JP7602726B2 - Sterilization method and device for food and beverage containers - Google Patents

Description

The present invention relates to a sterilization method and device for food and beverage containers. More specifically, it relates to a sterilization method and device for food and beverage containers such as milk cartons (paper containers for filling and storing liquid beverages such as milk, also known as milk cartons) and PET bottles.

For food and beverage manufacturers, it is important to thoroughly sterilize food and beverage containers. As consumer needs diversify, there are demands for low-salt foods and drinking water, the elimination of preservatives, and extended expiration dates, and this calls for thorough sterilization of containers.

Currently, non-heating, non-contact sterilization techniques are being developed to replace or be used in conjunction with heat treatment and chemical sterilization. Light pulse sterilization is attracting attention as a non-heating, non-contact sterilization technique. Light pulse sterilization uses a xenon flash lamp. The light emitted by a xenon flash lamp contains a large amount of ultraviolet light with a wavelength of 200 to 300 nm, which is effective for sterilization.

The flash sterilization process using a xenon flash lamp has the following advantages: a strong sterilization effect, easy pulse control of light emission, no residue is produced because it is non-contact, and the extremely short pulse irradiation has little effect on food and beverage containers.

On the other hand, the flash pulse sterilization process has the disadvantage that it can only sterilize parts that can be irradiated. There is a risk that the light does not reach parts that are difficult to irradiate from the outside of the container, such as parts of the inside of the container (such as the bottom of the container or the shoulder of a bottle with a small opening), and sufficient sterilization may not be achieved.

For this reason, a sterilization method has been proposed in which part of a lamp is inserted inside the container and irradiated with pulsed light as a technology for sterilizing the inner surface of a container, which is difficult to irradiate from outside the container. In other words, it has been proposed to make the lamp U-shaped and insert it into the container, so that the entire inner surface of the container can be irradiated with good light.

JP 2001-247108 A "Container sterilization method and device" (Publication date: 2001/09/11) Applicants: IHI Corporation, Prima Meat Packers Co., Ltd., Food Industry Electronics Application Technology Research Association JP 2017-226187 "Preform sterilization method and device" (Publication date: December 28, 2017) Applicant: Dai Nippon Printing Co., Ltd. JP Patent Publication No. 6-191521 "Container Sterilizer" (Publication Date: 1994/07/12) Applicant: Toyofuri Scientific Industries Co., Ltd. JP 2000-53111 "Container sterilization method and device" (Publication date: 2000/02/22) Applicants: IHI Corporation, Ishikawajima-Harima Heavy Industries Co., Ltd. JP 2020-4549 "Xenon flash lamp for container sterilization" (Publication date: 2020/01/09) Applicant: Iwasaki Electric Co., Ltd. JP 2020-4550 "Xenon flash lamp for container sterilization" (Publication date: 2020/01/09) Applicant: Iwasaki Electric Co., Ltd.

In a sterilization method in which a lamp is inserted partially inside a container and irradiated with pulsed light, it was found that, due to the container's structure, the amount of light emitted by the lamp is lower at the bottom than at the opening. Therefore, in order to sufficiently sterilize the entire inner surface of the container, it is necessary to determine the amount of light emitted by the lamp to obtain the necessary sterilization effect at the bottom. As a result, the area near the opening of the container on the opposite side (i.e., the side where the lamp is inserted) is exposed to a higher amount of light than necessary.

It was discovered that problems occurred near the opening of the container where excessive light was irradiated, impairing the functionality of the container. Specifically, the UV light caused deterioration of the container base material, and the heat generated by the lamp caused deformation and melting of the container. The occurrence of this problem was also influenced by factors such as the shape of the container opening and the distance between the opening and the lamp.

In view of the above problems, the present invention aims to provide a sterilization method and device for food and beverage containers that can prevent deterioration of the container caused by UV light and heat and can sufficiently sterilize the entire inner surface of the container in a sterilization process in which a lamp is partially inserted into the container and pulsed irradiation is performed.

In view of the above object of the invention, the sterilization method for food and beverage containers according to the present invention, which involves inserting part of a lamp into a container and irradiating it with pulsed light, includes, in one aspect, the steps of preparing the food and beverage container, inserting part of a lamp into the container and turning it on, determining the amount of lamp light required to sterilize the entire inner surface of the food and beverage container, determining the amount of light reduction required for the excess light amount near the opening of the food and beverage container, and determining a dimming means capable of achieving the required amount of light reduction.

Furthermore, in the sterilization method for food and beverage containers, the light-reduction means may be a method of placing a cylindrical metal between the opening of the food and beverage container and the lamp, and the cylindrical metal may have a light-shielding rate capable of realizing the required amount of light reduction.

