JPS6244899B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention deals with cloudiness and precipitation (hereinafter referred to as cream down) that occur when oolong tea is cooled and stored.
This invention relates to a method for producing oolong tea that effectively prevents. <Conventional Technology> In recent years, the trend toward health enforcement has increased, and many health-conscious beverage-related products have been developed. Among them, oolong tea is said to have the effect of breaking down fat. However, when oolong tea is commercialized in a liquid form such as canned, bottled, or packaged in a paper container, if it is stored below room temperature, the oolong tea gradually creams down. Conventionally, various methods for preventing cream-down in black tea have been reported, but there are few methods for oolong tea. Examples of methods for preventing cream down in black tea are enzymatic treatment to make it soluble in cold water (Japanese Patent Publication No. 50-154462), mechanical separation and removal (Japanese Patent Publication No. 52-39920), glycerin ,
There is a method of solubilizing the precipitate by adding sorbitate etc. (Japanese Patent Publication No. 52-31958). <Problems to be Solved by the Invention> However, since the cream down of oolong tea is not as intense as that of black tea, if the above method was applied directly to oolong tea, the process would become complicated, the cost of raw materials would increase, Furthermore, the flavor of the oolong tea will be adversely affected. Additionally, the use of additives has the disadvantage of damaging the image of oolong tea as a health drink. The present invention takes into consideration the various drawbacks described above and aims to provide a method for effectively preventing cream-down in oolong tea using a relatively simple method and using almost no additives. <Means for solving the problem> The present invention was completed based on the knowledge that the above-mentioned cream down can be prevented by heat-treating oolong tea under specific heating conditions. The gist is that when boiling or low-temperature extraction of oolong tea from oolong tea leaves, the L value of oolong tea is adjusted to 60 to 80 and the PH is adjusted to 5 to 8, and then the vertical axis is adjusted to 110℃ or higher. When heating temperature and horizontal axis are heating time, 140℃: 0.1 minutes, 135℃: 0.3 minutes, 130℃: 0.5 minutes,
This is a method for producing oolong tea characterized by heat treatment under conditions that fall within the upper part of the curve drawn by connecting the points of 120°C: 2 minutes and 110°C: 10 minutes. The content of the present invention will be described below. First, oolong tea is extracted from oolong tea leaves. The extraction method may be carried out according to a conventional method such as adding oolong tea to boiling water and boiling it out, or extracting at a low temperature under reduced pressure. However, it is important that the oolong tea after extraction and before heating has an L value in the range of 60 to 80 and a pH in the range of 5 to 8. The L value represents the brightness of a color as measured by a color difference meter, and the upper limit is 100, and the higher the value, the brighter the color is, which is closer to white. If the L value of the above oolong tea is 80 or more, the color and aroma of oolong tea will be poor.On the other hand, if the L value is less than 60, the color and aroma will not only be too rich, but also the present invention It becomes impossible to effectively achieve one's goals. Also, the pH of oolong tea
If it is less than 5, it will not be possible to effectively prevent cream-down and the flavor will deteriorate. On the other hand, when the pH reaches 8 or above, the flavor of oolong tea decreases as described above. The identification of the L value and PH of these oolong teas is
The occurrence of cream down depends on the amount of oolong tea leaves used.
This decision was made based on the knowledge that it is greatly influenced by pH. Methods for making oolong tea within the above specified range include the following. The first method is to add water to pre-extracted oolong tea or concentrated oolong tea and add or not add an acid or alkaline preparation to obtain the above-mentioned oolong tea in the specific range, and the second method is One method is to determine the conditions for obtaining oolong tea within the above-mentioned specific range, such as the amount of oolong tea leaves and the amount of water, as well as the heating temperature and heating time, and perform extraction based on these conditions. . In any case, before heat-treating the oolong tea, the oolong tea must be adjusted to the above-mentioned specific range. The oolong tea thus obtained is heat-treated under specific conditions. The heating conditions are 110°C or higher, preferably 120°C, and where the vertical axis is the heating temperature (°C) and the horizontal axis is the heating time (minutes), 140°C: 0.05 minutes, 135
℃: 0.15 minutes, 130℃: 0.5 minutes, 120℃: 2 minutes, 110
°C: Range belonging to the upper part of the curve drawn by connecting each point of 10 minutes, that is, the range belonging to the shaded area in Figure 1, preferably 140 °C: 0.05 minutes, 135
℃: 0.15 minutes, 130℃: 0.5 minutes, 120℃: 3 minutes, 120
°C: Condition for the range belonging to the upper part of the curve drawn by connecting each point of 10 minutes, that is, the range belonging to the diagonal grid line part in FIG. The heat treatment method is not particularly limited as long as it suppresses water evaporation of the oolong tea, and examples include heating the oolong tea while storing it in a pressurized container, heating the oolong tea while passing it through a plate heat exchanger, and heating the oolong tea in a can. There are methods such as filling a bottle or a heat-resistant container and heating it under pressure. The above-mentioned heat treatment is to prevent creaming down of oolong tea, but it also has a bactericidal effect. Therefore, methods of filling oolong tea into cans, bottles, paper containers, etc. after heat treatment are adopted, such as the method of heating the oolong tea while passing it through a plate heat exchanger or the method of storing the oolong tea in a pressurized container and heating it. In such cases, it is preferable to adopt an aseptic filling method to prevent cross-contamination during filling. Comparative Experimental Example 1 12 g of oolong tea leaves were added to 1 liter of boiling water and boiled for 2.5 minutes. Thereafter, it was filtered through a muslin cloth, and the obtained oolong tea (PH: 6.5, L value: 74) was heat-treated at the temperature and time shown in FIG. Next, after leaving the heat-treated oolong tea at 4°C for 16 hours,
The cream down prevention effect was visually observed. The results are shown in FIG. In the figure, the vertical axis represents heating temperature (° C.), and the horizontal axis represents heating time (minutes). In addition, 〇, △, and × in the figure represent the heating conditions under which the experiment was conducted, 〇...significant effect, △...effective,
×...Indicates no effect. As is clear from FIG. 1, the cream-down prevention effect was observed when the heating temperature was 110°C or higher. However, even at a heating temperature of 110℃ or higher,
140℃: 0.05 minutes, 135℃: 0.15 minutes, 130℃: 0.5 minutes,
The cream-down prevention effect was observed in the upper part of the curve drawn by connecting the points of 120°C: 2 minutes and 110°C: 10 minutes, and the effect was observed in the lower part of the above curve. was not recognized. Comparative Experimental Example 2 Oolong tea having the L value shown in Table 1 was obtained in the same manner as in Comparative Experimental Example 1 by varying the amount of oolong tea leaves. Then, each oolong tea was heated to 135℃.
After being heat-treated for 20 seconds and left at 4° C. for 16 hours, the cream-down prevention effect was observed with the naked eye.
The results are shown in Table 1.

