Modified atmosphere packaging with base-mounted micro-permeable patch

Abstract

A rigid or semi-rigid MAP container includes a raised cavity in its bottom surface, wherein a macroscopic hole penetrating the container bottom is covered by a semi-permeable patch so as to provide limited gas exchange between the container interior and the surrounding environment. The raised cavity extends to at least one edge of the bottom surface, so that gases can be exchanged with the cavity even when the container is placed on a flat surface. In embodiments, the sides are slanted outward, so that air passages accessible to the cavities are formed between adjacent containers in a stack. The container can be re-sealable, and can include an interior sealant layer. The patch can be naturally semi-permeable, microporous, or microperforated, and can be adhered to the container bottom by an adhesive applied about a perimeter thereof that does not overlap the hole.

I claim: 
     
         1 . A rigid or semi-rigid container configured for modified atmosphere packaging of produce, the container comprising:
 a base having a bottom and at least one side joined to the bottom by a bottom edge;   a lid removably engageable with the base so as to form a seal therebetween;   a raised region formed in the bottom of the container base and extending to the bottom edge thereof, so that when the container bottom is placed on a flat surface the raised region and flat surface form a cavity into which air from an environment surrounding the container can enter the cavity by passing under the bottom edge;   a hole formed in an upper surface of the raised region and penetrating the container bottom; and   a semi-permeable patch installed over the hole and configured to permit a limited exchange of gases between an interior of the container and the surrounding environment, so that a modified atmosphere is created within the container when respiring fresh produce is contained therein.   
     
     
         2 . The container of  claim 1 , wherein the lid can be re-engaged with the base after removal thereof so as to re-establish a modified atmosphere within the interior of the container when fresh produce remains contained 
     
     
         3 . The container of  claim 1 , wherein the side is slanted outward from the bottom edge, so that when the container is placed against a vertical surface or next to an adjacent container having a similar shape, a passage is formed along the side of the container through which air can flow to the bottom edge and from thence to the patch. 
     
     
         4 . The container of  claim 1 , wherein the patch is made from a material that is naturally semi-permeable to gases. 
     
     
         5 . The container of  claim 1 , wherein the patch is made from a microporous material. 
     
     
         6 . The container of  claim 1 , wherein the patch is made from a material that is substantially impenetrable to gases, the patch being microperforated so as to allow the limited exchange of gasses. 
     
     
         7 . The container of  claim 1 , further comprising sealant layers applied to interior surfaces of the base and lid, the sealant layers being sealable to each other when the lid is engaged with the base so as to form a hermetically sealed junction therebetween. 
     
     
         8 . The container of  claim 7 , wherein the sealant layers comprise at least one of polyacrylonitrile resin and polyester film. 
     
     
         9 . The container of  claim 1 , wherein the hole is between 1 mm and 10 mm in diameter. 
     
     
         10 . The container of  claim 1 , wherein the patch is adhered to the upper surface of the raised region by an adhesive that is applied to a perimeter of the patch but does not overlap the hole. 
     
     
         11 . The container of  claim 1 , wherein the raised region extends to a plurality of bottom edges that join a plurality of sides to the container bottom.