JP2001145456A - Method for reducing bitter astringent taste of tea - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a method for reducing the bitter astringent taste of tea, by which both the bitter taste and the bitter taste can be reduced without deteriorating the body taste of the tea just after prepared. SOLUTION: This method for reducing the bitter astringent taste of tea comprises storing the unrefined tea in a storage temperature range of 10 of 20 deg.C under a low oxygen atmosphere and storing the tea under a condition in a region surrounded by all of the equations (1), (2), (3) and (4) in the figure 1. Thereby, the body taste of the tea just after prepared can be increased, and both the bitter taste and the astringent taste just after prepared can be reduced. The tea having largely bitter and astringent tastes can be changed into a mild and easily drinkable tea.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for reducing the bitterness of tea, which reduces both the bitterness and the astringency without reducing the kokumi immediately after tea production.

[0002]

2. Description of the Related Art It is said that recent young people tend to dislike bitterness and astringency.
For this reason, if the bitterness and astringency can be reduced without reducing the kokumi of the tea, and the tea with strong bitterness can be easily drunk and the tea of the taste of young people can be provided, the spread of the tea is further promoted and the production is promoted. It can also be expected to reduce costs.

[0003] By the way, tea is conventionally stored at low temperature (0 ° C).
-5 [deg.] C.) to maintain the freshness of aroma and taste as much as possible. In some high-grade teas and the like, the inside of the storage container has been replaced with nitrogen gas in order to prevent oxidation that promotes deterioration of the tea, and the tea has been stored at an extremely low temperature of -20 ° C. On the other hand, some consumers have become more mellow flavors due to the storage of tea (also called after-ripened flavors)
For those who like such a so-called “kokumi” that is ripe and mild in taste, it has been practiced to shift the temperature to near 20 ° C. and store it for 3 to 5 weeks (“New” Completed Tea Industry, October 1, 1988, edited by the Shizuoka Prefecture Tea Industry Chamber, pp. 452-453). Also, in the past research on post-ripening, when tea packed with nitrogen gas, mainly tea from mountainous areas, is stored at 15 ° C for 5 months, the hard aroma turns into a deep aroma, and the rough taste is umami. There was also a report that increased body weight with sweetness (Shizuoka Prefecture Tea Research Laboratory Research Report No. 17, 1993).

[0004] Accordingly, the present invention focuses on such storage of tea, particularly on post-ripening, and by storing tea under certain conditions, it is possible to reduce the bitterness and astringency without reducing the kokumi immediately after tea production. The purpose is to aim.

[0005] However, when the research on the storage of tea is advanced, it has been quite difficult to reduce both the bitterness and the astringency of the tea without reducing the kokumi of the tea immediately after tea production. For example, when stored at 20 ° C. for 3 to 5 weeks based on the description in the above literature, the body taste slightly increases but the astringency cannot be sufficiently reduced, and storage causes a new bitter taste. It has been found that a heating deterioration odor is also generated. In addition, based on the above research results, it has been found that when stored at 15 ° C. for 5 months in a nitrogen gas atmosphere, although the astringency can be reduced, the bitterness generated by the storage is strongly felt.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on the relationship between the storage conditions of tea and the kokumi, bitterness and astringency of tea, and as a result, the following findings can be obtained. did it. When the storage temperature is lower than 10 ° C., the body taste is reduced when stored for a long period of time. Conversely, when the storage period is short, bitterness and astringency cannot be reduced. On the other hand, when the storage temperature is higher than 20 ° C., not only a new bitter taste comes out due to storage, but also a heating deterioration odor may be generated in some cases. -If the storage period is too long, new bitterness due to storage is generated, and if it is too short, the kokumi cannot be increased or the bitterness cannot be reduced. -When stored in a low oxygen atmosphere, in view of the object of the present invention, there is a preferable peak when stored at a storage temperature of about 15 ° C for 2 to 3 months (60 days to 90 days).

Based on the above findings, the present inventor has determined that tea is stored in a low oxygen atmosphere at a storage temperature of 10 ° C. to 20 ° C., and the storage temperature (° C.) is taken on the X-axis, and the storage days ( Day) is shown on the Y axis (FIG. 1), Expression: Y = −22.0X + 456.7 Expression: Y = −5.0X + 108.3 Stored under the conditions within the area surrounded by the above expression and the expression. I decided that.

[0008] The evaluation of tea quality, such as the richness, bitterness, and astringency of tea, is an extremely delicate problem, and it is difficult to quantitatively indicate it. However, when drinking tea stored under any of the conditions in such a region, it was found that at least the kokumi immediately after tea production was not reduced, and that both the bitterness and astringency immediately after tea production were reduced. Anyone can check. Therefore, for example, it is possible to make it easy to drink bitter-tasting tea while leaving a rich taste, or to provide tea for young people who tend to dislike bitter-tasting.

In addition to the above storage conditions, the following formula in FIG. 1 and the following formula: Y = -15.0X + 345.0 Formula: Y = -4.5X + 132.5 ~
By storing in the range of 20 ° C. under the conditions in the area surrounded by all of the above formulas, in addition to the above effects, the body taste can be increased, and a more mellow tea can be provided. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, conditions for carrying out the method for reducing bitterness of tea of the present invention will be described in detail.

