JP7506282B1 - Method for producing packaged green tea beverage and method for improving body of packaged green tea beverage - Google Patents

Abstract

[Problem] To produce a packaged green tea beverage that has a sense of concentration and richness, and more preferably does not precipitate over time and has a fragrant initial taste. [Solution] A method for producing a packaged green tea beverage, comprising extracting green tea leaves with an aqueous solvent to obtain a tea extract with a total nitrogen concentration of 20-60 mg/100 mL, and filtering the obtained tea extract through a filter aid with a median diameter (D50) of 5-30 μm in the cumulative particle diameter distribution (volume basis) after swelling. [Selected Drawing] None

Description

The present invention relates to a green tea beverage whose main component is a green tea extract extracted from green tea, a method for producing a packaged green tea beverage by filling this green tea beverage in a container such as a plastic bottle, and a method for improving the richness of the packaged green tea beverage.

Green tea beverages contain water-insoluble solids such as polysaccharides and proteins, as well as extraction residues. When filled into transparent containers, these appear as turbidity, which is not a problem in terms of quality but is undesirable in appearance.
The turbidity that occurs during storage after filling the container may take the form of suspended matter, white turbidity, flocs (cotton-like), or sediment, and is collectively referred to as "sediment."

As a method for removing such sediment-causing substances in the production of green tea beverages, for example, Patent Document 1 discloses a method in which tea is extracted with hot water, the obtained tea extract is cooled, tannic acid is added and the mixture is allowed to stand, fine tea particles are then removed by centrifugation or the like, and the mixture is then clarified by diatomaceous earth filtration.
Patent Document 2 discloses a method in which ascorbic acid is added to a tea extract obtained by extracting green tea to make it acidic, followed by rapid cooling, centrifuging, and then filtering through diatomaceous earth to clarify the extract.

Patent Document 3 discloses a new manufacturing method suitable for packaged green tea beverages for sale heated, which includes an extraction step in which green tea leaves are extracted with heated water at 70 to 100°C, an adsorption step in which silica is added to the obtained tea extract to adsorb sediment components in the tea extract onto the silica, a silica removal step in which the silica is removed from the tea extract, a sterilization step, and a container filling step.

Patent Document 4 discloses a method for producing a packaged green tea beverage, which is characterized by adjusting the total sugar concentration (the concentration of reducing sugars and the concentration of non-reducing sugars) in the green tea beverage to 50 ppm to 250 ppm, adjusting the ratio of the concentration of non-reducing sugars to the concentration of reducing sugars (non-reducing sugars/reducing sugars) to 8 to 24, and adjusting the particle size at 90% cumulative mass (D90) to 3,500 μm or more by filter cake filtration using either or both of a silica-containing filter agent and a porous medium, in order to provide a packaged green tea beverage that has a strong, fragrant aroma, a long-lasting aroma, little unpleasant flavor, is transparent, and can be enjoyed even when cooled.

Japanese Patent Application Laid-Open No. 6-269246 Japanese Patent Publication No. 7-97965 JP 2005-229918 A Patent Document 1: WO2012-29131

Conventionally, clear green tea beverages have been designed and manufactured with a focus on aroma. In addition, for the raw tea used in clear green tea beverages, the effective ingredients must be extracted in a short time from the viewpoint of production efficiency, so studies have focused mainly on improving the elution rate. On the other hand, studies have also been conducted on devising manufacturing processes such as filtration to remove substances that cause sediment and maintain the clarity of the beverage.
In recent years, there has been a trend for clear green tea beverages to have not only an "aroma" but also a "richness" as a flavor variation (concentration). There is also a trend for the beverage to have a strong aroma that does not settle over time and has an initial flavor. However, as mentioned above, it was not easy to remove the substances that cause sediment and maintain the clarity of the green tea beverage while enhancing the richness of the green tea beverage.

The first object of the present invention is to propose a method for producing a packaged green tea beverage and a method for improving the richness of a packaged green tea beverage, which can produce a packaged green tea beverage that has a rich aftertaste due to its umami and aroma while maintaining the clarity of the green tea beverage by removing substances that cause sediment, and a second object of the present invention is to propose, in addition to the first object, a packaged green tea beverage that has a good flavor felt immediately after putting the beverage in the mouth and that has a good persistence of the flavor felt immediately after putting the beverage in the mouth even after aging, or a method for producing a packaged green tea beverage that does not produce an oxidative deterioration odor or sediment immediately after production or after aging.

To solve these problems, the present invention proposes the following aspects:

[1] The first aspect of the present invention is a method for producing a packaged green tea beverage, which comprises extracting green tea leaves with an aqueous solvent to obtain a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL, and filtering the tea extract through a filter aid having a median diameter (D50) of 5 to 30 μm in the cumulative particle diameter distribution (volume basis) after swelling.

[2] A second aspect of the present invention is a method for producing a packaged green tea beverage according to the first aspect, wherein the filter aid is derived from a mineral.
[3] A third aspect of the present invention is the method for producing a bottled green tea beverage according to the first or second aspect, wherein the filter aid has a darcy of 0.11 to 0.25.
[4] A fourth aspect of the present invention is a method for producing a packaged green tea beverage according to any one of the first to third aspects, wherein the filter aid has a cumulative particle size distribution (volume basis) D90 after swelling of 20 to 60 μm.
[5] A fifth aspect of the present invention is a method for producing a packaged green tea beverage according to any one of the first to fourth aspects, wherein the filter aid has a ratio of D90 to D50 (D90/D50) of the cumulative distribution (volume basis) of particle sizes after swelling of 1.0 to 6.0.

[6] A sixth aspect of the present invention is a method for producing a packaged green tea beverage according to any one of the first to fifth aspects, wherein the tea extract has a median diameter (D50) of 2 to 20 μm in a cumulative particle diameter distribution (volume basis) of particles contained in the extract.
[7] A seventh aspect of the present invention is a method for producing a packaged green tea beverage according to any one of the first to sixth aspects, wherein the tea extract has a potassium content of 25 to 70 mg/100 mL.
[8] An eighth aspect of the present invention is a method for producing a packaged green tea beverage according to any one of the first to seventh aspects, wherein the tea extract has a gallate-type catechin content of 30 to 200 mg/100 mL.
[9] A ninth aspect of the present invention is a method for producing a packaged green tea beverage according to any one of the first to eighth aspects, wherein the tea extract contains particles whose cumulative particle size distribution (volume basis) has a ratio of D90 to D50 (D90/D50) of 2.0 to 10.0.

[10] The tenth aspect of the present invention is a method for improving the richness of a packaged green tea beverage, comprising extracting tea leaves with an aqueous solvent to obtain a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL, and filtering the tea extract through a filter aid having a median diameter (D50) of 5 to 30 μm in the cumulative particle diameter distribution (volume basis) after swelling.

