An indispensible element for people, oxygen is a major cause of the reactions associated with food spoilage. Oxidative degradation can affect the delicate color, flavor, and microbial stability of a variety of foods such as coffee & tea, nuts, chocolate, cheese, meat, gourmet snacks, and retorted products.
Vacuum packaging, removing the air from a package, and modified atmosphere packaging (MAP), replacing the air in a package with nitrogen or carbon dioxide, are the two primary approaches to avoid undesirable oxygen-induced reactions through shelf life. Maintaining product quality using either approach relies on the packaging film’s ability to act as a barrier, overcoming the natural drive created by the difference in oxygen partial pressures inside the package (0-2%) vs. outside the package (21%).
Oxygen transmission rate, also referred to as “OTR,” is the steady state rate at which oxygen gas can permeate through a film. OTR is expressed as a volume of oxygen that penetrates a given area in a one-day period; cc/m2/24hr…or…cc/100 in2/24hr, measured at a standard temperature of 73°F (23°C), and 0% relative humidity (RH).
General comparisons of barrier capabilities are as follows:
Relative Oxygen
Barrier Capability | cc/m2/24hrs | cc/100 in2/24hr |
High-Barrier | ~ 1-10 | ~ 0.06-0.65 |
Moderate Transmitter (of O2) | ~ 1000 | ~ 64.50 |
High Transmitter (of O2) | ~ 10,000 | ~ 645.20 |
OTR can be tailored to specific product needs by utilizing specialized films such as foil, metalized PET, or metalized CPP, EVOH, AlOx or SiOx. OTR of non-coated or metalized films can be improved by increasing thickness, but may be limited by cost. Adjusting copolymer ratios, plasticizer content, and polymerization processes, allows packaging design specialists to customize complete packaging systems with performance characteristics optimized for your unique product needs.
While testing for OTR is done under dry conditions, it is important to note that increased relative humidity (RH) can have a major impact on the barrier properties of certain films. The OTR of EVOH, for example, increases dramatically when RH exceeded 75%. (Journal of Applied Polymer Science, Vol 82: 1866–1872, 2001).
To learn more about optimizing oxygen transmission rates to enhance the quality of your product, or to be sure you’re using the best barrier film for your application, contact Flair today.