Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
  • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
  • A61L2/18—Liquid substances or solutions comprising solids or dissolved gases
  • A61L2/186—Peroxide solutions
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
  • A61L2/02—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using physical phenomena
  • A61L2/08—Radiation
  • A61L2/10—Ultraviolet radiation
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
  • A61L2/16—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor using chemical substances
  • A61L2/20—Gaseous substances, e.g. vapours
  • A61L2/208—Hydrogen peroxide
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2/00—Methods or apparatus for disinfecting or sterilising materials or objects other than foodstuffs or contact lenses; Accessories therefor
  • A61L2/26—Accessories or devices or components used for biocidal treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B55/00—Preserving, protecting or purifying packages or package contents in association with packaging
  • B65B55/02—Sterilising, e.g. of complete packages
  • B65B55/04—Sterilising wrappers or receptacles prior to, or during, packaging
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2202/00—Aspects relating to methods or apparatus for disinfecting or sterilising materials or objects
  • A61L2202/10—Apparatus features
  • A61L2202/18—Aseptic storing means

Definitions

• the present invention relates to an improved method and apparatus for sterilizing a packaging sheet material of the kind used for packaging pourable food products such as milk, tomato puree, yoghurt, fruit juices, wine, tea, etc.
• a packaging sheet material of the kind used for packaging pourable food products such as milk, tomato puree, yoghurt, fruit juices, wine, tea, etc.
• Such laminated packaging sheet material has a multi-layered structure including a fibre-based layer made of a material such as paper, which is coated on either side with a heat-sealable plastics material such as polyethylene.
• the face of the packaging material destined to be placed in contact with the food product is also provided with a layer of barrier material, such as e.g., aluminium, which is in turn covered with a layer of plastics material such as polyethylene.
• barrier material such as e.g., aluminium
• packaging material When manufacturing packages from the above-mentioned kind of packaging sheet material, it is imperative that no microorganisms are allowed to come into contact with the food product to be packaged. Therefore, the packaging material must be sterilized immediately prior to use for the manufacture of packages, and it must be retained in sterile conditions, until the package is completely sealed, thereby ensuring that the food product contained therein is free from any microorganisms which would otherwise spoil the food and/or transmit diseases to the consumer.
• Laminated packaging material may be produced in the form of web which can be continuously fed into a package forming, filling and sealing machine.
• Such machines include e.g., the TBA/19 ® and TBA/21 ® filling machine, manufactured by Tetra Brik Packaging Systems, Via Delfini 1 , Modena, Italy.
• the web is sterilized with a sterilizing agent such as e.g., hydrogen peroxide, which is thereafter removed by evaporation.
• the sterile packaging material is then maintained in an aseptic chamber, then longitudinally sealed to form a continuous tube, which is filled with liquid food product to be packaged.
• the tube is then damped and transversely sealed at regular intervals to produce pillow-shaped packages, which are mechanically folded to produce finished packages.
• Such types of packages include e.g., parallelepiped packages known by the registered trademarks Tetra Brik Aseptic ® and Tetra Brik ® , and substantially parallelepiped packages with bevelled corners commonly known by the registered trademarks Tetra Prisma ® and Tetra Prisma Aseptic ® .
• the laminated packaging sheet material may be cut into blanks and then formed into packages on mandrels. Such packages are sterilized by spraying with hydrogen peroxide.
• the spray produces a thin layer of hydrogen peroxide on the hydrophobic, thermoplastic outer layer of the packaging sheet material.
• a source of UV light in the 200-325nm range is irradiated onto the hydrogen peroxide-covered outer layer of packaging material.
• the synergy occurring between the hydrogen peroxide and the UV light achieves has a killing effect on any microorganisms on the packaging material.
• the hydrogen peroxide is removed and the packages are filled with liquid food product and sealed to produce gable-top container commonly known by the registered trademark Tetra Rex ® .
• United States patent No. 3,904,361 describes a process wherein, in order to prevent or at least minimize evaporation of a peroxide film on a packaging material web during its passage through a sterilization chamber, to prolong its contact with the web face and obtain the desired sterilization, the chamber is saturated with steam and hydrogen peroxide vapours obtained by spraying hydrogen peroxide through nozzles into the chamber.
• 4,225,556 disclosed the use of a first treatment station with a container for hydrogen peroxide through which the packaging material was passed, and a second treatment station comprising a chamber with an inlet and an outlet for the packaging material web, and a nozzle for spraying hydrogen peroxide onto a heated surface.
