Interference of Gallic and Chlorogenic Acid with Starch-Iodine Reaction

Addition of gallic and chlorogenic acid to the reaction mixture caused a marked inhibition of starch-iodine reaction. This inhibition, however, could be partially alleviated by enhancing the level of iodine-potassium iodide reagent (IKI) in the reaction mixture. It is likely that these phenolics deplete the iodine from the system which could account for inhibition of reaction. IKI addition to the solution of gallic and chlorogenic acid induced a change in the absorption spectra of the respective phenolic compound causing a shift in the absorption peaks. Such a change may be ascribed to a complex being formed between the tested compounds and iodine.