During winemaking process, malolactic fermentation (MLF) is an important step to improve wine quality. MLF is a secondary fermentation that transforms the dicarboxylic L-malic acid in the monocarboxylic L-lactic acid, by lactic acid bacteria (LAB). This transformation causes acid reduction, flavour modification and also contributes to microbiological stability of red wine (Ribereau-Gayon et al., 2006). The use of a fast and cheap analytical device (Flores et al., 2013) able to measure the change in MLF progress, such as screen-printed carbon amperometric biosensor, represents a key point for quality wines production because an uncontrolled MLF can causes a risk of wine spoilage and off-flavours development. The amperometric biosensor for the monitoring of MLF takes advantage of the specific reaction between lactate oxidase enzyme (LOX) and L-lactic acid, that is the only isomeric form of lactic acid produced by malolactic enzymes. The enzymatic reaction between LOX and L-lactic acid produces H2O2 detected at 0.7 V vs. Ag/AgCl on electrodes surface. At high potential some electroactive compounds, such as polyphenols and ascorbic acid, may interfere during the hydrogen peroxide measurement giving mistakes in the results. For this reason electrochemical mediators able to detect hydrogen peroxide at low potential are required. Some authors overcome interference problem, related to the application of LOX biosensors in the analysis of food samples, using polyaniline-co-fluoroaniline films (Suman et al., 2005) or combining polysulfone multiwalled nanotubes with ferrocene (Perez and Fabregas, 2012). Others studies used chitosan …