JPS61146149A - Method of firing and processing green tea - Google Patents

Abstract

PURPOSE:To make it possible to prevent the deterioration of green tea and increase the processing temperature and obtain a good product having a strong taste and flavor, by roasting green tea leaves in an atmosphere of an oxygen- free gas or low-oxygen gas. CONSTITUTION:For example, green tea leaves are roasted while supplying an oxygen-free gas or low-owygen gas to the interior of a rotating drum 1 of a rotating cylindrical firing machine by a gas supply pump 9. In this case, the rotating drum 1 is heated. However, the oxygen-free gas or low-oxygen gas may be heated and then blown on the green tea leaves.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method and apparatus for pasteurizing green tea, and is particularly characterized in that green tea material is treated in an oxygen-free gas or low oxygen concentration gas atmosphere. .

(Prior Art) Green tea is produced by processing fresh raw tea leaves picked from a tea garden into rough tea, then drying and storing the leaves, and if necessary, drying and pasteurizing the leaves before shipping. In other words, drying and pasteurization are finishing processes for green tea, and the main purpose of drying is to prevent deterioration of the green tea product and increase its shelf life, while pasteurization imparts flavor and aroma to green tea. The main purpose is to improve the quality of the products.

In particular, the effect of pasteurization can be further enhanced by appropriately adjusting the degree of dryness of green tea, so in recent years, drying and pasteurization processes have been separated in the finishing process to optimize processing conditions and produce better quality green tea. In order to obtain this, various dryers with good drying efficiency and pasteurization machines with good pasteurization effect have been proposed.

The conventional pasteurization method is a type of roasting treatment in which green tea is heated by contacting it with a hot plate, and in many cases the green tea is put into a rotating cylinder whose inner wall is heated. It is something. When green tea is heated to a higher temperature, the reaction that reveals its flavor and aroma increases, but on the other hand, as the temperature rises, the green tea changes color and loses its flavor and aroma. The quality of the product will deteriorate. Therefore, in the past, the conditions for pasteurization had to be kept below a certain level, making it impossible to fully bring out the original taste and aroma inherent in green tea.

(Problems to be Solved by the Invention) In recent years, preferences for the taste of tea have diversified, and teas with strong fire, that is, strong taste and aroma, are generally preferred. Therefore, there was a desire to develop a method for heating green tea that would not reduce quality.

(Means for Solving the Problems) In view of the above-mentioned points, the present inventor studied the cause of deterioration of green tea as the pasteurization temperature increases. As a result, the deterioration of green tea is due to the oxygen in the treatment atmosphere, and the more green tea is pasteurized in an oxygen-free gas or low oxygen concentration gas atmosphere, the less deterioration occurs.
Therefore, since the processing temperature can be raised, it is possible to obtain excellent products with strong taste and aroma, and it is also possible to improve work efficiency. Moreover, if the green tea is in an oxygen-free or low-oxygen gas atmosphere, the green tea will have a sufficient pasteurization effect through contact with the heated gas without being roasted. By adjusting the drying speed of green tea to suppress overdrying, creating a hot air flow atmosphere, or irradiating it with far infrared rays, the efficiency of pasteurization can be further increased, and drying treatment can also be used in combination. I discovered what I could do.

(Example ■) The present invention will be specifically explained below based on the illustrated example.

The figure shows an example of a rotary barrel-type pasteurization machine, in which reference numeral 1 is a rotary barrel, 2 is a housing, and 1 rotary barrel 1 is a hot plate that heats and stirs green tea material. There is one
Wheel receivers 3 are provided at both front and rear ends, and the wheel receivers 3 are supported by wheels 4 to rotate.

The rotating barrel 1 is open at one end and serves as an outlet 6 for the product green tea.The inner wall of the rotating barrel 1 is provided with a large number of spiral guide protrusions 7. A heater 8 is provided on the bottom surface. These are similar to a normal rotary barrel pasteurizer of this kind, and by rotating the rotary barrel 1, the green tea material introduced into the barrel from the input hopper 5 is gradually transferred to the outlet 6 side, and the heater 8
The rotary cylinder 1 is heated and brought into contact with the green tea material. In addition, a gas supply pump 9 is attached to the rotating barrel 1 to supply oxygen-free gas such as nitrogen gas or low oxygen concentration gas into the barrel, and the right-handed rotating barrel 1 functions as a gas chamber. As a result, the inside of the shell is filled with oxygen-free gas or low oxygen concentration gas.

When pasteurizing the green tea material, the gas supply pump 9 is operated to supply oxygen-free gas or low-oxygen concentration gas into the rotating barrel 1 to create an oxygen-free gas or low-oxygen concentration gas atmosphere inside the rotation I'ff41. While rotating the rotating barrel 1 while heating it according to a conventional method, green tea material is introduced into the rotating barrel 1 from the hopper 5, and is roasted by the heat of the inner wall surface of the rotating barrel 1. Here, since the rotary barrel 1 is in an oxygen-free gas or low oxygen concentration gas atmosphere, the material green tea undergoes very little deterioration due to oxidation, so the taste and aroma produced by pasteurization are hardly impaired, and the so-called strong green tea This results in a high quality green tea product.

Of course, in this case, the oxygen-free gas or low oxygen concentration gas in the barrel is heated by the heat of the rotating barrel 1, so the green tea material is roasted by the hot plate and contact heated by the heated gas. When there is a shortage of gas, pre-heated gas is supplied.