According to the method for producing a packaged green tea beverage and the method for improving the richness of a packaged green tea beverage proposed by the present invention, it is possible to provide a packaged green tea beverage that has a rich aftertaste due to its umami and aroma while maintaining the clarity of the green tea beverage by removing substances that cause sediment. It is possible to provide a packaged green tea beverage that has a good flavor felt immediately after putting the beverage in the mouth and that has a good persistence of the flavor felt immediately after putting the beverage in the mouth, or a packaged green tea beverage that does not produce an oxidative deterioration odor or sediment immediately after production or over time.

An example of an embodiment of the present invention will be described below. However, the present invention is not limited to the embodiment described below.

<<Production method of the present invention>>
A method for producing a packaged green tea beverage according to one embodiment of the present invention (also referred to as the "production method of the present invention") comprises extracting green tea leaves with an aqueous solvent to obtain a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL (extraction step), removing extraction residue from the tea extract as necessary (crude filtration step), subjecting the tea extract to centrifugation as necessary (centrifugation step), filtering the tea extract using a specified filter aid (filtration step), and then producing a packaged green tea beverage via a blending step and a sterilization/packaging step.

However, this manufacturing process is merely one example. It is also possible to change the order of each process, and to insert other processes between each process.

The production method of the present invention makes it possible to produce a packaged green tea beverage that has a rich aftertaste and a rich aroma, so the production method of the present invention can also be used as a method for improving the richness of packaged green tea beverages.

<Raw material tea>
The green tea leaves, i.e., raw tea leaves, can be any type of tea as long as they are picked from the tea plant (scientific name: Camellia sinensis), regardless of the variety, place of origin, picking time, picking method, cultivation method, etc.
Raw tea leaves (including leaves and stems) can be used as the raw tea leaves. Furthermore, it is also possible to use raw tea leaves that have been subjected to a process for stopping enzyme activity by steaming or roasting the raw tea leaves.
As the crude tea, any type of tea can be used as the raw material tea leaves, for example, Sencha, Kamairicha, Kabusecha, Gyokuro, Tencha, Matcha, Bancha, Hojicha, Steamed Tamaryokucha, Kamairoise Tamaryokucha, Ureshinocha, Aoyagicha, etc. Two or more types of these crude teas may be combined, or flavorings may be added.

In particular, from the viewpoint of obtaining a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL, it is preferable to use raw tea leaves that satisfy the standard of a total nitrogen concentration in the tea leaves of 4 g/100 g or more as the raw tea leaves for the production method of the present invention. Examples of such raw tea leaves include teas rich in amino acids, such as first-season tea, gyokuro, and kabuse tea. In particular, from the viewpoint of making it easier to prepare a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL, it is even more preferable to use raw tea leaves that satisfy the standard of a total nitrogen concentration in the tea leaves of 5 g/100 g or more or 7 g/100 g or less, and of these, 6.4 g/100 g or less.

<Extraction process>
The green tea leaves are preferably extracted with a water-soluble solvent at 70 to 100°C.
The extraction method may be any currently known extraction method. For example, extraction may be performed using an extraction device called a kneader in the usual manner, with a water-soluble solvent at 70 to 100°C in an amount 20 to 100 times the amount of the raw tea, for about 1 to 10 minutes, stirring once or several times as necessary, at normal pressure. However, the extraction method and extraction conditions are not particularly limited, and for example, drip extraction using a dripper or pressurized extraction may also be performed.

Examples of the water-soluble solvent used for extraction include pure water (including hard water, soft water, and ion-exchanged water), as well as an aqueous solution containing ascorbic acid and pH-adjusted water.
From the viewpoint of obtaining a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL, the amount of the water-soluble solvent to be brought into contact with the raw material tea is preferably 20 to 60 times the amount of the raw material tea, more preferably 25 times or more or 50 times or less, and even more preferably 30 times or more or 45 times or less.
The extraction temperature, i.e., the temperature of the hot water used for extraction, may be adjusted to 70 to 100°C. From the viewpoint of obtaining a tea extract with a total nitrogen concentration of 20 to 60 mg/100 mL, it is more preferable to extract at a temperature of 72°C or higher or 99°C or lower, of which 75°C or higher or 98°C or lower, and of which 78°C or higher or 97°C or lower.
The extraction time, i.e., the time for which the tea leaves are in contact with the water-soluble solvent, is preferably 1 to 9 minutes, more preferably 2 minutes or more or 8 minutes or less, and even more preferably 3 minutes or more or 7 minutes or less, from the viewpoint of obtaining a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL.

[Total nitrogen concentration]
As described above, it is preferable to adjust the total nitrogen concentration of the tea extract obtained by extraction to 20 to 60 mg/100 mL.
Since components that affect the richness of tea beverages, such as caffeine and amino acids, contain nitrogen, the total nitrogen concentration of tea extract is an indicator of the content of components that affect the richness of tea beverages.
A total nitrogen concentration of 20 mg/100 mL or more in the tea extract is preferable because it can impart a rich, savory aftertaste, whereas a total nitrogen concentration of 60 mg/100 mL or less is preferable because it is difficult to detect unpleasant aftertastes.
From this viewpoint, the tea extract obtained by extraction is preferably adjusted to have a total nitrogen concentration of 20 mg/100 mL or more, more preferably 22 mg/100 mL or more, even more preferably 24 mg/100 mL or more, even more preferably 26 mg/100 mL or more. On the other hand, the total nitrogen concentration is preferably adjusted to 60 mg/100 mL or less, more preferably 50 mg/100 mL or less, even more preferably 40 mg/100 mL or less, even more preferably 35 mg/100 mL or less.

The total nitrogen concentration in the tea extract can be adjusted by selecting the type of tea used as the raw material, the tea season, the fertilization method, etc., or by adjusting the extraction conditions, but is not limited to these.
Gyokuro, Ichibancha, and other varieties contain a lot of amino acids, which allows for a high total nitrogen concentration. The total nitrogen concentration can also be increased by increasing the extraction temperature or lengthening the extraction time.

<Rough filtration process>
The coarse filtration process is a process for removing extraction residues such as tea leaves and large fine powders. For example, a stainless steel filter, a flannel cloth, a strainer, or any other filtering method currently used to remove extraction residues can be used.

The tea extract that has been through the crude filtration process can be cooled to around 5-40°C if necessary, and at the same time, or before or after, ascorbic acid or sodium ascorbate can be added to the tea extract to make it acidic (pH 4-5) if necessary. Cooling the tea extract or adjusting its acidity can prevent oxidation of the extracted components, and can also precipitate the components that cause primary sediment, increasing the efficiency of the subsequent centrifugation process.

