Technical field
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The present invention relates to sterilization of packaging material within a packaging machine for filling packages with food products, typically liquid food products. Especially, a sterilization based on a combined irradiation of the packaging material within UV-light and an electron beam. It is further to be noted that whenever sterilization is discussed herein, it also applies to disinfection, depending on the target for the irradiation using UV-light and an electron beam.
Background of the invention
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Within the food industry today, the food package technology plays an important part. The food package has several important functions. Apart from branding of the product and presenting the customers with information, the food package also has an important role of ensuring food safety. The packaging materials used in the food package can be designed to provide strength and stability, so that the packages are not damaged during transportation. Furthermore, the packaging materials can form a protective environment for the food product so that it is protected from for example bacteria, germs, oxygen and sun light, thus prolonging shelf life. However, the packaging material is not the only thing that is important in the package. The package need to be subjected to sterilization before filling the package with food. This in order to increase shelf life of the food in the package and to ensure food safety.
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Performing sterilization of packaging material may be challenging and a variety of sterilization methods, including thermal methods, such as steam sterilization and hot air sterilization, chemical methods, such as hydrogen peroxide (H2O2) sterilization and peracetic acid sterilization, and irradiation methods, such as gamma irradiation, electron beam irradiation and ultra violet, UV, light irradiation, have been implemented in the industry. Current sterilization methods of packaging material leave room for improvements, especially when it comes to high speed packaging machines in which a time window for performing the sterilization is narrow.
Summary of the invention
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The herein disclosed technology seeks to at least partly mitigate, alleviate or eliminate one or more of the above-mentioned deficiencies and disadvantages in the prior art. In particular, it is an object to provide efficient sterilization of packaging material within a packaging machine. The inventors of the present inventive concept has realized a new and improved way of sterilizing packaging material, especially in connection with high speed filling in a packaging machine.
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Various aspects and embodiments of the disclosed invention are defined below and in the accompanying independent and dependent claims.
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According to a first aspect, a method for sterilization of packaging material within a packaging machine configured to fill packages with a food product is provided. The method comprising: subjecting, at a UV-light irradiation station, a surface of the packaging material for UV-light irradiation; and subjecting, at an electron beam irradiation station, the surface of the packaging material for electron beam irradiation.
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The surface of the packaging material being subjected for the UV-light irradiation and the electron beam irradiation is a same portion of the packaging material. However, the UV-light irradiation and the electron beam irradiation is typically not subjected to the same portion of the packaging material simultaneously. Instead, a portion of the surface of the packaging material is first subjected for the UV-light irradiation and thereafter the portion of the surface of the packaging material is subjected for the electron beam irradiation, or vice versa.
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According to the present inventive concept UV light irradiation and electron beam irradiation is combined in order to achieve packaging material sterilization. Using a compact UV-LED based systems for the UV-light irradiation makes it easy to fit in a UV-light irradiation station in a packaging machine. The present invention allow for exploiting a synergetic effect that has been realized by the inventors, namely that irradiating the packaging material with both UV-light and an electron beam drastically increases the effectiveness of killing microorganism as compared with using UV-light and electron beam irradiation separately. Using this surprising effect allow for reducing the dose needed from the electron beam irradiation. Tests conducted by the inventors indicate that a pre-irradiation with UV-light may reduce the required electron beam dramatically. According to tests conducted by the inventors an exposure to 3 kGy electron beam irradiation does not result in any detectable inactivation of Clostridium Botulinum. Exposure to 8 mJ/cm2 UV light exposure gives an inactivation of a log count reduction of 1.6. However, when exposing first to 8 mJ/cm2 UV light, followed by exposure to 3 kGy electron beam irradiation, then the resulting log count reduction was 4.5, i.e. the combined effect of the two types of exposure resulted in three log count reduction higher inactivation than expected if the contributions from the respective exposures would be additive. These tests are summarized in connection with Table 1 to be found further down this text. Further, these tests are also to be compared with nominal process values for electron beam dosage that is typically 30 kGy in order to achieve log count reduction above 4. Using this result when sterilizing packaging material is allowing to downsize the electron beam irradiation station, extending the lifetime of the electron beam irradiation station and/or decreasing the power consumption. Further, by being able to reduce the dose from the electron beam irradiation station, problems with off-taste and reduced sealability due to electron beam irradiation of the packaging material may be reduced. Moreover, a lifetime of the electron beam irradiation station may be prolonged. Furthermore, reducing the dose from the electron beam irradiation station allow for sterilizing more delicate packaging material, e.g. a packaging material with new barrier structures replacing the Aluminum foil.
