JPS61234737A - Method for improving quality of oolong tea - Google Patents

Abstract

PURPOSE:To obtain oolong tea, having improved flavor and hue, and extractable even with cold water and water at ordinary temperature in a short time without grassy smell, by hydrating oolong tea leaves, heat-treating the hydrated oolong tea leaves, roughly rolling the tea leaves or subjecting the tea leaves to both the treatments at the same time, and drying the resultant tea leaves while heating. CONSTITUTION:Oolong tea leaves are hydrated, preferably hydrated to 50-80 wt% moisture content, heated, preferably at 35-60 deg.C tea leaf temperature, roughly rolled or subjected to both treatments at the same time, dried while heating, preferably heated at 50-90 deg.C tea leaf temperature to 10-30 wt% moisture content, and then dried at 1104n170 deg.C tea leaf temperature to <=4 wt% moisture content, to afford the aimed oolong tea.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for improving the quality of oolong tea, and more specifically, to provide an oolong tea that has good flavor and color and is particularly effective for cold water use. It is something to do.

(Prior Art) Oolong tea contains vitamins and minerals, and has recently attracted attention as a health drink or a recreational drink because it has a favorable flavor and color tone.

(Problems to be solved by the invention) However, all of these oolong teas cannot have the flavor and color mentioned above unless the oolong tea leaves are soaked in hot water, and cannot be obtained with cold water or room temperature water. It was not possible to extract the flavor and color of oolong tea in a relatively short time. Therefore, for example, when obtaining cold oolong tea in the summer, it is necessary to cool the oolong tea that has been extracted in hot water in advance. In order to avoid this inconvenience, if you brew oolong tea with cold water or room temperature water for a long time, the flavor of the resulting oolong tea will have a strong raw odor reminiscent of green grass, and the sweet flavor unique to oolong tea will be weakened. This had the disadvantage that it was unsuitable as a recreational drink.

The present inventors focused on this point and conducted research on improving the quality of oolong tea in order to be able to obtain oolong tea that has the flavor and color tone of oolong tea in a relatively short time even with room-temperature water. As a result, the above-mentioned purpose was effectively achieved by satisfying the above-mentioned process of adding water and heat treatment to Coulomb tea leaves obtained by conventional methods, followed by rough rolling treatment, and then drying. We obtained the knowledge that it is possible to achieve this goal.

(Means for Solving the Problems) The gist of the present invention, which was completed based on these findings, is that after oolong tea leaves are subjected to water addition and heat treatment, or at the same time, they are subjected to rough rolling treatment, and then heated and dried. This is a method for improving the quality of oolong tea.

The contents of the present invention will be described in detail below.

In the present invention, first, oolong tea leaves are subjected to water addition and heat treatment. Oolong tea leaves that can be used in the present invention include those that have been processed by conventional methods and those that are commercially available.

Generally, oolong tea leaves are obtained by drying raw tea in the sun, further withering it indoors, roasting it in a pot, rolling it, and drying it.

When adding water to such oolong tea leaves, the moisture content of the oolong tea leaves should be 28% by weight or more, preferably 50% to 50% by weight.
It is carried out so that it becomes 80% by weight. If the amount of water added is too small, it will not be possible to obtain oolong tea having the flavor and color tone targeted by the present invention even if the subsequent steps are carried out in the same manner as in the present invention.

On the other hand, if the water content is too high, a stuffy odor will occur during the next heat treatment, impairing the flavor of the oolong tea, and the rough rolling process will take more time.

When adding water, heat treatment may be performed simultaneously or thereafter. The purpose of this heat treatment is to impart the unique flavor of oolong tea and to increase the efficiency of the subsequent rough rolling process. The temperature is preferably 25 to 70°C, and more preferably 35 to 60°C.

If this temperature is too low, the tissue of the tea leaves will not become soft and breakage of the oolong tea leaves will occur, causing the oolong tea to become cloudy. On the other hand, if the temperature becomes too high, the tea leaves will become steamy and the flavor will deteriorate.

