JPH05168407A - Preparation of green tea drink packed in container - Google Patents

Abstract

PURPOSE:To obtain the subject drink containing natural catechins in desirable state and having excellent taste, flavor and color by extracting tea leaves such as green tea leaves with extraction water of acidic pH range, filling the extract in a container and sterilizing the product. CONSTITUTION:Leaves of green tea such as middle-grade green tea, low-grade green tea or roasted green tea are extracted with extraction water of pH 4.5-5.5, preferably 4.8-5.3 and the extract is filled in a container and thermally sterilized or, after thermally sterilizing, the extract is filled in a container in an aseptic atmosphere. The extraction water is preferably incorporated with an organic acid and/or its salt such as L-ascorbic acid and the dissolved oxygen content of the extraction water is preferably decreased before adjusting the pH of the water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a packaged green tea beverage. More specifically, the present invention relates to a method for producing a packaged green tea beverage having excellent flavor and color tone, in which natural catechins, which are a functional component peculiar to green tea, are well preserved.

[0002]

2. Description of the Related Art In the conventional method for producing a packaged green tea beverage, changes in flavor, color tone and active ingredient occur during extraction of tea leaves, filling into containers, and sterilization in a sealed manner. In order to prevent this change, for example, a method of extracting tea leaves under an inert gas atmosphere (Japanese Patent Laid-Open No. 2-291230), and a method of flowing a nitrogen gas into the head space when filling and sealing the container (Japanese Patent Publication No. Sho 6).
2-42580) and the like have been proposed.

[0003]

However, none of the above-mentioned conventional methods is sufficient from the aspect of retaining functional ingredients, and especially green teas (non-fermented teas) that contain a large amount of catechins and are liable to change. In this case, it was necessary to develop a manufacturing method capable of more effectively maintaining quality.

As a result of recent advances in research into the functionality of foods,
The most important functional ingredient of teas is catechins, which is a kind of flavonoid compound, and among them, gallic acid esters are (-)-epicatechin gallate and (-).
-It has been clarified that epigallocatechin gallate is important (for example, "Science of Tea" edited by Keiichiro Matsumura, published by Asakura Shoten, 1991). The functional catechins here include natural catechins such as (−)-epicatechin, (−)-epigallocatechin, (−)-epicatechin gallate and (−)-epigallocatechin gallate. Pointing,
Other catechins, such as (+)-catechin, that may have a secondary formation are not included.

The present inventors have paid attention to this point, and have established the conditions under which these functional natural catechins are favorably retained during extraction, filling, and sterilization operations during the production of packaged green tea beverages,
The present invention has been achieved as a result of research for the purpose of establishing a method for producing a packaged green tea beverage containing these in a stable and abundant manner.

[0006]

[Means for Solving the Problems] A method for producing a packaged green tea beverage which achieves the above-mentioned object of the present invention is to fill a container with an extract obtained by extracting tea leaves of green teas such as sencha, bancha, kamairicha with drinking water. In a method for producing a packaged green tea beverage in which the container is sealed and then heat-sterilized or the container is filled and sealed in an aseptic atmosphere after heat-sterilization, the pH is 4.5 or more and 5.5 or less, preferably 4.8 or more 5. It is characterized in that tea leaves are extracted with water for extraction of 3 or less.

In the method for producing a packaged green tea beverage, various conditions when extracting tea leaves have a great influence on the quality after packaging. Research on these revealed that the main factors were 1) pH and pH stability during extraction, 2) atmosphere during extraction, particularly oxygen, and 3) influence of various ions contained in the extracted water.

1) pH at the time of extraction Generally, it has been conventionally said that when tea leaves are extracted with an acidic solution having a low pH, the extraction efficiency of the active ingredient is low and the color tone is poor. Studies on this point have revealed that, surprisingly, the extraction efficiency with a weakly acidic solution is higher than that with a neutral solution. Furthermore, the extractability and stability of functional catechins are significantly reduced when the pH exceeds 6.0, and the color tone is thickened when the pH exceeds 6.5. This is due to the polyphenols associated with the polymerization of catechins. It was revealed that this is the coloring of the compound and has nothing to do with the original color tone of green tea. Along with the change in the concentration of each catechin with pH, vitamin C also causes a large loss when the pH of the extraction water is 5.5 or more. Caffeine, which is an important component of green tea, is hardly affected by pH.

