The market for roast-in-the-bag poultry and fish is growing, said TCL. In many cases, these products are packaged in-store. “In other cases, I know of companies working on pre-packaged parsnips and potatoes for roasting, but there’s nothing on the market as yet,” md Mike Golding explained.
TCL itself has developed a range of polyester films for this type of application, printed using high-temperature inks. Over a period of 18 months, testing specialist Smithers Pira checked for any migration through TCL’s mono-layer films at temperatures up to 200°C and laminates up to 220°C. “We believe ours are the only films to have tested comprehensively and safely at these higher temperatures,” said Golding.
Standard nitrocellulose-based inks cannot be used for high-temperature applications because of the molecular breakdown which occurs.
Carcinogenic
At higher temperatures, the nitrogen and oxides which are produced can migrate through the film and may react with foodstuffs to produce potentially carcinogenic nitrosamines. Specialist high-temperature inks, such as those used by TCL, do not break down in this way, it claimed.
So are other UK converters using standard inks, which are potentially unsafe in these applications? “I’m 100% sure this is the case,” said Golding. “And I’m pretty upset by it.”
He added that he had purchased high-temperature inks from the UK’s only supplier. It would not be difficult to work out where inks had been correctly specified in other commercialised films and where not. Indeed, there would be nothing to stop tests on third-party films being commissioned.
‘Scare the world away’
“This particular area of the market could grow fast,” he said. “Unfortunately, there are a handful of [products] out there which could scare the world away from having anything to do with it.”
According to Golding, buyers of ovenable and microwaveable films should ask to see converters’ test certificates and reports relating to high-temperature testing.
The adhesives used in film/film and film/paper laminates are another potential source of harmful migration, said TCL. “I’m sure there are adhesives that aren’t suitable for these applications,” said Golding. “So even laminates could potentially have this problem.” But generally, the risks from non-printed structures were lower, he added.
Smithers Pira uses a generic food simulant called Tenax for migration testing. “But a packer or retailer might want to consider testing a given film with their own specific product,” Golding suggested.