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IVES 9 IVES Conference Series 9 OENO IVAS 9 Category: OENO IVAS 2019

Proceedings of OENO IVAS 2019

From June 25th to June 28th 2019, the research unit in Enology, ISVV, University of Bordeaux, organized jointly the 11th symposium of Enology, Œno2019 and the 11th edition of In Vino Analytica Scientia IVAS 2019. 

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Analysis and composition of grapes, wines, wine spiritsIVES Conference SeriesOENO IVAS 2019

Correlation between skin cell wall composition and phenolic extractability in Cabernet sauvignon wines

The phenolic component of red wine is responsible for important elements of flavor and mouthfeel, and thus quality of the finished wine. Additionally, many of these phenolics have been associated with health benefits such as reduction of the risk of developing cardiovascular disease, cancer, osteoporosis and preventing Alzheimer’s disease. While the origins, concentrations, and chemistries of the phenolics in a finished red wine are well known, the fundamental mechanisms and kinetics of extraction of these phenolics from grape skins and seeds during red wine fermentation are poorly understood. This lack of knowledge regarding the extraction mechanisms of phenolics during red wine fermentation makes informed manipulations of the finished wine’s phenolic composition difficult.

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IVES Conference SeriesOENO IVAS 2019Œnological Practices and Process

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

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.

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IVES Conference SeriesOENO IVAS 2019Œnological Practices and Process

Importance of matrix effects (wine composition) on protein stability tests of white and rosé wines

The presence of unstable proteins in wines can affect their stability and clarity. Before bottling, winemakers need to be sure that the wine is stable. A large number of stability tests have been proposed, usually based on heating a sample with a specific time-temperature couple. In practice, none is effective to accurately assess the risk of instability. Moreover, the interpretation of the results of these tests changes according to the region.

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IVES Conference SeriesOENO IVAS 2019Œnological Practices and Process

The affinity of white wine proteins for bentonite is dependent on wine composition and is directly related to their thermal stability / sensitivity

Bentonite fining is commonly used in oenology to remove all or parts of white wine proteins, which are known to be involved in haze formation. This fining is effective, but has disadvantages: it is not selective, thus molecules responsible for aroma are also removed, it causes substantial volume losses, and finally it generates wastes. Over the last decades, the knowledge of wine proteins has increased: they have been identified, their structures are known, some of them have been crystallized.

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