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The electron beam irradiation may be performed after the UV-light irradiation. It has been realized that this order of irradiation is especially effective.
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The UV-light irradiation station and the electron beam irradiation station may be stationary stations. The method may further comprise feeding the packaging material through the UV-light irradiation station and the electron beam irradiation station during subjecting the surface of the packaging material for the UV-light irradiation and the electron beam irradiation, respectively.
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The packaging material may be provided in the form of a web of packaging material. Feeding the web of packaging material through the UV-light irradiation station and the electron beam irradiation station may be made continuously.
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A full width of the web of packaging material may be irradiated in the UV-light irradiation station and in the electron beam irradiation station, respectively.
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Both sides of the web of packaging material may subjected for the UV-light irradiation and the electron beam irradiation, respectively.
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The present invention relates to a method combining UV-light and electron beam irradiation for sterilization. This approach takes advantage of the differing sensitivities of microorganisms to UV and electron beam treatments, resulting in a synergistic effect that enhances sterilization efficacy while allowing for reduced treatment intensities. This synergy enables effective microbial inactivation while minimizing material degradation and operational costs.
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The present invention relates to a method and arrangement for sterilizing packaging material within a packaging machine by sequentially subjecting the same surface of the packaging material to ultraviolet (UV) light irradiation followed by electron beam irradiation. These irradiation steps are performed at dedicated, stationary UV-light and electron beam irradiation stations integrated within the packaging machine, through which the packaging material, typically provided as a continuous web, is fed.
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This combined sequential irradiation provides a synergistic sterilization effect that significantly enhances the inactivation of microorganisms compared to using either UV-light or electron beam irradiation alone. As a result, the required electron beam dose can be substantially reduced. This reduction leads to several important advantages, including lower power consumption, decreased wear on the electron beam equipment, and importantly, minimized risk of off-taste development in the packaged food product.
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"Off-taste" refers to undesirable changes in flavour or odour of the food product caused by chemical or physical alterations in the packaging material due to high doses of electron beam irradiation. By lowering the electron beam dose through the synergistic effect with UV-light, the present invention helps preserve the original taste and quality of the food.
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The integration of these irradiation stations allows for efficient sterilization compatible with high-speed packaging operations, ensuring food safety and prolonging product shelf life without compromising packaging material integrity.
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In the present inventive concept, ultraviolet light-emitting diodes (UV-LEDs) are used as the preferred source for UV-light irradiation in the UV-light irradiation station. UV-LEDs provide a compact and energy-efficient light source that facilitates easy integration within the packaging machine, which often has limited space and requires high-speed and precise operation. The UV-LEDs have long operational lifetimes and allow for rapid and accurate control of UV-light exposure, enabling optimal microbial inactivation.
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The UV-LEDs are configured to emit UV-light with a peak wavelength in the range of 260-275 nm, preferably between 265-275 nm, which is especially effective for inactivating microorganisms. Without being bound by theories this wavelength range may contribute to the synergistic sterilization effect achieved by sequentially subjecting the packaging material to UV-light irradiation other factors, such as the timing between irradiations and sample handling, may also influence the synergy. Regardless of the exact cause, the combined treatment results in significantly enhanced microorganism inactivation compared to either irradiation alone.
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By employing UV-LEDs, the UV-light irradiation station can be positioned in close vicinity to the electron beam irradiation station within the packaging machine, minimizing the risk of recontamination of the packaging material between irradiation steps. This arrangement enables a compact and efficient sterilization solution well suited for high-speed packaging operations.
