Sterilization method and device for food and beverage containers

Abstract

To provide a sterilization method and a sterilization device for a drink / food container that can prevent a container from deteriorating owing to UV light and heat generation and sufficiently sterilize the entire inner surface of the container in sterilization processing in which pulse irradiation is performed with a part of a lamp being inserted into the container.SOLUTION: The present invention relates to a sterilization method for a drink / food container in which pulse irradiation is performed with a part of a lamp being inserted into a drink / food container to perform sterilization processing. The sterilization method includes the steps of: preparing the drink / food container; inserting the part of the lamp into the container and turning on the lamp; determining a lamp light quantity needed to sterilize a bottom face peripheral edge part of the drink / food container; determining a dimming quantity needed for an excessive quantity of light nearby an opening part of the drink / food container; and determining dimming means capable of actualizing the needed dimming quantity.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a sterilization method and a sterilization device for food and beverage containers, and more specifically to a sterilization method and a sterilization device for food and beverage containers such as milk cartons (paper containers for filling and storing liquid beverages such as milk, also called milk packs) and PET bottles. [Background technology]

[0002] It is important for food and beverage manufacturers to thoroughly sterilize food and beverage containers. Due to diversifying consumer needs, there are demands for low-salt foods and drinking water, elimination of preservatives, and extension of expiration dates, and therefore reliable sterilization of containers is required.

[0003] Currently, non-heating, non-contact sterilization technologies are being developed to replace or be used in combination with heat treatment and chemical sterilization. Flash pulse sterilization is attracting attention as a non-heating, non-contact sterilization technology. Flash 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.

[0004] Flash sterilization 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.

[0005] On the other hand, the flash pulse sterilization process has the disadvantage that it can only sterilize parts that can be irradiated. For example, light does not reach parts of the container that are difficult to irradiate from the outside (such as the bottom of the container or the shoulder of a bottle with a small opening), and there is a risk that sterilization will not be sufficient.

[0006] For this reason, a sterilization method has been proposed in which a 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 the outside of the container. That is, a lamp with a U-shape is proposed to be inserted into the container, so that the entire inner surface of the container can be irradiated with good light. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] 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 [Patent Document 2] JP 2017-226187 "Preform sterilization method and device" (Publication date: December 28, 2017) Applicant: Dai Nippon Printing Co., Ltd. [Patent Document 3] JP Patent Publication No. 6-191521 "Container Sterilizer" (Publication Date: 1994 / 07 / 12) Applicant: Toyofuri Scientific Industry Co., Ltd. [Patent Document 4] JP 2000-53111 "Container sterilization method and device" (Publication date: 2000 / 02 / 22) Applicants: IHI Corporation, Ishikawajima-Harima Heavy Industries Co., Ltd. [Patent Document 5] JP 2020-4549 "Xenon flash lamp for container sterilization" (Publication date: 2020 / 01 / 09) Applicant: Iwasaki Electric Co., Ltd. [Patent Document 6] JP 2020-4550 "Xenon flash lamp for container sterilization" (Publication date: 2020 / 01 / 09) Applicant: Iwasaki Electric Co., Ltd. Summary of the Invention [Problem to be solved by the invention]

[0008] In a sterilization method in which a part of a lamp is inserted into a container and irradiated with pulses, it was found that the light intensity of the lamp is lower at the bottom of the container than at the opening due to its structure. Therefore, in order to sufficiently sterilize the entire inner surface of the container, it is necessary to determine the light intensity of 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 lamp insertion side) is exposed to a higher light intensity than necessary.

[0009] It was found that excessive light exposure near the opening of the container caused problems that impaired 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.

[0010] In view of the above problems, the present invention aims to provide a sterilization method and device for food and beverage containers that prevents deterioration of the container caused by UV light and heat generation and can sufficiently sterilize the entire inner surface of the container in a sterilization process in which part of a lamp is inserted into the container and pulsed irradiation is performed. [Means for solving the problem]

[0011] In view of the above-mentioned object of the invention, a sterilization method for food and beverage containers according to the present invention, which performs sterilization by inserting part of a lamp into a container and irradiating it with pulsed radiation, 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 excess light near the opening of the food and beverage container, and determining dimming means capable of achieving the required amount of light reduction.

