Engineering & ArchitectureVicente Ferreira
Universidad de Zaragoza, Aragon Institute for Engineering Research (I3A), Zaragoza, Spain
Origin and genesis of reduction and oxidation aromas: Unveiling two precious wine secrets
Oxidation and reduction aromas represent a high proportion of faulty wines and are today a kind of Russian roulette which often happens in wines which have spent some time in the bottle. Inevitably, the closure is blamed for such problems: too much or too less permeable to oxygen.
This lecture will show, however, that a large part of the problem is in fact already present in the wine at the moment of being bottled, since in both cases, a major source of the faulty aromas are pre-accumulated off-odors concealed under the form of non-volatile and odorless complexes.
Oxidation aromas which chemically are aldehydes, accumulate mainly under the form of SO2 adducts while reduction off-odors, that chemically are mercaptans, accumulate mainly under the form of Cu(II) complexes. Its major origin appears to be in both cases fermentation, where they bind to the free SO2 or Cu(II) present to form the corresponding odorless adducts.
Aldehydes are slowly released once free SO2 begins to react with O2 or with polyphenols. Mercaptans are released due to the cleavage of Cu-complexes caused likely by its chemical reduction.
De novo formation is in both cases possible under some circumstances which will be discussed.
Vicente Ferreira short CV
Full Professor in Analytical Chemistry at the University of Zaragoza and co-founder and actual Head of the Laboratory for Aroma Analysis and Enology (LAAE).
His scientific activity has focused on the understanding of the chemical basis of flavor perception. His main interest has always been wine flavor. He has authored more than 180 scientific contributions about different aspects of aroma analysis and wine chemistry which have had a very high impact on the scientific and technical communities.
Major contributions are about the development of analytical methods for the screening and quantitative determination of most odorants, about the understanding of the nature and role of the different odorants and savors on wine flavor, and about the chemical and biochemical routes of their formation.