Would cornstarch be positive or negative in a iodine reagent?

Cornstarch would yield a positive result with iodine reagent, producing a deep blue or purple color. This reaction occurs because the iodine interacts with the helical structure of amylose, a component of starch. In contrast, simple sugars and other carbohydrates do not produce this color change. Thus, the presence of cornstarch can be confirmed using iodine.