JP2002306143A - Method for sterilizing granular material, and floating, migrating and sterilizing apparatus usable therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sterilizing granular material such as grain by thoroughly irradiating the whole surface of each of the granular material with electronic beam with low energy, and further to provide an apparatus to be used in the method. SOLUTION: This method for sterilizing the granular material 3 is characterized in that the surface of the floating and migrating granular material 3 is irradiated with the electronic beam F with the low energy. The floating, migrating and sterilizing apparatus has a feeding device 1 for dropping and feeding the granular material 3 in an irradiation chamber 2, an ascending current- generating device 4 for sending a gas from the lower part of the irradiation chamber 2, and an electron beam-accelerating tool 9 for radiating the electron beam F with the low energy from the side surface of the irradiation chamber 2, installed in the middle position between both of the devices.

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 granules such as spices and grains used as a raw material of food and a floating electrophoresis sterilizing apparatus used therefor. Method for uniformly irradiating the surface of a granular material with a low-energy electron beam to sterilize microorganisms existing on the surface of the granular material and the very surface layer such as the backside of the epidermis, and a floating electrophoresis sterilizer used therefor About.

[0002]

2. Description of the Related Art As an example of a conventional method of sterilizing granules by electron beam irradiation, low-energy soft electrons are applied to a thin-layer granule transferred by a conveyor from above. Some are irradiated. However, in this case, even if the granular material is completely in a single layer state, the low-energy radiated electrons are not transmitted to the upper surface layer of the granular material due to its straightness and weak permeability (non-penetrability). However, there is a drawback that there is a high risk of insufficient sterilization of the back surface layer portion, which is shaded by the granules, since the irradiation effect is only exerted.

As another example of the prior art, there is a method of irradiating an electron beam from the side while dropping a granular material. In this method, since the falling speed of the granular material is high, it is very instantaneous. It is difficult to obtain sufficient time for sterilization.In addition, if the granules overlap in the irradiation direction of the electron beam or are not rotating, the straightness of the electron beam For this reason, there has been a defect that the entire surface of each granular material cannot be uniformly irradiated with an electron beam.

[0004]

The problem to be solved by the present invention is, in a nutshell, a low-energy electron beam having low permeability to granules such as cereals. This is how to irradiate the surface uniformly. If this problem can be solved, only the surface layer portion of the granular material can be entirely and effectively sterilized, and high sterilization efficiency can be obtained. A non-heatable, non-chemical sterilization method that does not impair the flavor can be realized.

[0005]

Means for Solving the Problems The present inventor has conducted various studies to solve the above-mentioned problems. As a result, it has been found that the granular material is likely to be fluidized in the updraft, Let's fall at a low speed while floating electrophoresis,
The present invention has been achieved by paying attention to phenomena such as random and active circulating electrophoresis while violently rotating in a strong ascending airflow.

A first aspect of the present invention is a method for sterilizing granules, which comprises irradiating a surface of the granules undergoing the electrophoresis with a low-energy electron beam. According to a second aspect of the present invention, there is provided a supply device that drops and supplies a granular material into an irradiation chamber, an ascending airflow generator that feeds gas from below the irradiation chamber, A floating electrophoresis sterilizer comprising an electron beam accelerator for irradiating an energy electron beam.

[0007] According to the above method and structure, the granules are subjected to floating electrophoresis (as if the granules vigorously rotate and mix and migrate as if they were in a state like boiling of a liquid), thereby providing an infinite number of granules. The electron beam can be uniformly and evenly applied to the entire surface of the substrate.

Further, the strength (flow velocity) of the updraft in the irradiation chamber
The length of irradiation time, such as controlling the falling velocity of countless granules by the appropriate control of the number of granules, or temporarily suspending the granules by performing the circulating movement of the granules in the irradiation chamber That is, since the irradiation energy amount for each granular material can be adjusted, the optimum sterilizing operation conditions for various types of granular materials can be set using one electron beam accelerator. The energy of the irradiation electron beam required at this time depends on the type of the target granular material, but is generally at a low level due to an acceleration voltage of 20 keV to 280 keV, and the material penetration depth is as small as about 20 to 150 μm. The superficial portion, which is a convenient depth for performing surface sterilization without losing taste.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partial cross-sectional view showing an embodiment of a buoyant electrophoresis sterilizer according to the present invention. This buoyant electrophoresis sterilizer is provided with a supply device 1 for quantitatively dropping and supplying countless granules 3 into the irradiation chamber 2. Arrow C indicates the falling direction. As the supply device 1, for example, a screw conveyor, a belt type or an electromagnetic type conveyor is used. Granules 3 introduced from the direction of arrow A
Is quantitatively conveyed in the supply device 1 in the direction of arrow B, and is dropped and supplied into the irradiation chamber 2 at a specified supply speed as indicated by arrow C.

