JP2000069908A - Sterilization method of tea powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sterilizing tea powder using an electron beam without causing any discoloration and deterioration of flavor. SOLUTION: Tea powder such as matcha tea or powdered tea is sufficiently dried, and while oscillating or blowing air in the closed room to make the tea powder flutter or to flutter, the irradiation electron energy is increased. (Voltage) 200 kev to 3
An electron beam of 00 keV and a dose of 5 kGy to 20 kGy, preferably 5 to 10 kGy is applied. Irradiation with an extremely low-energy electron beam enables tea powder to be sterilized without giving any slight deterioration in flavor. Moreover, when the electron beam is irradiated again after the tea powder is fluttered, the overlapping portion of the tea powder can be eliminated and all the tea powder can be uniformly irradiated with the electron beam, so that more reliable sterilization can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sterilizing tea powder such as matcha tea or powdered tea without deteriorating the quality.

[0002]

2. Description of the Related Art In recent years,
The demand for green tea beverages, foods, and even powdered teas that can be easily drunk has been expanding, and as a result, the flavor is excellent, the quality does not deteriorate, and stable quality can be secured. It is desired to establish a method for sterilizing tea powder.

[0003] As a conventional method for sterilizing powdery substances, first, there is an "air flow sterilization method" using steam heated air or the like. However, since this sterilization method is carried out at a high temperature of 100 ° C. or more, when applied to tea powder, there is a problem that not only browning of the color but also drastic changes in the contents occur, thereby deteriorating the quality of the product. Was.

On the other hand, recently, a method of sterilizing an animal feed by irradiating an electron beam with a current value of 10 to 40 mA at an irradiation electron energy of 3 to 5 Mev (Japanese Patent Laid-Open No. 4-20035)
No. 3), and a dose of 1 to 50 at 0.8 Mev to 10 Mev.
a method for disinfecting a dye, which comprises irradiating a kGy electron beam (JP-A-6-263996), or 0.8 Me
A sterilization method of a powdery substance using an electron beam, such as a sterilization method of a gum-based sterilization method characterized by irradiating an electron beam with a dose of 1 to 50 kGy at v to 10 Mev (JP-A-6-263996). It has been disclosed.

[0005] However, such a conventional method of sterilizing powder using an electron beam can suppress the deterioration of the product quality as compared with the above-mentioned air-flow sterilization method, but when applied to foods, There was a problem that deterioration was observed in terms of flavor. Particularly in the case of tea, slight changes in flavor and color directly affect market trends, so that even slight changes in flavor and color due to sterilization must be avoided. Further, the conventional method of sterilizing powders using an electron beam requires an enormous amount of equipment, so that it cannot be easily installed in each factory, and there is a problem that the irradiation place is limited. Furthermore, in Japan, radiation, X-rays and γ-rays, which are electron beams of 1 MeV or more, cannot be used under food laws.

Therefore, the present invention can sufficiently disinfect microorganisms and the like adhering to the tea powder in order to solve the above-mentioned conventional problems, and, of course, does not cause any discoloration and deterioration of flavor. It is intended to provide a new method of sterilizing tea powder that can be used without any problem under the law.

[0007]

According to the present invention, there is provided a method for sterilizing tea powder according to the present invention, wherein the irradiation electron energy (voltage) is 200 kev to 300 kev and the dose is 5 kev.
An electron beam of kGy to 20 kGy, preferably 5 to 10 kGy, is applied to the brown powder. Thus, in the present invention, the irradiation electron energy is 200 to 300.
By using an electron beam with an extremely low energy of 5 to 20 kGy in kev, the tea powder was successfully sterilized without giving any deterioration in flavor. In addition, since the electron beam used in the present invention has extremely low energy, the penetration depth of the electron beam is about 0.6 mm, but sufficient sterilization is possible because of sterilization of powder such as tea powder. .

As described above, the electron beam used in the present invention has an irradiation electron energy (voltage) of 200 to 300 ke.
v and the dose is 5 to 20 kGy, preferably 5 to 10 kGy.
It is an extremely low energy electron beam of kGy. 20
If it is less than 0 keV, the number of bacteria may be reduced but it may not be completely killed. On the other hand, if it exceeds 300 kev, quality may be deteriorated. If the dose is less than 5 kGy, the number of bacteria may be reduced but it may not be completely killed. If the dose exceeds 20 kGy, the bactericidal effect may not be improved and the fragrance may be slightly reduced.

In the sterilization method of the present invention, it is preferable that the tea powder to be sterilized is sufficiently dried. Since the sterilization by the electron beam sterilizes microorganisms adhering to the powder surface by using a radical reaction, moisture in the tea powder may also be affected by the radical reaction and affect the flavor.

