If we chew rice or bread for a few minutes it starts tasting sweet?

When you chew rice or bread for a few minutes, the enzymes in your saliva break down the starches into sugars. Sugar has a sweet taste so that is the reason why rice and bread become sweeter. This process is called starch hydrolysis. Saliva contains an enzyme called amylase, which breaks down starch into simpler sugars such as maltose and glucose. These sugars can then be absorbed by your body and used as energy. This is why you may feel a burst of energy after eating a starchy food like rice or bread.