<Centrifugation step>
The tea extract that has been subjected to the coarse filtration step is preferably subjected to centrifugation, if necessary.
Centrifugation may be carried out under conditions of, for example, a flow rate of 200 to 500 L/h and a rotation speed of 5,000 to 20,000 rpm. In this case, the clarity (T%) of the final packaged green tea beverage can be adjusted by changing the flow rate, rotation speed, centrifugal sedimentation area (Σ), etc.
As mentioned above, it is preferable to cool the tea extract to about 5 to 40° C. before centrifuging, but cooling is not essential.

Fine powder can be removed by centrifugation, but centrifugation is not always necessary if there is another process capable of removing fine powder.
By carrying out centrifugation before the filtration step, the burden on the filtration step can be reduced. For example, the filtration time can be shortened by increasing the permeation flow rate and decreasing the permeation pressure. However, since fine powder can also be removed in the filtration step, it is possible to omit centrifugation when carrying out the filtration step, although the burden will be somewhat greater.

In place of centrifugation, filtration using flannel cloth (Flannel filtration), filtration with a 80 to 200 mesh stainless steel filter, filtration with a back filter with a mesh size of 1 to 100 μm, or treatment to reduce the catechin content using PVPP may be performed.
The catechin content reduction treatment using PVPP is a method in which polyphenols (mainly catechins) are adsorbed onto PVPP (polyvinyl polypyrrolidone) having a crosslinked structure by contacting the tea extract with the PVPP, and then the PVPP is filtered using a filter, diatomaceous earth, etc. In this case, the amount of catechins, etc., reduced can be adjusted by the amount of PVPP added and the contact conditions.

(Tea extract supplied to filtration process)
The tea extract to be subjected to the next filtration step is preferably adjusted so that the median diameter (D50) of the cumulative particle diameter distribution (volume basis) of particles contained in the extract is 2 to 20 μm.
It is preferable that the median diameter (D50) of the cumulative particle diameter distribution (volume basis) of particles contained in the tea extract supplied to the filtration step is 2 μm or more, since the full-bodied aroma can be felt in the middle of the flavor even after aging, that is, immediately after the beverage is put in the mouth, and continues to be felt, whereas it is preferable that the median diameter is 20 μm or less, since the full-bodied aroma can be felt in the first half of the flavor even after aging, that is, immediately after the beverage is put in the mouth, and continues to be felt,
From this viewpoint, the tea extract to be subjected to the filtration step is preferably adjusted so that the median diameter (D50) of the cumulative particle diameter distribution (volume basis) of particles contained in the liquid is 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, even more preferably 5 μm or more, and on the other hand, it is preferably adjusted so that it is 20 μm or less, more preferably 16 μm or less, even more preferably 13 μm or less, even more preferably 10 μm or less.
In order to adjust the median diameter (D50) of the cumulative particle diameter distribution (volume basis) of particles contained in the tea extract to be subjected to the filtration step to fall within the above range, it is preferable to obtain the necessary fine particles by adjusting the stirring speed and number of times in the extraction step, and then remove the coarse particles using a stainless steel filter in the filtration step, although the method is not limited to this.

In addition, the tea extract to be subjected to the subsequent filtration step is preferably adjusted so that the ratio of D90 to D50 (D90/D50) of the cumulative particle size distribution (volume basis) of particles contained in the liquid is 2.0 to 10.0.
It is preferable that the particle ratio (D90/D50) contained in the tea extract supplied to the filtration step is 2.0 to 10.0, since the flavor is well-balanced from the first half to the second half even after aging, and the full-bodied aroma can be felt.
From this viewpoint, the ratio of particles contained in the tea extract liquid to be subjected to the filtration step (D90/D50) is preferably adjusted to 2.0 or more, more preferably 2.5 or more, even more preferably 3.0 or more, and more preferably 3.5 or more, while it is preferably adjusted to 10.0 or less, more preferably 6.0 or less, even more preferably 5.0 or less, and more preferably 4.0 or less.
In order to adjust the particle size of the tea extract to be subjected to the filtration step to fall within the above range, it is preferable to appropriately select the mesh size of the filter in the coarse filtration step, for example, although the method is not limited to this.

In addition, the tea extract to be subjected to the next filtration step is preferably adjusted so that the potassium content in the liquid is 25 to 70 mg/100 mL.
The potassium content in the liquid is an index of the amount of mineral components, and if the potassium content in the liquid is 25 mg/100 mL or more, it is preferable because the richness combined with the umami taste is felt in the middle of the flavor even after aging, whereas if it is 70 mg/100 mL or less, it is preferable because the bitterness accompanying the saltiness in the first half of the flavor is suppressed even after aging.
From this viewpoint, the tea extract to be subjected to the filtration step is adjusted so that the potassium content in the liquid is preferably 25 mg/100 mL or more, more preferably 27 mg/100 mL or more, even more preferably 29 mg/100 mL or more, even more preferably 31 mg/100 mL or more, and on the other hand, it is adjusted so that the potassium content is 70 mg/100 mL or less, more preferably 69 mg/100 mL or less, even more preferably 67 mg/100 mL or less.
In order to adjust the potassium content in the tea extract to be subjected to the filtration step to the above range, it is preferable to, for example, select or appropriately mix the tea leaves used for extraction, although the method is not limited to this.

Furthermore, the tea extract to be subjected to the next filtration step is preferably adjusted so that the content of gallate-type catechins in the extract is 30 to 200 mg/100 mL.
Here, the content of gallate-type catechins means the total content or total concentration of epigallocatechin gallate (EGCg), epicatechin gallate (ECg), gallocatechin gallate (GCg) and catechin gallate (Cg).
Since the content of gallate-type catechins in a liquid is an index of concentration, a catechin content of 30 mg/100 mL or more in a tea extract is preferred because it provides an astringent flavor suitable for a tea beverage in the middle stage even after aging, whereas a content of 200 mg/100 mL or less is preferred because it provides a mellow flavor with suppressed astringency in the first half of the flavor even after aging.
From this viewpoint, the tea extract to be subjected to the filtration step is adjusted so that the content of gallate-type catechins contained in the liquid is preferably 30 mg/100 mL or more, more preferably 40 mg/100 mL or more, more preferably 45 mg/100 mL or more, and even more preferably 50 mg/100 mL or more, while the content is preferably 200 mg/100 mL or less, more preferably 170 mg/100 mL or less, and even more preferably 150 mg/100 mL or less.
In order to adjust the content of gallate-type catechins in the tea extract to be subjected to the filtration step to the above range, it is preferable to adjust the temperature of the water-soluble solvent used for extraction, for example, although the method is not limited to this.

Furthermore, the tea extract to be subjected to the filtration step may contain the following components, so long as the effects of the present invention are not impaired.
That is, the tea extract may contain tannins in an amount of 100 mg/100 mL or more, preferably 150 mg/100 mL or more, and may contain tannins in an amount of 400 mg/100 mL or less, preferably 300 mg/100 mL or less.
The tea extract may contain caffeine in an amount of 10 mg/100 mL or more, preferably 20 mg/100 mL or more, or may contain caffeine in an amount of 100 mg/100 mL or less, preferably 80 mg/100 mL or less.
The tea extract may contain amino acids in an amount of 1 mg/100 mL or more, preferably 5 mg/100 mL or more, or 80 mg/100 mL or less, preferably 50 mg/100 mL or less.

