Question

why does a piece of bread taste sweet when chewed for sometimes ????

Answer 1

If the bread is chewed for some time it tastes sweet since foods like bread and potatoes are nourishments that are generally made of starch. Starch is an atom that plants make with a specific end goal to store sugar. It comprises of long chains of glucose (some of them branch).

In your salvation you have a chemical called amylase, this will cut up the vast starch particles at random until you are left with sugars made of 1,2 or 3 glucose atoms long (glucose, maltose or dextrin). Starch doesn't t taste sweet, yet glucose and maltose do, so as you chew the bread it will gradually turn out to be somewhat debilitated sweet.