Question

how to know that there is presence of starch

Answer 1

IODINE TESTING IS THE BEST WAY TO RECOGNIZE THE PRESENCE OF STARCH IN ANY SUBSTANCE. WHEN IODINE MIXES WITH THE STARCH IT TURNS INTO BLUE BLACK SPOT. WHICH INDICATES THAT THE SUBSTANCE HAS STARCH IN IT.

Answer 2

TO TEST THE PRESENCE OF STARCH WE CAN USE IODINE SOLUTION ON THAT THING. IF IT TURNS BLUE-BLACK THEN IT MEANS IT CONTAINS STARCH.