JP5409447B2 - Purification method of tea extract - Google Patents

Description

  The present invention relates to a method for purifying a tea extract.

  Demand for tea-based beverages is increasing due to diversification of consumer preferences and health-conscious enhancement. Tea-based beverages are usually manufactured by blending a tea extract obtained from tea, but the flavor balance is disrupted by the tannin concentration in the blended tea extract, or the aggregation of tea components in the tea extract, etc. As a result, turbidity was generated and the commercial value could be lost.

  Conventionally, as a method for improving the flavor of the tea extract, for example, nitrogen was injected into the tea extract obtained from tea leaves at room temperature to perform bubbling, and further agitated to foam, and formed on the surface of the tea extract. A method for removing bubbles has been proposed (Patent Document 1). In addition, as a method for producing a high-clarity tea extract, a tea extract obtained from tea leaves is treated with a zeta membrane, and a median diameter of 1 to 3 is contained in a solution containing a tea extract purified to a turbidity of about 0.03. There has been proposed a method of releasing bubbles of 200 μm and then removing the bubble layer formed on the liquid surface (Patent Document 2).

JP-A-2005-176761 JP 2008-113621 A

The method described in Patent Document 1 is effective in improving the flavor balance, but the improvement in clarity is insufficient. Moreover, although the method of patent document 2 can obtain the tea extract with high clarification degree, since it requires a long time to highly clarify, there is room for improvement in terms of manufacturing efficiency.
Therefore, the subject of this invention is providing the purification method which clarifies a tea extract efficiently and highly.

  Usually, when a physical shearing force is applied to a tea extract containing fine bubbles, it is predicted that the purification efficiency is reduced due to the burst of fine bubbles, the dissociation of substances adsorbed on the fine bubbles, and the like. However, the present inventors surprisingly made the tea extract and the fine bubbles agitated and contacted to remove the foam layer formed on the liquid surface, so that the refining efficiency was not lowered to a high degree. It was found that a clarified purified tea extract is obtained.

  That is, the present invention uses a tea extract purification method and a method in which a tea extract and fine bubbles having a median diameter of 1 to 200 μm are stirred and contacted, and then a foam layer formed on the liquid surface is removed. Beverages are provided.

  According to the present invention, a tea extract can be clarified efficiently and highly efficiently by a simple operation, and a refined tea extract having a good taste with little astringency can be obtained. As described above, the purified tea extract obtained by the purification method of the present invention has high clarity and good flavor, and is useful as a raw material for non-tea beverages such as tea beverages and sports drinks. .

It is a schematic diagram which shows one Embodiment of the tea extract refinement | purification apparatus of this invention. It is a schematic diagram which shows other embodiment of the tea extract refinement | purification apparatus of this invention. It is a figure which shows the relationship between processing time and ratio (after refinement | purification / before refinement | purification) of the turbidity of the tea extract before and behind refinement | purification. It is a figure which shows the relationship between processing time and ratio (after refinement | purification / before refinement | purification) of the turbidity of the tea extract before and behind refinement | purification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. For the convenience of illustration, the dimensional ratios in the drawings do not necessarily match those described.

First, the tea extract refiner | purifier of this invention is demonstrated.
(First embodiment)
FIG. 1 is a schematic diagram showing a tea extract purification apparatus according to the first embodiment of the present invention. The tea extract refining device 10 includes a fine bubble generating means 11, a processing tank 12, and a stirring means 22. The fine bubble generating means 11 is connected to the processing tank 12 through a circulation path, and the stirring means 22 is disposed in the processing tank 12.

  The fine bubble generating means 11 is not particularly limited as long as bubbles having a predetermined median diameter can be generated. For example, a device using a pressure dissolution method, a swirl method, a shock wave method, a pore method, a shear method, or an ultrasonic method is used. It is possible to use a commercially available fine bubble generator. Here, the pressure dissolution method is a method in which a gas is dissolved in a liquid under pressure and then released under reduced pressure to generate fine bubbles. The swirling method is a method in which a cavity is generated by a swirling flow of bubbles and water, and fine bubbles are generated by a swirling flow difference before and after the cavity. The shock wave method is a method of generating fine bubbles by supplying a gas to a narrow path portion and applying a shock wave (cavitation) to the narrow path portion. The pore method is a method of generating fine bubbles by extruding gas at high pressure from fine pores of a filter or shirasu porous glass film. The shearing method is a method of generating fine bubbles by applying a mechanical cutting force such as a water jet. The ultrasonic method is a method of generating fine bubbles by supplying gas from a thin needle tip into water in an ultrasonic field. Among these, the pressure dissolution method is particularly preferable in that it produces the largest amount of fine bubbles.