The present invention is applicable not only to varieties, production areas, plucking times, cultivation methods, etc., but also to any kind of tea. In particular, it can be preferably applied to tea having relatively strong bitterness or astringency. The tea to be applied to the present invention is a steamed step, a cooling step, a variety of kneading steps and a drying step, and the `` product tea '' step obtained through a finishing step. Tea may be used, but the effect of the present invention is more apparent with crude tea. Moreover, the "rough tea" to be stored has a water content of about 0.1 to 10%, particularly about 3 to 10%.
The one adjusted to 7% is preferable.

[0012] The environment for storing tea is made of a material having no air permeability such as a plastic film or aluminum foil,
Alternatively, it may be in a container such as a bag or a box wrapped by these members, or in a room or a warehouse capable of ensuring airtightness. In short, there is no particular limitation as long as the environment can maintain a low oxygen state. However, it is preferable in an environment that can be stored in a light-shielded state, because it is possible to prevent the generation of an unpleasant odor such as sun odor by shading light.

The term "under a low oxygen atmosphere" in the present invention means that the storage environment has a residual oxygen concentration of 0 to 0 by evacuating air from the storage environment to a vacuum or a state close to vacuum, or by replacing with an inert gas. 10 vol%, desirably 5 vol% or less. The inert gas in this case is preferably nitrogen gas economically, but is not limited thereto. Further, the volume ratio in the storage environment is not particularly limited, but 80 vol.
% Or more.

Assuming that the storage temperature and the storage period are set in the range of 10 ° C. to 20 ° C., FIG.
Is stored under any condition in the region surrounded by the formula and the formula, and preferably further stored under any condition in the region surrounded by the formula and the formula. When the storage temperature is lower than 10 ° C., the kokumi is reduced when stored for a long time, and when it is short, the bitterness and astringency cannot be reduced. Also, in FIG. 1, the bitterness due to storage is generated and a heating deterioration odor is generated as the position goes diagonally to the upper right of the formula, and the bitter taste is maintained in the diagonally lower left of the formula. become. On the other hand, all of the formulas are the approximate lines of the upper limit value and the lower limit value of the storage condition value in which the bitterness and astringency could be reduced without reducing the kokumi in the test described later, and A more favorable effect has been recognized in the region surrounded by. Further, the expression is an approximation line of the upper limit value and the lower limit value of the storage condition value in which the body taste has increased in comparison with the conventional storage temperature (0 ° C. to 5 ° C.) in the test described below, and furthermore, the region surrounded by these. Among them, a more favorable effect on the increase of kokumi is recognized. Therefore, if the conditions are within the region surrounded by the formula, the body taste increases, and yet the bitterness and astringency can be reduced. Among them, the most preferable result is obtained when the storage temperature is about 15 ° C. and the storage period is about 3 months (90 days). Incidentally, this condition corresponds to the storage temperature of 10 in FIG.
C. to 20.degree. C., near the center of gravity of the region enclosed by the equation.

The tea leaves which have been treated according to the present invention can be used for ordinary infused tea, of course.
Leaf tea bag tea, powdered tea, matcha tea, SD / FD tea,
It can be used for various uses such as raw tea for drinks, raw tea for foods, feed, and pharmaceutical raw materials.

Next, the effects of the present invention will be described based on test results.

(Test 1) Tea leaves having different production areas, varieties, production areas, plucking times and cultivation methods were stored under different conditions, and the quality of the tea after storage was measured.

The test subjects were subject 1 (Yutakamidori, flatland, middle to late April, cover cultivation), subject 2 (Yabukita, mountainous area, early to mid-May, open cultivation), subject 3
(Yabukita, flatland, late April to early May, open-field cultivation), all of which are made of rough tea stage tea produced through steaming, drying, etc. In a vacuum nitrogen atmosphere, the inside of the aluminum gusset bag is replaced with nitrogen gas to form a vacuum nitrogen state (residual oxygen concentration of 5 vol% or less). A normal air atmosphere (residual oxygen concentration 20.9%) was used. Then, the tea was stored under a predetermined temperature condition, and the quality of tea was measured every month by sensory inspection and near infrared analysis.

In the sensory test, the tea leaves were extracted with boiling water, and as for the aroma, the tea leaves were scooped out with a scoop net and the odor was smelled.
The evaluation was given with a score from point (none) to 5 (strong) (Table 1). In addition, for the taste, after removing the tea leaves with a rake net, drink the extract and inspect the taste,
Put tea leaves in a teapot, add hot water cooled to about 80 ° C, extract for 1 minute, pour this extract into the tea bowl until the last drop and drink it to test the taste, astringency, body taste, bitterness and damage. Were evaluated with a score from 0 (none) to 5 (strong) (Table 2). In addition, since there was no significant difference due to the difference between the subjects, the representative values of the subjects 1 to 3 are shown in Tables 1 and 2 below.

