Devices and methods for controlling headspace humidity and oxygen levels

Abstract

A humidity control device for use in maintaining the desired humidity of a closed environment, e.g., a container, while also decreasing headspace oxygen, the device including a water vapor and oxygen permeable pouch, an aqueous salt solution containing humidity controlling salts in combination with salts of ascorbic acid or isomers thereof.

What is claimed is: 
     
         1 . A liquid humidity and oxygen control device for use in an enclosure for maintaining a desired relative humidity and oxygen level of the enclosure, comprising:
 (a) a water vapor and oxygen permeable and liquid impermeable pouch, the pouch formed from material comprising a water vapor transmission rate and an oxygen transmission rate and defining an interior space within the pouch; and   (b) an effective amount of a humidity and oxygen control solution disposed within the interior space and comprising:
 a saturated aqueous salt solution, 
 salts of ascorbate isomers containing an amount of a salt solution from about 5% to 70% salt, and 
 ascorbic acid salts, or isomers thereof, from 5 to 60%, 
   wherein the water vapor transmission rate of the pouch material comprises transmission of about 1% to about 50% by weight of the initial pouch contents in a 24-hour period when exposed to an atmosphere of less than 10% relative humidity and absorption of about 1% to about 50% by weight of the initial pouch content when exposed to an atmosphere having a relative humidity of 85%, and
 wherein the oxygen transmission rate of the pouch material is such that 20 in 2  of the pouch material will transfer a minimum of 80 ml of headspace oxygen over 20 days at 70 degrees F. and atmospheric pressure. 
   
     
     
         2 . The humidity and oxygen control device of  claim 1 , wherein the salt solution comprises cations and anions, wherein the cations are selected from the group consisting of: lithium, sodium, potassium, calcium, and magnesium, and the anions are selected from the group consisting of: chloride, formate, acetate, phosphate, sulfate, citrate, lactate, malate and tartrate. 
     
     
         3 . The humidity and oxygen control device of  claim 1 , wherein the solution further comprises non-ionic substances selected from the group consisting of: propylene glycol, glycerin, and at least one simple sugar. 
     
     
         4 . The humidity and oxygen control device of  claim 3 , wherein the at least one simple sugar is selected from the group consisting of: glucose and fructose and sugar alcohols. 
     
     
         5 . The humidity and oxygen control device of  claim 4 , wherein the sugar alcohol is selected from the group consisting of: xylitol, sorbitol and mannitol. 
     
     
         6 . The humidity and oxygen control device of  claim 1 , wherein the pH of the solution is between 6.0 and 10. 
     
     
         7 . The humidity and oxygen control device of  claim 1 , where the solution contains ascorbate isomer salts and/or erythorbic isomer salts. 
     
     
         8 . The humidity and oxygen control device of  claim 7 , wherein the ascorbate isomer salts comprise sodium salts of ascorbic acid and/or potassium salts of ascorbic acid, and wherein the erythorbic isomer salts comprise sodium salts of erythorbic acid and/or potassium salts of erythorbic acid. 
     
     
         9 . The humidity and oxygen control device of  claim 1 , where the salt solution comprises ascorbate and/or erythorbic isomer salts and at least one metal. 
     
     
         10 . The humidity and oxygen control device of  claim 9 , wherein the at least one metal comprises iron. 
     
     
         11 . The humidity and oxygen control device of  claim 8 , wherein the ascorbate isomer salts comprise sodium salts of ascorbic acid and/or potassium salts of ascorbic acid, and wherein the erythorbic isomer salts comprise sodium salts of erythorbic acid, and/or potassium salts of erythorbic acid. 
     
     
         12 . The humidity and oxygen control device of  claim 1 , wherein said humidity control solution is thickened by an amount of one or more compatible viscosity control agents selected from the group consisting of chemically modified cellulose and xanthan gum. 
     
     
         13 . The humidity and oxygen control device of  claim 1 , wherein the pH of the humidity control solution is adjusted by adding an amount of an acid or base selected from the group consisting of citric acid, lactic acid, formic acid, phosphoric acid, phosphate salts, sodium hydroxide, and potassium hydroxide. 
     
     
         14 . The humidity and oxygen control device of  claim 1 , wherein said polymeric material of said pouch is selected from the group consisting of polyesters, polyamides, poly lactate, polyolefin, and combinations thereof. 
     
     
         15 . The humidity and oxygen control device of  claim 1 , further comprising a vapor-permeable outer pouch for containing said pouch as a further protection against leaks. 
     
     
         16 . The humidity and oxygen control device of  claim 1 , wherein the solution contains elemental iron. 
     
     
         17 . The humidity and oxygen control device of  claim 1 , wherein the solution contains a ferrous salt. 
     
     
         18 . The humidity and oxygen control device of  claim 16 , wherein the ferrous salt comprises ferrous sulfate. 
     
     
         19 . A method for controlling the oxygen and humidity within an enclosure, comprising:
 providing an impermeable enclosure comprising an interior volume and a closure mechanism;   contacting the interior volume with a humidity and oxygen control device comprising:
 (a) a water vapor and oxygen permeable and liquid impermeable pouch, the pouch formed from material comprising a water vapor transmission rate and an oxygen transmission rate and defining an interior space within the pouch; and 
 (b) an effective amount of a humidity and oxygen control solution disposed within the interior space and comprising:
 a saturated aqueous salt solution, 
 
 salts of ascorbate isomers containing an amount of a salt solution from about 5% to 70% salt, and 
 ascorbic acid salts, or isomers thereof, from 5 to 60%, 
   wherein the water vapor transmission rate of the pouch material comprises transmission of about 1% to about 50% by weight of the initial pouch contents in a 24-hour period when exposed to an atmosphere of less than 10% relative humidity and absorption of about 1% to about 50% by weight of the initial pouch content when exposed to an atmosphere having a relative humidity of 85%, and   wherein the oxygen transmission rate of the pouch material is such that 20 in2 of the pouch material will transfer a minimum of 80 ml of headspace oxygen over 20 days at 70 degrees F. and atmospheric pressure.   
     
     
         20 . The humidity and oxygen control device of  claim 19 , wherein the salt solution comprises:
 cations and anions, wherein the cations are selected from the group consisting of: lithium, sodium, potassium, calcium, and magnesium, and the anions are selected from the group consisting of: chloride, formate, acetate, phosphate, sulfate, citrate, lactate, malate and tartrate; and   non-ionic substances selected from the group consisting of: propylene glycol, glycerin, and at least one simple sugar, wherein the pH of the solution is between 6.0 and 10.