[0012] Furthermore, in the sterilization method for food and beverage containers, the dimming 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 blocking rate capable of achieving the required amount of light reduction.

[0013] Furthermore, in one aspect of the sterilization device for food and beverage containers of the present invention, in which a part of a lamp is inserted into a container and a sterilization process is performed by irradiating it with pulsed radiation, the lamp is a xenon flash lamp, and the xenon flash lamp is set to an amount of lamp light such that the part of the inner surface of the food and beverage container with the lowest amount of light can be irradiated with an amount of light sufficient for sterilization, and the xenon flash lamp is equipped with a dimming means for suppressing excessive light near the opening of the container under the lamp light amount.

[0014] Furthermore, in the above-mentioned food and beverage container sterilization device, the dimming means may be a cylindrical metal having a predetermined opening ratio, which is installed between the xenon flash lamp and the vicinity of the opening of the food and beverage container.

[0015] Furthermore, in the above-mentioned food and beverage container sterilization device, the dimming means may be a cylindrical glass coated with an IR-cut film or a UV-cut film, installed between the xenon flash lamp and near the opening of the food and beverage container.

[0016] Furthermore, the food and beverage container sterilization device may further include a jacket covering the xenon flash lamp, and the dimming means may be attached to the jacket.

[0017] Furthermore, the food and beverage container sterilization device may further include a light blocking means for blocking light emitted from a portion of the xenon flash lamp that is not inserted into the food and beverage container. Effect of the Invention

[0018] According to the present invention, a sterilization method and sterilization device for food and beverage containers can be provided that prevents deterioration of the container due to UV light and heat generation and can sufficiently sterilize the entire inner surface of the container in a sterilization process in which part of a lamp is inserted into the container and pulsed irradiation is performed. [Brief description of the drawings]

[0019] [Figure 1A] FIG. 1A is a diagram illustrating an example of a sterilization device for food and drink containers used in this embodiment. [Figure 1B] FIG. 1B is a diagram showing an example of a power supply unit used in the food and drink container sterilizer shown in FIG. 1A. [Diagram 2] 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. [Diagram 3] FIG. 3 is a flow diagram for determining the specifications of the light-attenuating portion. [Figure 4A] FIG. 4A is a block diagram of a sterilization device used for a milk carton according to the first embodiment. [Figure 4B] FIG. 4B is an enlarged view of a portion of the pasteurizer and milk carton of FIG. 4A. [Figure 5A] FIG. 5A shows data showing 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 was inserted inside the plastic bottle and pulsed irradiation was performed. [Figure 5B] FIG. 5B similarly shows data showing the amount of light measured along the bottom surface of the plastic bottle (Y direction). [Figure 6A] FIG. 6A is a block diagram of a sterilization device used for PET bottles according to the second embodiment. [Figure 6B] FIG. 6B is an enlarged view of a portion of the sterilization device and a plastic bottle in FIG. 6A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the embodiment of the sterilization method and sterilization device for food and beverage containers according to the present invention will be described in detail with reference to the accompanying drawings. Note that the same elements are given the same reference symbols and duplicated explanations will be omitted.

[0021] [Sterilization device using 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 diameter 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.

[0022] 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 integrally formed 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 for preventing 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).

[0023] When the lamp 10a is turned on, forced cooling is performed to cool the heat generated by the arc tube 2. The cooling may be either water cooling or air cooling. A partition plate 36 is provided so that the U-shaped portion 2b of the arc 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 arc 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 the case of air cooling.

[0024] (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 supply 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.

[0025] [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).

[0026] In the graph shown in FIG. 2, looking at the comparative example (conventional example) indicated by the dashed line, 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 peripheral edge of the bottom.

[0027] As the graph shows, milk carton 12c tends to have the lowest light intensity at the bottom periphery. In order 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 periphery. If the amount of light at the bottom is determined according to the necessary sterilization level, the amount of light in the area from tip A to point B will be excessively high.

[0028] The milk carton 12c, due to its container-specific nature, has a resin coating applied to the inside and the opening needs to be sealed after it is filled with milk. If excessive UV light is applied to the area from tip A to point B, the resin coating on the inside 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 applied to this area during UV light irradiation. As a result of using the dimming means 40, the amount of light from the lamp 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 applied to the area from tip A to boundary portion B is suppressed.

