THE IMPACT OF NON-SACCHAROMYCES YEASTS ON THE WHITE WINE QUALITY

Mycobiota encountered from vine to wine is a complex and diversified ecosystem that may impact grape quality at harvest and the sensorial properties of wines, thus leading to off-flavors [1-3]. Among known off-flavors in wine, fresh mushroom aroma (FMA) has been linked to some mold species, naturally pre-sent on grapes, producing specific volatile organic compounds (VOC) [4-5]. The most well-known are 1-octen-3-ol and 1-octen-3-one, although many other VOC are likely involved. To better understand the FMA defect, biotic and abiotic factors impacting growth kinetics and VOC production of selected fungal species in must media and on grapes were studied.

Sulfur dioxide (SO₂) is the most commonly used additive during winemaking to protect wine from oxidation and from microorganisms. Thus, since the 18th century, SO₂ was almost systematically present in wines. Recently, wines produced without any addition of SO₂ during all the winemaking process including bottling became more and more popular for consumers. A recent study dedicated to sensory characterization of Bordeaux red wines produced without added SO₂, revealed that such wines were perceived differently from similar wines produced with using SO₂ and were characterized by specific fruity aromas and coolness1,2.

Oak tannin extracts are commonly used to improve wine properties. The main polyphenols found in oak wood extracts are ellagitannins¹ that release ellagic acid upon hydrolysis and comprise numerous structures². Moreover, oak tannin extracts contain other compounds giving a complex mixture. Consequently, the official OIV method based on gravimetric analysis of the tannin fraction adsorbed on polyvinylpolypyrrolidone is not sufficient to describe their composition and highlight their chemical diversity.

The strategy for sustainability in the wine sector of the EU refers to a set of practices and principles that aim to minimize the negative impact of wine production on the environment, social and economic sustainability. Sustainable wine production involves a range of practices that are designed to reduce waste, conserve resources, and promote the well-being of workers and communities.

Taints and off-flavours are one of the major concerns in the wine industry and even if the issues provoked by them are harmless, they can still have a negative impact on the quality or on the visual perception of the consumer. Nowadays, the frequency of occurrence of mousy off-flavours in wines has increased.
The reasons behind this could be the significant decrease in sulphur dioxide addition during processing, the increase in pH or even the trend for spontaneous fermentation in wine. This off-flavour is associated with Brettanomyces bruxellensis or some lactic acid bacteria metabolisms.