Sealed flexible sachet and a method for its production

Abstract

A sachet for preparation of a beverage. The sachet has a compact roast and ground coffee cake having first and second cake opposed surfaces extending between to a peripheral cake edge. The first opposed surface is substantially convex and configured for ensuring leaktightness in an extraction chamber that is configured for injecting water and extracting the coffee. The peripheral edge has a peripheral surface that is generally normal to the opposed surfaces. An outer sheet of a flexible material is impermeable to oxygen and water vapor and contains and impermeably seals the cake therein.

What is claimed is:  
     
         1 . A sachet for preparation of a beverage, comprising: 
 a compact roast and ground coffee cake having first and second cake opposed surfaces extending within a peripheral cake edge, the first opposed surface being substantially convex and configured for ensuring leaktightness in an extraction chamber that is configured for injecting water into the sachet and extracting the coffee, the peripheral edge having a peripheral surface that is generally normal to the opposed surfaces; and    an outer sheet of a flexible sheet material that is impermeable to oxygen and water vapor, the outer sheet containing and impermeably sealing the cake therein.    
     
     
         2 . The sachet of  claim 1 , wherein the peripheral surface is substantially cylindrical.  
     
     
         3 . The sachet of  claim 1 , wherein the second opposed surface is substantially convex and configured for ensuring leaktightness in the extraction chamber.  
     
     
         4 . The sachet of  claim 3 , wherein the first and second opposed surfaces substantially extend to the peripheral edge.  
     
     
         5 . The sachet of  claim 3 , wherein the sachet has a substantially lenticular shape.  
     
     
         6 . The sachet of  claim 1 , wherein the outer sheet has a sheet surface adjacent the first opposed surface and having a convex shape.  
     
     
         7 . The sachet of  claim 1 , wherein the sheet comprises first and second sheets disposed adjacent the first and second opposed surfaces, respectively.  
     
     
         8 . The sachet of  claim 7 , wherein the sheets extend beyond the peripheral cake edge and are sealed together to enclose the cake therebetween and to form a sealed edge that substantially defines a plane through the sachet, the sachet being substantially symmetrical with respect to the plane, wherein the cake has a volume less than the internal volume of the sachet so that there is free space between the cake and the first and second sheets of less than 20% of the sachet internal volume and sufficient for allowing expansion of the coffee during extraction.  
     
     
         9 . The sachet of  claim 1 , wherein the sheet material is plastically prestretched for reducing or avoiding folds therein due to volume expansion of the cake.  
     
     
         10 . The sachet of  claim 1 , wherein the outer sheet material comprises a multilayer structure that includes: 
 an outer layer,    an inner layer made of a plastic, and    an central layer made of an aluminum material and disposed between the outer and inner layers.    
     
     
         11 . The sachet of  claim 10 , wherein the outer layer is made of a plastic.  
     
     
         12 . The sachet of  claim 10 , wherein: 
 the outer layer comprises PET, PE, PP, PA, or PS; and    the inner layer comprises PE, PP, or OPP.    
     
     
         13 . The sachet of  claim 10 , wherein the inner layer is made of OPP and the outer layer is made of PET.  
     
     
         14 . The sachet of  claim 1 , wherein the outer sheet is configured for maintaining a leaktightness about piercing members that pierce the sachet during extraction of the coffee.  
     
     
         15 . The sachet of  claim 1 , wherein the outer sheet is configured with a plasticity selected for controlling and reducing the size of tears therein when pressurized against raised portions of the extraction chamber.  
     
     
         16 . The sachet of  claim 1 , wherein the outer sheet comprises a tongue configured for facilitating positioning in the extraction chamber.  
     
     
         17 . The sachet of  claim 1 , wherein at least one of the opposed surfaces defines impressions configured as circulation channels for improving premoistening of the cake during extraction.  
     
     
         18 . A sachet for preparation of a beverage, comprising: 
 a compact roast and ground coffee cake having first and second cake opposed surfaces extending between to a peripheral cake edge; and    an outer sheet of a flexible material that is impermeable to oxygen and water vapor, the outer sheet containing and impermeably sealing the cake therein, wherein the outer sheet material comprises a multilayer structure that includes: 
 an outer layer made of plastic,  
 an inner layer made of a plastic, and  
 an central layer made of an aluminium material and disposed between the outer and inner layers.