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The sequential configuration of the irradiation systems results in a synergistic effect, wherein the overall performance exceeds the sum of the effects produced by the individual systems operating separately. This indicates that the sequential arrangement enables emergent properties or cooperative interactions that are not achievable through independent use.
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According to a second aspect a sterilization arrangement for sterilization of packaging material within a packaging machine configured to fill packages with food product is disclosed. The sterilization arrangement comprising: a UV-light irradiation station configured to subject a surface of the packaging material for UV-light irradiation; and an electron beam irradiation station configured to subject the surface of the packaging material for electron beam irradiation.
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The electron beam irradiation station may be located in vicinity of the UV-light irradiation station as seen along a traveling direction of the packaging material being subjected for the sterilization in the sterilization arrangement. In this context, in vicinity refer to a distance in the order of 0 meter to 10 meters.
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The packaging material may be provided in the form of a web of packaging material. The UV-light irradiation station and the electron beam irradiation station may be configured to irradiate a full width of the web of packaging material, respectively. The UV-light irradiation station and the electron beam irradiation station may be configured to irradiate both sides of the web of packaging material, respectively.
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The above mentioned features of the first aspect, when applicable, apply to this second aspect as well. In order to avoid undue repetition, reference is made to the above.
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According to a third aspect a packaging machine configured to fill packages with a food product is provided. The packaging machine comprising: a sterilization arrangement according to the second aspect, wherein the UV-light irradiation station and the electron beam irradiation station are stationary stations; and a feed unit configured to feed packaging material through the sterilization arrangement. The packaging machine may be configured to form the packaging material into the filled packages . The packaging material may be provided as a web of packaging material.
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The electron beam irradiation station may be located downstream of the UV-light irradiation station along a feeding direction of the packaging material being feed through the packaging machine by the feed unit.
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The packaging machine may further comprise a filling station configured to fill the packages with the food product.
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The packaging machine may be configured to fill at least 4000 packages per hour per packaging line.
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The above mentioned features of the first aspect, when applicable, apply to this third aspect as well. In order to avoid undue repetition, reference is made to the above.
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A further scope of applicability of the present disclosure will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred variants of the present inventive concept, are given by way of illustration only, since various changes and modifications within the scope of the inventive concept will become apparent to those skilled in the art from this detailed description.
Brief description of the drawings
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The above and other aspects of the present inventive concept will now be described in more detail, with reference to appended drawings showing variants of the present inventive concept. The figures should not be considered limiting the invention to the specific variant; instead, they are used for explaining and understanding the inventive concept.
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As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of variants of the present inventive concept. Like reference numerals refer to like elements throughout.
- Fig. 1 schematically illustrates a packaging machine configured to fill packages with a liquid food product, the packaging machine being equipped with a packaging sterilization arrangement comprising both a UV-light irradiation station and an electron beam irradiation station.
- Fig. 2 is a block diagram of a method for sterilization of packaging material within a packaging machine configured to fill packages with a food product, the sterilization being based on subjecting the packaging material for both UV-light and electron beam irradiation.
Detailed description
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The present inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred variants of the inventive concept are shown. This inventive concept may, however, be implemented in many different forms and should not be construed as limited to the variants set forth herein; rather, these variants are provided for thoroughness and completeness, and fully convey the scope of the present inventive concept to the skilled person.
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It will also be appreciated that when the present disclosure is described in terms of a method, it may also be embodied in an apparatus or device comprising one or more processors, one or more memories coupled to the one or more processors, where computer code is loaded to implement the method. For example, the one or more memories may store one or more computer programs that perform the steps, services and functions disclosed herein when executed by the one or more processors.
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It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. It should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may refer to more than one unit in some contexts, and the like. Furthermore, the words "comprising", "including", "containing" do not exclude other elements or steps. It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps, or components. It does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. The term "and/or" is to be interpreted as meaning "both" as well and each as an alternative. The term "obtaining" is herein to be interpreted broadly and encompasses receiving, retrieving, collecting, acquiring, and so forth.
