SSC CPO SI and ASI Model Paper 1

(1) Food items containing starchgive blue-black colour with iodinesolution. Starch is found in fooditems, like potatoes, bread, rice,etc.
 Boiling the food does not kill thestarch. So when we test boiled andmashed potatoes for the presenceof starch, it would give a positivetest. A slice of bread also containsstarch. So, it will also give blueblackcolour with iodine solution.Chewed rice would not give apositive test for starch because therice is mixed with saliva. In saliva,the digestive enzyme–salivaryamylase is present, which breaksdown starch into sugar. Sugardoesn’t give a positive test withiodine solution. Coconut oil doesnot contain starch. So, it does notgive blue-black colour with iodine.