Would Starch Give a Positive Fehling's Test?
Starch would not give a positive Fehling's test. This test is used for testing the presence of sugars, such as fructose, glucose and maltose, with the exception of sucrose.
The Fehling's test is considered positive when the solution turns from blue to orange. To test the presence of starch chemically, iodine solution is used. If it turns from red to black or blue, the test is positive. For example, when drops of iodine solution are added to a peeled potato, its color changes to blue or black. Though starch is formed from units of glucose, it has a complex molecule configuration and is not as sweet as glucose.