Moisture absorbing device for food packaging

Abstract

There is disclosed a vapor absorbing device for capturing moisture released by fresh food stored in an unvented and closed container. The device may comprise a vapor-permeable carrier fabric having a food side for facing the fresh food and a container side opposite the food side. An absorbent matrix having a matrix thickness may layer across the container side of the carrier. The matrix may comprise a fibrous substrate and a food-safe hydrogel infusing the substrate. The hydrogel may include a water soluble polymer. The device may be configured to dispose a container side of the matrix against an interior surface of the food container. And, the matrix may be configured to capture the moisture at a predetermined vapor absorption rate.

What is claimed is: 
     
         1 . A vapor absorbing device for capturing moisture released by fresh food stored in an unvented container, the device comprising:
 a vapor-permeable carrier fabric having a food side for facing the fresh food and a container side opposite the food side;   an absorbent matrix having a matrix thickness and layering across the container side of the carrier, the matrix comprising:   1) a fibrous substrate; and   2) a food-safe hydrogel infusing the substrate and including a water soluble polymer; and   where the device is configured to dispose a container side of the matrix against an interior surface of the food container, and where the device is calibrated to capture the moisture at a predetermined vapor absorption rate.   
     
     
         2 . The device of  claim 1 , wherein:
 the fibrous substrate is formed of a non-woven fabric.   
     
     
         3 . The device of  claim 1 , wherein:
 the fibrous substrate is formed of viscose polyester (polyviscose).   
     
     
         4 . The device of  claim 1 , wherein:
 the water soluble polymer is polyvinyl alcohol (PVOH) or a salt thereof.   
     
     
         5 . The device of  claim 4 , wherein:
 an upper limit on the PVOH concentration is around 2% by weight.   
     
     
         6 . The device of  claim 1 , further comprising:
 a deliquescent embedded in the hydrogel for enhancing the predetermined vapor absorption rate of the device.   
     
     
         7 . The device of  claim 6 , wherein:
 the matrix thickness and a concentration of the deliquescent are adjusted together in approximate direct proportion for optimizing the predetermined absorption rate operative during a freshness period over which the moisture capturing is intended to occur.   
     
     
         8 . The device of  claim 6 , wherein:
 the deliquescent is calcium chloride (CaCl 2 )).   
     
     
         9 . The device of  claim 7 , wherein:
 the concentration of the CaCl 2 ) is less than around 20% by weight.   
     
     
         10 . The device of  claim 1 , further comprising:
 a matrix mass of the absorbent matrix for establishing the predetermined vapor absorption rate is between approximately 30 and approximately 150 grams per quart of a container volume, depending on a food exudation.   
     
     
         11 . The device of  claim 1 , further comprising:
 an activation liner disposed on the carrier food-facing side for sealing the absorbent matrix from moisture prior to use.   
     
     
         12 . The device of  claim 1 , further comprising:
 an attaching layer disposable on the matrix container side for attaching the device to the interior surface of the food container.   
     
     
         13 . The device of  claim 12 , wherein:
 the attaching layer is a pressure sensitive adhesive.   
     
     
         14 . The device of  claim 1 , further comprising:
 a barrier cloth layering across an opposite side of the hydrogel matrix and edge-sealed to the carrier fabric along their respective perimeters to form a sachet isolating the absorbent matrix from the fresh food.   
     
     
         15 . The device of  claim 1 , further comprising:
 a fluted, corrugated, or porous ventilation layer mountable between the absorbent matrix and the container interior, the ventilation for increasing a surface area of the matrix.   
     
     
         16 . A temporary container for keeping fresh food crispy or dry during transportation and storage over a freshness period, the temporary container comprising:
 a lid closable to a tray for substantially forming a sealed container;   a vapor-permeable carrier sheet having a food side for facing the fresh food and a container side opposite the food side;   an absorbent patch having a patch thickness and disposed on the container side of the carrier sheet, the patch comprising:
 1) a non-woven hydrophilic fabric; and 
 2) a hydrogel infusing the non-woven fabric and including a water soluble polymer; and 
   where the patch is configured to mount its container side to an interior surface of the lid or the tray, and where the temporary container is configured to capture the moisture at a predetermined vapor absorption rate.   
     
     
         17 . The container of  claim 16 , further comprising:
 a deliquescent embedded in the hydrogel for enhancing the predetermined vapor absorption rate of the container.   
     
     
         18 . The container of  claim 17 , wherein:
 the soluble polymer is a polyvinyl alcohol having a matrix concentration of between about 0.2% and about 2%, and wherein the deliquescent is CaCl 2 ) having a matrix concentration of between about 1% and about 10%.   
     
     
         19 . A method for packaging fresh food to stay crispy or dry during transportation and storage over a freshness period, the method comprising:
 providing a closable container comprising a lid and a tray for substantially sealing the container;   applying a hydrophilic patch to an interior surface of the lid or the tray, the patch comprising:   1) a vapor-permeable carrier fabric having a food side for facing the fresh food and a container side facing the lid or the tray;   2) a hydrogel matrix layered across the container side of the carrier and comprising a polyviscose substrate infused with polyvinyl alcohol (PVOH) and particles of calcium chloride (CaCl 2 )); and   selecting the patch having a predetermined vapor absorption rate calibrated to match the freshness period.   
     
     
         20 . The device of  claim 19 , wherein:
 the patch, when selected for the lid of a hot food-to-go container, is calibrated to a hot freshness period of between about 15 minutes and an hour, and where the patch, when selected for the tray of a refrigeration container, is calibrated to a cold freshness period of between about two days and about two weeks.   
     
     
         21 . The device of  claim 19 , wherein:
 the selected patch was calibrated by adjusting one or more of the following parameters: a size of the patch, a concentration of the PVOH, a concentration of the CaCl 2 ), and a permeability of the carrier fabric.