JP5420453B2 - 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.

  Accordingly, as a result of various studies on means for improving the clarity of the tea extract, the present inventors have controlled the pH of the tea extract to a specific region and brought it into contact with fine bubbles to form on the liquid surface. It was found that a highly clarified purified tea extract can be obtained efficiently by removing the foam layer.

  That is, the present invention adjusts the pH of the tea extract to 5.5 or less, then contacts it with fine bubbles having a median diameter of 1 to 200 μm, and then removes the foam layer formed on the liquid surface. A method for purifying an extract is provided.

  According to the present invention, a tea extract can be clarified efficiently and highly efficiently by a simple operation, and it can be a purified tea extract having a good taste with reduced bitterness and astringency. Thus, the purified tea extract obtained by the purification method of the present invention is useful as a raw material for tea-based beverages because of its high clarity and good flavor.

It is a schematic diagram which shows an example of the refinement | purification apparatus applicable to the purification method 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.

Hereinafter, the purification method of the present invention will be specifically described.
First, a tea extract is prepared. As the tea extract, a tea extract or a concentrate thereof is exemplified, and these may be mixed and used.
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 the solvent from the extract extracted from tea with hot water or a water-soluble organic solvent to increase the tannin concentration. For example, JP-A-59-219384 And JP-A-4-20589, JP-A-5-260907, JP-A-5-306279, and the like. Here, tannin 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.

  Adjust the pH of the prepared tea extract. The pH of the tea extract (20 ° C., the same applies hereinafter) is 5.5 or less, but is preferably 5 or less, more preferably 4.5 or less, and particularly preferably 4 or less from the viewpoint of improving the clarity. The lower limit of the pH is not particularly limited as long as the member of the manufacturing 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 an inorganic acid and / or an organic acid for pH adjustment, for example, hydrochloric acid and ascorbic acid are used suitably.

  In the present invention, the temperature of the tea extract may be adjusted. The temperature of the tea extract is preferably less than 100 ° C., more preferably 5 to 90 ° C., and still more preferably 20 to 70 ° C., from the viewpoint of improving clarity and flavor. 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 after pH adjustment is brought into contact with fine bubbles having a median diameter of 1 to 200 μm. As a result, the fine bubbles adsorb turbid components and bitter and astringent components in the tea extract and float on the liquid surface to form a foam layer. As a result, the tea extract is highly clarified and a purified tea extract having a refreshing taste with reduced bitterness and astringency.

In order to bring the tea extract into contact with the fine bubbles, the fine bubbles may be released into the tea extract. The means for generating fine bubbles is not particularly limited as long as bubbles having the above particle diameter can be generated, and examples thereof include a pressure dissolution method, a swirl method, a shock wave method, a pore method, a shear method, and an ultrasonic method, and are commercially available. A fine bubble generator can be used.
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. More specifically, with reference to FIG. 1, the gas supplied from the gas introduction pipe 19 is sucked by the pump 18, and the gas is dissolved in the tea extract 13 in the gas-liquid dissolving means 16 under a pressurized condition. Then, the reduced pressure is released and the fine bubbles 14 are discharged from the fine bubble generating nozzle 17 into the tea extract 13 in the treatment tank 12. The swirl method is a method in which a cavity is generated by a swirl flow of bubbles and water, and fine bubbles are generated by a swirl 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 median diameter of the bubbles to be contacted is preferably 1 to 150 μm, more preferably 1 to 100 μm, and particularly preferably 5 to 60 μm, from the viewpoints of improving the clarity, stability of the bubbles and particle size control. The “median diameter” can be measured by a batch cell using a laser diffraction method (such as SALD-7100 manufactured by Shimadzu Corporation).

  Although the kind of gas to discharge | release is not specifically limited, In order to prevent the quality degradation by oxygen, it is preferable that carbon dioxide, nitrogen, and other inert gas are included. 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.

From the viewpoint of purification efficiency, the volume of the gas to be released is preferably 0.1 to 10% by volume, more preferably 0.2 to 10% by volume, particularly as a converted value at 25 ° C. and 1 atm with respect to the tea extract. Preferably it is 0.2-5 volume%. The number density of bubbles in the tea extract 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 (KS-17A manufactured by RION) or the like.

  The contact time between the tea extract and the fine bubbles is preferably 20 to 120 minutes, more preferably 30 to 90 minutes, and particularly preferably 40 to 60 minutes from the viewpoint of further improving the clarity.

  From the viewpoint of contact efficiency between the tea extract and the fine bubbles, the bubble release position is preferably near the bottom of the treatment tank 12 shown in FIG.

