Testing Foods for Starch

Testing foods for starch is such an easy and inexpensive chemistry experiment. Iodine is an indicator as it turns black or blue if there is starch present. If it remains reddish brown, there is no a significant amount of starch. Third Student tested an apple slice, which stays brown, and a mini marshmallow, which turns black.
Third Student was surprised that peanut butter tested positive for the presence of starch.