Oxygen scavenger systems look set to topple passive barrier films

For the last 10 or 12 years says RPC Barrier Containers, France ready meals with especially oxygen-sensitive products have typically been protected by a combination of OS systems, in the middle layer of a polypropylene-based film, and an ethyl vinyl alcohol (EVOH) barrier layer. In Germany, according to sales manager Roland Schultz, the proportion of ready meal trays incorporating OS systems could be as high as 80%.

The principle role of any OS system has been to cover for the EVOH barrier during 'retort shock', when the impact of heat sterilisation temporarily renders the barrier ineffective.

But that could soon change. Schultz said: "Our German OS supplier Albis is working on its next-generation iron-oxide system, where a far finer particle size in the scavenger provides a much-improved function. It could operate for over a year, and means that you might not need a costly EVOH layer at all." ​

But at the Fraunhofer IVV research institute in Germany, senior scientist Kajetan Mueller was more cautious. "In most cases, there has to be a combination of passive and active barrier for an optimised function," ​he said.

There may be examples where an OS additive alone was sufficient, but they would need to be proved on a case-by-case basis. Nor is the comparative cost-efficiency of the two strategies clear without a product-specific analysis, he argued.