Identification of a New Lactone Contributing to Overripe Orange Aroma in Bordeaux Dessert Wines via Perceptual Interaction Phenomena

International audienceRecent studies have demonstrated the existence of a typical sensory concept for Bordeaux dessert wines, including the world famous wines of Sauternes. Volatile compounds from several chemical families (thiols, aldehydes, and lactones) were identified and correlated with aromatic typicality in these wines. However, these studies were unable to indicate "key" aromas of overripe fruits, especially overripe orange. The alternative strategy developed in this research combined both analytical and sensory studies of fractions of dessert wine extracts obtained by semipreparative high-performance liquid chromatography (HPLC). Multidimensional gas chromatography coupled to olfactometry and mass spectrometry (MDGC-O/MS) was applied to some of the HPLC fractions recalling "overripe fruit", and a new lactone, 2-nonen-4-olide, was identified. Reconstitution and omission tests using the HPLC fractions highlighted the importance of specific compounds, particularly 2-nonen-4-olide, in the expression of overripe orange notes. Although this lactone presents minty and fruity odors, its key contribution to the typical aroma of orange in Bordeaux dessert wines was revealed through perceptual blending

Ann. microbiol.

Purpose Brettanomyces bruxellensis is a serious source of concern for winemakers. The production of volatile phenols by the yeast species confers to wine unpleasant sensory characteristics which are unacceptable by the consumers and inevitably provoke economic loss for the wine industry. This ubiquitous yeast is able to adapt to all winemaking steps and to withstand various environmental conditions. Moreover, the ability of B. bruxellensis to adhere and colonize inert materials can be the cause of the yeast persistence in the cellars and thus recurrent wine spoilage. We therefore investigated the surface properties, biofilm formation capacity, and the factors which may affect the attachment of the yeast cells to surfaces with eight strains representative of the genetic diversity of the species.[br/] Methods The eight strains of B. bruxellensis were isolated from different geographical and industrial fermentation origins. The cells were grown in synthetic YPD medium containing 1% (w/v) yeast extract (Difco Laboratories, Detroit), 2% (w/v) bacto peptone (Difco), and 1% (w/v) glucose. Surface physicochemical properties as electrophoretic mobility and adhesion to hydrocarbon of the cells were studied. The ability of the strains to form biofilm was quantified using a colorimetric microtiter 96-well polystyrene plate. Biochemical characteristics were examined by colorimetric methods as well as by chemical analysis.[br/] Result Our results show that the biofilm formation ability is strain-dependent and suggest a possible link between the physicochemical properties of the studied strains and their corresponding genetic group.[br/] Conclusion The capacity to detect and identify the strains of the spoilage yeast based on their biofilm formation abilities may help to develop more efficient cleaning procedures and preventing methods

The complexity of wine: clarifying the role of microorganisms

The concept of wine complexity has gained considerable interest in recent years, both for wine consumers and wine scientists. As a consequence, some research programs concentrate on the factors that could improve the perceived complexity of a wine. Notably, the possible influence of microbiological factors is particularly investigated. However, wine complexity is a multicomponent concept not easily defined. In this review, we first describe the actual knowledge regarding wine complexity, its perception, and wine chemical composition. In particular, we emphasize that, contrary to expectations, the perception of wine complexity is not related to wine chemical complexity. Then, we review the impact of wine microorganisms on wine complexity, with a specific focus on publications including sensory analyses. While microorganisms definitively can impact wine complexity, the underlying mechanisms and molecules are far from being deciphered. Finally, we discuss some prospective research fields that will help improving our understanding of wine complexity, including perceptive interactions, microbial interactions, and other challenging phenomena