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.

DOI:

Publication date: June 23, 2020

Issue: OENO IVAS 2019

Type: Article

Authors

Richard Marchal

Faculté des Sciences de Reims 
BP1039 – 51687 Reims Cedex02

Contact the author

Keywords

proteases, white wine, heat instability tests, proteic composition 

Tags

IVES Conference Series | OENO IVAS 2019

Citation

Related articles…

SO2 consumption in white wine oxidation: approaches to low-input vinifications based on rapid electrochemical analyses and predictive enology

Oxidative stability is a critical factor in wine shelf-life. SO₂ is commonly added to wine due to its strong antioxidant activity, although there is a general push to reduce SO₂ use in vinification.

Climate change impacts on Douro Region viticulture and adaptation measures

Climate has a significant impact in the success of any agricultural system, with a direct influence on the crops suitability to a given region, interfering on yield and quality and also with the economic sustainability of the productive activity. In the Douro Demarcated Region (RDD), as in most regions of the Mediterranean climate, the scarce precipitation (33% has less than 600 mm per year), and your high variability, associated with high rates of evapotranspiration during the summer, is usually one of the fundamental factors that limit the grapevine development, as well as the production and quality of the harvest. Thus, facing the scenario in temperature changes for the next decades (1.5-2.5°C) and confirming the predictions of precipitation decreases and/or great variability in the occurrence of heat waves and intense rainfall, the consequences for slope stability in mountain viticulture and sustainability of all operations involved, are risks to be taken into account. In this way, a deepest and sustained knowledge regarding the adaptation measures to adverse environmental conditions is of a crucial importance, enabling a more efficient adaptation of plant growth conditions and the optimization of production and quality of the grapevines. The development of this work, carried out in two commercial vineyards, one located in Soutelo do Douro, São João da Pesqueira, Cima Corgo sub-region, and another located in Numão, Vila Nova de Foz Côa, Douro Superior sub-region, it seeks to establish a relationship between climatic elements and physiological, productive and qualitative parameters, as well as to evaluate the effectiveness of adaptation measures, including different types of deficit irrigation (2002-2019) and the application of shading nets (2019-2020) in the physiological, viticultural and oenological behavior in the Touriga Nacional and Moscatel Galego Branco varieties, respectively. The results showed that the application of deficit irrigation allowed to significantly reduce the impact of the adverse weather conditions at key moments in the development of the grapevine, particularly in the period immediately before veráison and maturation, reducing the negative effects on the physiological processes and productivity, without compromise the must quality parameters. On the other hand, the application of shading nets significantly reduced de leaves temperature, allowing to increase the water potential, stomatal conductance and photosynthetic rate of grapes, which was reflected in the yield increase in the 2nd year of the study. For the maturation indicators, higher levels of total acidity, malic acid and assimilable nitrogen were obtained. The last measure presents a huge potential, being essential to carry out more years of trials to obtain stronger conclusions in terms of production parameters, but also in characteristics as important as the grape ripening components and the organoleptic characteristics of wines.

Influenza del sito di coltivazione nella espressione aromatica del Moscato liquoroso di Pantelleria

ln 1997, twenty six cultivation sites of cv. Muscat of Alexandria different for pedological conditions, altitude and exposition were selected through ail Pantelleria isle. ln each site, described and classified according to USDA Soil Taxonony and FAO Soil Classification methods, grapes, collected at technological ripening, were microvinificated, following a standard procedure which allowed to obtain the naturally sweet wine DOC Moscato di Pantelleria. Wines, five months after vinification, were analysed by gaschromatography.

Wine tourism as a catalyst for sustainable competitive advantage: unraveling the role of winery image and reputation

This study examines the impact of wine tourism development on the sustainable competitive advantage of Spanish wineries, while also exploring the mediating roles of winery image and winery reputation in this relationship.

Hidden costs of wine: quantifying environmental externalities of organic and integrated management

Agriculture is one of the largest contributors to environmental pollution and causing significant impacts on human health, ecosystems, and resource availability.