Chemistry Help?

Question

When flour mixed with Iodine / Lugol's, the flour turned purple on contact, but why did this happen? The flour and Iodine were mixed inside a test tube with water, although I don't think this info would be necessary.

So...

Why does flour turn purple when mixed with Iodine?

Answer 1

The starch in the flour forms a complex with Iodine which reflects the blue and red wavelengths of incident white light. This is a definitive qualitative test for starch in foodstuffs