The tea extract may contain catechins in an amount of 50 mg/100 mL or more, preferably 100 mg/100 mL or more, or 300 mg/100 mL or less, preferably 250 mg/100 mL or less.
The amount of catechins is the total amount of eight types of catechins (epicatechin (EC), epicatechin gallate (ECg), epigallocatechin (EGC), epigallocatechin gallate (EGCg), catechin (C), gallocatechin (GC), catechin gallate (Cg), and gallocatechin gallate (GCg)).

The soluble solids content (Brix) of the tea extract should be 0.5 or more, preferably 0.6 or more. On the other hand, it should be 2.0 or less, preferably 1.5 or less.

<Filtration process>
In the filtration step, the tea extract is filtered using a specific filter aid.
In this case, it is preferable to use a filter aid derived from a mineral from the viewpoint of its effect on the flavor of the green tea beverage.
Examples of mineral-derived filter aids include diatomaceous earth derived from fossil minerals, perlite derived from volcanic rock, etc. Among these, diatomaceous earth is preferred in terms of liquid permeability.

Diatomaceous earth is a type of soil that is made up of minute diatom shells that have accumulated over many years as phytoplankton known as diatoms accumulate on the bottom of oceans and lakes and turn into fossils. Diatomaceous earth has a diameter of several to several tens of μm, and has countless minute holes of 0.1 to 1.0 μm on its surface, forming a dense cake layer of filter aid on wire mesh or filter cloth, which allows clear liquid to be obtained during filtration.
The main component of diatomaceous earth is silica (SiO ₂ ), particularly amorphous silica, and for use as a filter aid, it is generally purified by calcination.

Diatomaceous earth filtration is a cake filtration that uses diatomaceous earth as a filter aid.
The diatomaceous earth filtration method involves forming an auxiliary layer (precoat) made of diatomaceous earth on the surface of the filter carrier, and, if necessary, injecting (body feeding) the diatomaceous earth filtering agent into the raw liquid (tea extract as unfiltered liquid), while feeding the raw liquid (tea extract as unfiltered liquid) to the auxiliary layer.
Here, "pre-coating" refers to dispersing an auxiliary agent in a clear liquid prior to a filtration operation, circulating the liquid, and forming a layer of the auxiliary agent several mm thick on the surface of a filtration carrier (e.g., a metal leaf, thick filter pad, laminated metal candle, ceramic candle, etc.), which prevents suspended solids from directly adhering to the filter material and contaminating it, and also improves the clarity of the filtrate.
As a filtration method, for example, ultrafiltration, microfiltration, precision filtration, reverse osmosis membrane filtration, electrodialysis, membrane filtration such as biological functional membrane, or a combination of two or more of these may be used. However, since tea beverages are susceptible to oxygen deterioration, it is more suitable from the viewpoint of flavor balance to adopt clarifying filtration such as cake filtration using a filter aid than the cross-flow method generally used in membrane filtration and ultrafiltration.

Diatomaceous earth may also be mixed with other filter aids such as silica gel, perlite, or cellulose.

In the filtration step, it is preferable to use a filter aid having a median diameter (D50) of 5 to 30 μm in the cumulative particle diameter distribution (volume basis) after swelling.
It is preferable to use a filter aid with a D50 of 5 μm or more after swelling because it is possible to feel a rich aftertaste due to the aroma, while it is preferable to use a filter aid with a D50 of 30 μm or less because it is possible to drink the beverage without feeling rough on the tongue.
From this viewpoint, the filter aid used has a median diameter (D50) in the cumulative distribution (volume basis) of particle diameter after swelling of 5 μm or more, more preferably 7 μm or more, more preferably 10 μm or more. On the other hand, it is preferably 30 μm or less, more preferably 25 μm or less, more preferably 20 μm or less.
The swelling conditions for measuring the cumulative particle size distribution (volume basis) of the swollen filter aid are as follows: 10 g of each filter aid is dispersed in 50 times its amount of pure water, and the filter aid is immersed for 15 minutes to swell.

The filter aid used preferably has a darcy of 0.11 to 0.25.
If the darcy of the filter aid is 0.11 or more, the overall richness of the tea components can be felt even after aging, which is preferable, whereas if it is 0.25 or less, the generation of sediment over time can be suppressed, which is preferable.
From this viewpoint, the filter aid used preferably has a darcy of 0.11 or more, more preferably 0.13 or more, and even more preferably 0.15 or more. On the other hand, it is preferably 0.25 or less, more preferably 0.23 or less, and even more preferably 0.20 or less.
In addition, "filter aid with darcy of 0.11 to 0.25" means a filter aid with a darcy permeability K in the range of 0.11 to 0.25. "Darcy permeability K" is one of the indicators showing the permeability of a filter aid, and can be determined by a water permeability method or an air permeability method. Currently, "darcy" is so commonly used that filter aids can be purchased by specifying this value.

In the filtration step, it is preferable to use a filter aid having a D90 of 20 to 60 μm in the cumulative particle size distribution (volume basis) after swelling.
It is preferable to use a filter aid having a D90 of 20 μm or more after swelling because it can be produced without losing the freshness of the flavor even after aging. On the other hand, it is preferable to use a filter aid having a D90 of 60 μm or less because it can maintain the fresh flavor over time.
From this viewpoint, the filter aid used has a D90 in the cumulative distribution (volume basis) of particle diameter after swelling of 20 μm or more, more preferably 25 μm or more, more preferably 30 μm or more, and even more preferably 35 μm or more.On the other hand, it is preferably 60 μm or less, more preferably 55 μm or less, more preferably 50 μm or less, and even more preferably 45 μm or less.

It is preferable to use a filter aid having a ratio of D90 to D50 (D90/D50) of cumulative distribution (volume basis) of particle diameters after swelling of 1.0 to 6.0.
It is preferable to use a filter aid having a post-swelling ratio (D90/D50) of 1.0 to 6.0, since the richness due to the aftertaste aroma can be stably maintained over time from the time of production.
From this viewpoint, the ratio (D90/D50) of the particle diameter cumulative distribution (volume basis) of the filter aid used after swelling is preferably 1.0 or more, more preferably 1.5 or more, more preferably 2.0 or more, more preferably 2.5 or more.On the other hand, it is preferably 6.0 or less, more preferably 5.0 or less, more preferably 4.5 or less, more preferably 4.0 or less.