  The fine bubble generating means 11 according to the present embodiment is a fine bubble generating device using a pressure dissolution method. Specifically, the fine bubble generating means 11 includes a gas-liquid dissolving means 16 for dissolving a gas in the tea extract 13 and a fine bubble generating nozzle 17 for discharging the fine bubbles 14. A circulation pump 18 for supplying the tea extract 13 from the processing tank 12 to the gas-liquid dissolving means 16 is disposed upstream of the gas-liquid dissolving means 16 in the circulation path. Is equipped with a gas introduction pipe 19 for supplying gas. Further, on the downstream side of the gas-liquid dissolving means 16 in the circulation path, a gas-liquid separating means 20 equipped with a gas discharge pipe 21 for discharging undissolved gas to the tea extract 13 is disposed. . In the tea extract refining device 10 of the first embodiment, the fine bubble generating nozzle 17 is disposed below the treatment tank 12 and the fine bubble discharge surface faces the liquid surface side. Contact efficiency with the bubbles 14 can be increased.

(Second Embodiment)
Next, the tea extract refiner | purifier which concerns on 2nd Embodiment of this invention is demonstrated. FIG. 2 is a schematic diagram showing the tea extract purification apparatus according to the present embodiment.
The tea extract refining apparatus 100 of this embodiment has the same device configuration as the tea extract refining apparatus 10 of the first embodiment in that it includes fine bubble generating means 11, a processing tank 12, and a stirring means 22. However, it differs from the tea extract refining apparatus 10 in that the fine bubble discharge surface of the fine bubble generation nozzle 17 faces the bottom side of the processing tank 12. In addition, each apparatus structure and arrangement | positioning of the tea extract refinement | purification apparatus 100 of this embodiment are as having demonstrated in 1st Embodiment except the said difference.

  In the tea extract purification apparatus 100 of the second embodiment, the fine bubble generating nozzle 17 is disposed above the processing tank 12 and the fine bubble discharge surface faces the liquid surface side. The contact efficiency with the bubbles 14 can be increased.

Next, the purification method of the present invention will be described with reference to the drawings.
First, a tea extract is prepared. Examples of the tea extract 13 include a tea extract obtained by extraction from tea or a concentrate thereof, and these may be used in combination.
Here, the tea extract is one extracted from tea using hot water or a water-soluble organic solvent by kneader extraction, column extraction, or the like, and has not been concentrated or purified. When extracting tea, a salt of an organic acid such as sodium ascorbate can be added to the extraction solvent in advance from the viewpoint of oxidation stability. Moreover, you may use together the method of extracting in so-called non-oxidative atmosphere, ventilating inert gas, such as boiling deaeration and nitrogen gas, and removing dissolved oxygen.

  Examples of the tea used for the extraction include tea trees selected from the genus Camellia, for example, C. var. Sinensis (including Yabuta species), C. var. Assamica, and hybrids thereof. Tea can be roughly classified into non-fermented tea, semi-fermented tea, and fermented tea depending on the processing method. Examples of non-fermented tea include green tea such as sencha, bancha, mochi tea, kettle tea, stem tea, stick tea, and bud tea. Examples of the semi-fermented tea include oolong tea such as iron kannon, color type, golden katsura, and martial arts tea. Furthermore, examples of fermented tea include black teas such as Darjeeling, Assam, Sri Lanka and the like. These can be used alone or in combination of two or more.

The concentrate of tea extract refers to a product obtained by partially removing a solvent from tea extract extracted from tea with hot water or a water-soluble organic solvent to increase the tannin concentration. 219384, JP-A-4-20589, JP-A-5-260907, JP-A-5-306279, and the like. Here, “tannin” in the present specification is a concept including non-polymer catechins, ester derivatives thereof (for example, gallic acid esters) and condensates thereof.
Commercially available products may be used as the concentrate of the tea extract, for example, green tea extraction such as “Polyphenone” from Mitsui Norin Co., “Theafranc” from ITO EN, “Sunphenon” from Taiyo Kagaku Co., Ltd. Examples of product concentrates. As a form of the concentrate of a tea extract, various things, such as solid, aqueous solution, and a slurry form, are illustrated.