After or simultaneously with these treatments, the oolong tea leaves are subjected to a rough rolling treatment. This rough rolling process forms many cracks on the surface of the oolong tea leaves, thereby improving the extraction efficiency of the oolong tea. At the same time, it is possible to make the water content of the oolong tea leaves uniform, thereby preventing uneven drying during subsequent heating and drying, and making the oolong tea have a good flavor.

After the above-mentioned rough rolling treatment, it is heated and dried. This heat drying substantially improves the flavoring and coloring of the oolong tea. In other words, the fishy odor of oolong tea is removed, the sweet flavor unique to oolong tea is imparted, and the oolong tea leaves are colored by oxidation of catechins, browning due to the aminocarbonyl reaction, caramelization of sugar, etc., resulting in a light and refreshing taste. imparts a good taste. Therefore, any heating drying means may be used as long as it can achieve the above-mentioned effect, and specific examples thereof include direct heating drying, temporary heating drying, microwave drying, and the like.

Next, the heat drying described above may be performed in a single stage method or in a two stage method, but in order to improve the flavor and color tone of the oolong tea, it is preferable to employ the latter method. The effect of the above two-stage heat drying process is that the first stage mainly brings out the moisture inside the oolong tea leaves, and the second stage heat-drying process eliminates the stuffiness and grassy smell, giving the oolong tea leaves a pleasant flavor. The goal is to provide the following. And the second
The main purpose of the stages is to adjust the favorable flavor obtained in the first stage, sweeten the tea leaves, and further add color to the oolong tea leaves. Therefore, the processing conditions are as follows. That is, the drying conditions for the first stage are such that the temperature of the oolong tea leaves is 50 to 90°C and the moisture content is 10 to 30% by weight. The heating drying conditions for the second stage are such that the temperature of the oolong tea leaves is 110 to 170°C and the moisture content is 4% by weight or less.

The oolong tea leaves processed in this way are cut and filled and packaged into tea bags etc. by appropriate means.
Prior to this, known quality improvement methods may be applied, such as applying oolong tea extract to the oolong tea leaves to improve the flavor and color tone of the oolong tea, or teas other than oolong tea, such as puerh tea, bouji tea, green tea, etc. There is no problem in adding extracts or powders of various teas as appropriate. Especially in the latter case, by adjusting the addition port,
Oolong tea with an extremely pleasant flavor that cannot be obtained with ordinary oolong tea can be obtained.

In addition, when filling tea bags with oolong tea leaves whose quality has been improved by the above method, it is preferable to appropriately mix oolong tea leaves that have not been treated by the method of the present invention, that is, untreated oolong tea leaves. Thereby, when the tea bag is placed in water, it is possible to effectively prevent the tea bag from settling in the water or floating on the water surface. For this purpose, the mixing ratio of the quality-improved oolong tea leaves of the present invention and untreated oolong tea leaves is as follows:
The weight ratio is preferably in the range of 0.5 to 15:1.

(Effects of the present invention) The oolong tea leaves of the present invention obtained by the above method are as follows:
Its flavor and color are superior to traditional oolong tea leaves,
By placing the oolong tea leaves in room temperature water or hot water, oolong tea with excellent flavor and color tone can be extracted in a relatively short time. These effects are most effective when the oolong tea leaves of the present invention are used for cold water.

Example 1 Oolong tea leaves (moisture 6 weight t% > 40 Kfl and water 50
XZ was added and the mixture was roughly rubbed for 33 minutes while heating at 130°C. The temperature of the oolong tea leaves after rough rolling was 40 to 50°C. After that, it was dried at 220℃ for 42 minutes and the product temperature was 16℃.
Dried oolong tea leaves were obtained at 5°C and with a moisture content of 0.05%. This was cut and sized to obtain 20 to 35 mesh pieces, which were filled in 8 g into tea bags to obtain oolong tea in tea bags.

