and a" Dama "with a size of 3-4 mm remained on the water surface. Even if this was stirred, "damage" remained and the dispersibility was poor.

(Comparative Example 6) The suspension treated with the high-pressure homogenizer obtained in Example 1 was vacuum dried at 25 ° C under a condition of a vacuum dryer to dehydrate until the water content became 75% by weight. I got paste tea. When 250 ml of 80 ° C hot water was added to 2 g of this paste tea and stirred, the dispersion was poor,
The fine powder of tea leaves settled immediately. It was found that the hue was that of light barley tea and that browning had progressed. When this was sampled, there was no taste or scent, and there was only a rough feeling.

(Comparative Example 7) The paste tea obtained in Comparative Example 6 was further vacuum dried at room temperature to obtain powdered tea. When 250 ml of hot and cold water at 80 ° C. was added to 0.5 g of this powdered tea and stirred, the results were all the same as in Comparative Example 6.

Comparative Example 8 0.5 g of centrifugally ground tea was added to 80 g at 80 ° C.
250 ml of hot water was added and freeze-dried under the conditions of Example 1 until the water content became 75% by weight to obtain paste tea. When 250 ml of hot water at 80 ° C was added to 2 g of this paste tea and stirred, the dispersibility was poor, and many "dama" with a size of 4 to 5 mm were deposited on the bottom, and the "dama" was dispersed even with stirring. There wasn't. When sampled, Comparative Example 1
There is a feeling of roughness as well as, and bitterness and astringency are noticeable,
The bad result was that no sweetness was felt.

(Comparative Example 9) The paste tea of Comparative Example 8 was further freeze-dried to obtain powdered tea. 8 to 0.5g of this powdered tea
When 250 ml of hot and cold water at 0 ° C. was added, it dispersed without stirring. However, when tasting was carried out, the result was similar to that of Comparative Example 8.

[0059]

[Table 1]

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say. For example, although dried tea is used as a tea leaf raw material in the examples, raw tea before drying or finished tea sold as a product may be used as a tea leaf raw material.

[0061]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

(1). There is little roughness, bitterness and astringency,
Paste tea and powdered tea with a lot of sweetness were obtained.

(2). Good dispersibility in hot water or water,
Paste tea and powdered tea, which can be used as tea drinks without stirring, were obtained.

(3). The active ingredient contained in the tea leaves can also be taken.

(4) Since the extraction amount is large, paste tea and powdered tea are economical because the same active ingredient can be used in a small amount.

[Brief description of the drawings]

FIG. 1 is a graph showing the particle size distribution of powdered tea, which is an ultrafine powder obtained by wet pulverization.

FIG. 2 is a graph showing the particle size distribution of commercially available matcha.

FIG. 3 (a) is a flow chart showing a production process of the paste tea of the present invention, and (b) is a flow chart showing a production process of the powder tea of the present invention.

Claims (4)

[Claims] 1. A method for producing paste tea, which comprises pulverizing a tea leaf raw material and freeze-dehydrating a suspension containing powdered tea obtained by pulverizing. 2. A tea leaf raw material is preliminarily pulverized to have a particle diameter of 1 mm or less, and powder tea obtained by preliminary pulverization is suspended in a liquid, and a high pressure homogenizer is used to obtain an average particle diameter of about 10 μm or less. A method for producing paste tea, which comprises wet pulverizing into fine powdered tea, and freeze-drying a suspension containing the powdered tea obtained by pulverizing. 3. A method for producing a powdered tea, which comprises pulverizing a tea leaf raw material, and freeze-drying a suspension containing the powdered tea obtained by the pulverization. 4. A tea leaf material is preliminarily pulverized to have a particle diameter of 1 mm or less, and powder tea obtained by preliminary pulverization is suspended in a liquid, and a high pressure homogenizer is used to obtain an average particle diameter of about 10 μm or less. A method for producing powdered tea, which comprises wet pulverizing into fine powdered tea, and freeze-drying a suspension containing the powdered tea obtained by pulverizing.