White Wine Protein Analysis by Capillary Zone Electrophoresis

Abstract

Capillary zone electrophoresis was evaluated as a method for the analysis of wine proteins. Seven wines from three different varieties, Chardonnay, Sauvignon blanc, and Muscat of Alexandria, were used in this systematic analysis of the effect of variables of capillary electrophoresis conditions on wine protein profiles. While there was some differences in the magnitude of protein peaks as a function of vintage and winemaking conditions, each of the varieties displayed a distinct and distinguishable protein profile. If wine is analyzed directly, both proteinaceous and nonproteinaceous UV-absorbing materials are detected. The protein fraction can be obtained from wines by ultrafiltration and analyzed separately. Resuspension of the retentate proteins following ultrafiltration under conditions allowing sample stacking yielded the greatest number and sharpest separation of peaks. The electrophoresis running buffer impacted protein profiles and number of peaks, as expected. Protein peaks were found to be protease-sensitive, suggesting that wine proteins are not intrinsically resistant to protease degradation. Hazes induced by heat/chill treatment effectively stripped the wines of protein content. Capillary zone electrophoresis represents an excellent tool in the analysis of wine proteins and has the potential to differentiate wine varietals.