JPS6219816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing powdered tea rich in vitamin C.

BACKGROUND ART Powdered tea, which is made by boiling down the infusion of tea leaves and turning the extract into powder, is conventionally known. Powdered tea can be easily and immediately consumed, and has the advantage of not producing tea leaves, but because it takes a long time to boil down, most of the vitamin C is destroyed, and the disadvantage is that the amount of vitamin C that can be drunk is extremely low. It was hot.

According to the 4th edition of the "Japanese Food Standard Composition Table" published by the Science and Technology Agency, sencha produced using tea leaves harvested using the normal uncovered cultivation method contains 250mg per 100g.
However, the content of vitamin C when brewing tea is 4mg (10g of sencha tea is mixed with 90℃ hot water).
When brewed after 1 minute using 430ml, the volume is less than 1/6, and I still have to dispose of the tea leaves.

According to the 4th edition of the Japanese Food Composition Table, oolong tea fermented in the latter half of the harvest and black tea fermented after the harvest.
Vitamin C content is 8mg and 0mg per 100g, respectively.
Therefore, the content of vitamin C when brewing tea is 0 mg.

Gyokuro and Matcha are often cultivated by covering the tea to prevent direct sunlight during cultivation, so according to the 4th edition of the Japanese Food Composition Table, the vitamin C content of each is
They are 110mg and 60mg in 100g, which is 1/1 of the content of Sencha.
It does not even reach 2 or 1/4.

Matcha leaves no tea leaves and can be drunk as is.
The entire amount of vitamin C contained in green tea can be drunk as is, but since the vitamin C content is less than 1/4 of that of sencha, the amount of vitamin C that can be drunk is small.
In addition, since it is ground finely using an old-fashioned stone mill, it takes an extremely long time, is extremely expensive, and has the disadvantage that the production volume is small. Furthermore, there are two types of vitamin C: reduced vitamin C and oxidized vitamin C. Oxidized vitamin C changes and disappears quickly, but oxidized vitamin C changes and disappears due to the frictional heat of matcha grinding and oxidation in the air. I often do that.

The present invention has a vitamin C content of approximately 500mg/100g.
This is more than double the amount of sencha tea, and since the entire amount is drinkable, powdered tea with an extremely large amount of drinkable vitamin C can be produced in large quantities at low cost.

The method of the present invention has a vitamin C content of approximately 100mg/
A process of heat-treating 100g or more of fresh tea leaves for a short time, a process of drying the heat-treated tea leaves, a process of freezing the dried tea leaves using liquid nitrogen, and a process of turning the frozen tea leaves into powder. This is a method for producing powdered tea rich in vitamin C, which is characterized by producing powdered tea with a vitamin C content of about 500mg/100g or more.

As for the raw material tea leaves, the vitamin C content is about 50 to 62.5 compared to the vitamin C content of regular tea leaves.
Use tea leaves that have been increased to at least about twice the amount of mg/100g fresh leaves. Such tea leaves are disclosed in Japanese Patent Application No. 57-233117 (Japanese Unexamined Patent Publication No. 59-1988) filed by the present applicant.
120027).
This method is the same as the regular tea cultivation method in that it is cultivated without cover, so it receives sunlight and is high in vitamin C and inexpensive.
Because it is a special cultivation method that generates fasted roots by applying a small amount of water and nitrogen fertilizer, which is about 1/10 to 1/100 of the conventional amount,
Tea leaves containing at least about 2 to 40 times more vitamin C than regular tea leaves can be produced with even less effort and expense. In one cultivation example, the vitamin C content was 2000 mg/100 g fresh leaves. In order to eliminate the activity of vitamin C-degrading enzymes, it is preferable to use tea leaves that have just been harvested.

Fresh tea leaves (containing about 75-80% water) are
Heat-treat with boiling water at about 80-100℃ for about 10 seconds to 2 minutes.
or high-temperature steam, e.g. about 80-100°C water vapor.
Heat treat for 10 seconds to 3 minutes. If the heat treatment time is long, both reduced vitamin C and oxidized vitamin C are easily destroyed by heat, so the treatment time should be as short as possible. This increases the shelf life of reduced vitamin C.

Heat-treated tea leaves are heated or wind-powered to reduce moisture by approximately 3.
Dry to ~10%. Reducing the moisture content increases the storage and transportability of heat-treated tea leaves and reduces the loss of oxidized vitamin C.

Dried tea leaves are treated with liquid nitrogen in a tank at about -40 to -180°C for about 1 to 30 minutes and then frozen. Since liquid nitrogen is used and there is no oxygen, oxidized vitamin C is not destroyed.

The frozen tea leaves are ground at high speed in a freezing tank or other grinding machine. It is preferable to perform pulverization when or immediately after dispersing liquid nitrogen as a gas in order to prevent oxidation. Grinding can be carried out, for example, by stainless steel blades rotating at high speed, and the tea leaves, weakened by freezing, are easily and quickly ground in a very short time. The powder level should be slightly coarser than matcha, for example, but adjust as necessary.

The powdered tea of the present invention, which has become a fine powder with a high content of vitamin C, does not have any part to throw away as dashi, and can be drunk or eaten in its entirety. As described above, the powdered tea according to the present invention can be considered as "edible tea" and has a high absorption of vitamin C in the human body. It also has a high content of nutrients such as vitamin A and vitamin B.
All of the valuable plant fibers that were previously thrown away as dashi garnish are now being used, which helps prevent various diseases such as colon cancer and stomach cancer. Furthermore, it can be produced in large quantities at low cost. Therefore, it is extremely useful.

Of course, various changes and modifications may be made without departing from the broader spirit and scope of the invention.

Claims (1)

[Claims] 1. A step of heat-treating tea leaves with a vitamin C content of about 100 mg/100 g of fresh leaves or more for a short time, a step of drying the heat-treated tea leaves, and a step of drying the dried tea leaves with liquid nitrogen. A method of producing powdered tea containing about 500 mg/100 g or more of vitamin C by combining a step of freezing the tea leaves using a powder and a step of powdering the frozen tea leaves. Many methods of producing powdered tea. 2. A method according to claim 1, in which tea leaves having a vitamin C content of about 125 mg/100 g of fresh leaves are heat-treated. 3. A method according to claim 1, in which tea leaves produced by uncovered cultivation are heat-treated. 4. A method according to claim 1, in which tea leaves are heat-treated immediately after harvesting. 5. The method according to claim 1, in which tea leaves are heat-treated with boiling water at about 80 to 100°C for about 10 seconds to 2 minutes. 6. The method according to claim 1, in which tea leaves are heat-treated with high-temperature steam for about 10 seconds to 5 minutes. 7. The method according to claim 1, in which heat-treated tea leaves are dried to a moisture content of about 3 to 5% using thermal power or wind power. 8. The method according to claim 1, in which dried tea leaves are frozen at about -40° to 80°C for about 1 to 30 minutes using liquid nitrogen. 9. A method according to claim 1, in which frozen tea leaves are crushed at high speed in a freezing tank.