Rapid and Sensitive Fingerprinting of Wine Proteins by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry

Abstract

To obtain fast and accurate protein and peptide fingerprints, eight wines were analyzed by both matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) and surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF). Most of the major proteins detected were common to all wines analyzed. The major protein had a mass of 21.3 kDa. Other significant peaks were observed with masses of 7.2, 9.1, 13.1, and 22.2 kDa. A broad peak centered at 16.6 to 16.8 kDa was variable in intensity among vintages and cultivars. The greatest variation was seen in the peptide region: the two Chardonnay wines contained less peptide material than Sauvignon blanc or Muscat of Alexandria wines. In SELDI-TOF iminodiacetate chelated copper ions were used to selectively bind proteins and peptides from wine. This effectively concentrated minor components in wine, permitting detection. On the other hand, several other, more abundant proteins did not interact with the immobilized copper ion functional group, suggesting different surface chemistries. A heat-generated haze from a commercially produced Sauvignon blanc wine was also evaluated. MALDI-TOF analyses revealed an enrichment of the 16.6 kDa material, but with very little 21.3 kDa, present in the haze. Both MALDI-TOF and SELDI-TOF are excellent tools for analysis of wine proteins and haze.