If the food is positive for simple sugars the. To find out if a food contains starch iodine a reagent is placed on the food. Pin On Biology A test for simple sugars involves mixing the food with a liquid blue reagent called Benedicts solution and then heating the mixture. . Get help with your Organic chemistry homework. Sugars can be detected in foods through a simple lab test. Access the answers to hundreds of Organic chemistry questions that are. A food containing starch will turn black when in contact with iodine. Organic Chemistry Questions and Answers. Macromolecules virtual lab answer key.