Nit de Nin 2005

Speciaal voor Juan die liefhebber is van theoretisch geneuzel en voor Mathieu die zich afvraagt wat hij nu in zijn sauternes ruikt, heb ik nog wat scheikundige theorie over de materie van Squires gekopieerd

Ik durf niet te beweren dat ik het helemaal begrijp, maar volgens mij

- ruikt volatile acid (VA) naar azijn

- ruikt ethyl acetate (EA) naar velpon, nagellak verwijderaar

- komen de twee vaak in cominatie met elkaar voor

- zit sauternes vaak redelijk ‘vol’ met VA en is dit onderdeel van wat mensen een typische botrytis geur noemen

- vervaagt/vervliegt VA en EA niet in de loop der tijd en zit het dus ook in oudere Sauternes (als het er al jong inzat)

- de geur van VA/EA kan wel iets naar ‘achter’ worden gedrukt als andere elementen in de wijn meer naar voren komen (heb je ook soms met een wijn met lichte kurkbesmetting waar je de TCA even naar de achtergrond kan drukken door fruit aroma's op te wekken door te walsen)

- is een beperkte dosis VA/EA ‘typerend’ en niet per definitie negatief voor bepaalde wijnen zoals voor sommige wijnen uit CdP of Amarone (of dus Sauternes)

- is teveel VA en zeker EA in droge rode wijn iets wat door de meesten als ‘wijnfout’ wordt geclassificeerd

- wat ‘teveel’ is, is subjectief net als bijvoorbeeld het geval is met ‘brett’ (en anders dan het geval is met TCA; volgens de opvatting van de experts althans want volgens mij genieten er ook veel mensen van wijnen met een dusdanig lage concentratie TCA dat ze het niet opmerken)

Maar zoals zo vaak met wijn, is vast over alles discussie mogelijk

Veel leesplezier. Svp alleen inhoudelijke reacties

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Originally posted by Christopher:Just to review, what does VA smell like, and what are the likely causes? Be as detailed as you care…

VA smells are not caused by acetic acid but by its ethyl-ester ethyl-acetate. It smells of nail polish remover.

The forming of esters is a natural by product - and a very desired one too as many flavor components are esters - of alcoholic fermentation and ALL wines therefore contain VA.

So the more precise question should be if EXCESS VA is a problem?

VA is detectable by nose from levels of 0,5 gr/l on. Most wines stay below that level, reaching around 0,4 gr/l at most, but there are exceptions, most of which relate to the winemaking process. Late picked and botrytis infected grapes classically give high VA levels in the later wine; in fact part of the chemical tone of what is typically called botrytis flavor is due to increased VA-levels. So your highly paid bottle of Yquem does have pretty high VA, and I have yet to hear anyone call that a faulty wine.

Another winemaking technique that results in increased VA is the ripasso (or vin de paille in France) technique used in Italy, wind drying the grapes to increase concentration. The exposure of grape material to oxygen (air) leads to natural oxydation and thus to increased VA. In an Amarone that leads to a perfectly natural and generally accepted typicity, as said with high VA.

All other wine handling after fermentation that exposed wine to oxygen in a faulty way or brings the wine into contact with acetobacter (like not topping up casks, faulty cleaning of hoses) can lead to increased VA.

So there is also faulty increased VA, and I would say it also has to do with where a wine comes from. The generally much cleaner style of New World wine making often considers detectable VA a fault. In an old Chateauneuf (the discussion about brettanomyces comes to mind here) increased VA levels integrate into mature flavors that are generally considered typical for that style of wine. And personally I don't mind that at all, as long as the wine remains in balance. If there is a bacterial cause for excess VA production, a wine will soon go off. If it's higher level in a balanced and otherwise stable wine, it may be something you do not particularly like, but it would not be faulty.

Hope this helps.

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Originally posted by Mark Squires:1. Some VA is not perceptible and you say it's not a flaw. Ok. But it's not perceptible. We don't know it's there. If it is, it's a flaw.

I would appreciate my writing being read correctly.

VA in Yquem is perceptible and it's not a flaw. VA in Chateauneuf is perceptible and it's not a flaw. VA in classic Old Rioja, wood aged Port and Madeira is perfectly perceptible, sometimes in large doses. And it's not a flaw whatsoever.

Wines without perceptible VA still contain it; you can't make wine without having the fermentation produce VA.

Quote:

2. You say it adds to botrytis and Yquem–a new one on me. But then it is equally true it is overwhelmed by the botrytis aspects. Of course, grapes with noble rot are not exactly traditional winemaking. But again, it's not really perceptible.

It may be new on you, but that's no reason to make it sound as if I'd be wrong. Trust me, I am not. And neither is the VA overwhelmed by other flavours: it is perfectly perceptible, and adds to the typicity of the aroma of a botryticized wine. Try a good Quarts de Chaume and you'll get a serious dose of VA in a perfectly undisturbing way. Those who don't know part of that smell is VA will love it. But as soon as one talks VA all lights seem to be on red alert. Without a very good reason, I think.

Actually ALL traditional wine making (and making wines from noble rot grapes is VERY traditional wine making) including fermentation in open casks produces levels of VA considered excessive by the New World. That's largely due to the fact that they are not used to it. But the New World based style of very clean wine making is in fact the only style of winemaking that produces very low levels of VA. That is neither good nor bad, it's just different.

Sniff your classic dry Vouvray properly and you will get very faint whiffs of VA as well as oxidative tones never present in a New World style wine. Faulty? I don't think so. Perceptible VA? Yes, sometimes.

Quote:

When you can taste VA it is a problem.

It is not, not necessarily anyway. It's maybe the question if one is willing to accept that it need not be.

Howard Sherry:

Quote:

Originally posted by Mark Squires:>if you find it is in balance with the other elements then it is a positive attribute

tomm

Juan

tomm

Hendrik de vierde

tomm

tomm

ChrisW

ChrisW

Juan

Willem G