Modified atmosphere package systems with gas-permeable plastic membranes and window for packaging of fresh fruits, vegetables and cut flowers in modified euro trays

Abstract

This invention relates to novel package systems for refrigerated modified atmosphere packaging of fresh fruit, vegetables and cut flowers. More particularly, this invention relates to the design, construction, closure, sealing and use of gas-permeable paperboard package systems and shipping trays for prolonging the storage life of fresh fruits, vegetables and cut flowers under modified atmosphere in the headspaces of the closed package system. A gas permeable paperboard comprising: (a) a first layer of kraft paper; (b) a layer of polymer having a gas permeability which permits gas to be transmitted through the polymeric film at prescribed levels; (c) a second layer of kraft paper, said first and second layers of kraft paper sandwiching the polymer between them.

1 . A gas-permeable modified atmosphere paperboard combination comprising:
 (a) a first layer of kraft paper;   (b) a layer of controlled gas permeable polymer with no natural pinholes therein; and   (c) a second layer of kraft paper, said first and second layers of kraft paper sandwiching the layer of polymer between them.   
   
   
       2 . A paperboard combination as claimed in  claim 1  wherein the gas permeability of the polymer is between about 50 and 100,000 cc 3 /m 2  24 hr. 1 atm. 
   
   
       3 . A paperboard combination as claimed in  claim 1  wherein the first layer of kraft paper, the layer of polymer and the second layer of kraft paper are affixed together in one step. 
   
   
       4 . A paperboard combination as claimed in  claim 1  wherein the layer of polymer is extruded on one side of the first layer of kraft paper and the second layer of kraft paper is then affixed to the layer of polymer on the side opposite the first layer of kraft paper. 
   
   
       5 . A paperboard combination as claimed in  claim 1  wherein the layer of polymer is preformed and is then laminated between the first layer of kraft paper and the second layer of kraft paper. 
   
   
       6 . A paperboard combination as claimed in  claim 1  wherein the layer of polymer is low density polyethylene. 
   
   
       7 . A paperboard combination as claimed in  claim 1  wherein the layer of polymer is high density polyethylene. 
   
   
       8 . A paperboard combination as claimed in  claim 1  wherein the layer of polymer is a copolymer of low density polyethylene and ethylenebutylacetate. 
   
   
       9 . A paperboard combination as claimed in  claim 1  wherein the overall permeability of the paperboard combination is regulated by regulating the thickness of the polymer and the processing conditions in forming the paperboard combination so that no natural pinholes are formed. 
   
   
       10 . A paperboard combination as claimed in  claim 1  wherein the overall permeability of the paperboard combination is regulated in part by regulating the the composition of the polymer layer and the type of kraft paper. 
   
   
       11 . A paperboard combination as claimed in  claim 1  wherein the polymer is selected from the group consisting of ethylene vinylacetate (EVA), ethylbutyl acetate (EBA), a crosslinked ionomer resin, cast polyester (PET), a polyamide and polycarbonate (PC). 
   
   
       12 . A paperboard combination as claimed in  claim 1  wherein a portion of the first layer of kraft paper and a corresponding opposite portion of the second layer of kraft paper are absent so that the intermediate polymer layer forms a window. 
   
   
       13 . A paperboard combination as claimed in  claim 12  wherein the polymer layer at the location of the window includes an anti-fog agent. 
   
   
       14 . A paperboard combination as claimed in  claim 13  wherein the anti-fog agent is silicone, non-ionic surfactant or oil-based material. 
   
   
       15 . A paperboard modified atmosphere package container suitable for packaging fruits and vegetables under refrigerated modified atmosphere conditions comprising:
 (a) a container constructed of an erected paperboard blank having flaps, side panels, end panels, base panel and lid panel with flaps, side panels and end panels formed therein and fold and joint lines impressed therein, said paperboard blank being constructed of:
 (i) a first layer of kraft paper; 
 (ii) a layer of polymer having a gas permeability which permits gas to be transmitted in either direction through the polymer at prescribed levels; and 
 (iii) a second layer of kraft paper, said first and second layers of kraft paper sandwiching the polymer between them; and 
   (b) glue applied to intersecting joints, flaps, side panels, end panels, and lid panels to provide a hermetic seal to the erected container, said container having a required overall permeability which permits gas to be transmitted into or out of the container.   
   
   
       16 . A container as claimed in  claim 15  wherein the flaps, side panels, end panels and base panel of the container are formed from one piece of paperboard and the lid panel with flaps, side panels and end panels are formed from a second piece of paperboard. 
   
