Authorities are testing an orange purchased at a Brisbane fruit and vegetable shop that turned purple after it was cut.
Neti Moffitt cut the orange for her two-year-old son on Tuesday, giving him some slices but leaving others out overnight.
The following day, both the remains in the bin and the leftover slices had started to turn bright purple.
"It looked like someone had dipped it on an ink pad, which I guarantee you we haven't," she told the ABC on Friday.
"My first thought was I hope it has had no ill effect on my child. But he's fine, absolutely not a drama."
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Ms Moffitt contacted Queensland Health who came to collect the orange, along with the knife used to chop it and the family's knife sharpener.
She told the ABC the official was "very, very excited" by the case.
Queensland Health confirmed to the ABC that the items "have been taken to Queensland Health Forensic and Scientific Services for testing".
There appears to be only one other reported incident of an orange turning purple in Queensland.
In 2015, Angela Postle had the same phenomenon occur.
"I cut some [oranges] up and they went in my kids' lunchboxes for school, and I left some out because I was going to give them to my baby," she told Channel Nine at the time.
"However I ended up making mango and banana puree, so they were left in a bowl overnight, and we noticed the purple colour in the morning."
Testing ruled out artificial colouring and no iodine was found in those samples.
Ms Moffitt said she hoped her case would reveal answers.
"I'm so keen to find out what has happened," she said.
