Image copyright Neti Moffitt Image caption The fruit changed colour within hours of being cut up with a knife What could cause a freshly sliced orange to suddenly turn purple?Australian health authorities say they have solved a mystery that prompted much speculation earlier this month.It began when a Brisbane woman, Neti Moffitt, asked for an…
What could cause a freshly sliced orange to suddenly turn purple?
Australian health authorities say they have solved a mystery that prompted much speculation earlier this month.
It began when a Brisbane woman, Neti Moffitt, asked for an investigation into why an orange – partially eaten by her son – had later changed colour.
Scientists have now revealed it was due to a natural reaction between the fruit and a sharpened knife. The orange did not pose a health risk, they added.
Stewart Carswell, Queensland Health’s chief chemist, said “numerous tests” were conducted to determine the cause of the colour change.
The results revealed that anthocyanins – a naturally occurring antioxidant in oranges – had reacted with iron particles from the newly sharpened blade, he said.
Ms Moffitt told the BBC that it was “brilliant” have the mystery solved.
The orange turned purple sometime after Ms Moffitt’s two-year-old son had eaten a few slices.
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