It is preferable to use a filter aid in which the difference between D90 and D10 (D90-D10) of the cumulative distribution (volume basis) of particle diameters after swelling is 25.0 to 80.0 μm.
It is preferable to use a filter aid having a difference between D90 and D10 after swelling (D90-D10) of 25.0 to 80.0 μm, since the full-bodied aroma from the first half to the latter half of the flavor can be stably maintained over time from the time of production.
From this viewpoint, the filter aid used has a difference (D90-D10) between D90 and D10 of the cumulative distribution (volume basis) of particle diameter after swelling of 25.0 μm or more, more preferably 30.0 μm or more, more preferably 35.0 μm or more, and even more preferably 40.0 μm or more. On the other hand, it is preferably 80.0 μm or less, more preferably 70.0 μm or less, more preferably 60.0 μm or less, and even more preferably 50.0 μm or less.

<Mixing process>
In the preparation, water (hard water, soft water, ion-exchanged water, natural water, etc.), ascorbic acid, sodium ascorbate, sodium bicarbonate, sugars, dextrin, flavorings, emulsifiers, stabilizers, other flavoring materials, etc., or a combination of two or more of these may be added to mainly adjust the pH, concentration, and taste. For example, the pH may be adjusted to about 6 and the Brix may be adjusted to about 0.3.

<Sterilization and container filling process>
Heat sterilization may be carried out by reheating (hot packing) the beverage in a can as necessary, filling the beverage, and then performing retort sterilization (for example, heat sterilization at 121° C. for 7 minutes under appropriate pressure (e.g., 1.2 mmHg)). In the case of a beverage in a plastic bottle, UHT sterilization (holding the prepared liquid at 120 to 150° C. for 1 second to several tens of seconds) may be carried out.

The above-mentioned manufacturing process, i.e., the manufacturing process of manufacturing a green tea beverage through the extraction process, the coarse filtration process, the centrifugation process, the filtration process, the blending process, and the sterilization and container filling process, is merely one example of the present invention and is not limited to this. For example, the order of the processes can be changed, or other processes can be added.

The T% (660 nm) of the beverage liquid in the packaged green tea beverage after filling is preferably 90.0% or more. If the T% (660 nm) is 90.0% or more, the clarity is high and a refreshing taste is obtained. From this viewpoint, it is more preferable that the T% (660 nm) of the beverage liquid in the packaged green tea beverage after filling is 93.0% or more.
On the other hand, the upper limit can be assumed to be 99.0% or less, and in particular 98.0% or less.

<<Terminology explanation>>
In this specification, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", as well as "preferably larger than X" or "preferably smaller than Y".
Furthermore, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also includes the intention that "it is preferably greater than X" or "it is preferably less than Y".

The present invention will now be described in further detail with reference to the following examples and comparative examples.

Example 1
30 g of raw green tea (first-grade tea of the Yabukita variety produced in Shizuoka, total nitrogen concentration 5.1 g/100 g) was extracted with 900 mL of hot water at 70° C. using a kneader for 5 minutes to obtain extract A. The total nitrogen concentration of the obtained tea extract A was measured.
Next, the obtained tea extract A was roughly filtered through an 80 mesh stainless steel filter, and the roughly filtered tea extract was forced to cool to 30°C, allowed to stand, and then filtered through a flannel cloth with 50 μm mesh.

Next, the filtrate after the flannel filtration was subjected to diatomaceous earth filtration using the filter aid A to obtain a diatomaceous earth filtered liquid. In this case, the diatomaceous earth filtration was performed by forming an auxiliary layer (precoat) made of diatomaceous earth on the surface of the filter carrier and sending the tea extract to the auxiliary layer.
Filter aid A was diatomaceous earth having a darcy of 0.16, a D50 of 15.0 μm, a D90 of 40.0 μm, and a D90/D50 of 2.7 (see Tables 1, 3, and 4).

Next, the diatomaceous earth filtrate was mixed with pure water in a 1:1 ratio, 300 ppm of ascorbic acid was added, and the pH was adjusted to 6 with sodium bicarbonate. The mixture was then UHT sterilized (135°C, 30 seconds), cooled on a plate, and filled into a transparent plastic container (PET bottle) at 85°C to obtain a bottled green tea beverage. The cap was then sterilized by inverting for 30 seconds and immediately cooled.

The D50 and D90 of the filter aids are the median diameters (D50) and D90 in the cumulative particle size distribution (volume basis) after 10 g of each filter aid is dispersed in 50 times the amount of pure water and immersed for 15 minutes to allow it to swell. These measurements were performed using a laser diffraction particle size distribution analyzer SALD-2300 manufactured by Shimadzu Corporation.

Example 2
60 g of the same raw material as in Example 1 was extracted with 900 mL of hot water at 70° C. for 5 minutes using a kneader to obtain extract B.
In addition, the filtrate after the Nel filtration was subjected to diatomaceous earth filtration using filter aid B (see the table for particle size distribution and darcy, the same applies to other filter aids) to obtain a diatomaceous earth filtered liquid. A packaged green tea beverage was obtained in the same manner as in Example 1, except that the filtrate after the Nel filtration was subjected to diatomaceous earth filtration using filter aid B (see the table for particle size distribution and darcy, the same applies to other filter aids).

Example 3
A bottled green tea beverage was obtained in the same manner as in Example 1, except that the filtrate after filtering the extract B through the flannel was filtered through diatomaceous earth using filter aid C to obtain a diatomaceous earth-filtered liquid.

Example 4
The green tea raw material was changed to a 1:1 mixture of first-catch tea and autumn/winter bancha tea of the Yabukita variety produced in Shizuoka, and 30 g of the green tea raw material was extracted with 900 mL of hot water at 70°C using a kneader for 5 minutes to obtain extract C.
In addition, the filtrate after the flannel filtration was subjected to diatomaceous earth filtration using filter aid B to obtain a diatomaceous earth-filtered liquid. In the same manner as in Example 1, except for this, a packaged green tea beverage was obtained.

Example 5
A bottled green tea beverage was obtained in the same manner as in Example 1, except that the filtrate after filtering extract C through a filter aid C was filtered through diatomaceous earth to obtain a diatomaceous earth-filtered liquid.

<Comparative Example 1>
A packaged green tea beverage was obtained in the same manner as in Example 1, except that the green tea raw material was changed to Gyokuro produced in Fukuoka (total nitrogen concentration 6.5 g/100 g), and 60 g of the green tea raw material was extracted with 900 mL of hot water at 70° C. using a kneader for 10 minutes to obtain extract J.

<Comparative Example 2>
A packaged green tea beverage was obtained in the same manner as in Example 1, except that the green tea raw material was changed to Shizuoka-grown Yabukita variety autumn winter bancha tea (total nitrogen concentration 3.8 g/100 g), and 30 g of the green tea raw material was extracted with 900 mL of 70°C hot water using a kneader for 5 minutes to obtain extract K.

<Comparative Example 3>
A bottled green tea beverage was obtained in the same manner as in Example 1, except that the filtrate after filtering the extract A through the flannel was filtered through diatomaceous earth using filter aid D to obtain a diatomaceous earth-filtered liquid.