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Fig. 1 generally illustrates, a packaging machine 100 configured to fill packages with a food product, according to some examples a liquid food product. The packaging machine 100 may be a roll-fed packaging machine used for producing packages. That is, the packaging machine 100 may be feed with a web 102 of packaging material to be formed into filled packages. The web 102 of packaging material is typically flat. More specifically, the packaging machine 100 may be used for packaging food products in carton-based packages. Already in the 1940s this type of packaging machines was introduced by Tetra Pak® and it is today a well-known approach for packaging milk and other food products in a safe and cost-efficient manner. The packaging material typically comprises a carton layer and at least one plastic layer. The packaging material is often printed and prepared in packaging material production centers, also referred to as converting factories, and shipped to a site where the packaging machine 100 is placed, e.g. a dairy. For a roll-fed packaging machine 100 the packaging material is loaded onto a reel before being transported. After arriving at the site, the reel is placed in the packaging machine 100, and a web 102 of packaging material is fed in the packaging machine 100 by a feed unit 110. The feeding of the web 102 of packaging material is typically continuous.
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The packaging machine 100 further comprises a packaging sterilization arrangement 120. The packaging sterilization arrangement 120 is configured to sterilize the packaging material, in the in Fig.1 illustrated example the packaging material is provided in the form of the web 102. Especially, the packaging sterilization arrangement 120 may be configured to sterilize packaging material within the packaging machine 100 before a respective package is formed and filled with the food product. More, specifically the packaging sterilization arrangement 120 may be configured to sterilize both sides of the web 102 of packaging material before the respective package is formed and filled with the food product.
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The sterilization arrangement 120 will now be discussed in more detail. The sterilization arrangement 120 is designed based on an insight made by the inventors, namely that irradiating the packaging material with both ultra violet, UV, light and a beam of electrons is resulting in an increased inactivation of microorganisms as compared with only performing a separate UV-light irradiation and only performing a separate irradiation with a beam of electrons. Table 1 below is a summary of experimental results illustrating the combined effect of using UV-light and a beam of electrons.
Table 1. Inactivation of Clostridium Botulinum of strain 33A for different combinations of UV-light and eBeam irradiation. | UV-light irradiance mJ/cm2 | eBeam dose kGy | Logarithmic Cycle Reduction |
| 0 | 3 | 0 |
| 2.5 | 0 | 0.4 |
| 2.5 | 3 | 2.5 |
| 8 | 0 | 1.6 |
| 8 | 3 | 4.5 |
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The found combined effect of using UV-light and a beam of electrons (eBeam) allows for downsizing the sterilization arrangement, extending the lifetime of the sterilization arrangement and/or decreasing the power consumption.
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Hence, the sterilization arrangement 120 has been designed to comprise both a UV-light irradiation station 122 and an electron beam irradiation station 124. Preferably, just as in the in Fig. 1 illustrated example, the electron beam irradiation station 124 is located downstream of the UV-light irradiation station 122 along a feeding direction of the packaging material being feed through the packaging machine 100 by the feed unit 110. Further, the electron beam irradiation station 124 is preferably located in vicinity of the UV-light irradiation station 122 as seen along a traveling direction of the packaging material being subjected for the sterilization in the sterilization arrangement 120. In this context, in vicinity refer to a distance in the order of 0 meter to 10 meters. Preferably, the UV-light irradiation station 122 is to be located as close to the electron beam irradiation station 124 as possible. There is no minimum distance required from the process perspective. It is more a matter of physical integration of the stations 122, 124. The maximum distance between the stations 122, 124 is not a fixed limit either. The principle should be to minimize the distance to minimize the risk of recontamination between exposures at the different stations 122, 124.
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Both the UV-light irradiation station 122 and the electron beam irradiation station 124 are typically stationary stations with the packaging machine 100.
