Method for preserving foodstuffs

Abstract

A method for preserving foodstuffs, in which the foodstuffs are heated in the moist state in a container suitable for transport and storage with ventilation openings. The foodstuffs are heated for a defined period by a microwave, for at least such a time as hot steam forms in the container and exits through the ventilation openings. Gas is injected into the container after the heating process for at least partial compensation of the pressure drop in the container.

What is claimed is: 
     
         1 . A conveyance system for pasteurizing and sealing food in a package assembly, the system comprising:
 providing the package assembly, wherein the package assembly includes:
 a container having a peripheral edge, 
 food in a moist state within the container, 
 a cover film sealed to the peripheral edge of the container, and 
 a vent opening in the cover film; 
   conveying the package assembly through a tunnel to pasteurize the food in the package assembly, wherein during pasteurization steam forms in the packaging assembly and exits through the vent opening in the film cover;   after conveying the package assembly through the tunnel, conveying the package assembly to an injection station, wherein a cannula punctures the cover film proximal the vent opening to form a puncture hole, wherein the cannula injects gas into the puncture hole to flush the internal atmosphere of the package assembly through the vent opening; and   after conveying the package assembly to the injection station, sealing the puncture hole and the vent opening with a patch.   
     
     
         2 . The conveyance system of  claim 1 , wherein conveying the package assembly through the tunnel includes conveying the package assembly through the tunnel to create a temperature of at least about 80° C. in a core zone of the food. 
     
     
         3 . The conveyance system of  claim 1 , wherein the flush begins less than about 150 seconds from the end of pasteurization. 
     
     
         4 . The conveyance system of  claim 3 , wherein the duration of the flush is about 1 second to about 20 seconds. 
     
     
         5 . The conveyance system of  claim 4 , wherein the gas is cooled. 
     
     
         6 . The conveyance system of  claim 5 , wherein the gas includes an inert gas. 
     
     
         7 . The conveyance system of  claim 1 , wherein the gas has a temperature of less than about 12° C. 
     
     
         8 . The conveyance system of  claim 1 , wherein the cover film has a thickness from about 40 microns to about 3000 microns. 
     
     
         9 . The conveyance system of  claim 1 , wherein the vent opening and the puncture hole are sealed in less than about 60 seconds from end of the flush. 
     
     
         10 . The conveyance system of  claim 1 , wherein the packaging assembly is conveyed on a linear conveyor. 
     
     
         11 . A conveyance system for pasteurizing and sealing food in a package assembly, the system comprising:
 providing the package assembly, wherein the package assembly includes:
 a container having a peripheral edge, 
 food in a moist state within the container, 
 a cover film sealed to the peripheral edge of the container, and 
 a vent opening in the cover film; 
   conveying the package assembly through a microwave tunnel to pasteurize the food to create a temperature of at least about 80° C. in a core zone of the food, wherein during pasteurization steam forms in the packaging assembly and exits through the vent opening in the film cover;   conveying the package assembly to an injection station, puncturing the cover film with a cannula proximal the vent opening to form a puncture hole and injecting gas into the puncture hole for about 1 second to about 20 seconds to flush the internal atmosphere of the package assembly through the vent opening; and   in less than about 60 seconds from the end of the flush, sealing the puncture hole and the vent opening with a patch.   
     
     
         12 . The conveyance system of  claim 11 , wherein the gas includes an inert gas. 
     
     
         13 . The conveyance system of  claim 11 , wherein the gas is cooled to a temperature of less than about 12° C. 
     
     
         14 . The conveyance system of  claim 11 , wherein the cover film has a thickness from about 40 microns to about 3000 microns. 
     
     
         15 . The conveyance system of  claim 11 , wherein the packaging assembly is conveyed on a linear conveyor. 
     
     
         16 . A conveyance system for pasteurizing and sealing food in a package assembly, the system comprising:
 providing the package assembly, wherein the package assembly includes:
 a container, 
 food in a moist state within the container, 
 a cover film sealed to the container, and 
 a vent opening in the cover film; 
   conveying the package assembly through a microwave tunnel to pasteurize the food, wherein during pasteurization steam forms in the packaging assembly and exits through the vent opening in the film cover;   in less than about 150 seconds after pasteurization, conveying the package assembly to an injection station and injecting gas into a hole in the cover film to flush the internal atmosphere of the package assembly through the vent opening; and   in less than about 60 seconds from the end of the flush, sealing the hole and the vent opening with a patch.   
     
     
         17 . The conveyance system of  claim 16 , wherein the duration of the flush is about 1 second to about 20 seconds. 
     
     
         18 . The conveyance system of  claim 16 , wherein the packaging assembly is conveyed on a linear conveyor. 
     
     
         19 . The conveyance system of  claim 16 , wherein the gas is a cooled gas. 
     
     
         20 . The conveyance system of  claim 16 , wherein the gas is an inert gas.