Wine and chemistry

During the course of Dialogues of Pistoia, which is a cultural festival that took place this year a few days ago, while I was telling about the evolution of wine throughout history, a gentleman asked me a question asking “but when are we going to get rid of all this chemistry in wine?“. One thing we often hear, accompanying the request with that of a greater clarity in labels, which should state all additives that are used in winemaking.

I begin by saying that some “demonized” additives then are not so dangerous, since they do not stay in the wine. Any examples? La bentonite, which is an inert compound that does not combine with wine, and the animal jellies, usually isinglass, which is so harmless that it is used in baking to cook panna cotta and puddings. Therefore, very well say what is in the wine, but not only as additives, also as substances that are formed during winemaking, and that in some cases may not be good precisely if precautions are not used. I therefore repost an old editorial that dealt with acetaldehyde, so to understand it more.

Professor Luigi Moio has the floor

“Food wholesomeness and safety cannot be left to chance but are the result of robust scientific knowledge applied to total process control. See the acetaldehyde problem that is almost never considered. Obviously biochemically and chemically it is a complex phenomenon since this molecule is both a fermentative and an oxidative metabolite, and the technical implications are different between red and white wines. However, it is well known that In oxidized wines, oxygen slowly “attacking” ethyl alcohol transforms it into acetaldehyde 
which in some cases can reach high levels. It must be remembered that this molecule is more toxic than ethyl alcohol and in association with the latter is even classified as carcinogenic. In addition, this same molecule “binds” the SO2 resulting in an increase in the total amount and a decrease in the molecular share, which is precisely what performs the antioxidant and antiseptic actions. So if you really want to reduce the amount of SO2 in wine one must first manage acetaldehyde by keeping it at very low levels“.

I never venture to make oenological and technical considerations, not having adequate knowledge of chemistry, biology and physics. I rely on those who know more than I do and try, at best, to disseminate the opinion of internationally renowned scholars. In this case the statements quoted above are from Professor Luigi Moio, a professor at the University of Naples Federico II, president of the OIV and universally regarded as one of our country’s leading wine scholars.

The acetaldehyde problem

Trying to translate into more understandable terms: Moio recalls how little the problem of high levels of acetaldehyde, an extremely reactive volatile substance responsible for the so-called “oxidized” odor in wines reminiscent of that emanating from “bruised” or even rotten apple, the production of which is linked to both fermentative and oxidative processes. A little-addressed topic, he argues, despite having no small consequences, not only organoleptically, but even in relation to the wholesomeness of wines.

Not only sulfur then, Moio would seem to say, but the real problem lies in the knowledge and subsequent control of biochemical and chemical processes in an overall picture in which acetaldehyde and SO2 are very close to each other so it is necessary to address the problem holistically. In addition, it is good to reflect on the fact that the use of inadequate yeasts can be the cause of slowing down or even stopping fermentation and consequently producing negative, even dangerous, substances, such as acetaldehyde.

The downside of “natural” processes

All this makes us reflect on the fact that some themes brandished as the ultimate in “naturalness,” linked To the use of indigenous yeasts and the non-use of sulfur dioxide, actually have a particularly disturbing downside, because it is precisely from such practices that elevated Accumulations of natural metabolites of toxicological significance With all the problems that come with it.

Then I wonder why some wine-related issues are covered all the time and other, far more important issues are not. Possible that there are “fashionable” topics and issues that nobody cares about instead, and instead have comparable and if possible worse effects?

Respect for consumer health and not just slogans

I am well aware that I am a voice against the tide and that what I am writing will elicit negative reactions from many proponents of so-called “naturalness” of wines. And this is even though it is not my intention at all to criticize those who honestly and consistently try to produce with a sense of responsibility and with respect for the environment and consumer health. It’s just that I would like everyone, including them, to consider other aspects as well, and especially the consequences of practices that perhaps have not yet been thoroughly analyzed beyond statements of principle.