On the other hand, an updraft generator 4 for feeding gas is provided below the irradiation chamber 2. The updraft generator 4 includes a gas inlet 5, a pressure regulating chamber 6, a filter 7, and a rectifier 8 composed of a wire mesh or a perforated plate. As the rectifier 8, a porous material such as unglazed or canvas is also effectively used. From the gas inlet 5 of the updraft generator 4 configured as described above, an arrow D
When a gas such as air or nitrogen is sent at a predetermined pressure as shown by a symbol, the gas is reduced in flow rate once in the pressure regulating chamber 6 so that the pressure is uniformly adjusted, and then the gas is purified by the filter 7. 8, flow into the irradiation chamber 2 via an arrow E
The rising airflow E has a uniform flow velocity as shown by. The gas in the irradiation chamber 2 is finally discharged to the outside via the exhaust port 12 as shown by the arrow G.

Next, an electron beam accelerator 9 is provided on the side of the irradiation chamber 2 at an intermediate position between the supply device 1 and the updraft generator 4, and the electron beam F is irradiated from the irradiation window 10 of the electron beam accelerator 9.
Is irradiated to countless granular materials 3 in the irradiation chamber 2. Since the electron beam F has a low energy, it does not penetrate the individual granular material 3 and can effectively sterilize microorganisms existing on the surface and the very surface layer such as the backside of the epidermis.

Further, a plate-shaped beam catcher 11 is provided at a position facing the irradiation window 10 of the electron beam accelerator 9, and is not absorbed by the granular material 3 floating and migrated in the irradiation chamber 2. It functions to receive and absorb the flying electron beam F. However, in this case, if the width L in the irradiation direction in the irradiation chamber 2 is set to be substantially the same as the range of the electron beam F in the gas in the irradiation chamber 2, the beam catcher 11 does not need to be provided.

[0013] In the floating electrophoresis sterilizer based on the structure described in detail above, when the granules 3 are dropped and supplied from the supply device 1 into the irradiation chamber 2 in which the updraft E is generated, countless granules are generated. It was found that the object 3 received the resistance of the upward airflow E, and its falling speed was reduced, and at the same time, the object 3 was falling while performing floating electrophoresis with irregular rotation.
The falling speed of the granular material 3 at this time depends mainly on the average diameter, surface area and density of the granular material 3 and the average rising flow velocity and viscosity of the gas. The irradiation time of the electron beam F can be adjusted by controlling the average flow velocity to control the falling velocity of the particulate matter 3 in suspension migration.

The innumerable granules 3 whose floating migration falling speed is appropriately controlled as described above are uniformly irradiated on all surfaces thereof by being irradiated with the electron beam F from the electron beam accelerator 9. Instead, it is sterilized with the required irradiation energy, and then falls onto the upper surface of the rectifier 8. In this case, there is a considerable chance that the granules 3 during the floating electrophoresis overlap in the irradiation direction of the electron beam F. However, by appropriately controlling the supply amount of the granules 3 and the flow velocity of the updraft E, the individual The conditions for uniformly irradiating the entire surface of the granular material 3 can be easily found.

The granular material 3 that has fallen on the upper surface of the rectifier 8 in this manner is moved by 3 ° in the direction of the outlet 13 by the rectifier 8.
Since it is provided so as to have a slight inclination of about 7 °, while being fluidized by the updraft E sent from the surface of the rectifier 8, it is automatically turned to the outlet 13 by the air slide effect. It moves and is discharged to the outside as shown by arrow H.

