Method for Heat Treating a Product Contained in a Package Such as a Tray

Abstract

Disclosed is a tray including at least one deformable wall. The product contained in the tray is heated, the vapour produced by the heating being allowed to escape through an opening in the pack. The product is heated, being taken to a desired temperature, a temperature-holding stage is carried out, the vapour being allowed to escape, a gaseous fluid is introduced into the pack at the end of this temperature-holding stage and the pack is closed totally.

1 - 13 . (canceled) 
   
   
       14 . A method for heat treatment of a product, in particular a food product, contained in a pack having at least one deformable wall, wherein the product contained in the pack is heated so as to be taken to a desired temperature, a temperature-holding stage is carried out, vapour produced by the heating is allowed to escape through an opening in the pack during heating and temperature holding, a gaseous fluid is introduced into the pack at the end of said temperature-holding stage and the pack is totally closed. 
   
   
       15 . The method according to  claim 14 , wherein the gaseous fluid introduced is at a temperature at least close to a temperature of the pack vapour during the temperature stage. 
   
   
       16 . The method according to  claim 15 , wherein the temperature of the gaseous fluid introduced is between 80% and 130%, preferably between 90% and 110%, of the vapour temperature during the temperature-holding stage. 
   
   
       17 . The method according to  claim 14 , wherein a volume of gaseous fluid is introduced, corresponding at least approximately to a volume of vapour which escapes from the pack during heating and temperature holding. 
   
   
       18 . The method according to  claim 17 , wherein the volume of gaseous fluid introduced is determined in such a way that this volume is substantially equal to the said volume of vapour, preferably slightly lower than this volume, when the said volumes are adjusted to the same temperature. 
   
   
       19 . The method according to  claim 14 , wherein the gaseous fluid is introduced into the pack, causing deformation of the said deformable wall and the pack is closed when it is found that the said deformation has reached a given level. 
   
   
       20 . The method according to  claim 14 , wherein the gaseous fluid is introduced into the pack for a predetermined length of time, at the end of which the pack is closed. 
   
   
       21 . The method according to  claim 14 , wherein the gaseous fluid is a neutral gas. 
   
   
       22 . The method according to  claim 14 , wherein the gaseous fluid is air, advantageously filtered. 
   
   
       23 . The method according to  claim 14 , wherein the gaseous fluid is introduced through the said opening in the pack. 
   
   
       24 . The method according to  claim 14 , wherein the opening is formed by at least one interruption in a sealing strip between two walls of the pack and, at the end of the stage of introducing the gaseous fluid into the pack, the latter is closed by completion of this welding strip. 
   
   
       25 . The method according to  claim 14 , wherein the opening is formed by at least one hole in a pack wall and, at the end of the stage of introducing the gaseous fluid into the pack, this hole is closed by means of a cap. 
   
   
       26 . The method according to  claim 14 , wherein the pack is a tray made of plastic, the top wall of which is formed by a film sealed at the tray edge.