Furthermore, in one aspect of the sterilization device for food and beverage containers according to the present invention, which performs sterilization by inserting a part of a lamp into the container and irradiating it with pulsed radiation, the lamp is a xenon flash lamp, and the xenon flash lamp is set to a lamp light intensity that can irradiate the part of the inner surface of the food and beverage container with the lowest light intensity with a sufficient amount of light for sterilization, and is equipped with a dimming means that suppresses excessive light intensity near the opening of the container under the lamp light intensity.

Furthermore, in the above-mentioned food and beverage container sterilization device, the dimming means may be a cylindrical metal member having a predetermined aperture ratio, which is installed between the xenon flash lamp and the vicinity of the opening of the food and beverage container.

Furthermore, in the above-mentioned food and beverage container sterilization device, the dimming means may be a cylindrical glass coated with an IR-cutting film or a UV-cutting film, which is installed between the xenon flash lamp and the vicinity of the opening of the food and beverage container.

Furthermore, the food and beverage container sterilization device may further include a jacket that covers the xenon flash lamp, and the dimming means may be attached to the jacket.

Furthermore, the food and beverage container sterilization device may be provided with a light shielding means for blocking light emitted from the portion of the xenon flash lamp that is not inserted into the food and beverage container.

The present invention provides a sterilization method and device for food and beverage containers that can prevent deterioration of the container caused by UV light and heat and can sufficiently sterilize the entire inner surface of the container in a sterilization process in which a lamp is partially inserted into the container and pulsed irradiation is performed.

FIG. 1A is a diagram illustrating an example of a sterilization device for food and beverage containers used in this embodiment. FIG. 1B is a diagram showing an example of a power supply unit used in the food and beverage container sterilization device shown in FIG. 1A. FIG. 2 shows data showing the amount of light measured along the inner surface of a milk carton (X direction) when a part of the lamp was inserted inside the milk carton and pulsed irradiation was performed. FIG. 3 is a flow diagram for determining the specifications of the light-attenuating portion. FIG. 4A is a block diagram of a sterilization device used for a milk carton according to the first embodiment. FIG. 4B is an enlarged view of a portion of the pasteurizer and milk carton of FIG. 4A. FIG. 5A shows data indicating the amount of light measured along the inner surface (X direction) of a plastic bottle when a part of the lamp according to the second embodiment is inserted inside the plastic bottle and pulsed irradiation is performed. FIG. 5B similarly shows data showing the amount of light measured along the bottom surface of the plastic bottle (Y direction). FIG. 6A is a block diagram of a sterilization device used for PET bottles according to the second embodiment. FIG. 6B is an enlarged view of a portion of the sterilization device and a plastic bottle of FIG. 6A.

The following describes in detail an embodiment of a sterilization method and sterilization device for food and beverage containers according to the present invention, with reference to the attached drawings. Note that the same elements are given the same reference symbols, and duplicate explanations will be omitted.

[Sterilization device using a xenon flash lamp]
FIG. 1A is a diagram showing an example of a sterilizer 10 for food and beverage containers using a xenon flash lamp 10a. The arc tube 2 of the lamp 10a has a central portion 2b formed in a U-shape downward, and both ends 2a, 2a are formed in the horizontal direction. Both ends 2a, 2a are formed relatively thick, and an anode electrode is disposed on one side and a cathode electrode is disposed on the other side. The tube diameter of the central portion 2b is formed thin compared to the tube diameters of both ends 2a, 2a, and is shaped so that it can be easily inserted into a food and beverage container for sterilization. A trigger wire for starting is wound around the outer circumferential surface of the arc tube 2 of the lamp 10a, but is omitted in order to simplify the drawing and make it easier to see.

The arc tube 2 is surrounded almost entirely by jackets 6a and 6b. The central portion (U-shaped portion) 2b of the arc tube 2 is surrounded by the jacket 6a, and both ends (horizontal portions) 2a, 2a are surrounded by the jacket 6b. The jackets 6a and 6b are integrated to form the same space that communicates with each other. The jackets 6a and 6b are used for cooling the arc tube 2 when it is lit, and to prevent fragments from scattering inside the container if the arc tube is broken. The jacket 6a is typically made of quartz. The jacket 6b is made of a fluorine-based resin film, typically Teflon (registered trademark).