<Comparative Example 4>
A bottled green tea beverage was obtained in the same manner as in Example 1, except that the filtrate after filtering the extract A through a filter aid E was filtered through diatomaceous earth to obtain a diatomaceous earth-filtered liquid.

<Analysis of extract>
(Total nitrogen concentration)
The total nitrogen concentration in the extract was measured by the Kjeldahl method using a Kjeltec 8400 manufactured by PHOSS Japan Co., Ltd.

<Beverage liquid T%>
The packaged green tea beverages obtained in the Examples and Comparative Examples were shaken well, and 4.0 mL of each was sampled in a standard glass cell. The transmittance (660 nm) was measured using a Shimadzu UV-1800 ultraviolet-visible spectrophotometer, and the result was expressed as clarity (T%).

<Sensory evaluation test>
For the packaged green tea beverages obtained in the Examples and Comparative Examples, 11 panelists engaged in the manufacture of tea beverages were selected and conducted an evaluation based on the following evaluation method. After consensus was reached, it was decided to adopt the most common evaluation. For the overall evaluation, the above-mentioned evaluations were scored and a total score was calculated to evaluate whether the problem in question had been solved.

The evaluation items for each sensory evaluation were as follows:
"Richness due to umami in the aftertaste" was evaluated as the lingering umami flavor remaining on the tongue after swallowing the packaged green tea beverage, and "richness due to aroma in the aftertaste" was evaluated as the lingering aroma that escapes from the mouth to the nostrils after swallowing.

(Rich aftertaste due to umami flavor)
4: The aftertaste has a strong umami richness, very good 3: The aftertaste has a strong umami richness, good 2: The aftertaste has a slightly weak or strong umami richness, but has a slightly unpleasant off-flavor 1: The aftertaste has a weak or strong umami richness, but has a noticeable off-flavor, unsuitable

(Aftertaste richness due to aroma)
4: The aftertaste has a strong aroma and rich flavor, very good 3: The aftertaste has a strong aroma and rich flavor, good 2: The aftertaste has a slightly weak or strong aroma and rich flavor, but the tongue feels rough and undesirable 1: The aftertaste has a weak or strong aroma and rich flavor, but the tongue feels rough and undesirable

(Discussion)
From the results of the above Examples and Comparative Examples, as well as the results of tests conducted by the present inventors thus far, it has been found that by adjusting the type of green tea leaves, the tea season, the extraction conditions, etc. to obtain a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL, and filtering the obtained tea extract through a filter aid having a median diameter (D50) of 5 to 30 μm in the cumulative distribution (volume basis) of particle sizes after swelling, it is possible to produce a packaged green tea beverage that has a delicious aftertaste and a rich aroma.
In this case, it was found that the desired packaged green tea beverage cannot be produced simply by adjusting the total nitrogen concentration of the extract, and the desired packaged green tea beverage cannot be produced simply by adjusting the D50 of the filter aid. It was found that in order to produce the desired packaged green tea beverage, it is necessary to adjust both of these factors.

In Comparative Example 1, the total nitrogen concentration of the green tea raw materials was high, and the amount of the green tea raw materials was also large, so the total nitrogen concentration of extract J was high. Although the packaged green tea beverage had a strong sense of richness due to the umami of the aftertaste and richness due to the aroma, it also had a slightly unpleasant unpleasant taste and a rough texture on the tongue, which is thought to have resulted in a poor evaluation of richness.
In Comparative Example 2, the total nitrogen concentration of the green tea raw material was low, so the total nitrogen concentration of the extract K was low, and the packaged green tea beverage had a somewhat weaker richness due to the umami of the aftertaste and the richness due to the aroma, which is thought to have resulted in a poor evaluation of richness.
In Comparative Example 3, since the D50 of filter aid D was large, the packaged green tea beverage had a noticeable roughness on the tongue and was unsuitable, which is thought to have resulted in a poor evaluation of richness.
In Comparative Example 4, since the D50 of filter aid E was small, the body of the packaged green tea beverage was felt to be weak due to the aftertaste aroma and was unsuitable, which is thought to have resulted in a poor evaluation of body.

Next, in the manufacturing method for a packaged green tea beverage that allows the user to feel the umami taste and rich aroma in the aftertaste as described above, further tests were conducted to produce a packaged green tea beverage that has a good early and middle flavor even after aging, more specifically, a packaged green tea beverage that has a good flavor felt immediately after putting the beverage in the mouth and a good persistence of the flavor felt immediately after putting the beverage in the mouth even after aging.

Example 6
34 g of green tea raw material (Gyokuro produced in Fukuoka Prefecture) was extracted with 900 mL of hot water at 70° C. using a kneader for 10 minutes to obtain extract D. The total nitrogen concentration of the obtained extract D was measured.
Next, the obtained extract D was roughly filtered through an 80 mesh stainless steel filter, and the roughly filtered tea extract was forced to cool to 30° C., allowed to stand, and then filtered through a flannel cloth.
The filtrate after filtering through the filter was measured for the contents of potassium, aluminum and gallate-type catechin contained in the liquid, and the particle size distribution of the particles contained in the liquid was measured to determine D50 and D90.

Next, the filtrate after the flannel filtration was subjected to diatomaceous earth filtration using filter aid A to obtain a diatomaceous earth-filtered liquid.
Here, filter aid A was a diatomaceous earth with a darcy of 0.16, a D50 of 15.0 μm, a D90 of 40.0 μm, and a D90/D50 of 2.7.

Next, the diatomaceous earth filtrate was mixed with pure water in a 1:1 ratio, 300 ppm of ascorbic acid was added, and the pH was adjusted to 6 with sodium bicarbonate. The mixture was then UHT sterilized (135°C, 30 seconds), cooled on a plate, and filled into transparent plastic containers (PET bottles) at 85°C to produce a bottled green tea beverage. The cap was then sterilized by inverting for 30 seconds, and immediately cooled.

Example 7
A packaged green tea beverage was obtained in the same manner as in Example 6, except that the green tea raw material was changed to first-grade tea of the Yabukita variety produced in Shizuoka, and 22.5 g of the green tea raw material was extracted with 900 mL of hot water at 70°C using a kneader for 5 minutes to obtain extract E.

Example 8
A packaged green tea beverage was obtained in the same manner as in Example 6, except that the green tea raw material was changed to second-grade tea of the Yabukita variety produced in Kagoshima, and 56 g of the green tea raw material was extracted with 1,160 mL of hot water at 95°C using a kneader for 8 minutes to obtain extract F.

