Dr. Lekutat's answer:
The natural fruit acid in fresh fruit can cause a burning sensation if you have a sore throat. Your mucous membranes are already raw and fruit acid can make it worse. But the vitamins and minerals in fresh fruit help your body fight infections by supporting your immune system. So try to eat less-acidic fruit when you have a throat infection, like bananas, apricots or pears, rather than oranges. They won't hurt your throat and will strengthen your immune system.