Research by Vincente Ferreira, winner of the 2015 International Oenoppia-SIVE (Italian Society of Viticulture and Oenology) award, was presented at the SIMEI trade show in Milan on 4 November 2015. This research is overturning conventional approaches to reduction phenomena and providing new elucidations. The following summary explains.

What we know about reduction
Reduction is the opposite chemical reaction to oxidation. Reduction is the gain of electrons whereas oxidation is the loss of electrons. Reduction in wine that has lacked oxygen is expressed by the formation of unpleasant odours, which are well-known to wine-makers and rejected by experienced tasters. The molecules responsible for these odours are sulphur derivatives, the most well-known of which are hydrogen sulphide (H2S) and mercaptans (MeSH). These are volatile sulphur compounds. The intensity of their organoleptic impact varies from slight hints of sewage, cabbage and onion to extremely repulsive rotten egg odours. In all cases, reduction masks wine aromas and makes it undrinkable. An initial remedy for reduction is to decant the wine into a carafe. Fortunately, these faults are often temporary if there is an adequate oxygen supply. In the worst cases, however, they are sometimes irreversible when too much reduction has occurred. In these cases, the wine loses all its initial qualities. Wine-makers are aware of this issue and are very vigilant to ensure the correct balance between oxidation and reduction throughout the wine-making and maturation process. 
All wines potentially risk developing reduction odours. H2S is formed naturally during yeast fermentation from sulphur already present in grapes, sulphates and even from commonly added sulphites. Difficult fermentation conditions (high alcohol, yeast nutrient deficiencies) encourage yeast to produce H2S. In these cases, wine-makers supply oxygen or perform fining using copper-based preparations. To this end, wine-makers of old put wine into copper containers for a period. Try it yourself: put a copper coin into wine with reduction odours. You’ll notice that they disappear. 
Despite all this, wine may develop reduction odours either during maturation or much later, after bottling. The prevailing hypotheses in oenology handbooks used to be that this is due to sulphur-based compounds in wine spontaneously reducing into mercaptans (apart from yeast action). But this explanation is inadequate and even erroneous. 
What we did not know and that has been discovered by Vincente Ferreira
Ferreira’s team has demonstrated for the first time that H2S and mercaptans in wine are not only present in volatile (odorous) form. They also exist in odourless complexes (with other other molecules) and are hence undetectable. Wine contains many sulphur compounds that may be released throughout its life span in bottles since these combinations are reversible.  
Which molecules combine with H2S and mercaptans? 
Copper combines with all volatile sulphur compounds and is precisely the substance used by wine-makers of old to correct reduction faults. What they did not know, however, is that these harmful molecules did not disappear. They were simply concealed…just waiting for favourable conditions (no oxygen in bottles) under which to resurface. 
Iron also combines with these molecules, although with less intensity. 
What happens to sulphur compounds in complexes? 
Complexes formed with metal cations are completely stable and soluble. No precipitation was observed during experiments and these complexes are not removed by filtration. 
Ferreira’s research has shown above all that volatile sulphur compounds increase continuously under favourable conditions (no oxygen, high temperature). Ferreira has also proved that small quantities of mercaptans are formed in some wines from the remains of sulphur amino acids. This ability is also linked to the catalytic activity of some metals. 
Ferreira’s team has created models to predict long-term developments in wine reduction odours according to various factors and thus recommend appropriate preventive measures.   
The only effective prevention proved to date by Ferreira’s team is micro-oxygenation over prolonged periods. But this new knowledge will undoubtedly open up the scope for new oenological treatments to remove metal complexes containing sulphur compounds…watch this space! 
This is the purpose of wine science: to improve understanding in order to improve practice. 
Vincente Ferreira received the 2015 Oenoppia-SIVE award at the SIMEI trade show in Milan on 4 November 2015. The award comes with €7,500 to support research on reduction phenomena in wine carried out by his laboratory (LAAE, Laboratory of Aroma Analysis and Enology at the University of Zaragoza, Spain). 
Full English version of Vincente Ferreira’s scientific article will be published shortly
OENOPPIA is a professional association created in 2009 and grouping together the principal parties involved in the production and development of oenological products.  The members of Œnoppia represent approximately 85% of oenological products used by wine makers throughout the world. They have a strong wine culture and an international approach to the vitivinicultural world, which is expressed via the creation of this association. The groups comprising Œnoppia have for decades founded their development on research and innovation, and for the oldest, for over a hundred years. Their expertise in oenological applications is the result of internal development or long term partnerships with major universities and institutes throughout the world. They have initiated a large number of publications and patents guided by the research of the best possible expression of the potential quality of the grapes. 
Marco Manfredini, president of OENOPPIA, declares: “The International OENOPPIA SIVE Award is the further concrete expression of oenological profession involvement to support innovation and general knowledge about wine”.
To know more about Oenoppia:
SIVE (Italian Society of Viticulture and Oenology) is a non-profit association of wine professionals operating in all Italian regions and companies active in the wine industry.  Since 1996 promote education and professional training on wine; through its Secretariat VINIDEA, has organized more than hundred between congresses, seminars, workshops and educational tours in Italy and several other wine countries. Every two years SIVE and VINIDEA organize the event Enoforum
Since 2005, SIVE policy is to promote a better cooperation between wine producers and scientists, helping the production people to better identify their need and to formulate clear and suitable queries to researchers, and these last to prioritize their work on the topics of most usefulness for wine production.
SIVE awards were established to contribute in reaching this goal and – since 2007 to now – 236 researches participate the competition that, therefore, represents a very wide view of scientific production in the last decade, brought to the knowledge of thousands of stakeholders.
The SIVE AWARDS are granted on the basis of the judgment expressed by wine industry stakeholders.  
The selection procedure foresees three phases: 
  • the abstracts of the submitted researches will be anonymously evaluated by the SIVE Scientific Committee for the criterion “degree of innovation and interest on the topic”.
    the works that receive the highest scores will be orally presentation at the next Enoforum; participants attending Enoforum and the SIVE associated judge them on the basis of the criterion “benefit of research for the development of the wine industry”.
    SIVE Scientific Committee further judges the researches with respect to the criterion “scientific value”, based not only on the summary, but on the full presentations.
Two SIVE Award has been established, each with a grant of € 7.500:
  • VERSINI Award since 2007, reserved to Italian researchers
  • OENOPPIA Award, established in 2013 and open to scientists of any country
The winner of the past editions were:
-VERSINI Award 2007: Emilio CELOTTI, Giuseppe CARCERERI de Prati and Paolo FIORINI – “Moderno approccio alla gestione della qualità delle uve rosse”
-VERSINI Award 2009: Raffaele GUZZON, Agostino CAVAZZA and Giovanni CARTURAN -“Immobilizzazione di starter malo lattici. Tecnologia, effetti biologici e fermentazioni sperimentali con ceppo di O. oeni immobilizzati in matrici ibride silice/alginato” 
-VERSINI Award 2011: Matteo GATTI, S. CIVARDI, F. BERNIZZONI, S. PONI – “Effetti differenziali del diradamento dei grappoli e della defogliazione precoce su resa, composizione delle uve e qualità dei vini in Sangiovese” 
-VERSINI Award 2013: Diana GAZZOLA, S. VINCENZI, A. CURIONI – “Valutazione delle capacità chiarificanti di un nuovo coadiuvante proteico estratto da vinaccioli”
The VERSINI Award 2015 was won by Fabio CHINNICI and Claudio Riponi, of the University of Bologna, with the research “Controllo dell’ossidazione di (+)-catechina mediante chitosano: ipotesi di utilizzo in vinificazioni a ridotto contenuto in solfiti”