  The tea extract used in the present invention is preferably at least one green tea extract selected from a green tea extract and a concentrate thereof.

  In the present invention, the tea extract may be used as it is as the tea extract, or the tea extract and / or the concentrate of the tea extract may be concentrated or diluted with water as necessary. After tea extraction, for example, even if the tea extract obtained from tea is filtered with a punching metal or a wire mesh of about 100 mesh to separate it from tea leaves, an opening of 5 μm is used to remove tea-derived fine particles. You may filter with the filter of a grade.

  As described above, the tea extract used in the present invention does not need to be highly purified, and it is possible to use a tea extract with low clarity. The turbidity (OD 660 nm) of the tea extract is preferably 0.015 to 0.6, more preferably 0.02 to 0.45, and particularly preferably 0.05 to 0.4. In the present specification, “turbidity” is a value measured by the method described in the Examples below.

  Moreover, you may use what was processed with enzymes, such as tannase, as a tea extract. Here, “tannase treatment” refers to bringing a tea extract and / or a concentrate thereof into contact with an enzyme having tannase activity. In addition, a well-known method can be employ | adopted for the specific operation method in a tannase process, For example, the method as described in Unexamined-Japanese-Patent No. 2004-321105 is illustrated.

The tannin concentration in the tea extract is not particularly limited, but is preferably 10 to 500 mg / 100 mL, more preferably 20 to 400 mg / 100 mL, and particularly preferably 30 to 350 mg / 100 mL.
The Brix of the tea extract is not particularly limited, but is 0.05 to 5%, more preferably 0.15 to 3.5%, and particularly preferably 0.4 to 3%.
In the present specification, “tannin concentration” and “Brix” are values measured by the method described in the examples below.

Next, the prepared tea extract 13 is supplied to the treatment tank 12.
In the present invention, the pH of the tea extract 13 supplied into the treatment tank 12 may be adjusted. The pH of the tea extract 13 (20 ° C., the same shall apply hereinafter) is preferably 5.5 or less, more preferably 5 or less, still more preferably 4.5 or less, and particularly preferably 4 or less. Thus, by setting the pH of the tea extract to 5.5 or less, turbid components in the tea extract 13 and the like are easily adsorbed on the surface of the fine bubbles 14. The lower limit of the pH is not particularly limited as long as the member of the apparatus does not corrode, and can be appropriately determined depending on the material of the member. For example, when the member is a corrosion-resistant material such as titanium, the pH is preferably 2, and when the member is a material with relatively low acid resistance such as SUS, the pH is preferably 2.8, and particularly preferably 3. In addition, it is possible to use inorganic acid and / or organic acid for pH adjustment, for example, hydrochloric acid and ascorbic acid are used suitably.

  Moreover, in this invention, you may adjust the temperature of the tea extract 13 supplied in the processing tank 12. FIG. The temperature of the tea extract 13 is preferably 30 to 100 ° C., more preferably 35 to 90 ° C., still more preferably 35 to 80 ° C., and particularly preferably 40 to 70 ° C. from the viewpoint of clarity and flavor improvement. In order to control to such a temperature, for example, a heating means or a heat retaining means may be provided in the processing tank 12 shown in FIG.

Next, the tea extract 13 supplied into the treatment tank 12 is stirred. In addition, you may start stirring before discharge | release of the microbubble mentioned later or simultaneous discharge | release of a microbubble.
Stirring can be performed using stirring means 22 such as a stirrer having a stirring blade. The type of the stirring blade is not particularly limited, and for example, a paddle blade, a turbine blade, a propeller blade, an anchor blade, a helical screw blade, or the like can be used. The number of blades can be selected as appropriate, but is usually 2 to 8 blades. The blade diameter is not limited as long as the tea extract 13 in the treatment tank 12 is designed to be sufficiently mixed, but from the viewpoint of mixing efficiency and power, the blade diameter is relative to the inner diameter of the treatment tank 12. Therefore, it is preferably about 50 to 80%. Further, in the present invention, even if stirring is performed in the vicinity of the fine bubble generating nozzle 17, the purification efficiency is not impaired. Therefore, the installation position of the stirring blade does not inhibit the generation of the fine bubbles and does not interfere with the fine bubble generating nozzle 17. If it is, it will not specifically limit. In addition, it is preferable to install in the position away from the liquid surface in the processing tank 12 in order not to entrain the floating matter generated at the time of mixing.

