Ik denk dat het er heel erg van afhangt wat het is, waarbij je heel erg moet oppassen om niet de verkeerde benaming aan een geur te hangen. Het is best lastig om blind alle mogelijke geuren te benoemen en denk dat het wat ver gaat om - zonder dat enigszins zeker is welke chemische samenstelling nu echt in de wijn is waargenomen - al bij elkaar de spreekwoordelijke hersens in te slaan 
Op het Squires forum is er veel over te vinden. Bijvoorbeeld in:
http://dat.erobertparker.com/bboard/showthread.php?t=221215&highlight=ethyl+acetate
en
http://dat.erobertparker.com/bboard/showthread.php?t=217705&highlight=ethyl+acetate
Niet iedereen heeft daar toegang toe, dus ik zal hieronder wat stukjes kopiëren.
In het kort komt het er volgens mij op neer dat ze daar zeggen dat als het om Ethyl Acetaat gaat het niet zomaar kan vervliegen. Als je echt zin heb om scheikundige te worden, moet je niet alleen de onderstaande stukken lezen maar vooral ook de rest van de postings op Squires waar ik naar heb verwezen
Re: Can Brett, VA, and other flaws, just blow off????
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John, (yes, I'm a pchemist) I'm not sure we disagree in the grand scheme, I just don't think it makes much sense to think about the topic at hand in terms of redox. It's fine to talk about oxidation and reduction potentials for oxidative and reductive processes, such as reactions involving oxygen, sulfur compounds, tannins, etc. The topic of this thread is how the presence of stable compounds like TCA, 4-EP, 4-EG, acetic acid, ethyl acetate might change once a bottle is opened. None of those is reactive with air, none of them undergoes oxidation or reduction under normal conditions.
I like the idea that Waterhouse has postulated: that much of what we detect as changes in wine aromas after opening is due to dissipation of sulfur compounds that mask the presence of other aromas. So in that sense, I guess you could say that redox, through the introduction of oxygen, plays an indirect role once a wine is opened in changing the nature or concentration of any sulfur compounds present.
I honestly don't think that has any bearing on the aromas of acetic acid (or ethyl acetate for that matter). In the case of acetic, the only important consideration is the pH of the solution, which (as I know you well understand, but I'm writing for others reading) determines the relative fraction of the protonated compound (volatile) and dissociated acetate ion (non-volatile). The pKa is an indicator of the break point for which species is the higher fraction. Most wines have pH well below 4.7, meaning that the acidity is high enough to keep the relatively weak acetic acid in its protonated form. That's not oxidation/reduction, it's simple acid/base chemistry. Want to test that? Take a wine, add a tsp of vinegar. Should now have a VA odor. If you have some sodium hydroxide based drain cleaner (such as Liquid Plumr or Drano) around, add a tsp or two of that, stir, and you should notice that the vinegar smell disappears. All you're doing is changing the pH of the solution, but that's not oxidation or reduction.
Cheers
When the flaw of Volatile Acidity might be something else…..
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Recently a group of us tasted two different bottles of the 1997 Harlan Red. The first bottle was extremely flawed, and the second bottle was fine. I posted my notes, and in my notes I said that we thought that the first bottle was flawed due to VA (volatile acidity). I’ve had a chance to think about the VA issue, do some research, and talk to some winemakers. I now think that the flaw in the first bottle probably was NOT VA as such. Rather, I think that the flaw in the first bottle primarily was due to ethyl acetate.
Some of the reasons why I started to doubt the VA flaw hypothesis were:
1. Don Weaver of Harlan has said that they have not found any VA taint in the 1997 Harlan. I presume that means they have tested it and have not found that the VA exceeds the legal limit of 1.2 grams/liter for red wine. I have no reason to think that Mr. Weaver incorrectly reported their testing results.
2. VA is something for which wine is routinely tested as part of the winemaking process. Thus, if there had been truly excessive levels of VA in the process of producing the 1997 Harlan, then it is likely that Harlan’s winemaking team would have discovered that during the routing testing process. Similarly, if they tested some “off bottles” after bottling, their tests presumably would have shown whether excessive levels of VA were in the wine.
3. The main component of VA is acetic acid (vinegar). Had the wine been flawed solely due to excessive VA levels, then the wine would have had noticeable vinegar elements in both the nose and the taste. When we tasted the first bottle, no one described the wine flaw with a vinegar descriptor.