[0020]

[Table 1]

[0021]

[Table 2]

In the near-infrared analysis, tea leaves were finely pulverized, and moisture, total nitrogen, free amino acids, theanine, fiber, caffeine, and tannin were measured using a near-infrared analyzer (INSTALAB600, manufactured by Shizuoka Seiki Co., Ltd.). That is, the component analysis of the tea leaf itself. Here, as a representative value of the near-infrared analysis, data of the subject 1 when stored for 3 months is shown in Table 3 below.

[0023]

[Table 3]

(Results) The bluish odor tended to decrease with heating and aging. Odor odors occurred in the presence of oxygen and the reaction tended to be faster and stronger at higher temperatures. The heating odor occurred when stored at 15 ° C. for 5 months or more. In terms of eliminating blue odor and no unpleasant harmful smell or heating odor, it is 15 ° C in a vacuum nitrogen atmosphere.
The result showed that storage for 2 to 4 months was preferable.

On the other hand, the astringency decreases with heating and aging, but if the heating is continued in an oxygen atmosphere, another astringency such as sticking of the tongue appears. As for the kokumi, the original kokumi decreases over time, but only when stored at 15 ° C., a swelling spread in the mouth and a new koku occur. However, the peak tended to decrease after three months. Regarding the damage, a metallic (iron rust) taste was felt in an oxygen atmosphere, and this became stronger with temperature and aging.
From the viewpoint that mellowness and richness are increased and bitterness is reduced, the result that storage in a vacuum nitrogen atmosphere at 15 ° C for 2 to 4 months is preferable. In addition, looking at the results of the near-infrared analysis, in almost all cases, water,
Total nitrogen, free amino acids, theanine, fiber, caffeine,
There was no significant difference for the measurement items of tannin.

(Test 2) Object 4 (Yutakamidori, flat ground,
(Mid-April to late April, cover cultivation), the tea was stored in a vacuum nitrogen atmosphere at a wider temperature range than Test 1, and the quality of the tea after storage was measured by sensory test.

The storage environment is such that crude tea stage tea produced through steaming and drying steps is stored in an aluminum gusset (multi-layer laminated film) bag (volume ratio is 95 vol% or more), and the inside of the aluminum gusset bag is stored. The atmosphere was replaced with nitrogen gas to obtain a vacuum nitrogen state (residual oxygen concentration of 5 vol% or less), which was stored under a predetermined temperature condition, and subjected to a sensory test after storage for a predetermined period.

In the sensory test, tea leaves are extracted with boiling water, and as for the fragrance, the tea leaves are scooped out with a scoop net and the odor is smelled. ) Were evaluated (Table 4). In addition, for the taste, after removing the tea leaves with a rake net, drink the extract to test the taste, put the tea leaves in a teapot, add hot water cooled to about 80 ° C, and extract for 1 minute. Was poured into a tea bowl to the last drop and drunk, and the taste was inspected, and each of astringency, body taste, and bitterness was evaluated with a score from 0 (none) to 5 (strong) (Table 5). ). In addition, data is not taken in the blank section of the following table. Table 6 summarizes the overall evaluation of the taste.

[0029]

[Table 4]

[0030]

[Table 5]

[0031]

[Table 6]

In the storage temperature range of 10 ° C. to 20 ° C. shown in Table 5, compared with the conventional storage temperature range of 0 ° C. to 5 ° C., the bitterness and astringency were reduced without reducing the body taste. The storage condition values that could be reduced were selected, plotted with ● in FIG. 2, and approximate lines of these upper and lower values were obtained as an equation and an equation by the least squares method. Formula: Y = -22.0X + 456.7 Formula: Y = -5.0X + 108.3

In Table 5, the storage temperature is 0 ° C. to 5 ° C.
In comparison with the case of the above, storage condition values in which the body taste is further increased were selected, and approximate lines of the upper limit value and the lower limit value were obtained as an equation and an equation by the least square method. Formula: Y = -15.0X + 345.0 Formula: Y = -4.5X + 132.5

[Brief description of the drawings]

FIG. 1 is a graph showing formulas for defining regions of storage temperature and storage period in the method for reducing bitterness of tea according to the present invention.

FIG. 2 is a graph in which test results are plotted and the relationship between these plots and expressions as approximate lines is shown.

Claims (3)

[Claims] Claims 1. Tea is stored in a low oxygen atmosphere at a storage temperature of 10 ° C or more.
When stored in the range of 20 ° C. and the storage temperature (° C.) is plotted on the X-axis and the storage days (days) is plotted on the Y-axis,
A method for reducing bitterness of tea, wherein the method is stored under the following formula and a condition in an area surrounded by the formula. Formula: Y = -22.0X + 456.7 Formula: Y = -5.0X + 108.3 2. The method for reducing bitterness of tea according to claim 1, wherein the tea is stored under the conditions in a region surrounded by the following formula and the formula. Formula: Y = -15.0X + 345.0 Formula: Y = -4.5X + 132.5 3. The method for reducing bitterness of tea according to claim 1, wherein the low oxygen atmosphere has a residual oxygen concentration in the storage environment of 5 vol% or less.