The color changes that represent a positive reaction for the presence of starch using the iodine test would be a change from the traditional iodine color (yellow/brown) to a blue-black color.
Starch is generally made up of two main components, namely:
The amylose content of starch primarily reacts with iodine to form a blue black color. The iodine molecules embed themselves into the structure of the amylose molecules thus resulting in a change of color of the iodine.
In other words, the blue-black color that results from the reaction of amylose in starch with iodine represents a confirmatory test for the presence of starch in a substance.
More about test for starch can be found here: https://brainly.com/question/5351497