• a first treatment station with a container for hydrogen peroxide through which the packaging material was passed
• a second treatment station comprising a chamber with an inlet and an outlet for the packaging material web, and a nozzle for spraying hydrogen peroxide onto a heated surface.
• the packaging material is passed through a bath containing hydrogen peroxide sterilizing solution, and in order to cope with ever-increasing production rates, the hydrogen peroxide baths have been increased in size to maintain contact time between the packaging material and the sterilizing solution.
• the intensified contact between the hydrogen peroxide solution and the packaging material is of course an advantage from the point of view of bacteriological killing. However, the intensified contact also increases the risk that the hydrogen peroxide solution will penetrate into and degrade the liquid-absorbent fibrous layer of the packaging material web through the cut edges of the web.
• the over-dimensioning of the bath also results in a further increase in hydrostatic pressure which further increases the risk of liquid penetrating into the web in the deeper parts of the bath. Furthermore, since packaging material located in the bath during machine stoppages is discarded, the deeper baths caused greater wastage of material upon each machine stop.
• United States patent No. 4,366,125 to Kodera et al disclosed a system including a first station for applying a thin film of hydrogen peroxide at low concentration at room temperature onto the outer surfaces of a packaging material.
• a second station located downstream of the first station with respect to a travel direction defined by the material to be sterilized, was provided for irradiating the outer hydrogen peroxide-coated surfaces with UV radiation.
• United States patent No. 5,114,670 to Duffey disclosed a sterilization chamber including inlet and outlet means for the material to be sterilized, means for introducing gaseous hydrogen peroxide into the sterilization chamber, and means for simultaneously irradiating the material to be sterilized with UV energy.
• WO 97/35768 discloses a method of sterilizing food packaging containers comprising a first step of depositing a hydrogen peroxide-containing solution having a concentration in a range of 0.05 - 0.20 wt.% into an interior of a packaging container; a second step of irradiating the interior of the container with ultraviolet light after the hydrogen peroxide-containing solution is deposited in the interior of the container, and a third step of removing hydrogen peroxide from the interior of the container.
• the removing of hydrogen peroxide is performed after the irradiating with UV light, any microorganisms present on the packaging material are, at least to some extent, shielded by the layer of excess hydrogen peroxide covering the packaging material.
• the method is applied to intermittently transferred and stopped packaging containers, and is not suitable for sterilizing a continuously moving web or sheet of packaging material.
• All of the above-mentioned sterilization techniques are susceptible to improvement relating to the killing effect achieved and the time necessary to guarantee elimination of all pathogenic microorganisms, on the packaging material, for compatibility with modern high-speed liquid food packaging machines which can form, fill and seal 18000 or even more aseptic packages per hour, and wherein the packaging material moves at a speed of, or greater than 81.65 cm per second (48.990 meters per minute), such as the package forming, filling and sealing machine described in European patent application No. 97830312.1 , filed on June 27, 1997, by the same applicant. DISCLOSURE OF THE INVENTION.
• a main object of the invention is to provide a method and apparatus for sterilizing packaging sheet material, which achieves improved killing rates with respect to the known sterilization techniques, thereby improving the quality of sealed packages manufactured with the packaging sheet material and hence the product delivered to the consumer.
• Another object of the invention is to provide a method and apparatus for sterilizing packaging sheet material which is fully compatible with modern highspeed package forming, filling and sealing machines.
• a further object of the invention is to provide a method and apparatus for sterilizing packaging sheet material employing hydrogen peroxide, which minimizes the time that the sheet material remains in contact with the hydrogen peroxide, thereby avoiding any soaking of the hydrogen peroxide into the cut edge of the packaging sheet material.
• Yet another object of the invention is to provide a method and apparatus for sterilizing packaging sheet material employing hydrogen peroxide and UV radiation, wherein commercially available means for generating UV radiation can be used, at a power level which does not have any detrimental effects on the packaging material.
• a further object of the invention is to provide a method and apparatus for sterilizing packaging sheet material employing hydrogen peroxide and UV radiation, which can be integrated with current package forming, filling and sealing machines.