However, depending on the type of the granular material 3 and the number of adhered microorganisms, there may be a case where irradiation energy is not sufficiently given to the granular material 3 even when the floating electrophoresis drop method is used. In such a case, as shown in FIG. 2, by setting the flow velocity of the ascending airflow E to be higher than the fluidization start velocity of the granular material 3, the buoyant electrophoresis circulating motion is performed on the innumerable granular material 3. I can make it. Specifically, in this case, since the flow velocity of the rising airflow E in the irradiation chamber 2 is relatively fast, the flow velocity distribution 14 emphasizes the effect of friction with the side wall of the irradiation chamber 2 and is generally parabolic. The flow velocity at the center is the fastest. Therefore, countless granules 3
Performs the circulating motion of the floating electrophoresis in the direction indicated by the arrow J. By irradiating the electron beam F from the electron beam accelerator 9 to the countless granular materials 3 in the temporary stagnant state, which continue the floating electrophoresis circulating motion, the irradiation time can be arbitrarily lengthened. Thus, the irradiation energy for the granular material 3 can be increased to a required level. However, if the flow rate of the updraft E is set to be larger than the speed suitable for the circulating movement of the granular material 3, the granular material 3
It should be noted that the gas is discharged from the exhaust port 12 to the outside of the irradiation chamber 2 together with the turbulent airflow.

In order to carry out the electron beam irradiation under the circulation of the floating electrophoresis, after supplying an appropriate amount of the granular material 3 into the irradiation chamber 2, the operation of the supply device 1 is temporarily stopped, and the ascending air flow E Is set to be equal to or higher than the fluidization start speed of the granular material 3, and the granular material 3 is irradiated with the electron beam F while performing the circulating motion of the floating material. Then, after a predetermined irradiation time has elapsed, the flow rate of the ascending airflow E is reduced to cause the granules 3 to fall by floating electrophoresis, and after being taken out from the outlet 13 to the outside,
Further, the same operation is repeated. By performing such a batch continuous operation, even when an inexpensive electron beam accelerator 9 with a low rating is used, a process with high sterilization efficiency can be realized. Further, when performing a batch continuous operation similar to the above, the supply of the granular material 3 is not necessarily performed in the irradiation chamber 2.
It does not need to be done from above.

[0018]

Since the present invention has the above-described method and configuration, the following effects can be obtained.

According to the method of the present invention, the entire surface of the granules is uniformly and uniformly irradiated with an electron beam having the minimum energy required for sterilization while the granules are reliably floated and electrophoresed. By doing so, microorganisms adhering to the surface layer of the granular material can be sterilized with high efficiency under non-heated and non-drug conditions without impairing the aroma and flavor inherent to the granular material.

According to the apparatus of the present invention, the innumerable granular materials are subjected to floating electrophoresis falling with irregular rotational mixing / electrophoresis by applying an ascending air current from below to the entire countless granular materials. The surface can be evenly and uniformly irradiated with electron beams. In addition, by controlling the flow velocity of the ascending airflow, the length of time for irradiating the granular material with the electron beam can be appropriately adjusted. Therefore, a single electron beam accelerator can be used for various types of granular materials. Optimal sterilization operation conditions can be set.

Further, according to the apparatus of the present invention, the irradiation time is set by setting the flow rate of the updraft to be equal to or higher than the fluidization start velocity of the granules and causing the granules to carry out the floating electrophoresis circulation. Batch operation is possible in which can be set arbitrarily. Therefore, a high-efficiency sterilization process using a small and inexpensive electron beam accelerator with a low rating is possible.
This fact is, when using a very expensive electron beam accelerator to sterilize processed food granules,
It offers significant economic benefits.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing one embodiment of a device for sterilizing a hydrophoresis device according to the present invention.

FIG. 2 is a cross-sectional view showing the state of circulating suspension of the granular material in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Supply apparatus 2 Irradiation room 3 Granular material 4 Updraft generator 8 Rectifier 9 Electron beam accelerator 10 Irradiation window

Claims (3)

[Claims] 1. A method for disinfecting granules, which comprises irradiating the surface of the granules undergoing electrophoresis with a low-energy electron beam. 2. The method according to claim 1, wherein the granular material in the irradiation chamber is exposed to an ascending air current from below, and the granular material is irradiated with a low-energy electron beam while falling or circulating by floating electrophoresis. 3. A supply device for dropping and supplying the granular material into the irradiation chamber, an ascending airflow generating device for feeding gas from below the irradiation chamber, and a low-energy air-supplying device provided at an intermediate position between the two devices, A suspension electrophoresis sterilizer including an electron beam accelerator for irradiating an electron beam.