Laccases 2 & 3 as biomarkers of Botrytis cinerea infection in sweet white wines

•Five B. cinerea laccases were identified in sweet white wines.•A LC–MS/MRM method targeting laccase-2-BcLCC2 and laccase-3-BcLCC7 was developed.•Laccase-2-BcLCC2 and laccase-3-BcLCC7 were in higher amount in botrytized wines. Botrytized sweet wines are made with berries infected by the fungus Botrytis cinerea. The aim of this study was to identify biomarkers of B. cinerea infection in sweet wines with a focus on laccases which are exocellular oxidase enzymes produced by this fungus during fruit contamination. Total proteins from six commercial sweet wines, including three naturally botrytized wines and three non-botrytized wines were analysed by LC-QTOF-MS. Five laccases, namely laccase-1-BcLCC1, laccase-2-BcLCC2, laccase-3-BcLCC7, laccase-8-BcLCC8 and laccase-12-BcLCC12, were identified in both types of wine. Then, a targeted proteomic approach by LC-MRM was used to semi-quantify laccase-2-BcLCC2 and laccase-3-BcLCC7, in the six samples. LC-MRM targeted analysis of the two enzymes allowed the discrimination of botrytized versus non-botrytized sweet white wines.