Visual determination of azodicarbonamide in flour by label-free silver nanoparticle colorimetry

•A novel method for the detection of azodicarbonamide was developed by using label-free Ag NPs as a colorimetric probe.•When the azodicarbonamide concentration reaches 0.33 μM, the color change can be detected by the naked eye.•The as-constructed sensor displayed good reliability and could be used in the actual detection of azodicarbonamide in flour.