Fractionation of Sauvignon wine macromolecules by ultrafiltration and diafiltration: impact of protein composition on white wine haze stability

After ultrafiltration (UF) thermally unstable compounds of Sauvignon blanc wines were concentrated in the retentate fractions of 10-30 kDa increasing heat-induced haze 8.9-fold, while concentrating haze stabilising species into the retentate fractions of 100-300 kDa with a 5.3-fold reduction of heat-induced haze compared to unfiltered wine. Proteins having molecular weights of 18, 23, 33, 35, 40 and 60 kDa were identified as the main haze promoting agents for Sauvignon blanc, where the proteins of 56, 69 and 72 kDa were identified as thermally stable. Potassium sulphate (100 mg L-1) and magnesium sulphate (25 mg L-1) did not affect wine haziness at experimental diafiltration (DF) conditions using model wine solutions. Combination of UF and DF is a useful separation method of wine proteins, which is helpful to quantify haziness of individual species and to reveal the interactions between species involving protein haze.