(Comparative Example 1) Unprocessed oolong tea leaves were sized, and 8 g of 20 to 35 mesh was filled into a tea bag to obtain oolong tea in a tea bag.

In the case of cold water extraction: The oolong tea in tea bags obtained by the above method was poured into 10° C. water and extracted for 1 hour.

The comparison results are shown in Table 1].

Table 1 The color difference between the above-mentioned product of the present invention and the untreated product was 3.0. In terms of flavor, the product of the present invention loses its freshness and has a sweet, mellow flavor, while the untreated product has a raw, greenish taste.

For hot water extraction: Put the oolong tea in a tea bag into hot water of about 90℃,
The results are shown in Table 2 after extraction for 3 minutes.

Table 2 The color difference between the above-mentioned product of the present invention and the untreated product was 3.3. The product of the present invention had a strong taste and light taste with little astringency, whereas the untreated product had a weak taste and a strong astringency.

Example 2 40 kg of oolong tea leaves (6% water by weight) and 60 kg of water. z was added, and the mixture was roughly rubbed for 33 minutes while heating at 130°C. The product temperature after rough rolling was 40 to 50°C. After that, 15
The first drying was carried out at 0"C for 4 minutes.The temperature of the oolong tea leaves at this time was about 70℃, and the moisture content after drying was about 20% by weight.
Met. Thereafter, a second drying was performed at 220° C. for 38 minutes to obtain dried oolong tea leaves having a product temperature of 165° C. and a water content of 0.5% by weight. This was cut and sized to obtain 20 to 35 meshes, and 8 g of it was filled into tea bags to make oolong tea in tea bags.

(Comparative Example 2) Untreated oolong tea leaves were sized and 8 g of 20 to 35 mesh was filled into a tea bag to obtain oolong tea in a tea bag.

The oolong tea in tea bags obtained by the above method was subjected to cold water extraction and hot water extraction, and the color tone and flavor of each extract were compared.

For cold water extraction: Put each tea bag of oolong tea into 10℃ water and add 1
Time extracted. The comparison results are shown in Table 3.

Table 3 The color difference between the above-mentioned product of the present invention and the untreated product was 3.2. Regarding the flavor, the product of the present invention had a sweet, mellow flavor with no freshness, while the untreated product had a raw, greenish taste.

For hot water extraction: Each tea bag was placed in hot water at about 90°C and extracted for 3 minutes. The comparison results are shown in Table 4.

Table 4 The color difference between the product of the present invention and the untreated product was 3.5. Regarding the flavor, the product of the present invention had a strong taste, little astringency, and light taste, whereas the untreated product had a weak taste and a strong astringency.

Claims (6)

[Claims] (1) A method for improving the quality of oolong tea, which comprises subjecting oolong tea leaves to water and heat treatment, or at the same time subjecting them to rough rolling treatment, followed by heating and drying. (2) The method for improving the quality of oolong tea according to claim 1, characterized in that the amount of water added is 28% by weight or more. (3) The heat treatment conditions are such that the temperature of the oolong tea leaves is 25-7.
The method for improving the quality of oolong tea according to claim 1, characterized in that the conditions are such that the temperature is 0°C. (4) The method for improving the quality of oolong tea according to claim 1, wherein the heat drying is a two-step heat drying method. (5) The method for improving the quality of oolong tea according to claim 1, characterized in that the oolong tea leaves contain an extract or powder of oolong tea, Pu'erh tea, hojicha, or green tea. (6) In the first stage of heating and drying, the temperature of the oolong tea leaves is 5.
The process is carried out under the condition that the temperature of the oolong tea leaves is 0 to 90°C until the moisture content becomes 10 to 30% by weight, and the second stage is carried out under the condition that the temperature of the oolong tea leaves is 110 to 170°C and the moisture content is reduced to 4% by weight or less. The method for improving the quality of oolong tea according to claim 4, characterized in that the method is carried out until the quality of oolong tea is improved.