Australian health authorities say they have solved a mystery that prompted much speculation earlier this month: What could cause a freshly sliced orange to suddenly turn purple?
It began when a Brisbane woman 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. The Brisbane lady told the BBC she was elated that the mystery was solved.
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.
This Wednesday, Mr Carswell described the investigation as unusual: "We see samples that range from blood, urine, water, soil, fish and foodstuffs. So to have an orange come through was really different for our team.”