(Example ■) Figure 2 shows an example of a vibrating trough type firing machine in which oxygen-free gas or low oxygen concentration gas is used as a hot air stream. It is a hidden body. The trough conveyor 10 is a kind of vibrating conveyor, which is shaped like a trough and has, for example, a leaf spring 1.
2 to the machine frame 13, and is connected to the motor M via the crank mechanism 14, so that it vibrates back and forth as the motor rotates. The cover body 11 forms a gas chamber on the working surface of the trough conveyor 10 and is formed to cover the trough conveyor 10. The trough conveyor 10 also functions as a hot plate for heating the green tea material and a supply device for oxygen-free gas or low oxygen concentration gas to the green tea material, and the conveyor surface is formed in a box shape. A hot air generator 15 is connected to this, and the conveyor surface is heated by supplying heated oxygen-free gas or low oxygen concentration gas thereto.

A large number of blowholes 16 are formed on the conveyor surface, from which oxygen-free gas or low-oxygen concentration gas is blown out toward the gas chamber.

To heat green tea using the pasteurization machine configured in this way, first the hot air generator is activated and the trough conveyor 1 is heated.
The conveyor surface is heated to a predetermined temperature by sending hot air containing oxygen-free gas or low-oxygen concentration gas to Fill it up. and trough conveyor 1
While vibrating the 0, add green tea material from one end.

The green tea material then comes into contact with the working surface of the trough conveyor 10, is heated, and undergoes a pasteurization process. Moreover, at this time, the green tea material is present in the stream of hot air blown out from the blowhole 16 and is heated by this hot air, so the efficiency of the pasteurization process is further improved.

By the way, as mentioned above, when roasting and heating with heated gas are used together, the drying of the green tea material is accelerated, so preliminary drying of the green tea material can be omitted in some cases. It has a strong influence on processing efficiency, and when it is less than about 5%, the appearance of taste and aroma is significantly suppressed, so that the green tea product actually has a weak taste and aroma. Therefore, in such cases, it is desirable to adjust the drying rate of the green tea material by adding moisture to the oxygen-free gas or low oxygen concentration gas.

(Example ■) Figure 3 shows the above method combined with heating by a far-infrared heater, and the low oxygen concentration gas discharged from the heater is used as heating gas, thereby increasing the efficiency of thermal energy use. In addition, water is added to the gas. That is, cylinder number 17 in Figure 1 is a far-infrared heater. This device basically consists of a complete combustion type gas burner 18 and a radiator tube 19, which burns clean gas such as city gas or LPG, and guides the flame to the radiator tube 19, where it emits far infrared rays. It radiates. Furthermore, a fixed amount of combustion gas and air is supplied to the gas burner 18 of the far-infrared heater 17, so that the gas is completely combusted and the oxygen in the air is almost completely consumed, and the exhaust gas is The gas has a low oxygen concentration, almost an anoxic state.

An exhaust gas blower 21 is connected to this gas exhaust duct 20, and this is further connected to a hot air supply duct 22 to the trough conveyor 10.

To carry out the burning process using this device, first, the far-infrared heater 17 is activated to burn the fuel gas, and the generated high-temperature exhaust gas is sent to the trough conveyor 10 to heat the conveyor surface and turn the high-temperature exhaust gas into a fume. The gas is blown into the gas chamber through the port 16 to fill the gas chamber with high-temperature exhaust gas.

Then, the trough conveyor 10 is operated, and green tea material is introduced from one end thereof. The green tea is heated by contact with the conveyor surface of the trough conveyor 10 and by contact with the hot air blown from the blowhole 16, as well as by a far-infrared heater 17.
It is heated by far infrared rays emitted from the fire and is fired. Of course, here, the high-temperature exhaust gas discharged from the far infrared heater 17 is a low oxygen concentration gas close to an oxygen-free state, so the green tea material is processed in an oxygen-free gas or low oxygen concentration gas atmosphere, and Moisture (approximately 15% of the total) generated by burning the fuel gas is added to the high-temperature exhaust gas, making it much more humid than the original air, which prevents overdrying of the green tea material during processing. The process of pasteurization should be done properly.

(Effects of the Invention) As detailed above, the present invention heats and pasteurizes the green tea material in an oxygen-free gas or low oxygen concentration gas atmosphere, and the green tea material is prevented from deteriorating during processing. In addition to being able to raise the heating temperature, the heating method can also be used not only by roasting but also by contact heating with hot air and heating by far infrared rays, making it possible to produce products with strong flavors and aromas (strong fire). It can be obtained efficiently.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing one embodiment of the present invention, and Figs. 2 and 3 are schematic diagrams showing another embodiment. ;Far-infrared heater 18;Gas combustion chamber 19;Radiation cylinder 20;Exhaust duct

Claims (1)

[Scope of Claims] 1. A gas chamber is formed on the hot plate of a green tea pasteurization machine and filled with an oxygen-free gas or a low-oxygen concentration gas, and the material green tea is roasted in an oxygen-free gas or low-oxygen concentration gas atmosphere. A method for pasteurizing green tea, which is characterized by heating. 2. The method for pasteurizing green tea according to claim 1, characterized in that an oxygen-free gas or a low oxygen concentration gas is used as the heating gas stream, and the raw material green tea is heated with this gas. 3. A method for pasteurizing green tea according to claim 1 or 1, characterized in that a far-infrared heater is provided in the gas chamber, and the green tea material is heated by the radiant heat of the far-infrared heater. 4. Pasteurization of green tea according to claim 1, 2 or 3, characterized in that an appropriate amount of moisture is added to an oxygen-free gas or a low oxygen concentration gas to adjust the drying rate of the green tea material. Processing method.