OENO IVAS 2019 banner
IVES 9 IVES Conference Series 9 Removal of white wine heat unstable proteins by using proteases and flash pasteurization-comparison with bentonites treatments

Removal of white wine heat unstable proteins by using proteases and flash pasteurization-comparison with bentonites treatments

Abstract

White wine protein haze can be prevented by removing the grape juice proteins, currently achieved by bentonite addition. To avoid wine volume loss and to minimizes aroma stripping, degrading haze-forming proteins in wine with proteases is a particularly interesting alternative to bentonite. 

In the present study, two fungal proteases treatments combined with different heating (50, 60, 72 °C) + refreshing steps, were applied on Gewürztraminer grape juice, and compared to bentonite treatments. The impact of these 19 treatments on the wine haze risks was determined by using two heat tests at 50 °C (heating during 30 to 120 min) and 80 °C (heating during 5 to 60 min). The protein contents and compositions were also estimated using the SDS-PAGE + densitometric integration techniques. 

The heat instability tests of the 19 wines show strongly different results according to the test used. With the 50 °C heating tests, the wines showed logarithmic curves with a maximal value reached in 30 min. At the opposite, after the 80 °C heating tests, the white wines showed a linear increase of the turbidity during the 60 min of the heating, leading to linear curves with R2>0.99. Moreover, the turbidities observed were much higher when the wines were heated at 80 °C when compared with the wines after the 50°C tests. These results clearly pointed out the discrepancies between the test selected to estimate a white wine haze risk and the treatment necessary to avoid a haze after bottling. 

Concerning the wines obtained after juice bentonite treatments, we observed a dose effect with a high correlation at 50°C between the dose of swelling clay and the wine haze risk. 60 g/hL were necessary to reach the colloidal stability, whatever the test used (50 or 80 °C) and the heating time. The addition of proteases at 50 °C or 60 °C during 1 hr before a quick increase at 72 °C (as recommended by the OIV) and refreshing in cold water decreased the haze risk by 75 % and 85 % respectively when compared to the control wine, whilst the same heat treatment without enzymes only decreased the haze risk by 28 % and 17 % respectively. 

The ability for enological proteases to hydrolyze grape berry heat unstable proteins (observed by SDS-PAGE) was strongly evidenced with the heat test at 50 °C. Proteases reduced the heat instability by 40 % whilst the heat treatment alone was pretty ineffective. 

This study proved the possibility to use proteases as an efficient treatment to control white wine haze risk.

Related articles…

Mapping of canopy features in commercial vineyards using machine vision

Vineyard canopy features such canopy porosity and fruit exposure influenced microclimate, fungal disease incidence and grape composition. An objective, rapid and non-invasive method to assess and map the canopy status is needed to apply in precision viticulture. A new method for canopy status assessment and mapping based on non-invasive machine vision was applied in commercial vineyards in this work.

THE ODORIFEROUS VOLATILE CHEMICALS BEHIND THE OXIDATIVE AROMA DEGRADATION OF SPANISH RED WINES

It is a well-established fact that premature oxidation is noxious for wine aromatic quality and longevity. Although some oxidation-related aroma molecules have been previously identified, there are not works carrying out systematic research about the changes in the profiles of odour-active volatiles during wine oxidation.

Long-term drought resilience of traditional red grapevine varieties from a semi-arid region

In recent decades, the scarcity of water resources in agriculture in certain areas has been aggravated by climate change, which has caused an increase in temperatures, changes in rainfall patterns, as well as an increase in the frequency of extreme phenomena such as droughts and heat waves. Although the vine is considered a drought-tolerant specie, it has to satisfy important water requirements to complete its cycle, which coincides with the hottest and driest months. Achieving sustainable viticulture in this scenario requires high levels of efficiency in the use of water, a scarce resource whose use is expected to be severely restricted in the near future. In this regard, the use of drought-tolerant varieties that are able to maintain grape yield and quality could be an effective strategy to face this change. During three consecutive seasons (2018-2020) the behavior in rainfed regime of 13 traditional red grapevine varieties of the Spain central region was studied. These varieties were cultivated in a collection at Centro de Investigación de la Vid y el Vino de Castilla-La Mancha (IVICAM-IRIAF) located in Tomelloso (Castilla-La Mancha, Spain). Yield components (yield, mean bunch and berry weight, pruning weight), physicochemical parameters of the musts (brix degree, total acidity, pH) and some physiological parameters related with water stress during ripening period (δ13C, δ18O) were analysed. The application of different statistical techniques to the results showed the existence of significant differences between varieties in their response to stressful conditions. A few varieties highlighted for their high ability to adapt to drought, being able to maintain high yields due to their efficiency in the use of water. In addition, it was possible quantify to what extent climate can be a determinant in the δ18O of musts under severe water stress conditions.

Physical-mechanical berry skin traits as powerful indicators of resistance to botrytis bunch rot

The ongoing climate change results in increasing mean air temperature, which is manifested by weather extremes or sudden changes between drought and local heavy rainfalls. These changing conditions are especially challenging for the established grapevine varieties growing under cool climate conditions due to an increased biotic infection pressure. Thus, the scope of most grapevine breeding programs is the selection of mildew fungus-resistant and climatic adapted grapevines with balanced, healthy yield and outstanding wine quality. Since no resistances or candidate genes have yet been described for Botrytis bunch rot (BBR), physical-mechanical traits like berry size and thick, impermeable berry cuticles phenotyped with high-throughput sensors represent novel effective parameters to predict BBR.

Complantations : enjeux et facteurs de réussite

Dans le cadre de TerclimPro 2025, Coralie Dewasme a présenté un article IVES Technical Reviews. Retrouvez la présentation ci-dessous ainsi que l’article associé : https://ives-technicalreviews.eu/article/view/8486