• the invention provides a method of sterilizing a packaging sheet material, comprising the steps of; -applying hydrogen peroxide to a packaging sheet material, and; -irradiating the packaging sheet material with light including at least one UV wavelength between about 200nm and 320nm, characterized in that it comprises the intermediate step of removing the hydrogen peroxide from the surface of the packaging sheet material while retaining a residual or trace quantity at any microorganisms (30a), after the step of applying hydrogen peroxide and before the step of irradiating the packaging material, whereby said residual or trace quantity of hydrogen peroxide absorbed by or located adjacent to any microorganisms present on said packaging sheet material is directly targeted with UV radiation.
• an apparatus for sterilizing a packaging sheet material which comprises
• - means for applying hydrogen peroxide to a packaging sheet material moving in an advancement direction - means for irradiating the packaging sheet material with light including at least one UV wavelength between 200nm and 320nm, arranged downstream of said means for applying hydrogen peroxide, with respect to said advancement direction, and;
• said means for removing the hydrogen peroxide from the surface of the packaging sheet material are interposed between said means for applying hydrogen peroxide and said means for irradiating the packaging material with light including at least one UV wavelength between 200nm and 320nm, whereby a residual or trace quantity of hydrogen peroxide absorbed by or located adjacent to any microorganisms present on said packaging sheet material is directly targeted with UV radiation.
• Figure 1 is a schematic view of the apparatus according to the invention
• Figure 2 is an enlarged, schematic cross-sectional view of a portion of packaging sheet material irradiated with UV light according to the methods of the prior art, and;
• Figure 3 is an enlarged, schematic cross-sectional view of a portion of packaging sheet material irradiated with UV light according to the method of the present invention.
• the apparatus according to the invention is shown together with a packaging material sheet to be sterilized.
• the packaging material is in the form of a web 1
• the material may also be in the form of a cut blank.
• the web 1 is a laminated multi-layer material of the type commonly used for aseptic packaging of pourable food products.
• the laminated structure has a fibre-based layer 20 made of a material such as paper, and heat-sealable layers 21 , 22 made of plastics material such as polyethylene, provided on each side of the fibre-based layer 20.
• the face of the packaging material destined to be placed in contact with the food product is also provided with a layer of barrier material 23, such as e.g., aluminium, which is in turn covered with an additional heat-sealable layer 24 of plastics material such as polyethylene.
• barrier material 23 such as e.g., aluminium
• the apparatus includes means for applying hydrogen peroxide to the surface of the packaging sheet material 1 , moving in the advancement direction 2, which are preferably constituted by a bath 3 containing liquid hydrogen peroxide 4.
• the hydrogen peroxide 4 in the bath 3 may have a concentration of up to 50% by weight, and preferably has a concentration of from 10% by weight to 50% by weight, and most preferably has a concentration of from 20% by weight to 40% by weight.
• a conventional roller 5 is provided in the bath for guiding the packaging material 1.
• means 6 are also connected to the bath 3 for maintaining the hydrogen peroxide at a temperature preferably comprised between 15 degrees Centigrade and 80 degrees Centigrade, and may be constituted by a conventional thermostatically-controlled heating mechanism 6 as commonly used in the technical field of the invention, such as those present on the above cited TBA 19 ® and TBA/21 ® liquid food packaging machines, available from Tetra Brik Packaging Systems, Via Delfini 1 , Modena, Italy.
• the depth of the hydrogen peroxide bath can be reduced with respect to conventional baths, and the hydrogen peroxide 4 in the bath 3 preferably defines a liquid column having a height less than 50cm.
• the hydrogen peroxide 4 in the bath 3 preferably defines a liquid column having a height less than 50cm.
• spray means for applying hydrogen peroxide liquid or vapour to the surface of the packaging material may also be used, such as spray means.
• the UV light source 7 for irradiating the packaging sheet material may comprises a monochromatic source of UV light having a wavelength of 222nm.
• the monochromatic source of UV light having a wavelength of 222nm preferably comprises at least one excimer lamp.
• Such lamps are available from Heraeus Noblelight, Kleinostheim, Germany.
• a source of polychromatic UV light may also be used.
• Such polychromatic lamps are manufactured, for instance, by Berson UV-techniek, De Huufkes 23, NL-5674Nuenen, The Netheriands.
• Other lamps or lasers may also be used which emit light in the UV wavelengths.
• means 8 are also provided for removing hydrogen peroxide from the surface of the packaging sheet material 1 , or, as will be explained hereinafter, reducing the hydrogen peroxide on the surface of the packaging sheet material to a minimum.
