JP2001128618A - Method for producing tea - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce sanitarily excellent tea and unrefined tea by reducing the number of microorganisms in the unrefined tea to <=3,000 cfu/g, preferably <=1,000 cfu/g. SOLUTION: This method for producing the tea in which the unrefined tea is produced through at least a steaming process and a drying process, is characterized by washing raw tea leaves with water before the steaming process. In the steaming process, the steaming is deeply carried out using a cylinder rotation type steamer to reduce the number of microorganisms to <=3,000 cfu/g, preferably <=1,000 cfu/g. In the drying process, the drying is carried out under a condition that the highest end-point temperature in a drier is >=85 deg.C and under a condition that the integrated temperature is 10,000 to 60,000 deg.C.S. By the treatments, the number of the microorganisms in the unrefined tea can be reduced to <=1,000 cfu/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing tea which can provide tea with excellent hygiene by reducing the number of microorganisms in the production of crude tea.

[0002]

BACKGROUND OF THE INVENTION In order to produce sencha (green tea), it is necessary to first deactivate oxidase in fresh leaves to produce crude tea.
It is common to produce crude tea through the steps of steaming, cooling, rough rubbing, kneading, medium rubbing, fine rubbing, and drying ("Shincha Business Complete Works").
(See Shizuoka Prefectural Tea Industry Chamber, p. 311).

[0003] Conventionally, steaming in the production of crude tea has generally been carried out by a net rotary stirring type steamer or a feeding type steamer. Here, “steaming heat treatment with a mesh rotating and stirring type steamer”
In general, tea leaves are supplied into a steaming drum provided with a stirring shaft at the center, and the tea leaves are mixed by rotating the mesh drum and the stirring shaft while the enzyme is inactivated by the latent heat of steam in the drum. The steaming process is performed by averaging steaming during this time, and cooling the steamed one with a blower.The `` steaming heat treatment by a band-type steamer '' generally rotates longitudinally in a steaming chamber. Tea leaves evenly scattered on endless blinds (also called wire mesh belts) are steamed with steam that is blown out from above and below when sandwiching the blinds as they pass through the steam room, and the steamed leaves are brushed or blower Separated from the blinds by
Next, it is a process performed by cooling with a blower or a cooler.
This steaming heat treatment makes it possible to accurately and easily set the steaming time by operating the transmission, and furthermore, there is no "high-grade tea" made from extremely soft sprout because there is no pressing force or friction on the tea leaves. It is particularly suitable for producing high-quality tea such as "deep-steamed tea" which is subjected to long-term steam heat treatment.

[0004] The drying process in the conventional rough tea production uses a shelf-type dryer, and in the spring-summer production (first tea to third tea), the temperature setting of the dryer (actual temperature at the sensor) is set to 70. ~
The temperature is set to 80 ° C. and the residence time is set to 25 to 30 minutes.
C. and a residence time of 15 to 20 minutes was common.

In recent years, the demand for hygiene management for foods has further increased in response to the trend of O157 and the like, and with the adoption of the Cabinet Order of the Total Hygiene Management and Manufacturing Process (HACCP) for soft drinks, not only tea beverages as final products, As a raw material, the reduction of microorganisms has also been required for crude tea.

However, in the conventional method for producing sencha (green tea), it has not been considered to perform a treatment for actively reducing the number of microorganisms at the stage of producing crude tea. This is when sterilization is achieved as a result of burning in the finishing process, and is almost completely sterilized by hot water extraction when drinking tea, or when serving as a tea beverage in a PET bottle or a canned tea beverage. Strict sterilization treatment is also performed before and after packing in containers, which is considered to be partly because it was not necessary to consider the number of microorganisms at the stage of crude tea production.

