Foods containing starch will turn a blue-black colour. The iodine test can also be used with a microscope to stain starch grains in plant cells. Wear safety goggles. Sudan III solution is ...

Place one spatula of the food sample on a dish or 1 cm 3 if the sample is liquid. Using a dropper, place a few drops of iodine solution onto the food. Record any change in the colour of the solution.