Question

If we bite a bread and chew it in our mouth for sometimes it will taste sweet. Why

Answer 1

Bread is a type of starch that is made up of glucose molecules and glucose is, again, a form of sugar. 

If you chew on a piece of bread for a while, it will begin to taste sweet because the enzymes in saliva are already beginning to break down the starch into glucose.

Answer 2

bread contain starch which is a form of glucose which taste sweet. On chewing a piece of bread the enzymes present in saliva break the bread into
glucose and hence it taste sweet