Question

Why a vegetable stain term reddish brown when washed in a soap solution?

Answer 1

We know that soap solution is basic in nature and vegetables stain contains turmeric,(here) which is a natural indicator and turns reddish brown when base is in contact.

Answer 2

Answer:

It contains turmeric. Turmeric is an indicator which gives red colour with a base since soap is a base so we get red colour..