  In the present invention, a baffle plate may be disposed in the treatment tank 12 and may be in a completely baffle plate state, but from the viewpoint of further improving the clarity and flavor, the agitation conditions may be gentle. preferable. Specifically, as stirring conditions, the stirring Reynolds number (stirring Re) of the tea extract 13 is preferably 2300 to 60000, more preferably 5000 to 50000, still more preferably 10,000 to 45000, and particularly preferably 20000 to 40000. To do.

The stirring Re is represented by the following formula:
Re = nd ² ρ / μ
(Where n is the number of revolutions of the stirring blade [s ⁻¹ ], d is the diameter of the stirring blade [m], ρ is the density of the liquid [kg · m ⁻³ ], and μ is the viscosity of the liquid [Pa · s]. Represent)
Defined by

  Next, the tea extract 13 in the treatment tank 12 is transferred to the gas-liquid dissolving means 16 by the circulation pump 18 via the pipe L1. The pipe L1 is provided with a flow rate detection means FI for controlling the supply rate of the tea extract 13. The supply rate of the tea extract 13 is not particularly limited as long as the supply amount per minute does not exceed the capacity of the tea extract 13 supplied to the treatment tank 12, but from the viewpoint of improving the clarity, the supply amount per minute. Is preferably 50 to 80% by volume with respect to the capacity of the tea extract 13 supplied to the treatment tank 12.

  Next, the gas supplied from the gas introduction pipe 19 is sucked by the circulation pump 18, and the gas is dissolved in the tea extract 13 in the gas-liquid dissolving means 16 under a pressurized condition. The gas supply rate from the gas introduction pipe 19 is preferably 0.01 to 5 L / min, more preferably 0.1 to 1 L / min, and particularly preferably 0.3 to 0.7 L / min. The dissolution pressure is preferably 0.2 to 0.7 MPa. The circulation pump 18 and the valve of the gas introduction pipe 19 may be controlled based on the detection result of the flow rate detection means FI.

  The type of gas to be dissolved is not particularly limited, but preferably contains carbon dioxide, nitrogen, and other inert gases in order to prevent quality deterioration due to oxygen. Among these, nitrogen is particularly preferable because it has low reactivity with components in the tea extract and has low solubility in beverages and does not remain. The nitrogen concentration in the gas is preferably 95% by volume or more.

Next, the tea extract 13 in which the gas is dissolved in the gas-liquid dissolution means 16 is transferred to the gas-liquid separation means 20, and excess gas not dissolved in the tea extract 13 is discharged from the gas discharge pipe 21.
Next, the tea extract 13 in the gas-liquid separation means 20 is transferred to the fine bubble generating nozzle 17 by the circulation pump 18, and the fine bubbles 14 are released from the fine bubble generating nozzle 17 into the stirred tea extract 13. . Thereby, the tea extract 13 and fine bubbles are brought into contact with stirring. The supply rate of the tea extract 13 to the fine bubble generating nozzle 17 is preferably substantially the same as the supply rate from the processing tank 12 to the gas-liquid dissolving means 16.

  The median diameter of the fine bubbles 14 to be agitated and contacted is 1 to 200 μm, but preferably 1 to 150 μm, more preferably 1 to 100 μm, and particularly preferably 5 from the viewpoints of improving the clarity, stability of the bubbles and particle size control. ~ 60 μm. The “median diameter” can be measured by a batch cell using a laser diffraction method (such as SALD-7100 manufactured by Shimadzu Corporation).

The volume of the released gas is preferably 0.1 to 10% by volume, more preferably 0 as a converted value at 25 ° C. and 1 atm with respect to the tea extract 13 from the viewpoint of efficient removal of suspensions and the like. .2-7% by volume, particularly preferably 0.2-5% by volume. The number density of bubbles in the tea extract 13 is preferably 10 ² to 10 ⁶ / cm ³ , more preferably 10 ³ to 10 ⁵ / cm ³ . The number density of bubbles can be measured with a particle counter (manufactured by RION, KS-17A).

