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MALDI-TOF mass spectrometry has been shown to be an excellent method for the direct analysis of the composition of wine haze. Previously developed methods allow a subtractive evaluation of wine components, assay of the wine pre and post haze treatment, but are not useful for the analysis of the haze itself. MALDI-TOF in contrast to SDS-PAGE is not specific for protein and can be used to simultaneously assess the presence of non-proteinaceous material in haze. It also allows accurate investigation of low molecular weight components, poorly resolved by other techniques. The MALDI-TOF analysis has demonstrated that the two commonly used methods to induce haze in wine as a means of assessing protein stability, the heat/chill and ethanol assays, destabilize specific components within the wine, but do not yield hazes of an identical composition to each other or to hazes forming naturally in wine under commercial conditions. Phenolic compounds were found to play a role in haze formation in wines made from Muscat of Alexandria but not in wines made from Sauvignon blanc. More wines from each varietal need to be evaluated before more conclusive statements can be made. It appears that the difference is due either to the greater level of phenolic compounds in Muscat or to differences in the peptide fractions between the two varietals.