A Queensland "dairy-free" ice cream and yoghurt company was told its product wasn't suitable to be marketed as "dairy-free" years prior to the anaphylaxis death of a woman in the UK, court documents allege.

Last year the ABC revealed COYO, based on the Sunshine Coast, was being sued by its UK licensee, Planet Coconut, after it was embroiled in the death of a 42-year-old mother.

In 2014, COYO – founded by couple Sandra and Henry Gosling – licensed its product to Planet Coconut for 10 years, allowing it to exclusively manufacture and sell the product within the UK and Ireland.

In 2017, just after Christmas, Celia Mash was out shopping with her family in Bath when she bought a wrap that she believed was dairy-free from a British sandwich shop.

An inquiry into her death revealed she collapsed in the street after eating the wrap and was taken to hospital, but died less than half an hour after her husband called for an ambulance.

The wrap contained what was supposed to be a "dairy-free" coconut yoghurt manufactured by Planet Coconut, but later tests revealed it contained milk protein.

Last year, Planet Coconut launched a civil lawsuit in the Queensland Supreme Court, stating it lost millions of dollars in revenue as a result of the death of Ms Marsh. The company is now suing COYO for up to $10 million.

However, in response to the lawsuit, COYO has launched a counterclaim against the Australian and New Zealand branch of multi-national, billion-dollar food ingredient manufacturing company, Tate & Lyle.

Source of contamination allegedly in yoghurt stabiliser

COYO employed Tate & Lyle to produce a yoghurt stabiliser at its Wacol facility in Brisbane.

A stabiliser is added to yoghurt to give it its consistency and prevent water separation.

Court documents allege the source of the dairy contamination from the yoghurt Ms Marsh ate was in the yoghurt stabiliser, manufactured at a Tate & Lyle factory in the UK.

Court documents claim the order for the stabiliser was placed with Tate & Lyle's Wacol factory, and the order was sent to its UK factory to be completed, before the "contaminated stabiliser" was taken to Planet Coconut.

In court documents, Tate & Lyle allege that a product information form (PIF) was issued to COYO in 2014, which stated the ingredients in the stabiliser did not contain milk, but that milk powder was used in another product on the same manufacturing line.

COYO claims it was made aware in the PIF that "at most, the stabiliser might contain protein from milk powder in a concentration of something less than ten parts per million".

COYO said Tate & Lyle owed it a responsibility to ensure the stabiliser in both the UK and Australia was manufactured in line with its product information form, further alleging in court documents that if Tate & Lyle had done so, Planet Coconut's yoghurt would not have been contaminated and Ms Marsh would not have died.

However, in documents filed for Tate & Lyle's defence, it claimed it had warned COYO the stabiliser was not suitable to make "free" claims.

"[COYO] knew that milk and milk products were present in the Wacol factory and on the same production line and [there] were potential cross-contact contaminants when the stabiliser was manufactured," the defence document read.