[0029] (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 part 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 the dimming means 40 for the lamp, a method for determining the specifications of the dimming means for the milk carton 12c shown in Fig. 3 was established.

[0030] 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 apart from it at a certain distance. This is to take into consideration the hygiene of the milk carton and to prevent damage to the light emitting tube.

[0031] 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, reaches a required sterilization level.

[0032] In step S03, the amount of light reduction required to suppress excessive light intensity near the opening A to B of the milk carton 12c is determined. That is, 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 have a problem of impairing the function of the container structure. Therefore, the amount of light reduction is determined to reduce the amount of light so that no problem occurs near the opening of the container. This amount of light reduction differs depending on the light intensity of the lamp, the shape and material of the container, etc., and can be determined once the specific specifications of the lamp and container have been determined.

[0033] In step S04, the dimming means 40 (see FIG. 4B) capable of realizing the amount of dimming determined in step S03 for the lamp light amount determined in step S02 is determined, and this is adopted.

[0034] (sterilizer) 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.

[0035] 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 a plurality of 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.

[0036] The light-reducing means 40 is not limited to the method for the lamp. These light-reducing 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 light-reducing means 40, even if the light intensity is set to obtain the necessary sterilization effect on the bottom surface C, the problem of excessive irradiation of ultraviolet light to the vicinity A to B of the opening of the container can be avoided.

[0037] 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 as a whole. The wide U-shaped lamp is irradiated by light emitted from two lamps arranged in parallel except near the bottom surface, and the area near the bottom surface is additionally irradiated by light emitted from a portion d connecting the two lamps. The portion d connecting the two lamps is not limited to a straight tube shape. The connecting portion d may be made serpentine or reciprocating within a range that allows it to be inserted from the opening of the milk carton, and the lamp length may be increased to increase the amount of irradiation.

[0038] [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 maximum (boundary between the opening and the body) B as 100%. The horizontal axis indicates the measurement position in the direction from the tip A of the opening toward the bottom C (X direction).

[0039] Looking at the data for the comparative example (conventional product) indicated 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 toward the boundary B between the opening and the body, and immediately decreases to approximately 44% after passing the boundary. After that, it gradually decreases toward the bottom C, dropping to approximately 10% at the bottom.

[0040] 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 approximately 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.

[0041] 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 the tip A to the 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 FIG. 6B) is adopted for 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 the tip A to the boundary B is suppressed.

[0042] (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.

[0043] (sterilizer) Fig. 6A is a block diagram of a sterilization device for a plastic bottle 12b according to the second embodiment. Fig. 6B is an enlarged view of a part of the sterilization device and a plastic 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.

[0044] As shown in FIG. 6B, dimming means 40 is attached to portion 2b-2 of the lamp corresponding to the vicinity A to B of the opening of the plastic 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.

[0045] [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.

[0046] The light blocking means 42 may be made of any material capable of completely blocking out emitted light or any material capable of reducing light to a level that does not damage the eyes of the worker. One example of the light blocking means 42 is a method of attaching a cylindrical metal to the lamp. Alternatively, there is a method of coating the relevant portion of the lamp with a light blocking film. The light blocking means 42 is not limited to the lamp. The light blocking means 42 may be applied to the relevant portion of the jacket 6a. Either method or a combination of both methods may be used.

[0047] [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.

[0048] (2) In this embodiment, a sterilization device that realizes this novel sterilization method is provided.

[0049] (3) The sterilization device according to this embodiment is characterized by providing 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 targets (containers), the amount of lamp light required to sufficiently sterilize the entire inner surface of the container is calculated individually, and a sterilization method is established individually to determine a dimming means that can achieve the amount of dimming 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.

[0050] [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. [Explanation of symbols]

[0051] 2: arc tube, 2a: both ends, horizontal portion, 2b: central portion, U-shaped portion, 2b-1, 2b-2: portions of lamp corresponding to opening of 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 / 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

1. 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.

2. In the sterilization apparatus for food and beverage containers as described in 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.

3. 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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