   
       17 . A container as claimed in  claim 15  wherein the glue is hot melt glue which is applied to cover exposed and intersecting edges of the joints, flaps, side panels, end panels and lid panels. 
   
   
       18 . A container as claimed in  claim 15  wherein the glue is a foamed glue which is applied to cover exposed and intersecting edges of the joints, flaps, side panels, end panels and lid panels. 
   
   
       19 . A container as claimed in  claim 15  wherein the glue is cold set water resistant glue which is applied to cover exposed and intersecting edges of the joints, flaps, side panels, end panels and lid panels. 
   
   
       20 . A container as claimed in  claim 15  wherein at least some edges of the joints, flaps and panels are sealed with tape. 
   
   
       21 . A container as claimed in  claim 15  wherein at least some of the joints, flaps and panels are sealed with glue and tape. 
   
   
       22 . A container as claimed in  claim 15  wherein a first side of the first layer of kraft paper, opposite the side adjacent the polymer layer, is coated with a polymeric coating. 
   
   
       23 . A container as claimed in  claim 15  wherein edges of flaps intersecting with sides of the container are sealed with glue, and the flaps are bent around the corners of the glued edges, and are glued at a second location. 
   
   
       24 . A container as claimed in  claim 15  wherein a portion of the first layer of kraft paper and an adjacent portion of the second layer of kraft paper are absent to thereby form a window in the container. 
   
   
       25 . A container as claimed in  claim 15  wherein the layer of polymer is at least partially permeable to oxygen and carbon dioxide. 
   
   
       26 . A container as claimed in  claim 15  wherein exposed edges of flaps and sides are folded, and the exposed edges of the paperboard are sealed with glue. 
   
   
       27 . A container as claimed in  claim 15  wherein the lid panel has a window. 
   
   
       28 . A container as claimed in  claim 27  wherein the window has an anti-fog agent on its surface. 
   
   
       29 . A container as claimed in  claim 27  wherein the anti-fog agent is silicone, non-ionic surfactant or oil-based material. 
   
   
       30 . A container as claimed in  claim 15  wherein the layer of polymer is selected so that the container has a gas permeability which is within a predetermined gas transmission range which is selected in accordance with the respiration rate and characteristics of produce to be packaged in the container. 
   
   
       31 . A container as claimed in  claim 15  wherein the layer of polymer is flexible and has selected gas and moisture permeabilities. 
   
   
       32 . A paperboard as claimed in  claim 15  wherein the gas permeability of the polymer is between about 50 and 100,000 cc 3 /m 2  24 hr. 1 atm. 
   
   
       33 . A container as claimed in  claim 15  wherein the container is filled with produce, a modified atmosphere is injected into the container, and the container is held at a temperature between about 1° C. to 12° C. 
   
   
       34 . A paperboard modified atmosphere package container combination suitable for packaging fruits, vegetables and cut flowers under refrigerated modified atmosphere conditions comprising:
 (a) a container constructed of erected paperboard lid and body blanks having joints, flaps, side panels, end panels, base panels and lid panels formed therein and fold and joint lines impressed therein, said paperboard blanks being constructed of:
 (i) a first layer of kraft paper; 
 (ii) a layer of polymer having a gas permeability which permits gas to be transmitted in either direction through the polymer at prescribed levels; and 
 (iii) a second layer of kraft paper; 
   
     glue applied to intersecting joints, flaps, side panels, end panels, base panels and lid panels to provide a hermetic seal to the erected container; and
 (b) a Euro tray with recessed sides and ends holding the container. 
 
   
   
       35 . A container combination as claimed in  claim 34  wherein a plurality of erected containers containing fruit or vegetables are positioned in the Euro tray. 
   
   
       36 . A container combination as claimed in  claim 34  wherein the Euro tray has recessed ends and sides to facilitate circulation of cool air when the Euro trays are stacked upon one another. 
   
   
       37 . A paperboard combination as claimed in  claim 34  wherein a portion of the first layer of kraft paper and a corresponding opposite portion of the second layer of kraft paper are absent so that the intermediate polymer layer forms a window. 
   
   
       38 . A paperboard combination as claimed in  claim 34  wherein the polymer layer at the location of the window includes an anti-fog agent. 
   
   
       39 . A paperboard combination as claimed in  claim 34  wherein the anti-fog agent is silicone, non-ionic surfactant or oil-based material.