KM Packaging Services has fresh experience of this market, having produced polyethylene terephthalate (PET) lidding for a range of PET prepared food trays. The trays, understood to have been for Asda own-label products, were flushed with oxygen for the protein content. But the lidding required differentiated laser microperforation for the carbohydrate and vegetable components, which need varying rates of 'breathability'.
No additional barrier layer was built into the film, explained md Charles Smithson. "Even with a barrier, the shelf-life of the carbohydrate and vegetable portions would not have equalled that of the protein," he said.
The lidding, with tailored microperforations, or none at all, in the different sections, was designed to be applied and sealed in register. KM described the project as "one of the first lidding solutions of its kind".
UK and Ireland business manager Alan Lockhart said: "Knowing the behaviour and varying respiratory rates of different fresh produce items proved invaluable in completing the project on time."
The PET film material has antifog properties and offers high levels of clarity, said KM.
The seasonal product range, available during much of 2012, is now off the shelf, Smithson added.
So, a new departure in chilled foods? In fact, he said, KM produced its first film of this sort more than 25 years ago, before pre-cooked ready meals became the norm, and long before the 'ready-to-cook' vogue.