The main reason for the decrease of these catechins is that stereo-isomerization of the functional group bonded to the asymmetric carbon atom at the 3-position in the 3-oxyflavanone structure occurs before the oxidation and polymerization of the catechins occur. It is in. The loss of natural catechins and the production of secondary products due to this stereoisomerization leads to the loss of functionality of catechins and the loss of the original functions of green tea beverages, which is not preferable. Moreover, the isomerization reaction proceeds relatively slowly in the low pH region, but becomes rapid when the pH exceeds 5.5, and 6.0
If it exceeds, the liquid will be remarkably accelerated and the coloring of the liquid will be remarkable.

[0010] As a model, a citrate buffer solution of (-)-epicatechin (standard reagent) is isomerized when heated at 121 ° C for 6 minutes assuming retort sterilization to produce (+)-catechin. The case is shown in FIG. 1 together with the degree of browning of the solution in relation to pH. Further, FIG. 2 shows that the pH actually has a great influence on the retention of catechins in the green tea beverage during the heat sterilization by the residual ratio with respect to the initial catechin concentration. In FIG. 2, only (+)-catechin significantly increases as the pH increases, but (+)-catechin increases.
Originally, catechins are contained only in trace amounts in natural green tea, and such a significant increase in secondary products is not preferable from the viewpoint of maintaining the functionality of beverages. As the regulator used for adjusting the pH of the extraction water, L-
Organic acids such as ascorbic acid, erythorbic acid, citric acid, fumaric acid, malic acid, lactic acid, gluconic acid and / or salts thereof are preferable.

The pH range to be adjusted is 4.5 to 5.5 at 20 to 25 ° C., and more preferably 4.8 to 5.3. Depending on the type of tea, the higher side of Houjicha, bancha,
Kama-iricha is moderate, and green tea is low. When the pH exceeds 5.5, the coloration proceeds and the extraction efficiency seems to increase apparently, but the natural catechins, which are important components of green tea, are significantly worn. When the pH is lower than 4.5, the stability of catechins is great, but the apparent color tone becomes lighter.
Moreover, the sourness can be felt strongly. In addition, sencha may have a poor color tone due to damage to chlorophyll.
Most preferable is a range of pH 4.8 to 5.3 where catechins are highly stable and have little influence on flavor. Also pH
It may be difficult to adjust the above to a narrow range of weak acidity such as 4.8 to 5.3 to stabilize it. In that case,
When the salt of the above-mentioned acids such as sodium salt is extracted as a buffer solution, pH stability is enhanced. However, if the amount of salt added is increased, a large amount of sodium ions will be contained as a result, and it is necessary to pay attention to the influence on the flavor side. Further, when the extraction is carried out with a buffer solution, inorganic salts may be added to the above organic acid solution for buffering. This inorganic salt may be any substance as long as it is water-soluble as long as it is harmless to sanitary and does not affect the flavor, but is preferably an alkali or alkaline earth metal, that is, potassium, sodium, magnesium, calcium bicarbonate, carbonate of calcium,
Hydroxide, dibasic phosphate, tribasic phosphate, etc. are preferred.

Generally, the amount of the organic acid added varies depending on the kind of the acid, but in order to obtain the above pH range, it is in the range of 5 to 50 mg per 100 ml of extracted water. The addition amount of salts also varies depending on the acid composition and the type of salt, but if an excessive amount is added, turbidity or flavor deterioration may occur, and the inorganic ion concentration is preferably 10 mg or less per 100 ml of extracted water.

As a method for adjusting the pH of the extraction water to the above range, it is preferable to add and dissolve an organic acid and / or an organic acid salt in the extraction water in advance, but the method is not limited to this, and tea leaves are added to the extraction water. You may add an organic acid at the same time as the tea leaves when you put it in and extract it. When the tea leaves are mixed with an organic acid such as vitamin C in advance and the tea leaves are put in the extraction water, this organic acid dissolves. You can

2) Atmosphere during extraction, especially removal of oxygen Tea leaves contain many aroma components, taste components and functional components, and these are often easily oxidized when heated. In order to prevent this, conventionally, a method has been proposed in which extraction water simply boiled and degassed is used, or an inactive gas such as nitrogen gas is aerated to remove dissolved oxygen in the extraction water while extracting in a so-called non-oxidizing atmosphere. Was there. However, in these methods, the oxygen adsorbed in the tea leaves during the extraction of the tea leaves reacts rapidly with the extracted oxidizable components, or the oxygen in the air rapidly diffuses when agitated during the extraction, and the components are altered. Is inevitable.

