TECHNICAL IMPLEMENTATION
High Barrier Packaging Solutions for Food Storage at Elevated RH and Temp
Prior student groups have approached this project with hopes of developing reusable, sustainable, and appropriate solutions for food storage in Sierra Leone. These teams have made progress in researching and testing several desiccant pouches, intended to absorb moisture within the package. This testing was conducted using conventional polyethylene (PE) zip sandwich bags which, due to low moisture barrier properties, are not appropriate for this application. The scope of this research will examine a high-barrier packaging system, and outline potential implementation models of such a solution.
Within the flexible packaging field, material properties such as Moisture Vapor Transmission Rate (MVTR) and Oxygen Transmission Rate (OTR) are commonly used to quantify material specification. MVTR (measured in g-mil / 100 sq. in. /24 hours), describes the amount of moisture vapor that can permeate a material. Understanding and utilizing material with appropriate MVTR is critical in developing a packaging solution, especially in a high humidity climate such as Sierra Leone. Conventional PE "ZipLoc" sandwich bags exhibit MVTR of .5 g/100 sq. in / 24 hours which by industry standards is quite high. This section of the project will examine Aluminum Oxide Coated PE (AlOx PE)- a high-barrier metallized packaging film.
Aluminum Oxide PE is a packaging material that involves depositing a thin and transparent layer of aluminum upon a PE substrate. The result is a highly durable and flexible material with MVTR of .001 g-mil / 100 sq. in / 24 hours.
The following calculation provides a rough estimate of the amount of moisture that could penetrate the the proposed food storage system versus a low-barrier alternative during a 24 hour period. Calculations are based upon a 8” x 12” x 3” food storage pouch. These MVTR figures are based upon a 90% Rh at 100F. According to the NOAA, the average temperature and humidity of Sierra Leone are 90% Rh at 89F. Therefor, the MVTR used in these calculations were gathered at “worst-case” test conditions and would likely decrease given the climate of Sierra Leone.
MVTR Al2O3 Material: .001g / 100in2 / 24hr
Package Requires 264in2 of Material
264in2 / 100in2= 2.64 x .001g of Moisture Vapor = .00264g Moisture Vapor in 24 hr.
.00264g of Moisture Vapor = .00000264L = .000178 Tbsp of Moisture
MVTR PE Material: 1.5g / 100in2 /24hr
264in2 / 100in2= 2.64 x .1.5g of Moisture Vapor = 3.96g Moisture Vapor in 24 hr.
3.96g of Moisture Vapor = .00396 L = .267 Tbsp of Moisture
Using these rough calculations, the proposed food storage solution would allow 99.94% less liquid moisture (by volume) than it's low-barrier counterpart.
Technical jargon aside, the extremely high moisture barrier of AlOx PE, in combination with the CaCl desiccant shows potential as a promising food storage solution for Sierra Leone. One potential implementation would require the user to store the dried grains in the high-barrier pouch, along with the CaCl desiccant. Once sealed, the desiccant pouch will absorb the ambient moisture within the package. Once internal moisture has been absorbed, the high-barrier pouch can protect the contents from the high humidity and temperature of Sierra Leone.
Some points to consider would be the method by which the package is closed and sealed that could be performed without the use of any specialized equipment. Additionally, studies should be performed to determine the number of use cycles of the package and to perform a per/use cost. Finally, a lifecycle analysis accordant with ISO14000 should be performed to evaluate the environmental impacts of the proposed packaging solution.
Recommendations and Suggestions:
In future iterations of designs and testing, the team recommends that the CaCl desiccant pouches be retested within an Aluminum Oxide PE Pouch for MVTR performance and content preservation. This testing should be conducted within a validated atmospheric conditioning chamber to simulate the RH and Temperature of Sierra Leone. Finally, an accelerated aging test should be performed to determine the performance of the package over time.