  The released fine bubbles 14 come into contact with turbid components and astringency components in the tea extract 13, adsorb the components, and float on the liquid surface. The tea extract 13 is preferably circulated through a part or all of the inside of the apparatus and sufficiently brought into contact with the fine bubbles 14 from the viewpoint of further clarifying, and the circulation time is preferably 20 to 120 minutes. More preferably, it is 30 to 90 minutes, Most preferably, it is 40 to 60 minutes.

  Next, the foam layer 15 formed on the liquid surface is removed. As a method for removing the foam layer 15, for example, filter filtration, centrifugal separation, foam vacuum, or the like can be employed. Further, as a simple operation, a method of discharging the purified tea extract from the discharge pipe 23 below the processing tank 12 shown in FIG. 1 so that only the foam layer 15 formed on the liquid surface remains in the processing tank 12. Is exemplified.

The purified tea extract thus obtained has a ratio between the turbidity of the tea extract after purification and the turbidity of the tea extract before purification (after purification / before purification, “turbidity before and after purification”). The ratio may also be 0.6 or less, more preferably 0.55 or less, more preferably 0.5 or less, still more preferably 0.45 or less, and particularly preferably 0.4 or less. The lower limit of the turbidity ratio is not particularly limited.
The reason why such a highly clarified purified tea extract is obtained is not necessarily clear, but when it is stirred under mild conditions, the frequency of collision with the components in the tea extract is increased without disrupting the fine bubbles. As a result, the present inventors speculate that the adsorption efficiency is improved.

  Moreover, the obtained purified tea extract not only has a high degree of clarity, but also has a markedly reduced astringency. Therefore, the purified tea extract of the present invention can be used as it is or diluted or concentrated as necessary to make a beverage.

  Examples of the beverage include tea-based beverages and non-tea-based beverages. Examples of tea-based beverages include green tea beverages, oolong tea beverages, and black tea beverages. Non-tea beverages include soft drinks (eg fruit juice, vegetable juice, sports drinks, isotonic drinks), non-alcoholic drinks such as coffee drinks, nutrition drinks, beauty drinks, beer, wine, sake, plum wine. Examples include alcoholic beverages such as sparkling liquor, whiskey, brandy, shochu, rum, gin, and liqueurs.

  For beverages, antioxidants, fragrances, organic acids, organic acid salts, inorganic acids, inorganic acid salts, inorganic salts, pigments, emulsifiers, preservatives, seasonings, sweeteners, acidulants, gums, oils, vitamins, amino acids Additives such as fruit juice extract, vegetable extract, nectar extract, pH adjuster and quality stabilizer may be used alone or in combination.

  The pH (20 ° C.) of the beverage is preferably 2 to 7, particularly preferably 2 to 6.5, from the viewpoint of flavor and tannin stability.

  From the viewpoint of flavor, the tannin concentration in the beverage is 60 to 500 mg, more preferably 80 to 500 mg, and particularly preferably 100 to 400 mg per 100 mL of the beverage.

  Beverages can be provided by filling them into ordinary packaging containers such as molded containers (so-called PET bottles) mainly composed of polyethylene terephthalate, metal cans, paper containers combined with metal foil and plastic films, and bottles.

  In addition, beverages packed in containers, for example, can be sterilized under the sterilization conditions stipulated in the applicable regulations (Food Sanitation Act in Japan) if they can be heat sterilized after filling into containers such as metal cans. Can be manufactured. For PET bottles and paper containers that cannot be sterilized by retort, sterilize under the same conditions as above, for example, after sterilizing at high temperature and short time with a plate heat exchanger, etc. The method can be adopted. Moreover, you may mix | blend another component with the filled container under aseptic conditions. Furthermore, after sterilization by heating under acidic conditions, the pH can be returned to neutrality under aseptic conditions, or after sterilization by heating under neutral conditions, the pH can be returned to acidic conditions under aseptic conditions.

