Sterilisation of packaged articles

Abstract

An apparatus for sterilising a packaged product ( 16 ) such as food or drink comprises a pair of gas filled electrodes ( 1, 2 ) connected to a power supply ( 18 ) for generating a high voltage pulses between the electrodes ( 1, 2 ) sufficient to ionise the gas therein and to create a high electromagnetic field therebetween. A reflector ( 7 ) is provided for directing the generated field towards the package ( 16 ), such that the electromagnetic field penetrates through the wall of the package ( 16 ) and forms cold plasma from the trapped air inside the package ( 16 ). This cold plasma comprises ozone and other reactive oxygen based species which have a high oxidising potential and kill all micro organisms in contact with the ozone and reactive species resulting in the disinfection of the product as well as the interior of the sealed package.

1 . An apparatus for sterilising a packaged product, the apparatus comprising: two gas filled electrodes, a power supply which generates a high voltage between the electrodes sufficient to ionise a gas therein and to create a high electromagnetic field therebetween, the apparatus being arranged to irradiate a package containing said packaged product with said field. 
     
     
         2 . The apparatus claimed in  claim 1 , in which the electromagnetic field creates a cold plasma which is energetic enough to convert oxygen in air into ozone and other reactive oxygen based species. 
     
     
         3 . The apparatus claimed in  claim 1  comprising an open fronted cavity for directing the generated electromagnetic field towards the product to be sterilised. 
     
     
         4 . The apparatus claimed  claim 1 , in which each electrode is elongate. 
     
     
         5 . The apparatus claimed in  claim 4 , in which each electrode is curved, coiled, bent or otherwise non-linear along its length. 
     
     
         6 . The apparatus claimed in  claim 4 , in which each electrode comprises a plurality of interconnected linear sections. 
     
     
         7 . The apparatus claimed in  claim 3  in which each electrode is arranged in a generally planar configuration and said open fronted cavity is arranged to direct the electromagnetic field perpendicular to said plane towards the product to be sterilised. 
     
     
         8 . The apparatus claimed in  claim 1 , in which the electrodes extend side-by-side along their length and are separated by a substantially uniform gap. 
     
     
         9 . The apparatus claimed in  claim 3 , in which said open fronted cavity extends on one side of the electrodes and comprises a ferromagnetic material. 
     
     
         10 . The apparatus claimed in  claim 3 , in which said open fronted cavity at least partially extends between the electrodes. 
     
     
         11 . The apparatus claimed in  claim 3 , in which said open fronted cavity comprises a surface which is profiled to receive said electrodes. 
     
     
         12 - 14 . (canceled) 
     
     
         15 . The apparatus claimed in  claim 3  in which the cavity comprises a side wall or walls which extend around the electrodes and which are arranged to seal against the packaging of the product to be sterilised. 
     
     
         16 . The apparatus claimed in  claim 3 , in which a suction duct is provided for evacuating air or other gas from said cavity when the latter is sealed against the packaging of the product to be sterilised. 
     
     
         17 . The apparatus claimed in  claim 1 , in which said power supply produces voltage pulses in the range of 1 kV to 50 kV. 
     
     
         18 . The apparatus claimed in  claim 1 , in which said power supply has a constant voltage component which is of a magnitude sufficient to keep the gas within the electrodes ionised. 
     
     
         19 - 33 . (canceled) 
     
     
         34 . The apparatus as in  claim 4  in which the open fronted cavity comprises high magnetic permeability material such as ferrite or ferromagnetic material. 
     
     
         35 . A method comprising:
 positioning, in an electromagnetic field adjacent a high voltage electrode, a packet comprising a packaged food product;
 applying a varying voltage to said electrode to convert oxygen in air in said packet into ozone and other reactive oxygen based species. 
   
     
     
         36 . The method of  claim 35  wherein said high voltage electrode is arranged in a cavity having a face with at least one opening; the method further comprising reducing air pressure in the cavity to draw said packet toward the facie of the cavity. 
     
     
         37 . An apparatus for sterilising a packaged product comprising: two means for applying an electromagnetic field;
 means for generating a voltage between the two means for applying electromagnetic field, wherein said voltage is sufficient to ionise gas therein and to create a high electromagnetic field therebetween, the apparatus being arranged to irradicate a package containing said packaged product with said field.   
     
     
         38 . The apparatus claimed in  claim 37  in which means are provided for directing the generated electromagnetic field towards the product to be sterilised.