Oxygen and Water Vapor Permeability

The overall quality of a package may decrease over time due to product type, packaging and environmental factors. While the packaging acts as a barrier between the product and the environment to which the product/package system is exposed, the degree of protection can vary.

This variation is particularly important in connection with the transport of gases, vapors, water vapor or other low molecular weight compounds between the external environment and the inner packaging environment controlled by the packaging material.

Related to glass, metal and ceramic packaging, plastic packaging materials are permeable to small molecule substances such as gas, water vapor, organic vapors. Therefore, in terms of properties, plastic materials provide a wide range of mass transfer properties from excellent to low barrier values.

For the purposes of packaging design and optimization, it is important to consider how the mass transfer properties of the packaging material determine the transport of low molecular weight compounds both into and through the packaging. In polymer-structured packages, water vapor, oxygen, carbon dioxide, flavor and aroma compounds, additives and low molecular weight residuals can be transferred from the interior or exterior environment along the polymer package wall, causing a continuous change.

For the purposes of packaging design and optimization, it is important to consider how the mass transfer properties of the packaging material determine the transport of low molecular weight compounds both into and through the packaging. In polymer-structured packages, water vapor, oxygen, carbon dioxide, flavor and aroma compounds, additives and low molecular weight residuals can be transferred from the interior or exterior environment through the polymer packaging wall, resulting in a continuous change in product quality.

For example, in the case of a packaged product whose physical or chemical degradation is dependent on the equilibrium moisture content, the water vapor barrier properties of the package will be of great importance in maintaining or prolonging its shelf life. Similarly, the change in oxygen concentration in a permeable package will directly affect the oxidation rate of oxygen sensitive nutrients such as vitamins, fatty acids and proteins.

Similarly, the loss of certain aroma or flavor components or the acquisition of foul odors due to penetration can also lead to a reduction in product quality, resulting in reduced shelf life of products.

For these reasons, “Oxygen and Water Vapor Permeability” is one of the important test parameters in packages.