When the lamp 10a is lit, forced cooling is performed to cool the heat generated by the light-emitting tube 2. Cooling can be either water-cooling or air-cooling. A partition plate 36 is provided so that the U-shaped portion 2b of the light-emitting tube can be effectively cooled. In the case of water-cooling, cooling water is fed from the water supply port 18a into the right cavity of the jacket 6b, flows from the base of the central portion 2b of the light-emitting tube along the right side of the partition plate 36 to the tip, exceeds the partition plate, returns from the tip to the base along the left side of the partition plate 36, passes through the left cavity of the jacket 6b, and is discharged from the drain port 18b. The same applies to air-cooling.

(Lighting circuit)
Fig. 1B is a diagram showing an example of a lighting circuit 30 used in the sterilizer 10 shown in Fig. 1A. Here, reference numeral 10a denotes a lamp, and reference numeral 8 denotes a trigger wire. The lighting circuit 30 includes a commercial AC power source 38, a charging high-voltage power source circuit 24 that boosts and rectifies the commercial AC power source 38, a charging/discharging capacitor 26 that stores the output, and a waveform adjustment coil 28, and supplies a pulse voltage to the lamp 10a. Furthermore, the lighting circuit 30 includes an external trigger generating circuit 32 for starting, and a pulse step-up transformer 34 that boosts the trigger pulse and sends it to the trigger wire 8.

[First embodiment]
(Light intensity on the inside of a milk carton)
The first embodiment relates to a sterilization device and a sterilization method for milk cartons as containers. The graph in Fig. 2 shows the amount of light measured along the inner surface of a milk carton (X direction) when a lamp 10a is inserted inside the milk carton 12c and pulsed irradiation is performed. The vertical axis of the graph shows the relative amount of light normalized by setting the amount of light at point B (approximately 50 mm away in the X direction) where the amount of light is maximum as 100%. The horizontal axis shows the measurement position in the direction from the tip A of the opening toward the bottom C (X direction).

Looking at the comparative example (conventional) shown by the dashed line in the graph in Figure 2, the amount of light is approximately 69% of the maximum amount of light at the tip A of the opening (zero position in the X direction), gradually increases toward point B of the maximum amount of light, and after passing approximately 130 mm, gradually decreases toward the bottom C, dropping to approximately 22% at the edge of the bottom.

As the graph shows, milk carton 12c tends to have the lowest amount of light at the bottom edge. To sufficiently sterilize the inside of the milk carton, it is necessary to determine the amount of ultraviolet light so that the necessary sterilization level is achieved at the bottom edge. If the amount of light at the bottom is determined to match the necessary sterilization level, the amount of light in the area from tip A to point B will be excessively high.

The milk carton 12c is a container-specific item, and the inside surface is coated with a resin, and the opening needs to be sealed after it is filled with milk. If excessive UV light is irradiated from the tip A to point B, the resin coating on the inside surface near the opening may change (deteriorate), which may result in poor sealing. For this reason, a dimming means 40 (see FIG. 4B) is used to suppress the excessive amount of light in this area during UV light irradiation. As a result of using the dimming means 40, the amount of lamp light measured along the bottom surface C of the plastic bottle (Y direction) is corrected to the data of this embodiment (after dimming) shown by the solid line, and the amount of light in the area from tip A to boundary portion B is suppressed.

(Sterilization method)
It can be determined that the data on the amount of ultraviolet light irradiation in Fig. 2 shows that the tendency that the amount of light is lowest at the bottom peripheral portion C of the inner surface of the container remains unchanged even if the specifications of the container, the lamp, etc. are different. Therefore, when adopting a dimming means 40 for the lamp, a method for determining the specifications of the dimming means for a milk carton 12c shown in Fig. 3 was established.

In step S01, a container (milk carton 12c) is prepared, and a lamp is inserted and turned on. At this time, the U-shaped tip of the lamp (strictly speaking, the tip of the jacket surrounding the U-shaped tip) does not come into contact with the bottom of the milk carton 12c, but is spaced at a certain distance. This is to consider the hygiene of the milk carton and to prevent damage to the light-emitting tube.

In step S02, the lamp light intensity is determined so that the light intensity at the bottom peripheral portion C, where the light intensity is the lowest, is at the required sterilization level.

In step S03, the amount of dimming required to suppress excessive light intensity near the opening A to B of the milk carton 12c is determined. In other words, the area near the opening of the container is exposed to a higher amount of light than necessary. As a result, the areas near the opening A to B of the container are subject to problems that impair the functionality of the container structure. Therefore, the amount of dimming that reduces the amount of light so that problems do not occur near the opening of the container is determined. This amount of dimming differs depending on the light intensity of the lamp, the shape and material of the container, etc., and can therefore be determined once the specific specifications of the lamp and container have been determined.

In step S04, a dimming means 40 (see FIG. 4B) that can achieve the dimming amount determined in step S03 with the lamp light amount determined in step S02 is determined and adopted.