• the means 8 for removing hydrogen peroxide from the packaging sheet material preferably comprise at least one air knife 9 for blowing air onto the packaging material sheet 1. Such air knives are known from United States patent No.
• 4603490 to Hilmersson et al have a chamber 10 including an air inlet 11 and an air outlet 12 for a flow of air, a material inlet 13 and a material outlet 14 for a packaging material web 1 , and a baffle plate 15 disposed over the air outlet 12 at an angle in relation to the path of travel of the web 1 through the chamber 10.
• Air blown onto the web 1 at the air knife is preferably heated to a temperature of from 80 degrees Centigrade to 150 degrees Centigrade.
• conventional squeegee rollers or pinch rollers may also be used in addition to or instead of the air knife.
• FIG. 2 illustrates an enlarged sectional view of a portion of a multi-layer laminated packaging sheet material like the above-described web 1 , wherein identical layers of the laminated structure are identified by the same reference numerals. Additionally, the reference numeral 30 schematically indicates microorganisms present on the surface of the packaging material, and the reference numeral 31 indicates the layer of hydrogen peroxide applied to the surface of the packaging material.
• Figure 2 illustrates the treatment of a packaging sheet material according to the prior art methods, wherein hydrogen peroxide at a concentration no greater than 10% by weight is first applied to the packaging sheet material. Thereafter the hydrogen peroxide is irradiated with UV light, and the synergy between the hydrogen peroxide and the UV light has the known killing effect on the microorganisms 30.
• Figure 3 illustrates the treatment of a packaging sheet material according to the invention, wherein hydrogen peroxide, preferably at a concentration of up to 50% by weight, and preferably of from 10% to 50% by weight, is first applied to the packaging sheet material. Thereafter the hydrogen peroxide is removed from the surface of the packaging material. It would thus appear that if one irradiated the packaging material with UV light at this point, i.e., in the UV irradiation zone indicated by the reference numeral 19 in figure 1 , there could be no interaction between the UV light and hydrogen peroxide, because the latter has been removed. However, the applicant has discovered that on the contrary, the killing effect achieved is significantly improved with respect to known techniques.
• the layer of excess hydrogen peroxide 31 is removed and only the residual hydrogen peroxide located in, on or adjacent to any microorganisms any microorganisms 30a present on the surface of the packaging material is directly targeted with UV radiation. It will be understood that the positional relationship between the residual hydrogen peroxide and the and the microorganisms shown in figure 3 is purely schematic and representative of what is believed to be occurring.
• the irradiation of UV light is targeted to the residual hydrogen peroxide absorbed by or located adjacent to the microorganisms.
• the removal of the layer of excess hydrogen peroxide in practice has the surprising effect of significantly increasing the efficiency of the sterilization process.
• hydrogen peroxide preferably liquid hydrogen peroxide at a concentration of up to 50% by weight, preferably of from 10% by weight to 50% by weight, and most preferably at a concentration of from 20% by weight to 40% by weight, is applied to a to a packaging sheet material.
• this is achieved by immersing the packaging sheet material in a hydrogen peroxide bath at a temperature comprised between 15 degrees Centigrade and 80 degrees Centigrade, for a time interval of from 0.5 seconds to 2 seconds.
• the hydrogen peroxide is believed to be hydrophilically absorbed in, or become somehow entrapped adjacent to or on any microorganisms present on the packaging material.
• the height of the liquid column of hydrogen peroxide in the bath does not exceed 50cm above the packaging sheet material.
• this relatively short residence time and shallow depth obviate problems relating to edge-soaking or wicking of the hydrogen peroxide into the fiberous layer of the laminated packaging material.
• the excess hydrogen peroxide is removed from the surface of the packaging sheet material, preferably by blowing thereon a stream of air heated to a temperature of from 80 degrees Centigrade to 150 degrees Centigrade, to reduce the hydrogen peroxide on the surface of the packaging material to a minimum. This removes the excess hydrogen peroxide from the surface of the packaging material, but a trace quantity of residual hydrogen peroxide is retained at any microorganisms present on the surface of the packaging material.
• the material is irradiated with light including at least one UV wavelength between about 200nm and 320nm.
• the packaging sheet material is irradiated with UV light at a wavelength of 222nm, and most preferably, the UV light source is an excimer lamp.
• the UV light source is an excimer lamp.
• the sterilization system according to the invention is fully compatible with modern high-speed aseptic liquid-food packaging machines, producing up to 18000 or more packages per hour, wherein the packaging material moves at a speed of, or greater than 81.65 cm per second (48.990 meters per minute).
• the present invention may be further modified, without thereby departing from the purview of the appended claims.