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The UV-light irradiation station 122 is configured to subject a surface of the packaging material for UV-light irradiation while the packaging material is feed through the UV-light irradiation station 122. Typically, the UV-light irradiation station 122 is configured to irradiate a full width of the web 102 of packaging material. Preferably, the UV-light irradiation station 122 comprises a plurality of UV-LEDs. The plurality of UV-LEDs are typically arranged along a line transvers a feeding direction of the packaging material. The UV-LEDs are arranged to emit UV, light. Preferably, the UV-LEDs are arranged to emit UV-light having a peak wavelength in the range of 260-275 nm, more preferably in the range of 265-275 nm. Two examples of suitable UV-LEDs that can be used are OSRAM OSLON® UV 6060, SU CZHEF1.VC and OSRAM OSLON® UV 3535, SU CULEP1.VC. As understood by the skilled person, other UV-LEDs may of course be used. Further, as also understood by the skilled person, in the future UV-LEDs with higher power than available today will be developed. The plurality of UV-LEDs may all be of a same type having a same peak wavelength. Having, all UV-LEDs with the same peak wavelength will provide as high exposure as possible at that peak wavelength. Alternatively, the plurality of UV-LEDs may comprise two or more different types of UV-LEDs having different peak wavelengths. Having different peak wavelengths may be beneficial since different microorganism may have a different sensibility for different wavelengths. During operation of the UV-light irradiation station 122, the UV-LEDs are configured to emit UV-light towards the surface of the packaging material. As also understood by the skilled person, the UV-light irradiation station 122 may be based on other UV-light sources than UV-LEDs.
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The UV-light irradiation station 122 is configured to irradiate the surface of the web of packaging material with UV-light. The UV-light irradiation station 122 may comprise one set of UV-LEDs configured to irradiate a first side of the web 102 of packaging material and another set of UV-LEDs configured to irradiate a second side of the web 102 of packaging material. The first side of the web 102 of packaging material being the side of the web 102 of packaging material that will constitute an inside of the packages 104 being produced within the packaging machine 100. The second side of the web 102 of packaging material being the side of the web 102 of packaging material that will constitute an outside of the packages 104 being produced within the packaging machine 100. Accordingly, the UV-light irradiation station 122 may be configured to irradiate both sides of the web 104 of packaging material.
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The electron beam irradiation station 124 is configured to subject a surface of the packaging material for an electron beam irradiation while packaging material is feed through the electron beam irradiation station 124. Typically, the electron beam irradiation station 124 is configured to irradiate a full width of the web 102 of packaging material.
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In more detail, the electron beam irradiation station 124, also referred to as an eBeam station, is configured to emit a beam of electrons, or in short an eBeam. An eBeam is a stream of electrons used for various applications, including disinfection of packaging materials. The technology leverages the properties of high-energy electrons to effectively kill microorganisms and sterilize surfaces. Typically, eBeam systems for disinfection operate at energies of 10ths of keV up to 10 MeV. An electron beam is produced by an electron gun, which typically consists of a heated filament that emits electrons when a voltage is applied. The emitted electrons are accelerated using an electric field. This acceleration gives the electrons the energy needed for effectively kill microorganisms. The accelerated electrons may be focused into a narrow beam using magnetic or electrostatic lenses. Such a beam is then scanned across the target area, which in this case is the packaging material. This scanning ensures uniform exposure to the electron beam. Alternatively, the beam is a non-focused beam configured to irradiate the full width of the web of packaging material as the web passes the beam. The penetration depth of the electron beam depends on its energy. As mentioned above, eBeam systems for disinfection typically operate at energies of 10ths of keV up to 10 MeV. Higher energy beams penetrate deeper into materials, which is useful for ensuring that microorganisms embedded within the material are also killed. When the high-energy electrons from the eBeam collide with microorganisms on the surface of the packaging material, they cause ionization and excitation of the molecules within these organisms. This interaction damages the DNA and other critical cellular components of the microorganisms, effectively killing them or rendering them unable to reproduce. The process is very rapid making it suitable for high-throughput industrial applications. eBeam disinfection is a non-thermal process, meaning it does not rely on heat. This is advantageous for packaging materials that might be sensitive to high temperatures. The technology does not require the use of chemicals, making it environmentally friendly and reducing the risk of chemical residues on the packaging material. eBeam can be used on a variety of packaging materials, including cartoon, plastics, glass, and composites, without causing significant changes to their properties. Monitoring systems may be in place to ensure that a correct dose of radiation is administered. Sensors and feedback mechanisms may adjust the beam parameters to maintain optimal sterilization levels. eBeam facilities incorporate shielding and safety interlocks to protect operators from radiation exposure. Only the target material is exposed to the electron beam within a controlled environment.