  In the present invention, when the tea extract and fine bubbles are brought into contact with each other, they may be brought into contact with stirring. Stirring contact can be performed using a stirring means such as a stirrer having a stirring blade. The kind of stirring blade is not particularly limited, and for example, a paddle blade, a turbine blade, a propeller blade, an anchor blade, or the like can be used. The number of blades can be selected as appropriate. The blade diameter is preferably about 50 to 80% with respect to the inner diameter of the treatment tank 12 shown in FIG. Furthermore, the installation position of the stirring blade is not particularly limited, and may be installed in a place where the liquid phase can be sufficiently stirred.

  In the present invention, a baffle plate may be disposed in the treatment tank 12 shown in FIG. 1, and may be in a completely baffle plate state, but from the viewpoint of further clarifying and flavor, mild stirring conditions It is preferable that Specifically, as stirring conditions, the stirring Reynolds number (stirring Re) of the tea extract is preferably 2300 to 60000, more preferably 2300 to 50000, still more preferably 2300 to 45000, and particularly preferably 4000 to 40000. Can be mentioned.

  Next, the foam layer formed on the liquid surface is removed. As a method for removing the foam layer, for example, operations such as filter filtration, centrifugal separation, and bubble vacuum can be employed. Further, as a simple operation, there is exemplified a method of discharging the purified tea extract from the discharge pipe 22 below the treatment tank 12 shown in FIG. 1 so as to leave only the foam layer formed on the liquid surface.

  Further, at the time of floating separation, the liquid temperature may be controlled by the above-mentioned heating means or heat retaining means.

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 is also preferably 0.7 or less, more preferably 0.6 or less, and particularly preferably 0.5 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 always clear, but when the pH of the tea extract is 5.5 or less, the components in the tea extract are electrically connected to the surface of the fine bubbles. This is presumably due to the fact that the adsorption efficiency is improved and the adsorption efficiency is improved.

  Moreover, the purified tea extract obtained has not only high clarity but also reduced bitterness and 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.

  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.

  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.

  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 adjusted to pH 3.0 using 1 mol / L hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) and then made up to 20 kg with ion-exchanged water to obtain a green tea extract.
The obtained green tea extract was mixed with ion exchange water at 90 ° C. to obtain 20 kg of 55 ° C. 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%.
Hereinafter, the green tea extract was purified using the tea extract purification apparatus shown in FIG. First, 20 L of green tea extract adjusted to pH 3.0 was put into the treatment tank 12 (height 1000 mm × inner diameter 160 mm) and kept at 25 ° C. 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.
The turbidity was measured by sampling the liquid phase after 20 minutes and 30 minutes from the start of production. After 60 minutes from the start of production, bubbles floating on the liquid surface were 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, FIG. 2 shows the change in turbidity ratio (after purification / before purification) before and after purification with respect to the treatment time.

Example 2
A purified green tea extract was obtained in the same manner as in Example 1 except that the pH of the green tea extract was adjusted to pH 3.7 with 1N hydrochloric acid. 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 1 except that the pH of the green tea extract was adjusted to pH 4.6 with 1N hydrochloric acid. 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 pH of the green tea extract was adjusted to pH 5.1 with 1N hydrochloric acid. Table 1 shows the analysis results and sensory evaluation results of the obtained purified green tea extract. Table 2 shows changes in turbidity ratio (after purification / before purification) before and after purification with respect to the treatment time.

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 by the same operation as in Example 1, except that the pH of the green tea extract obtained by the same operation as in Example 1 was not adjusted. 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 3
A purified green tea extract was obtained in the same manner as in Example 1 except that the green tea extract obtained by the same operation as in Example 1 was adjusted to pH 7.5 with sodium bicarbonate. 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.

  From Table 1, the pH of the tea extract was adjusted to 5.5 or less, then brought into contact with fine bubbles having a median diameter of 1 to 200 μm, and then the foam layer formed on the liquid surface was removed. It was confirmed that a purified tea extract having a refreshing taste with reduced astringency and bitterness was obtained. Further, from comparison between Examples 1 and 2 and Comparative Example 2, it was found that the same turbidity can be achieved in half the production time with respect to the method described in Comparative Example 2.

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 discharge tube

Claims (2)

The pH of the tea extract is adjusted to 2.8 to 4.6 , then it is contacted with fine bubbles with a median diameter of 1 to 200 μm, and then the foam layer formed on the liquid surface is removed. Purification method.   The purification method according to claim 1, wherein the tea extract is a green tea extract.

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