Landscapes

• Health & Medical Sciences (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Apparatus For Disinfection Or Sterilisation (AREA)
• Containers And Plastic Fillers For Packaging (AREA)
• Basic Packing Technique (AREA)
• Auxiliary Devices For And Details Of Packaging Control (AREA)
• Agricultural Chemicals And Associated Chemicals (AREA)
• Wrappers (AREA)
• Laminated Bodies (AREA)
• Packages (AREA)
• Food Preservation Except Freezing, Refrigeration, And Drying (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (1)

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Family Applications (2)

Family Applications Before (1)

Country Status (16)

Cited By (1)

Families Citing this family (22)

Family Cites Families (9)

• 1997
  • 1997-10-29 DE DE69712207T patent/DE69712207T2/de not_active Expired - Lifetime
  • 1997-10-29 ES ES97830555T patent/ES2174211T3/es not_active Expired - Lifetime
  • 1997-10-29 DK DK97830555T patent/DK0919246T3/da active
  • 1997-10-29 AT AT97830555T patent/ATE216599T1/de active
  • 1997-10-29 EP EP97830555A patent/EP0919246B1/de not_active Expired - Lifetime
• 1998
  • 1998-10-28 BR BRPI9813144-3A patent/BR9813144B1/pt not_active IP Right Cessation
  • 1998-10-28 JP JP2000517751A patent/JP2001520963A/ja active Pending
  • 1998-10-28 ID IDW20000760A patent/ID24482A/id unknown
  • 1998-10-28 RU RU2000113195/13A patent/RU2217360C2/ru not_active IP Right Cessation
  • 1998-10-28 TR TR2000/01162T patent/TR200001162T2/xx unknown
  • 1998-10-28 EP EP98956888A patent/EP1027082A1/de not_active Ceased
  • 1998-10-28 CN CNB988106809A patent/CN1135116C/zh not_active Expired - Lifetime
  • 1998-10-28 WO PCT/EP1998/006846 patent/WO1999021593A1/en not_active Ceased
  • 1998-10-28 UA UA2000042414A patent/UA64767C2/uk unknown
  • 1998-10-28 KR KR1020007004611A patent/KR100580764B1/ko not_active Expired - Fee Related
  • 1998-10-28 AU AU13369/99A patent/AU1336999A/en not_active Abandoned
  • 1998-10-28 HU HU0004161A patent/HU228222B1/hu not_active IP Right Cessation

Non-Patent Citations (1)

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