Which heat test really represents the haze risk of a white Sauvignon wine ?

AIM: Different heat tests are used to predict a white wine haze risk after bottling. The most used tests are 30-60 min. at 80°C. Nevertheless, there is a lack of information about the relationship between the wine haze observed after such tests and the turbidities observed in the bottles after the storage/transport of the wines in more realistic Summer conditions (35-46°C during 3-12 days).

METHODS:  24 Sauvignon wines (Loire Valley – France) produced during the vintages 2018 and 2019 were studied. Six heat tests were applied on during 5-30-60 min. at 80°C and during 30-60-120 min. at 50°C. The results were compared with the turbidity reached by the wines under Summer conditions (35 to 46°C, from 1 to 14 days) and representing 6 tests too. The Pearson correlation coefficients (PCC) were calculated for all of these 12 heat tests when compared two by two.

RESULTS: The turbidities of the wines subjected to Summer temperature conditions (35-43°C) were highly correlated with the turbidities developed by the Sauvignon wines after heating 30 or 60 min.  at 50°C (0.980

CONCLUSIONS: Heat tests at 80°C encourage winemakers to use excessive bentonite doses leading to stripped wines. On the contrary, the heat test at 50°C, that can already be considered as a new tool to take oenological decisions, indicated that lower doses of bentonite (when compared with the bentonite doses necessary according to the 80°C heat test) were sufficient to ensure the absence of haze in the bottle. Thus, the realistic 50°C heat test showed also the possibility to better respect the varietal characteristics of the Sauvignon blanc wines due to a much lower aromas and colour decreases.