(1) Measurement of tannin The amount of tannin in each green tea extract or purified green tea extract was determined by the iron tartrate method, using ethyl gallate as a standard solution, and as a converted amount of gallic acid (reference: “green tea "Polyphenol" functional material effective utilization technology series No. 10 for food and drink. 5 mL of a sample was developed with 5 mL of iron tartrate standard solution, dissolved in 25 mL with a phosphate buffer, the absorbance was measured at 540 nm, and the amount of tannin was determined from a calibration curve with ethyl gallate.
Preparation of iron tartrate standard solution: 100 mg of ferrous sulfate heptahydrate and 500 mg of sodium / potassium tartrate (Rochelle salt) were made up to 100 mL with distilled water.
Preparation of phosphate buffer: 1/15 mol / L disodium hydrogen phosphate solution and 1/15 mol / L sodium dihydrogen phosphate solution were mixed and adjusted to pH 7.5.

(2) Measurement of turbidity After diluting each green tea extract or purified green tea extract with ion-exchanged water so that the tannin concentration is 65 mg / 100 mL, the wavelength is measured using a turbidimeter (U-2010 HITACHI). It measured at 20 degreeC by the 660 nm and 90 degree transmission-scattering comparison system.

(3) Measurement of Brix Each green tea extract or purified green tea extract was subjected to Brix measurement at 20 ° C. using a saccharimeter (Atago RX-5000α-Bev).

(4) Sensory evaluation After each purified green tea extract was diluted with ion-exchanged water so that the tannin concentration was 65 mg / 100 mL, the astringency and bitterness were evaluated by the following 5 panelists for the astringency and bitterness. Were determined.

Evaluation standard of astringency About the astringency of each refined green tea extract, the astringency of the green tea extract of Comparative Example 1 (tannin concentration 65 mg / 100 mL) was evaluated in 11 stages from 0 to 10 with a rating of 5 (reference). The lower the value, the weaker the astringency. The higher the value, the stronger the astringency.

Bitterness Evaluation Criteria The bitterness of each purified green tea extract was evaluated in 11 stages from 0 to 10, with the bitterness of the green tea extract of Comparative Example 1 (tannin concentration 65 mg / 100 mL) being rated 5 (reference). The lower the value, the weaker the bitterness, and the higher the value, the stronger the bitterness.

Example 1
Add 0.35 kg of green tea leaves to 10.5 kg of hot water at 65 ° C., stir by hand for 30 seconds and let stand for 1 minute and 30 seconds, then stir by hand for 10 seconds and leave for 2 minutes and 50 seconds, The mixture was filtered through a 120-mesh wire mesh, further filtered through a 5 μm mesh filter, and cooled to 25 ° C. to obtain a green tea extract.
The obtained green tea extract was made up to 20 kg with ion-exchanged water to obtain a green tea extract. The obtained green tea extract had a tannin concentration of 130 mg / 100 mL, a turbidity (OD660) of 0.071, and a Brix of 0.48%.
Next, the green tea extract 20L is put into the treatment tank 12 (height 1000 mm × inner diameter 160 mm) of the tea extract refining apparatus 10 shown in FIG. 1 and 100 rpm using a 45-degree inclined four-paddle blade (blade diameter 100 mm). (Stirring Re = 18000). Next, the green tea extract was transferred to the gas-liquid dissolving means 16 by a vortex pump 18 (M20LD, manufactured by Nikuni Co., Ltd.). Next, the nitrogen supplied from the gas introduction pipe 19 at a rate of 0.5 L / min is dissolved in the green tea extract at a nitrogen dissolving pressure of 0.4 MPa (pressure dissolving method), and then undissolved nitrogen is removed. The liquid was removed from the gas discharge pipe 21 of the liquid separation means 20. Then, the green tea extract in which nitrogen was dissolved was released under reduced pressure, and fine bubbles 14 (median diameter 50 μm) were discharged from the fine bubble generation nozzle 17 into the green tea extract in the treatment tank 12. The green tea extract was circulated at a speed of 10 L / min and kept at 25 ° C.
Sampling was performed after 20 minutes and 30 minutes from the start of production, and turbidity was measured. After 60 minutes from the start of production, the foam layer formed on the liquid surface was removed, and the turbidity of the obtained purified green tea extract was measured. Table 1 shows the analysis results and sensory evaluation results of the obtained purified green tea extract. In Table 1, A ₀ indicates the turbidity of the green tea extract before purification, and A ₂₀ , A ₃₀ and A ₆₀ indicate the turbidity of the green tea extract after 20 minutes, 30 minutes and 60 minutes from the start of production, respectively. Degrees. B ₀ represents the Brix of the green tea extract before purification, and B ₆₀ represents the Brix of the green tea extract 60 minutes after the start of production. Furthermore, the change of the turbidity ratio (after purification / before purification) before and after purification with respect to the treatment time is shown in FIG.