So if the first bottle was not flawed due to excessive VA levels, then the obvious question was what was causing the flaw that we found. In particular, what flaw caused the “nail polish remover” (or “paint thinner”) element that we found in the first bottle? In looking through the lists of standard wine flaws, it appears that the answer is not VA, but probably ethyl acetate:
http://en.wikipedia.org/wiki/Wine_fault#Ethyl_acetate
In doing more research, and in talking to some winemakers, it appears that the ethyl acetate hypothesis is the more likely explanation for the flaw in the first bottle of 1997 Harlan Red:
1. As confirmed in talking with some winemakers, “nail polish remover” is one of the standard descriptors of ethyl acetate.
2. While ethyl acetate is related to VA (it is the esterification of acetic acid and ethanol), ethyl acetate is not technically a component of VA. In other words, you could have a wine with significant levels of ethyl acetate without necessarily having improper levels of VA. Put another way, a reading of VA within acceptable limits does not say anything about the presence (or amount) of ethyl acetate.
3. Unlike VA, the amount of which is routinely tested by wineries throughout the winemaking process, it appears that wineries do NOT routinely test for ethyl acetate. Instead, it appears that testing for ethyl acetate is done when you already suspect it might exist. Accordingly, a wine could develop noticeable amounts of ethyl acetate long before the separate lab testing would confirm its presence.
4. While VA does not necessarily result in ethyl acetate, high levels of acetic acid (the main component of VA) are more likely to result in the production of ethyl acetate. Based on my tastings, the 1997 Harlan Red does appear to have higher than normal levels of VA compared to other vintages of the Harlan Red (such as the 1994), and thus under normal circumstances it would have been more likely to develop ethyl acetate than other vintages of Harlan Red. The fact that the grapes in 1997 were so much riper than normal, with presumably higher pH, would help explain the higher than normal VA levels.
5. The threshold for sensing ethyl acetate is much lower than VA. For ethyl acetate, the sensory threshold is just 150-200 mg/liter. For VA, the sensory threshold is >700 mg/liter.
6. In reading through some older tasting notes on the 1997 Harlan Red, I came across this note by winemaker Bob Bressler who explicitly mentioned ethyl acetate in the nose of this wine:
http://24.187.214.155/wine-forums/a…aft/110538.aspx
7. Reading through the literature, in terms of being able to taste and smell ethyl acetate, there appears to be a synergistic effect of elevated levels of VA along with the presence of ethyl acetate:
http://www.barkan-winery.com/Deskto…dex=3&tabid=114
“For example, 0.7 grams per liter of acetic acid in red wine, with no significant presence of ethyl acetate, will contribute to the complexity of the wine. On the other hand, the same content in the presence of ethyl acetate will cause the wine to taste volatile and damaged, although legally it is fine (since the concentration of the volatile acid satisfies legal requirements).”
I think this description is the most appropriate one for the flaws in some bottles of the 1997 Harlan Red. There are elevated VA levels in the wine, which, when combined with ethyl acetate, cause the wine to smell and taste volatile and thus flawed, EVEN THOUGH the VA levels may be within the legal limits.
Of course, this VA plus ethyl acetate hypothesis only tells us the part of the puzzle that asks WHAT was the flaw in at least some bottles of the 1997 Harlan Red. What it does not tell us is (a) how and when the combination of VA and ethyl acetate came into existence, and (b) why there appears to be such drastic bottle variation in the 1997 Harlan Red.
Since I previously had posted about the 1997 Harlan Red in terms of VA flaws, I felt I owed Harlan the courtesy of raising with them the ethyl acetate issue. I had emailed Don Weaver of Harlan about the prior VA thread, and he responded with a short response that he asked me to post. With that background, I emailed Don Weaver of Harlan about my conclusions about ethyl acetate, and I asked him if Harlan ever tested the wine for ethyl acetate. I have emailed him twice on this issue, and so far I have not received any response from him.
Anyway, since I previously had posted about the 1997 Harlan Red in relation to VA, and since I now think that ethyl acetate (perhaps in combination with the VA) is the main culprit, I felt I needed to post this to accurately reflect what I have found so far. More generally, I suspect that consumers sometimes think that the flaw in a wine may be VA when in fact the flaw might be ethyl acetate (again, perhaps in combination with elevated VA levels). For that reason as well, I thought it would be important to share this information.
Bruce Leiserowitz
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