In view of the above problems, an object of the present invention is to reduce the number of microorganisms in crude tea in order to provide hygienic tea and crude tea. When the number of microorganisms in the tea leaves is measured, the year and tea time (first tea, second tea,
There is almost no difference between the production plants (3rd tea, fall and winter tea) and several hundred thousand cfu / g to several million cfu / g. Also,
When the microbial count of the crude tea actually manufactured and sold is actually measured, as shown in FIG.
0000 cfu / g, but 100,000 cfu / g
Some of them exceeded g. In consideration of the number of microorganisms in such fresh tea leaves, the number of microorganisms of conventional crude tea, the standard of HACCP and the like, the present invention sets the number of microorganisms of crude tea to 300
The reduction of the number of microorganisms is intended to reduce the number of microorganisms to 0 cfu / g or less, preferably to 1000 cfu / g or less.

[0008]

Means for Solving the Problems In order to solve such problems, the present inventors first focused on the drying process in the production of crude tea, and studied the temperature and residence time of tea leaves in the drying process, the number of microorganisms before and after drying, and the content. As we examined the relationship such as moisture content, we found that the integrated temperature (temperature x time) in the dryer was a factor in reducing the number of microorganisms (Fig. 5).
Reference), and based on such knowledge, it was decided to set the integrated temperature in the drying step at 10,000 ° C. · S to 60,000 ° C. · S, preferably 20,000 ° C. · S or more. It was also found that the highest temperature in the dryer was also a factor in reducing the number of microorganisms (see FIG. 6).
The temperature was set to 5 ° C. or higher.

In the present invention, the “integrated temperature” is
It means the integrated value of the temperature inside the dryer (° C.) and the time (S (seconds)). Specifically, when the temperature inside the dryer is measured at intervals of several seconds, (interval of the seconds (S)) × temperature (° C.) ) Is the integrated value. For example, if the temperature is measured at intervals of 2 seconds, the total value of temperature (° C.) × 2 (S) is obtained, and if the temperature is measured at intervals of 1 second, the total value is temperature (° C.) × 1 (S).
Dryers used in the drying process include a shelf type, a belt type, a rotary type, and the like.In the basic test of the present invention, the temperature in the dryer is measured with time for the shelf type dryer among these types. As a result, it was found that the temperature was low in the initial stage of tea introduction, then gradually increased, and reached the maximum temperature at the end of drying. Also, even if the drying temperature is set to the same temperature,
It was also found that the temperature change and the maximum attainable temperature with the passage of time differ depending on the dryer. However, conventionally, since such a temperature change due to elapsed time and a difference in the maximum attained temperature were not disclosed, the temperature change due to the elapsed time and the maximum attained temperature were not considered, and only the temperature sensor attached to the dryer was used. The fact was that the drying temperature was set.

The present inventor has also focused on the steaming process in the production of crude tea, and as a result, comparing the steaming by the rotary stirring type steamer with the steaming by the feeding type steamer, shown in FIG. 2 and FIG. As described above, the number of microorganisms is reduced to about one-tenth by the steaming by the feeding type steamer, whereas the number of microorganisms is reduced to about one-thousand by the steaming by the body rotary type steamer. Even if it is reduced, the microorganisms remaining in the subsequent steps such as rough kneading, kneading, medium kneading, and fine kneading will proliferate with appropriate temperature, humidity, and nutrition to increase the number of bacteria (see FIGS. 2 and 3). Found that if the number of microorganisms was reduced to a certain level or less in the steaming step, the number of microorganisms could be kept low in the subsequent steps.

[0011] Therefore, the present invention, based on such knowledge, in the steaming step in the production of crude tea, the number of microorganisms to 3000
cfu / g or less, preferably 1000 cfu / g or less, especially 100 cfu / g or less. A preferred example of a means for reducing the number of microorganisms in the steaming step is to perform a so-called deep steaming using a rotary drum type steamer and set the steaming time to 20 seconds when the aim is to reduce the steaming rate to 3000 cfu / g or less. When the target is to reduce the steaming time to 1000 cfu / g or less, the heating time is set to 40 seconds to 45 seconds or more, and 100 cfu / g or more.
g for 45 seconds to 60 seconds.
Seconds or more.