On the other hand, in the present invention, a small amount of a reducing organic acid such as L-ascorbic acid or erythorbic acid and / or its salt is added and dissolved in the extracted water that has been degassed by the conventional method. By extracting tea leaves under a reducing atmosphere, it is possible to minimize the loss of active ingredients during extraction. The composition of this reducing atmosphere can be achieved by simply adding reducing organic acids to the extraction water, but oxidative loss due to oxygen dissolved in the extraction water occurs, its effect decreases and browning occurs during storage of the product. Since it may be promoted, it is more preferable to remove dissolved oxygen from the extracted water by a method such as boiling degassing, vacuum degassing, nitrogen gas aeration, or hollow fiber membrane degassing before addition. Is good.

Next, the addition amount varies depending on the type of tea, the quality of the extracted water, the tea leaf / extracted water ratio, the extraction temperature / time conditions, etc., but is generally 5 mg / 100 ml (5 mg%).
To 50 mg%, preferably 10 mg% to 2
The range of 0 mg% is good.

If the added amount is 5 mg% or less, no effect is recognized, and if the added amount is 50 mg% or more, the flavor may be adversely affected even after the pH is adjusted.

3) Effect of Ions Contained in Extracted Water It is well known that the flavor of tea is greatly affected by the quality of the extracted water used. If the raw water containing a large amount of metal cations such as iron and zinc, sodium, magnesium, calcium, etc. is used as the extraction water as it is, the color tone, turbidity and flavor of the tea beverage may be greatly affected. Also, chlorine, sulfate ions, etc. may affect the flavor. Therefore, the extracted water for tea beverage production is subjected to cation-anion exchange in advance, and more preferably, highly purified water from which organic matter in the raw water is sufficiently removed by treatment with activated carbon is used, and the above-mentioned additional components are added to this. Is good.

The container used for the packed tea beverage is a metal can,
A plastic container and a paper container combined with a metal foil or a plastic film. In the case of a plastic container, a molded container containing polyethylene terephthalate as a main component (so-called PET bottle) or a polyolefin as a main component and ethylene / A multilayer molding container (including a cup-shaped molding) containing an oxygen barrier layer of vinyl acetate saponified copolymer (EvOH) or polyvinylidene chloride can be used.

Further, the packaged green tea beverage can be produced by a general method which has been conventionally practiced, except for the feature of the present invention. That is, when it can be heat-sterilized after being filled in a container such as a metal can, it is manufactured by retort sterilization under the conditions of 120 ° C. and 4 minutes or more specified by the Food Sanitation Law. For PET bottles and paper containers that cannot be sterilized by retort, the same sterilization conditions as above, such as high temperature short time sterilization using a plate heat exchanger, etc., and cooling to a certain temperature before filling the containers, etc. Method is adopted.

[0021]

EXAMPLES Examples of the present invention will be described below. In the examples described below, the method for measuring caffeine and catechins was carried out using a high performance liquid chromatograph, ULTRON C ₁₈ for column reverse phase partition chromatography (Shinwa Kako Co., Ltd.), and the column temperature was 43 ° C and the gradient was used. I obeyed the law. That is, solution A is 0.1% acetonitrile and 5
% N, N-Dimethylformamide-containing 0.1% phosphoric acid solution, B solution is acetonitrile, sample injection volume is 10 μm
The wavelength of the UV detector was 280 nm. The vitamin C was measured by the xylene extraction method of 2,6-dichlorophenolindophenol complex.

Example 1 Using 600 g of medium-grade green tea from Yabukita varieties produced in Uji, 60 kg of purified water obtained by purifying raw water (Kawanishi City tap water) in the order of ion exchange, activated carbon treatment, and hollow fiber membrane filtration was boiled once, and then 60 ℃
After cooling to 12g, add 12g of Vitamin C (food grade) (20mg / 100g, pH 5.1) and dissolve, then add tea leaves while keeping at 60 ° C, extract for 3 minutes with gentle stirring, 250 mesh After filtering with a nylon filter cloth of No. 1 and heating to 95 ° C., it is filled in a 200-g-made tein-free steel adhesive can (Toyo Seikan Co., Ltd. Toyo Seam can) and the head space is flushed with nitrogen gas and the lid is closed. I wound it up. Next, this can was put in a steam retort and heated, and after the retort temperature reached 121 ° C., it was sterilized for 6 minutes, immediately taken out, and cooled in cold water.

