Magic or science?

What happens when we test the presence of glucose, proteins and starch in foods?

When we (3ºB) used certain indicators ( Fehling A, Feling B, copper sulphate or Iodine), we noticed some amazing facts: it is really easy  to test what some types of food  -like cheese, bread, apples, potatoes or jam- contain by observing how colour changes from blue to orange or purple, from yellow to dark blue...

 This is science, and we had a good time!