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During operation of the electron beam irradiation station 124, the electron beam irradiation station 124 is configured to irradiate the surface of the packaging material with a beam of electrons. The electron beam irradiation station 124 may be configured to irradiate both the first side of the web 102 of packaging material, being the side of the web 102 of packaging material that will constitute the inside of the packages 104 being produced within the packaging machine 100, and the second side of the web 102 of packaging material, being the side of the web 102 of packaging material that will constitute the outside of the packages 104 being produced within the packaging machine 100. Accordingly, the electron beam irradiation station 124 may be configured to irradiate both sides of the web 102 of packaging material.
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As been illustrated in table 1, the combined effect is apparent and strong at relatively low exposures and the effect is shown to be maintained also at higher exposures. The actual exposure of UV-light and electron beam required will depend on the application and the physical integration in the filling machine. Hence, an optimal distribution between UV-light exposure and electron Beam exposure is to be determined by considering different constraints and factors that needs to be taken into account when designing the sterilization arrangement 120. For example, assuming a flat web of packaging material, based on the data in table 1, we would arrive at LCR 4.5 of Clostridium Botulinum if exposed to 8 mJ/cm2 of UV-light followed by an exposure of 3 kGy of electron beam irradiation.
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Further, to determine which setting and alarm limits to use will require considerations not only on whether it is an aseptic application or a chilled application but also on e.g. dose monitoring limitations for both the UV-light irradiation station 122 and the electron beam irradiation station 124, variation in UV light output, variation in electron beam output, limitations in physical space, and/or if there are other pathogens we need to consider in the dimensioning of the process apart Clostridium Botulinum.
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After having been sterilized, by means of the sterilization arrangement 120, the packaging material is formed into packages 104 and filled with the food product at a filling station 130. Alternatively, the packaging material is formed into a tube which is filled with the food product and thereafter being formed into packages 104. The filled packages 104 are then transported away from the packaging machine by a conveyor system 140.
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In connection with Fig. 2, a method 200 for sterilization of packaging material within a packaging machine configured to fill packages with a food product will be discussed. As discussed above, the packaging material may be carton based. As also discussed above, the packaging material may be in the form of a flat web 102. Below, the different steps of the method 200 are described in more detail. The steps of the method 200 is performed within the packaging machine, e.g. the packaging machine 100 discussed in connection with Fig. 1. Some of the steps, or even all steps, of the method 200 may be executed by a control unit of the packaging machine.
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The method 200 comprises subjecting S202, at a UV-light irradiation station 122, a surface of the packaging material for UV-light irradiation. The method 200 further comprise subjecting S204, at an electron beam irradiation station 124, the surface of the packaging material for electron beam irradiation. The UV-light irradiation station 122 and the electron beam irradiation station 124 are discussed in more detail above, in order to avoid undue repletion reference is made to that discussion.
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In the steps of subjecting S202 the surface of the packaging material for UV-light irradiation and subjecting S204 the surface of the packaging material for electron beam irradiation it is a same portion of a the surface of the packaging material that is subjected for the respective irradiation. The same portion is typically a portion of the web 102 of packaging material being feed through the packaging machine 100. However, the same portion is normally not subjected for the UV-light irradiation and the electron beam irradiation simultaneously. Instead, a portion of the packaging material is first subjected S202 for UV-light irradiation and at a later time subjected S204 for electron beam irradiation, or in some situations vice versa. The time between UV-light irradiation and electron beam irradiation of a same portion of the packaging material depend on the speed of feeding the packaging material through the packaging machine 100 and on a distance between the UV-light irradiation station 122 and the electron beam irradiation station 124. The time between UV-light irradiation and electron beam irradiation of a same portion of the packaging material may be in a range of 0-10 seconds. In principle the time between UV-light irradiation and electron beam irradiation is to be minimized, this in order to protect the target surface from recontamination between the two irradiations. According to one specific embodiment, the irradiation of a same target surface with UV-light from the UV-light irradiation station 122 and the electron beam from the electron beam irradiation station 124 may be made simultaneously.