Further, in the sterilization method of the present invention, the tea powder is vibrated, or air such as nitrogen, carbon dioxide or the like is blown on the tea powder, or the tea powder is fluttered or fluttered by other means. After that, it is preferable to irradiate with an electron beam. Electron beam penetration depth is about 0.6
mm, the electron beam may not reach the overlapping portion of the tea powder. Therefore, by irradiating the electron beam onto the tea powder while or after the tea powder is fluttered, it is possible to eliminate a portion where the electron beam does not reach, and irradiate the electron beam evenly to all the tea powders. Therefore, sterilization can be performed more reliably. After irradiating with an electron beam as described above, or while performing such a dance, the electron beam is again irradiated, so that sterilization can be performed more reliably. In addition, as an environment in which the tea powder is allowed to flow, it is preferable to perform the operation in an airtight material in order to prevent the scattering of the tea powder.

[0011] The term "tea powder" to be used in the present invention refers to powdered and dried powdered matcha (all powdered tea), unfermented tea, semi-fermented tea, fermented tea, and the like. It is meant to include these mixed powdered tea and the like.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples.

(Example 1) In this example, the relationship between the electron beam irradiation conditions and the sterilizing effect was examined. 10 g of each matcha obtained by steaming and drying the coated fresh leaves and then pulverizing with a stone mill, and green tea powder obtained by pulverizing the manufactured tea leaves with a ball mill are taken and placed in a sample tray (width 2 mm).
(0 cm, vertical width 60 cm, depth 5 cm), and irradiated with an electron beam under various irradiation conditions to measure the bactericidal effect on general bacteria and coliform bacteria. Table 1 shows the results. The irradiation with the electron beam was performed using an electron beam device (an improved product of EBC300-60) manufactured by Nissin High Voltage Co., Ltd.

[0014]

[Table 1]

As a result, a remarkable bactericidal effect was observed at all voltages and doses, but the cells were not completely killed under the condition of 300 KeV-1 KGy. However, above 5 KGy, it was completely sterilized under all conditions.

(Embodiment 2) In this embodiment, the relationship between the electron beam irradiation method and the sterilizing effect was examined. Sample 1
Is to take 5 g each of matcha obtained by steaming and drying the coated fresh leaves and then pulverizing with a stone mill, and green tea powder obtained by pulverizing the tea leaves produced by a ball mill, and putting them in polyethylene bags. After that, the sample was set on an irradiation conveyor and irradiated with electron beams under various conditions (hereinafter, this sample 1 is referred to as “conveyor irradiation”). For sample 2, 10 g each of the same matcha and green tea matchas described above was placed on a sample tray (width: 20 cm, length: 60 cm, depth: 5 cm) and vibrated (vibration (70 times / min) and 70 times). The sample was shaken and then irradiated with an electron beam (hereinafter, this sample 2 is referred to as "vibration irradiation"). After the electron beam irradiation, the bactericidal effect of each sample was measured on general bacteria and coliform bacteria. Table 2 shows the measurement results for the common bacteria in both samples, and Table 3 shows the measurement results for the coliform bacteria in both samples.

[0017]

[Table 2]

[0018]

[Table 3]

[0019] As a result, it was found that both the general bacteria and the coliform bacteria showed a remarkable sterilizing effect in the case of irradiation with the conveyor, but did not achieve complete sterilization. This is because the electron beam of 300 KeV or less has a small penetration depth of about 0.6 mm, so that the microorganisms where the powders overlap each other cannot be sufficiently sterilized, and cannot be completely sterilized. Conceivable. On the other hand, vibration irradiation completely killed both common bacteria and coliform bacteria. This is thought to be due to the fact that all the tea powders could be evenly irradiated with the electron beam by vibrating the sample, which resulted in complete sterilization.

(Embodiment 3) In this embodiment, the relationship between the irradiation conditions of electron beam irradiation, the change in quality of matcha tea, and the results of sensory tests was examined. The color tone and flavor of the green tea irradiated by the method of Example 2 were inspected. As a control, the color tone and flavor of the heat-sterilized matcha were similarly examined, and the results are shown in Table 3. The overall evaluation was based on the results in Tables 1 and 4, that is, the results of the sensory test and the degree of the bactericidal effect were comprehensively evaluated. The color tone is determined by a color difference display method (L, a, b color system), where L is lightness, + is bright, and-is dark. In addition, a is red for + and-is green, b is + for yellow and-is blue.

[0021]

[Table 4]

As a result, at 300 KeV-1 KGy,
No deterioration in color tone and flavor was observed, and a bactericidal effect of microorganisms was also observed. However, complete killing was not achieved. On the other hand, the color tone is 5 to 20KGy,
No deterioration was observed in the flavor, and the bactericidal effect was remarkably good. However, 20K
Gy tended to have a slightly reduced flavor. On the other hand, 4
At 00 KeV, the flavor was weakened at all doses, and it was judged that it was not preferable overall. From the above results, it was found that the irradiation conditions were as good as the irradiation electron energy of 300 KeV or less and the dose of 5 to 20 KGy, preferably 5 to 10 KGy.

Claims (2)

[Claims] 1. Irradiation electron energy: 200 keV to 3
A method for sterilizing tea powder, which comprises irradiating the tea powder with an electron beam at a dose of 5 kGy to 20 kGy at 00 keV. 2. The method according to claim 1, further comprising: irradiating the tea powder with an electron beam while vibrating the tea powder, blowing a gas on the tea powder, or fluttering the tea powder by other means. A method for sterilizing tea powder according to claim 1.