<Example 9>
Extract liquid A was obtained in the same manner as in Example 1, and after crude filtration using an 80-mesh stainless steel filter, it was forcibly cooled to 30°C. The stationary extract liquid A was contacted with 12 g of PVPP for 30 minutes and filtered through a flannel cloth to reduce the content of gallate-type catechins using PVPP, thereby obtaining extract liquid G. A packaged green tea beverage was obtained in the same manner as in Example 6, except that the extract liquid A was obtained by coarse filtration using an 80-mesh stainless steel filter, and then forcibly cooled to 30°C. The stationary extract liquid A was contacted with 12 g of PVPP for 30 minutes and filtered through a flannel cloth to obtain extract liquid G.

Example 10
Extract liquid A was obtained in the same manner as in Example 1, coarsely filtered through an 80-mesh stainless steel filter, and then forcibly cooled to 30°C. Extract liquid A that had been allowed to stand was then filtered through a 200-mesh stainless steel filter to obtain extract liquid H. A packaged green tea beverage was obtained in the same manner as in Example 6, except that the extract liquid A was obtained in the same manner as in Example 1, coarsely filtered through an 80-mesh stainless steel filter, and then forcibly cooled to 30°C.

Example 11
Extract liquid A was obtained in the same manner as in Example 1, coarsely filtered through an 80 mesh stainless steel filter, and then forcibly cooled to 30°C. Extract liquid A that had been allowed to stand was then filtered through a bag filter having 1 μm mesh to obtain extract liquid I. A packaged green tea beverage was obtained in the same manner as in Example 6, except that the extract liquid A was obtained by coarsely filtering through an 80 mesh stainless steel filter and forcibly cooling to 30°C.

<Analysis of extract>
The components in the extracts D to I obtained in the examples were analyzed as follows. The same applies to the following examples.

(Total nitrogen concentration)
The total nitrogen concentration in the extract was measured by the Kjeldahl method using a Kjeltec 8400 manufactured by PHOSS Japan Co., Ltd.

(Potassium content)
The sample was shaken and extracted with 1% hydrochloric acid to prepare a test solution, which was then introduced into an atomic absorption spectrophotometer to measure the potassium content.
Measurement equipment: AA240FS (Agilent Technologies (formerly Varian))
Frame: Air-acetylene Measurement wavelength: 766.5 nm

(Aluminum content)
The sample was diluted with 1% nitric acid to prepare a test solution, which was then introduced into an ICP emission spectrometer to measure aluminum.
Measurement device: VISTA-PRO (Agilent Technologies (formerly Varian))
Measurement wavelength: 396.152 nm

(Gallate-type catechin content)
The amount of gallate-type catechins in the extract was measured by high performance liquid chromatography (HPLC, i-Series, manufactured by Shimadzu Corporation) under the following conditions and quantitatively determined by the calibration curve method.
Column: Wakosil 3C18HG φ3.0×100 mm (Wako Pure Chemical Industries, Ltd.)
Column temperature: 40°C
Mobile phase: Phase A 5% acetonitrile (containing 0.1% phosphoric acid)
Phase B: 50% acetonitrile (containing 0.1% phosphoric acid)
Flow rate: 0.43 mL / min
Injection volume: 5 μL
Detection: UV 230 nm
Catechin standard solution: (-)-epigallocatechin gallate (EGCg), (-)-epicatechin gallate (ECg), (-)-gallocatechin gallate (GCg), (-)-catechin gallate (Cg)
Gradient program:

(Particle size distribution)
The median diameter (D50) and D90 in the cumulative particle diameter distribution (volume basis) of the particles contained in the extract were measured using a laser diffraction particle diameter distribution measuring device SALD-2300 manufactured by Shimadzu Corporation.

<Beverage liquid T%>
The packaged green tea beverages obtained in the Examples and Comparative Examples were shaken well, and 4.0 mL was sampled in a standard glass cell. The transmittance (660 nm) was measured using a Shimadzu UV-1800 ultraviolet-visible spectrophotometer, and the result was expressed as clarity (T%).

<Sensory evaluation test>
The packaged green tea beverages obtained in the Examples and Comparative Examples were exposed to a heat cycle (repeated at 40°C for 12 hours and -2°C for 12 hours, after a total of 14 days had passed), and then 11 panelists engaged in the manufacture of tea beverages were selected and evaluated based on the following method. After deliberation, it was decided to adopt the most common evaluation, and for the overall evaluation, the aforementioned evaluations were scored and calculated as a total score to evaluate whether the second problem of this case had been resolved.

The evaluation items for each sensory evaluation were as follows:
The "first half of the flavor" was evaluated based on the bitterness, astringency, and aroma immediately after putting the flavor in the mouth, while the "middle half of the flavor" was evaluated based on its lingering flavor.

(First half of the flavor)
◎: Very good (bitterness, astringency, and aroma are optimal)
〇: Good △: Not good

(Mid-stage flavor)
◎: Very good (maintains the aroma from the first half)
〇: Good △: Not good

(Discussion)
From the results of the above Examples and Comparative Examples, as well as the results of tests conducted by the inventor thus far, it has been found that by adjusting the components and particle size of the extract, in other words the tea extract subjected to the filtration process, it is possible to produce a packaged green tea beverage which has good aroma and flavor in the early and middle stages even after aging, more specifically, a packaged green tea beverage which has a good aroma and flavor felt immediately after taking a sip of the beverage in the mouth, and which has a good persistence of the aroma and flavor felt immediately after taking a sip of the beverage, even after aging.
Regarding the components of the tea extract, the packaged green tea beverage made with tea extract with a high potassium content had a bitter taste in the first half of the aroma, while the packaged green tea beverage made with tea extract with a low potassium content had a weak aroma in the middle. Also, the packaged green tea beverage made with tea extract with a high content of gallated catechins had an astringent taste in the first half of the aroma, while the packaged green tea beverage made with tea extract with a low content of gallated catechins had a weak sense of concentration due to the astringency in the middle of the aroma.
Regarding the particle size of the tea extract, the packaged green tea beverage made with a tea extract having a large D50 had a weak first half of the flavor, while the packaged green tea beverage made with a tea extract having a small D50 had a weak mid-flavor due to the mouthfeel.

Next, further tests were conducted to produce a packaged green tea beverage that, as described above, has a rich aftertaste and aroma, and has a good early and middle flavor even after aging, and in which deterioration of both the internal quality and appearance during production and over time is suppressed, more specifically, a packaged green tea beverage that does not produce an oxidative deterioration odor or sediment immediately after production or after aging.

Example 12
30 g of raw green tea (first-grade tea of the Yabukita variety produced in Shizuoka) was extracted with 900 mL of hot water at 70° C. using a kneader for 5 minutes to obtain extract A. The total nitrogen concentration of the obtained extract A was measured.
Next, the obtained extract A was roughly filtered through an 80 mesh stainless steel filter, and the roughly filtered tea extract was forced to cool to 30° C., allowed to stand, and then filtered through a flannel cloth.
The filtrate after filtering through the filter was measured for the contents of potassium, aluminum and gallate-type catechin contained in the liquid, and the particle size distribution of the particles contained in the liquid was measured to determine D50 and D90.

