THE POTENTIAL USE OF SOLUBLE POLYSACCHARIDES TO PREVENT THE OXIDATION OF ROSÉ WINES

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.

Flow cytometry (FCM) is a powerful technique allowing the detection, characterization and quantification of microbial populations in different fields of application (medical environment, food industry, enology, etc.). Depending on the fluorescent markers and specific probes used, FCM provides information on the physiological state of the cell and allows the quantification of a microorganism of interest within a mixed population. For 15 years, the enological sector has shown growing interest in this technique, which is now used to determine the populations present (of interest or spoilage) and the physiological state of microorganisms at the different stages of winemaking.

Cognac is an outstanding french wine spirit appreciated around the world and produced exclusively in the Nouvelle-Aquitaine region, and more precisely in the Cognac area. According to AOC regulations (Appellation D’origine Controlée), the spirit required at least 2 years of continuous ageing in oak barrels to be granted the title of Cognac. The oak wood will import color, structure and organoleptic complexity. The different steps during barrel-making process, such as seasoning and toasting, influence the above quality attributes in both wines and spirits.

Ultrafiltration is a process that fractionates mixtures using semipermeable membranes, primarily on the basis of molecular weight. Depending on the nominal molecular weight cut-off (MWCO) specifications of the membrane, smaller molecules pass through the membrane into the ‘permeate’, while larger molecules are retained and concentrated in the ‘retentate’. This study investigated applications of ultrafiltration technology for enhanced wine quality and profitability. The key objective was to establish to what extent ultrafiltration could be used to manage phenolic compounds (associated with astringency or bitterness) and proteins (associated with haze formation) in white wine.

Selected strains of non-Saccharomyces yeasts showed a positive effect on sensory characteristics and aromatic complexity of wine. A sequential microbial culture of non-Saccharomyces and S. cerevisiae species is usually inoculated due to poorer fermentability of non-Saccharomyces species. The aim of the study was to investigate the role of non-Saccharomyces yeasts in the production of white wines. We evaluated how individual combinations of sequential inoculations of non-Saccharomyces and S. cerevisiae species affect the aromatic compounds (volatile thiols and esters) and sensory characteristics of the wines.