70% of commercial wines contain, without it being evident, the aromas that will cause their aromatic degradation when free SO2 level decreases.
Essentially there are two molecules with very aromatic power: metional and phenylacetaldehyde. Recent experiences have shown that these components are formed in large quantities during fermentation, but they form complexes with SO2. This combinations, being odorless, go unnoticed. The levels formed depend on the yeast and SO2 quantity.
These adducts break down when the free SO2 levels of the wine decreases, releasing the aldehydes with immediate and negative effects on the aroma. Depending on their concentration they will cause from a suppression of fruity note to the appearance of raisins or honeyed notes.
In addition to fermentation, these components can be formed by oxidation of precursor amino acids, if they are present and if the wine is exposed to oxygen in the almost total absence of SO2. However, as with acetaldehyde, these components can react with polyphenols, which will happen only if they are not protected by SO2.
Conditions to minimize this components in wine, increasing his longevity, will be briefly discussed in the talk.
The paper reproduced in this video-seminar was presented at the 11th edition of Enoforum (Zaragoza, Spain, May 31 – June 1 2018). Finalist work of the SIVE OENOPPIA Awards 2017
Annual Subscription to Infowine: The subscription – to the price of € 60,00 (VAT included) – gives unlimited access for one year to all the documents published on the website, historical archive included: Click here