Next, the filtrate after the flannel filtration was subjected to diatomaceous earth filtration using filter aid F to obtain a diatomaceous earth-filtered liquid.
Here, filter aid F was a diatomaceous earth with a darcy of 0.17, a D50 of 25.0 μm, a D90 of 65.0 μm, and a D90/D50 of 2.6.

Next, the diatomaceous earth filtrate was mixed with pure water in a 1:1 ratio, 300 ppm of ascorbic acid was added, and the pH was adjusted to 6 with sodium bicarbonate. The mixture was then UHT sterilized (135°C, 30 seconds), cooled on a plate, and filled into transparent plastic containers (PET bottles) at 85°C to produce a bottled green tea beverage. The cap was then sterilized by inverting for 30 seconds, and immediately cooled.

Example 13
The filtrate after the flannel filtration was subjected to diatomaceous earth filtration using filter aid G to obtain a diatomaceous earth-filtered liquid. Except for this, a packaged green tea beverage was obtained in the same manner as in Example 12.
Here, filter aid G was a diatomaceous earth having a darcy of 0.15, a D50 of 15.0 μm, a D90 of 19.0 μm, and a D90/D50 of 1.3.

<Example 14>
The filtrate after the flannel filtration was subjected to diatomaceous earth filtration using filter aid H to obtain a diatomaceous earth-filtered liquid, and other than this, a packaged green tea beverage was obtained in the same manner as in Example 12.
Here, filter aid H was a diatomaceous earth with a darcy of 1.3, a D50 of 25.0 μm, a D90 of 60.0 μm, and a D90/D50 of 2.4.

Example 15
The filtrate after the flannel filtration was subjected to diatomaceous earth filtration using filter aid I to obtain a diatomaceous earth-filtered liquid, and other than this, a bottled green tea beverage was obtained in the same manner as in Example 12.
Here, filter aid H was a diatomaceous earth having a darcy of 0.03, a D50 of 12.0 μm, a D90 of 58.0 μm, and a D90/D50 of 4.8.

<Beverage liquid T%>
The packaged green tea beverages obtained in the Examples and Comparative Examples were shaken well, and 4.0 mL of each was sampled in a standard glass cell. The transmittance (660 nm) was measured using a Shimadzu UV-1800 ultraviolet-visible spectrophotometer, and the result was expressed as clarity (T%).

<Sensory evaluation test>
The packaged green tea beverages obtained in the Examples and Comparative Examples were evaluated immediately after production and after two weeks of storage in a dark room at 37°C by 11 panelists engaged in the production of tea beverages, who carried out the evaluation based on the following method. After consensus was reached, it was decided to adopt the most common evaluation, and the overall evaluation was calculated by scoring the above-mentioned evaluations to determine whether the second problem of this case had been resolved.

The evaluation items for each sensory evaluation were as follows:
The "internal quality immediately after production" was evaluated based on the degree of oxidative deterioration during the production stage, which was caused by the time required for diatomaceous earth filtration and the occurrence of liquid retention, based on whether or not an oxidative deterioration odor (more specifically, an aroma with a metallic sourness) was observed compared to the control. As a control, a packaged green tea beverage obtained in the same manner as in Example 1, except that extract A after flannel filtration was not subjected to diatomaceous earth filtration, was used.
The "appearance and internal quality after aging" was evaluated by exposing the beverage to a heat cycle (repeated 12 hours at 40°C and 12 hours at -2°C for a total of 14 days), and then evaluating the degree of sediment generation in the appearance and the degree of thermal and oxidative deterioration in the internal quality, in comparison with a control. As controls, samples of the bottled green tea beverages obtained in Examples 12 to 15 that had been refrigerated in a dark room at 5°C for the same period were used.

(Inner quality immediately after production)
◎: Very good (same as control or slight difference)
〇: Good (small difference from control)
△: Not preferable (difference from control)

(Appearance and internal structure after aging)
◎: Very good (slight difference from control)
〇: Good (small difference from control)
△: Not preferable (difference from control)

(Discussion)
From the results of the above Examples and Comparative Examples, as well as the results of tests conducted by the present inventors thus far, it has been found that by using a filter aid having a particle size and darcy within a suitable range, it is possible to produce a packaged green tea beverage in which deterioration of both the internal quality and appearance during production and over time is further suppressed, more specifically, a packaged green tea beverage which does not produce an oxidative deterioration odor or sediment immediately after production or over time.
Regarding the particle size of the filter aid, the packaged green tea beverages filtered through diatomaceous earth using filter aids with a large D90 were confirmed to have an oxidative deterioration odor over time, while the packaged green tea beverages filtered through diatomaceous earth using filter aids with a small D90 were confirmed to have oxidative deterioration during the manufacturing process.
In addition, packaged green tea beverages filtered using diatomaceous earth with a high Darcy filter aid were found to produce secondary sediment over time, while packaged green tea beverages filtered using diatomaceous earth with a low Darcy filter aid overall lacked the sense of concentration expected of a green tea beverage.

Claims (9)

A method for producing a packaged green tea beverage, comprising extracting green tea leaves with an aqueous solvent to obtain a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL, and filtering the tea extract through diatomaceous earth as a filter aid having a median diameter (D50) of 5 to 30 μm in the cumulative particle diameter distribution (volume basis) after swelling. The method for producing a bottled green tea beverage according to claim 1 , wherein the filter aid has a darcy of 0.11 to 0.25. The method for producing a bottled green tea beverage according to claim 1 or 2, wherein the filter aid has a cumulative particle size distribution (volume basis) D90 after swelling of 20 to 60 μm. The method for producing a bottled green tea beverage according to claim 1 or 2, wherein the filter aid has a ratio of D90 to D50 (D90/D50) of the cumulative distribution (volume basis) of particle sizes after swelling of 1.0 to 6.0. The method for producing a packaged green tea beverage according to claim 1 or 2, wherein the median diameter (D50) of the cumulative particle diameter distribution (volume basis) of the particles contained in the tea extract is 2 to 20 μm. The method for producing a packaged green tea beverage according to claim 1 or 2, wherein the tea extract has a potassium content of 25 to 70 mg/100 mL. The method for producing a packaged green tea beverage according to claim 1 or 2, wherein the tea extract contains 30 to 200 mg/100 mL of gallate-type catechins. The method for producing a packaged green tea beverage according to claim 1 or 2, wherein the tea extract contains particles with a ratio (D90/D50) of D90 to D50 of the cumulative particle size distribution (volume basis) of 2.0 to 10.0. A method for improving the body of a packaged green tea beverage, comprising extracting tea leaves with an aqueous solvent to obtain a tea extract having a total nitrogen concentration of 20 to 60 mg/100 mL, and filtering the tea extract through diatomaceous earth as a filter aid having a median diameter (D50) of 5 to 30 μm in the cumulative particle diameter distribution (volume basis) after swelling.