The present inventor has also paid attention to pretreatment before the steaming step, and has decided to wash the fresh tea leaves with water before the steaming step in the production of crude tea. As described above, in the state of fresh tea leaves, it is several hundred thousand cfu / g to several million cfu / g, but about 40% to about 70% of microorganisms can be removed by washing with water. As described above, by reducing the number of microorganisms before the steaming step, the number of microorganisms can be reduced through the subsequent rough tea process.

[0013] Based on the above findings, the present invention relates to the most preferable method for producing tea, in which at least a steaming step and a drying step are carried out, and in the production of crude tea, the tea leaves are washed with water before the steaming step. 3000 microorganisms in the process
cfu / g or less.
It was performed under the conditions of 000 ° C. · S to 60000 ° C. · S.

The crude tea obtained by the production method of the present invention can be provided as a product tea that can be drunk as green tea by leaching tea bags or powdered tea, and can be bottled or plastic bottled beverages, tea It can be provided as a raw material for an extract powder. For example,
When used as a raw material for a tea extract powder, the obtained tea leaves can be crushed and further freeze-dried to obtain a tea extract powder, and finally, it can be provided as various foods and drinks containing the tea extract powder. In addition, for providing to other living things other than humans,
For example, it can be provided as feed for various animals, seafood, birds, insects, etc., as well as pet food, including livestock such as cattle, pigs, horses, chickens, and the like. Further, it can be provided as an industrial product obtained by mixing tea such as a deodorant and a catechin filter.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described based on preferred production examples.

In this production example, the freshly picked tea leaves are washed with water, and then the crude tea is produced through a steaming step, a kneading step and a drying step, and the microorganisms are reduced in each of the steaming step and the drying step. Processing will be performed.

The washing of fresh tea leaves with water can be performed using a washing machine or a washing machine. Specifically, a rotating washing machine with a dehydrator capable of putting fresh tea leaves into a water tank, stirring (publishing, rotating, mixing, etc.), pulling up, applying a finishing shower, and finally draining the water is preferred. Can be used. For draining, a dehydrator attached to the washing machine can be used. Furthermore, you may make it dry by warm air drying.

In this case, well water, city water, agricultural water and the like can be used as the washing water, and any of cold water, hot water and hot water can be used. However, it is preferable to use only fresh water without cycling the washing water. This is to prevent water-soluble components from being efficiently removed and to prevent the water from being contaminated by the washing water. A surfactant or a bactericide can be mixed into the washing water to increase the bactericidal ability. As the surfactant, an emulsifier having a strong detergency among emulsifiers approved for foods, for example, polyglycerin ester, sugar ester and the like can be suitably used. As a disinfectant, a conventionally known disinfectant which has been confirmed to be safe for the human body, for example, 1
5-40% ethyl alcohol, 1-20 ppm ozone water can be used.

Actually, a rotary washing machine with a dehydrator is used, and tap water which does not contain a surfactant and a bactericide is used as washing water, a fresh leaf flow rate is about 700 kg / hr, and a water quantity is about 20.
m ³ / hr, washing time of about 2 minutes for the fresh tea leaves,
Measurement of the number of microorganisms in the waste water, 1.5 × 10 ⁴ ~
It was 2.4 × 10 ⁴ cfu / mL. Therefore, fresh tea leaves 1
4.3 × 10 ^{5 to} 6.9 × 10 ⁵ cfu of microorganisms per g could be removed from fresh tea leaves, and 1 g of fresh tea leaves
Assuming that the number of microorganisms per one was about 1,000,000 cfu, it was found that about 40 to 70% of the microorganisms could be removed.

