A Protocol to Disclose the Protein Fingerprint of Commercial White Wines Based on Proteomic Tools

Proteins remaining in commercial wines are responsible for the protein haze in white wine unless they are effectively removed before bottling. To avoid this undesirable phenomenon, techniques of precipitation and filtration are applied in the white wine making process to eliminate a large part of them (fining processes) (Ribéreau-Gayon et al., Handbook of enology, vol 2, 3rd edn. Wiley, Hoboken, pp 369-406, 2021). After finding treatments, a minute amount of these genetically informative biomolecules remains in the commercialized product, which makes its extraction and identification extremely difficult. The protocol described here allows for the extraction and identification of proteins present in commercial white wines using a proteomic workflow of dialysis-lyophilization-precipitation-nanoLC-MS/MS analysis. Its application to three monovarietal commercial white wines allows us a varietal differentiation of the analyzed samples and the ability to detect and identify potentially allergenic proteins. To have this information before the consumption of wine is of great importance because (1) a varietal differentiation could be used for the authentication of the wine and (2) the identification of potentially allergenic proteins responsible for adverse reactions (from the grapes or the fining agents used) will allow for the protection of allergic consumers.