Example 2
A purified green tea extract was obtained in the same manner as in Example 1, except that three stirrer blades and six baffle plates were arranged so as to satisfy the complete baffle plate conditions and stirred at 200 rpm (stirring Re = 37000). It was. Table 1 shows the analysis results and sensory evaluation results of the obtained purified green tea extract. Moreover, the change of the turbidity ratio (after purification / before purification) before and after purification with respect to the treatment time is shown in FIG.

Example 3
A purified green tea extract was obtained in the same manner as in Example 2 except that stirring was performed at 300 rpm (stirring Re = 55000). Table 1 shows the analysis results and sensory evaluation results of the obtained purified green tea extract. Moreover, the change of the turbidity ratio (after purification / before purification) before and after purification with respect to the treatment time is shown in FIG.

Example 4
A purified green tea extract was obtained in the same manner as in Example 1 except that the temperature of the green tea extract was adjusted to 55 ° C. and the stirring speed was changed to 200 rpm (stirring Re = 37000). Table 1 shows the analysis results and sensory evaluation results of the obtained purified green tea extract. Moreover, the change of the turbidity ratio (after purification / before purification) before and after purification with respect to the treatment time is shown in FIG.

Example 5
The purified green tea extract was prepared in the same manner as in Example 1 except that the pH and temperature of the green tea extract were adjusted to pH 3.0 and 53 ° C., respectively, and the stirring speed was changed to 200 rpm (stirring Re = 37000). Obtained. Table 1 shows the analysis results and sensory evaluation results of the obtained purified green tea extract. Moreover, the change of the turbidity ratio (after purification / before purification) before and after purification with respect to the treatment time is shown in FIG.

Comparative Example 1
The green tea extract obtained by the same operation as in Example 1 was made up to 20 kg with ion-exchanged water to obtain a green tea extract. This green tea extract was analyzed and sensory evaluation was performed. The results are shown in Table 1.

Comparative Example 2
A purified green tea extract was obtained in the same manner as in Example 1 except that the mixture was not stirred. Table 1 shows the analysis results and sensory evaluation results of the obtained purified green tea extract. Moreover, the change of the turbidity ratio (after purification / before purification) before and after purification with respect to the treatment time is shown in FIGS.

  From Table 1, the tea extract and fine bubbles with a median diameter of 1 to 200 μm are brought into contact with stirring, and then the foam layer formed on the liquid surface is removed, so that it is highly clarified and has astringency. It was confirmed that a reduced purified tea extract was obtained. Further, it was found that when the tea extract was brought into contact with fine bubbles in a gentle stirring state, a refined tea extract having a further improved clarity and a markedly reduced astringency was obtained. Furthermore, it has been found that the flavor of the purified tea extract is further improved by controlling the pH and / or temperature of the tea extract.

DESCRIPTION OF SYMBOLS 10 Tea extract refiner 11 Fine bubble generation means 12 Processing tank 13 Tea extract 14 Fine bubbles 15 Foam layer 16 Gas-liquid dissolution means 17 Fine bubble generation nozzle 18 Circulation pump 19 Gas introduction pipe 20 Gas-liquid separation means 21 Gas discharge Tube 22 Stirring means 23 Discharge tube

Claims (3)

A method for purifying a tea extract, wherein a tea extract and fine bubbles having a median diameter of 1 to 200 μm are stirred and contacted under a condition of a stirring Reynolds number of 10000 to 60000, and then the foam layer formed on the liquid surface is removed. The tea extract is a green tea extract, a purification method of claim 1, wherein. A container-packed beverage in which the tea extract obtained by the purification method according to claim 1 or 2 is filled in a container as it is, or is diluted or concentrated and filled into a container.

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