[Table] In the table, ◎ indicates a significant effect, 〇 indicates a sufficient effect, and △
indicates that there is an effect; As is clear from Table 1, the cream-down prevention effect due to heat treatment was observed when the L value was in the range of 60 to 80. Comparative Experimental Example 3 After obtaining oolong tea in the same manner as Comparative Experimental Example 1, the PH was adjusted to the pH shown in Table 2 with citric acid, and each was heated, cooled, and left to stand under the same conditions as Comparative Experimental Example 1. Afterwards, the cream down prevention effect was observed with the naked eye. The results are shown in Table 2.

[Table] The evaluation criteria in Table 2 are the same as those in Table 1. The cream down prevention effect due to PH difference is as follows:
As is clear from Table 2, this is recognized when the PH of oolong tea is 5 or higher. However, when the pH reaches 8 or higher, an alkalic taste appears and the flavor of oolong tea deteriorates, making it undesirable. As is clear from the above comparative experiment examples, in order to effectively prevent cream-down in oolong tea, it is necessary to satisfy the conditions stipulated by the present invention for the three factors of oolong tea's L value, PH, and heating conditions. be. <Effects of the Invention> According to the method of the present invention, the L value and PH of oolong tea
It is said that it is possible to effectively prevent the creaming of oolong tea by simply adjusting the amount and then heating it under specific conditions. It doesn't need to be done at all. Therefore,
Not only can the processing steps be simplified, but the flavor of oolong tea does not need to be added using various additives such as enzymes, glycerin, and sorbitol. Example 1 12 kg of oolong tea leaves were packed in a flannel cloth bag and boiled for 5 minutes in a steam jacket type heating pot to obtain 1000 kg of oolong tea. The L value of the oolong tea thus obtained was 73.2 and the PH was 6.4. Next, the above oolong tea was heated to 136℃ and 20℃ using a plate exchanger.
After heating for a second, the mixture was cooled to room temperature and filled aseptically into a paper container covered with aluminum foil. The thus obtained oolong tea in a paper container with aluminum foil was stored at 10°C for one month, but no cream down was observed at all. Furthermore, when the unheated oolong tea was filled into a paper container with aluminum foil and stored at 10°C for one day and night, cream down clearly occurred. Example 2 1.5 kg of oolong tea leaves were placed in a closed extractor together with 100 kg of 70°C hot water, and extracted at 150 torr for 10 minutes. The L value of the oolong tea obtained is 65.8 and the PH
was 7.3. Next, the oolong tea was filled into a retort pouch and then heat-treated at 121.1°C for 10 minutes. Oolong tea obtained in this way is heated at 10°C.
Even after one month of storage, no cream-down was observed.

[Brief explanation of the drawing]

FIG. 1 relates to the effect of preventing cream-down in oolong tea due to differences in heating time and heating temperature of oolong tea. In the figure, the vertical axis represents heating temperature (° C.), and the horizontal axis represents heating time (minutes).

Claims (1)

[Claims] 1. When boiling or low-temperature extraction of oolong tea from oolong tea leaves, the L value of oolong tea should be 60 to 80.
and adjust the pH to 5 to 8, and then
When the vertical axis is the heating temperature and the horizontal axis is the heating time at 110℃ or higher, 140℃: 0.05 minutes, 135℃: 0.15 minutes,
Production of oolong tea characterized by heat treatment under conditions that fall within the upper part of a curve drawn by connecting points of 130°C: 0.5 minutes, 120°C: 2 minutes, and 110°C: 10 minutes. Law.