(Sterilization equipment)
Fig. 4A is a block diagram of a xenon flash lamp sterilizer for sterilizing a milk carton 12c according to the first embodiment. Fig. 4B is an enlarged view of the xenon flash lamp and the milk carton 12c in Fig. 4A. An example of the power supply unit 30 is the power supply unit shown in Fig. 1B. An example of the cooling unit 20 is the cooling unit described in Fig. 1A. The lamp housing 22 is used as a general term for the members of the sterilizer shown in Fig. 1A excluding the cooling unit 20 and the lamp central part 2b inserted into the container.

The lamp of the first embodiment employs a dimming means 40. The dimming amount of the dimming means 40 is set to be capable of realizing the required dimming amount determined in step S04 of FIG. 3. For example, as an example of the dimming means 40, a cylindrical metal (e.g., a cylindrical metal with multiple openings, a metal mesh, etc.) having a light blocking rate (conversely, an aperture rate) capable of realizing the required dimming amount is attached to the portion 2b-1 of the lamp corresponding to the vicinity A to B of the opening of the container. Alternatively, as the dimming means 40, a cylindrical glass or the like coated with an IR cut film and/or a UV cut film capable of realizing the required dimming amount is detachably attached to the corresponding portion of the portion 2b-1 of the lamp. The length of the dimming means 40 in the lamp axial direction is determined according to the shape of the container, etc.

The dimming means 40 is not limited to the method for the lamp. These dimming means 40 may be adopted for the portion of the jacket 6a corresponding to the vicinity of the opening of the container 12b. Any of these methods, or a combination of both, may be adopted. By adopting the dimming means 40, even if the light intensity is set to obtain the necessary sterilization effect on the bottom surface C, the problem of excessive exposure of ultraviolet light to the vicinity A to B of the opening of the container can be avoided.

As shown in FIG. 4B, the milk carton 12c has a rectangular body, and its opening is wider than that of a plastic bottle (see the second embodiment). Therefore, as shown in FIG. 4B, the container insertion portion (U-shaped portion) 2b of the lamp can be made wide U-shaped overall. The wide U-shaped lamp is irradiated by light emitted from two lamps arranged in parallel except near the bottom, and in addition, near the bottom, illumination by light emitted from the portion d connecting the two lamps is added. The portion d connecting the two lamps is not limited to a straight tube shape. The connecting portion d may be made serpentine or back-and-forth shaped within a range that can be inserted from the opening of the milk carton, and the lamp length may be increased to increase the amount of irradiation.

[Second embodiment]
(Light intensity on the inside of a plastic bottle)
The second embodiment relates to a sterilization device and a sterilization method for PET bottles. The graph in Fig. 5A shows data indicating the amount of light measured along the inner surface of a PET bottle (X direction) when a lamp is inserted inside the PET bottle 12b and pulsed irradiation is performed. The vertical axis of the graph indicates the relative amount of light normalized by setting the amount of light at the point where the amount of light is the maximum (boundary between the opening and the body) B as 100%. The horizontal axis indicates the measurement position in the direction (X direction) from the tip A of the opening toward the bottom C.

Looking at the data for the comparative example (conventional) shown by the dashed line, the amount of light is approximately 74% of the maximum amount of light at the tip of the opening (zero position in the X direction) A, gradually increases towards the boundary between the opening and the body B, immediately decreases to approximately 44% after passing the boundary, then gradually decreases towards the bottom C, dropping to approximately 10% at the bottom.

Figure 5B shows data indicating the amount of light from the lamp measured along the bottom surface C of the plastic bottle (Y direction). The vertical axis of the graph corresponds to the relative light amount on the vertical axis of the graph in Figure 5A. Because the bottom surface C is roughly circular, the horizontal axis shows data indicating the relative light amount measured in the diameter direction (Y direction) from the periphery (end) C. The central part D is approximately 20% of the maximum, decreasing to approximately 10% at the periphery C.

From this conventional data, it can be seen that if the lamp light intensity is determined according to the required sterilization level for the periphery (edge) C of the bottom surface, the light intensity for the area from tip A to boundary B will be excessively high. For this reason, in order to suppress the excessive light intensity during ultraviolet irradiation, a dimming means 40 (see Figure 6B) is used in the lamp. As a result, the lamp light intensity measured along the bottom surface C of the PET bottle (Y direction) is corrected to the data of this embodiment (after dimming) shown by the solid line, and the light intensity for the area from tip A to boundary B is suppressed.

(Sterilization method)
The method for determining the specifications of the light-dimming means 40 is the same as the method for determining the specifications of the light-dimming means for milk cartons shown in FIG.

