Oxygen transmission rate
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Oxygen transmission rate (OTR) is the measurement of the amount of oxygen gas that passes through a substance over a given period. It is mostly carried out on non-porous materials, where the mode of transport is diffusion, but there are a growing number of applications where the transmission rate also depends on flow through apertures of some description.
It relates to the permeation of oxygen through packaging[1] to sensitive foods and pharmaceuticals.
Measurement
Standard test methods are available for measuring the oxygen transmission rate of packaging materials.[2][3][4] Completed packages, however, involve heat seals, creases, joints, and closures which often reduce the effective barrier of the package. For example, the glass of a glass bottle may have an effective total barrier but the screw cap closure and the closure liner might not.
ASTM standard test methods include:
- F3136 Standard Test Method for Oxygen Gas Transmission Rate through Plastic Film and Sheeting using a Dynamic Accumulation Method
- D3985 Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor
- F1307 Standard Test Method for Oxygen Transmission Rate Through Dry Packages Using a Coulometric Sensor
- F1927 Standard Test Method for Determination of Oxygen Gas Transmission Rate, Permeability and Permeance at Controlled Relative Humidity Through Barrier Materials Using a Coulometric Detector
- F2622 Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using Various Sensors
Other test methods include:
- The ambient oxygen ingress rate method (AOIR) an alternative method for measuring the oxygen transmission rates (OTR) of whole packages
Wine
Also a factor of increasing awareness in the debate surrounding wine closures, natural corks show small variation in their oxygen transmission rate, which in turn translates to a degree of bottle variation.[5]