White and Rosé Wine Haze Risk (WHR) Estimation

The appearance of cloudiness in a white or rosé wine is a phenomenon that occurs in most countries around the world. To avoid this, winemakers treat their wines, in most cases with bentonite, and very often with excessive doses. But how are these inappropriate treatments chosen to obtain wine colloidal stability? They are based on a heat test in which the wine is heated to 80 °C for 30 min to 2 h, generally. At this temperature of 80 °C, many of the thermostable wine proteins that remain soluble during a heatwave (when a bottle of wine can rise to 35–42 °C) are insolubilized. It is therefore necessary to change the heat test. A study conducted in different wine-producing regions, with many grape varieties, was carried out over 4 years. The results showed that the most appropriate test was to heat the wine to 50 °C for 90 min. The cloudiness induced is very closely correlated with the cloudiness observed during a heat wave while maintaining a safety margin for winemakers. With this laboratory test, in which the wine is heated for 90 min at 50 °C, the doses of bentonite are considerably reduced compared with the doses deemed necessary on the basis of a test at 80 °C. For wines that present a low risk according to the 80 °C test, the 50 °C test shows that treatment with bentonite can even be abandoned. The use of this 50 °C test therefore radically changes the approach to protein stabilization of white and rosé wines.