Next, in the steaming step, the number of microorganisms is reduced to 3000 cfu / g or less, preferably 1000 cfu / g or less, and particularly preferably 100 cfu / g or less, by deep steaming using a drum rotating steamer. As conditions for deep steaming, when the number of microorganisms is targeted to be 3000 cfu / g or less, the steaming time is 20 seconds to 40 seconds or more, and the number of microorganisms is 100.
When the target is 0 cfu / g or less, the steaming time is 40 seconds to 45 seconds or more. When the number of microorganisms is 100 cfu / g or less, the steaming time is 40 seconds to 60 seconds or more.

[0021] Using a drum-rotating steamer, steaming temperature:
100 ° C, steam volume: 0.3 kg / kg of tea leaves
When steaming was performed under the conditions of hr and a vapor pressure of 0 N / m ² (atmospheric pressure), as shown in FIG. 4, the number of microorganisms could be reduced to 0 cfu / g for the first tea, and the microorganisms could be reduced for the second tea. The number could be about 100 cfu / g, and in each case after the drying step it could be less than about 1000 cfu / g.

Next, in the drying step, a shelf type dryer is used, and the temperature in the dryer is set at 50 ° C. to 120 ° C., preferably 60 ° C. to 110 ° C. using the attached temperature control as a measure of the temperature inside the dryer. , Residence time 10 minutes to 40 minutes, integrated temperature 10
000 ° C · S to 60000 ° C · S, preferably 2000
The temperature is set at 0 ° C. · S or higher, and the maximum attainable temperature in the dryer is 85 ° C. or higher, preferably 95 ° C. or higher.

The integrated temperature and the number of microorganisms (cfu / g) when drying is performed by actually using a shelf type dryer and setting the temperature in the dryer to 65 to 95 ° C. by setting the attached temperature.
FIG. 5 shows the relationship between the maximum temperature in the dryer and the number of microorganisms (cfu / g).

[Brief description of the drawings]

FIG. 1 shows the results of measuring the microbial count of crude tea that has been conventionally manufactured and sold.

FIG. 2 is a graph showing a change in the number of microorganisms in a crude tea production process when steaming is performed using a transport type steamer in factories in different seasons, years, and regions.

FIG. 3 is a graph showing a change in the number of microorganisms in a crude tea production process in which steam is heated using a rotary body type steamer in plants having different seasons, years, and regions.

FIG. 4 is a graph showing the change in the number of microorganisms in the rough tea production process when deep steaming is performed using a body rotating steamer, where は is a graph targeting first tea and ● is a graph targeting second tea. is there.

FIG. 5: Cumulative temperature and the number of microorganisms (cfu / c) when drying is performed in a rough tea plant in different seasons and regions when the temperature inside the dryer is set at 65 to 95 ° C. by a controller attached to the dryer.
7 is a graph showing the relationship with (g).

FIG. 6: Relationship between maximum temperature in the dryer and the number of microorganisms when the temperature inside the dryer is set to 65 to 95 ° C. by the controller attached to the dryer at the rough tea plant in different seasons and regions. FIG.

Claims (5)

[Claims] 1. A method for producing tea, wherein the drying step in the production of crude tea is performed under the conditions of an integrated temperature of 10,000 ° C. · S to 60000 ° C. · S. 2. The method for producing tea according to claim 1, wherein the maximum temperature in the dryer is 85 ° C. or higher. 3. A method for producing tea, wherein the number of microorganisms is reduced to 3000 cfu / g or less in the steaming step in the production of crude tea. 4. A method for producing tea, comprising washing fresh tea leaves with water before the steaming step in the production of crude tea. 5. A method for producing tea in which crude tea is produced through at least a steaming step and a drying step, wherein fresh tea leaves are washed with water before the steaming step, and the number of microorganisms is reduced to 3000 cfu / g or less in the steaming step. A method for producing tea, wherein the drying step is performed under the conditions of an integrated temperature of 10,000 ° C. · S to 60000 ° C. · S in the drying step.