(Sterilization equipment)
Fig. 6A is a block diagram of a sterilization device for a PET bottle 12b according to the second embodiment. Fig. 6B is an enlarged view of a part of the sterilization device and a PET bottle in Fig. 6A. For the power supply unit 30, the lamp housing 22, and the cooling unit 20, please refer to the description of Fig. 4A.

As shown in FIG. 6B, a dimming means 40 is attached to a portion 2b-2 of the lamp corresponding to the vicinity A to B of the opening of the PET bottle.
The amount of light reduction by the light reduction means 40 is set to be capable of realizing the necessary amount of light reduction determined in step S04 of FIG. 3, as described in the first embodiment.

[Third embodiment]
The third embodiment is an additional means to the first and second embodiments. Sterilization devices using xenon flash lamps emit high-intensity light, which may damage the eyes of workers at the manufacturing site. Therefore, a light-shielding means 42 is provided above the dimming means 40 shown in Figures 4B and 6B to prevent light emission from leaking to the outside when the lamp is turned on.

The light shielding means 42 can be any material capable of completely blocking out emitted light, or any material capable of reducing light to a level that does not damage the worker's eyes. One example of the light shielding means 42 is to attach a cylindrical metal member to the lamp. Alternatively, the relevant portion of the lamp can be coated with a light-shielding film. The light shielding means 42 is not limited to the lamp. The light shielding means 42 may also be applied to the relevant portion of the jacket 6a. Either method, or a combination of both, may be used.

[Features and advantages of this embodiment]
(1) In this embodiment, in a sterilization method in which a part of a lamp is inserted into a food container and irradiated with pulsed light, the lamp irradiates an amount of light that matches the sterilization level of the periphery of the bottom inside the container, which causes the amount of light from the lamp around the container opening to be relatively high, which can cause deterioration or damage to the container opening. This problem is not disclosed in prior art documents. Furthermore, a new sterilization method that solves this problem has been established.

(2) In this embodiment, a sterilization device that realizes this new sterilization method is provided.

(3) The sterilization device according to this embodiment is characterized by the provision of a dimming means near the opening of the container. However, in reality, it is not just a case of simply providing a dimming means on the container. For various types of sterilization objects (containers), a sterilization method is individually established to determine the amount of lamp light required to sufficiently sterilize the entire inner surface of the container, and a dimming means that can achieve the amount of light reduction required to avoid problems such as deterioration and damage to the container opening when this amount of lamp light is irradiated, and a method is provided for forming a dimming means appropriate for each sterilization method.

[summary]
The above describes the embodiment of the sterilization method and sterilization device for food and beverage containers according to the present invention, but these are examples and do not limit the present invention. Any deletions, modifications, additions, and improvements that a person skilled in the art can easily make to these embodiments are within the scope of the present invention. The technical scope of the present invention is defined by the appended claims.

2: Arc tube, 2a: Both ends, horizontal portion, 2b: Central portion, U-shaped portion, 2b-1, 2b-2: Parts of the lamp corresponding to the opening of the container, 6a, 6b: Jacket, 8: Trigger wire, 10a: Xenon flash lamp, lamp, 12b: Plastic bottle, 12c: Milk carton, 18a: Water inlet, 18b: Drain, 20: Cooling unit, 22: Lamp housing, 24: High voltage power supply circuit for charging, 26: Charging and discharging capacitor, 28: Waveform adjustment coil, 30: Power supply unit, 32: External trigger generating circuit for starting, 34: Pulse step-up transformer, 36: Partition, 38: Commercial AC power supply, 40: Dimming means, 42: Shading means,

Claims (3)

In a sterilization device for food and beverage containers, a part of a lamp is inserted into the container and pulsed irradiation is performed to sterilize the container.
The lamp is a xenon flash lamp and includes a jacket covering the xenon flash lamp.
The xenon flash lamp is set to a lamp light intensity such that the part of the inner surface of the food or beverage container with the lowest light intensity can be irradiated with a sufficient amount of light for sterilization, and a dimming means is provided to suppress excessive light intensity near the opening of the container under the lamp light intensity, the dimming means being attached to the jacket . The sterilization apparatus for food and beverage containers according to claim 1 ,
A sterilization device, wherein the dimming means is a cylindrical metal having a predetermined opening ratio and is installed between the xenon flash lamp and the vicinity of the opening of the food or beverage container. The sterilization apparatus for food and beverage containers according to claim 1 or 2 , further comprising:
A sterilization device comprising a light shielding means for blocking light emitted from a portion of the xenon flash lamp that is not inserted into the food or beverage container.

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