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Further, as discussed above, a full width of the web of packaging material is typically subjected for both the UV-light irradiation and the electron beam irradiation. Moreover, as also discussed above, both sides of the web of packaging material may be subjected for the UV-light irradiation and the electron beam irradiation. As a result, while being feed thought the packaging machine 100 the complete surface area of the packaging material will be subjected for both the UV-light irradiation and the electron beam irradiation. Particularly, subjecting S202 and S204 the complete surface area of the packaging material for the UV-light irradiation and the electron beam irradiation is made prior to filling the packages. Subjecting S202 and S204 the complete surface area of the packaging material for the UV-light irradiation and the electron beam irradiation may further be made prior to forming the packaging material into the packages.
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As being illustrated in connection with Fig. 2, subjecting S204 the surface of the packaging material for electron beam irradiation may be performed after subjecting S202 the surface of the packaging material for UV-light irradiation. It has been found by the inventors that such order of subjecting the surface of the packaging material for UV-light and electron beam irradiation provide for an increased killing effect of microorganisms as compared with first subjecting the surface of the packaging material for electron beam irradiation and thereafter subjecting the surface of the packaging material for UV-light irradiation. It is however, to be realized that for some applications subjecting S204 the surface of the packaging material for electron beam irradiation may be performed before subjecting S202 the surface of the packaging material for UV-light irradiation.
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As discussed above in connection with Fig. 1 and the discussion of the packaging machine 100 and the sterilization arrangement 120, the UV-light irradiation station 122 and the electron beam irradiation station 124 may be stationary stations. The method may further comprise feeding S201 the web of packaging material through the UV-light irradiation station 122 and the electron beam irradiation station 124 during subjecting S202 the surface of the packaging material for the UV-light irradiation and subjecting S204 the surface of the packaging material for the electron beam irradiation, respectively. Such feeding S201 of the web of packaging material through the UV-light irradiation station 122 and the electron beam irradiation station 124 may be made continuously.
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The person skilled in the art realizes that the present invention by no means is limited to what is explicitly described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.
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For example, alternatively, to that the packaging machine 100 is a roll-feed packaging machine it may be a blank-fed packaging machine in which the packaging material is provided as blanks to the packaging machine 100. The feed unit 110 is then feeding the blanks to the UV-light irradiation station 122 and the electron beam irradiation station 124 of the sterilization arrangement 120.
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According to another example, the packing machine 100 may be PET bottling machine in which the packaging material is provided bottles to the packaging machine 100. The feed unit 110 is then feeding the bottles to the UV-light irradiation station 122 and the electron beam irradiation station 124 of the sterilization arrangement 120.
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Hence, the same principle of sterilization as discussed above in connection with a roll-feed packaging machine may also be applied in a blank-fed packaging machine or a PET bottling machine. The sterilization as discussed above in connection with a roll-feed packaging machine may also be applied for sterilization of caps to be supplied to a filling machine.
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Furthermore, the packaging machine 100 may comprise a clean air system 150. The clean air system 150 being arranged to enclosed the sterilization arrangement 120 and a portion of the feed unit 110 set to feed the packaging material between the UV-light irradiation station 122 and the electron beam irradiation station 124 (or vice versa if the electron beam irradiation is to be performed before the UV-light irradiation). The clean air system 150 may further enclose the filling station 130. As readily understood by the skilled person, alternative to a clean-air system 150 other means of creating an environment protecting the surface from recontamination between UV-light and electron beam irradiation may be used.
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Additionally, variations can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.