In the case of the presence of catalase, this substance really gives a high interference with the biosensor response, since no distinct visual color change was observed at 1% of ethanol. This is due to the fact that the presence of catalse could reduce the biosensor response by ~35% (using RGB values) and becomes a limitation of this biosensor. Since catalase is well known to decompose H2O2 under these experimental conditions (pH 7.0 and 25 °C), the presence of catalase will therefore compete with the PANI in the reaction towards H2O2, which in turn, reduces the biosensor response due the resulting H2O2 concentration decrease. However, in the case of fermented beverages catalase is expected to be absent or present in trace amounts [45], so in real sample conditions, the catalase should not affect much the biosensor response.