At the same time, as a comparative example, vitamin C
Without addition (pH 5.8), Vitamin C 30g
The added product (50 mg / 100 g, pH 4.3) was also prepared and canned in the same process.

After the canned food was stored at room temperature for 2 weeks, the remaining caffeine catechins were analyzed by the above-mentioned method, and at the same time, a sensory evaluation was conducted by 6 specialist panels.

The results are shown in Table 1.

[0026]

[Table 1]

Example 2 Using Uji-produced Yabukita intermediate-grade sencha, 1% by weight of tea leaves was extracted at 60 ° C. for 3 minutes in the same manner as in Example 1. Prior to the extraction, purified water was mixed with 0.1 M citric acid and 0.2 M disodium phosphate aqueous solution at various ratios, and the citric acid concentration was added in the range of 3 mg to 30 mg per 100 g to give purified water having a pH of 4. 0, 5.0, 5.5, 6.
The pH was adjusted to 0, 6.5, 7.0 and 8.0, and the pH-adjusted water was used for extraction. After the extraction, the catechins and the amount of vitamin C, and the degree of coloration of the extract were determined by the absorbance at 430 nm by the above-mentioned method, and the tea leaves, which were the raw material, were shake-extracted with 50% acetonitrile for 30 minutes, and the catechins were similarly subjected to high performance liquid chromatography. Then, the extraction rate for each pH was determined by using this as the 100% extraction rate of catechins. Table 2 and Table 3 show the concentration of individual catechins, the extraction ratio (%) with respect to the total content in tea leaves, the concentration of vitamin C, and the results of the sensory test, and the effect of pH on the extraction rate of catechins and the liquid coloring. Is shown in FIG.

[0028]

[Table 2]

[0029]

[Table 3]

Example 3 The same sencha as in Example 1 was used, and the extraction conditions were as follows: tea leaf amount 1%, 6
After extraction with various extraction waters shown in Table 4 at 0 ° C. for 30 minutes, nitrogen pressure filtration was performed with a filter having a pore size of 10 μm,
Sterilized with a plate heat exchanger at 135 ℃ for 30 seconds at high temperature for a short time, cooled to 85 ℃, and then sterilized with ozone water 1.5.
PET bottles containing L were filled in a clean bench, immediately fitted with an aluminum cap, and cooled in cold water.

After this was stored at room temperature for 2 weeks, the amount of catechins present and the sensory change were examined.

The results are shown in Table 4.

[0033]

[Table 4]

[0034]

According to the present invention, when extracting green tea,
pH is 4.5 or more and 5.5 or less, preferably 4.8 or more and 5.
By extracting tea leaves with extraction water of 3 or less,
A natural catechin, which is a functional component peculiar to green tea, is well preserved, and a packaged green tea beverage excellent in flavor and color tone can be obtained.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between pH and the degree of (+)-catechin formation and the degree of browning of a solution.

FIG. 2 is a graph showing changes in caffeine and catechins with pH during sterilization of sencha extract by heating.

FIG. 3 is a graph showing changes in extraction rate depending on the pH of extraction water.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Ryoko Matsuda 1069-5 Sekiya, Kashiba City, Nara Prefecture (72) Kyoko Hara Inventor, Kyoko Hara 5-3-11, Ebi-cho, Suma-ku, Kobe

Claims (4)

[Claims] 1. A container is filled with an extract obtained by extracting tea leaves of green tea such as sencha, bancha, kamairicha, etc. with drinking water and sealed, and then heat sterilized, or after heat sterilization, the container is filled and sealed under an aseptic atmosphere. In the method for producing a packaged green tea beverage,
A method for producing a packaged green tea beverage, wherein tea leaves are extracted with water for extraction of 4.5 or more and 5.5 or less. 2. The method for producing a packaged green tea beverage according to claim 1, wherein tea leaves are extracted with extraction water having a pH of 4.8 or more and 5.3 or less. 3. The production of a bottled green tea beverage according to claim 1 or 2, wherein the extraction water having the pH is prepared by adding at least one of an organic acid and an organic acid salt to the extraction water. Method. 4. The method for producing a packaged green tea beverage according to claim 1, wherein the dissolved oxygen in the extraction water is reduced in advance before adjusting the pH of the extraction water.