Was having a tipple with a friend the other day and got into an "interesting" discussion. The (white) wine was particularly acidic and the discussion of whether it would/could improve with age arose. There _was_ a _hefty_ fruit component; it's just that the acidity was the overwhelming character.
I've heard that (appropriate) acidity is necessary for successful aging of wine, so I'm curious what the effect of time would be on a particularly acidic wine. I was always under the impression that the acidity would _not_ mitigate with time. My friend thought the acid _would_ temper with time. Where lies the truth?
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- Roy
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As with many aspects of the magic of wine.... You are both right. Some whites age well & the acids will intigrate into the wine... some will become teeth vibrating, test of manhood horrors. What kind of wine was it? Of course, the classic ageing whites are German Rieslings & Semillon (botrytis affected or otherwise)... Many Chards age well... But the whole topic of ageing whites would take up far too many kilobytes & far too much of this beautifull day.
I certainly think that acidic whites age better than rounder whites. But I don't think a wine that is actually unbalanced young is likely to age well.
You don't specify what the wine is. Young Savennieres can often have very high acidity, and probably ages as well as any dry white. The other main contenders would probably be Austrian or Alsace Rieslings (my experience with German trockens is limited) - wines that typically have a lot of acidity. White Burgundy also tends to age better in more acidic vintages, IMHO.
I'll leave it to the chemists here to say whether the acidity actually changed with age. My gut feeling of older Savennieres (and sec Vouvray) and older Alsace Rieslings is that these are still clearly acidic wines, but the development of secondary flavors helps the acidity integrate better.
In off-dry and sweet wines I think it's clear that acidity is a boon to aging. Dale
And Chablis -- which I would hazard is the most acidic chardonnay by and large -- is famous for its ability to age well.
One aspect of aging is purported to be the reaction of the acids with alcohol to form esters, one component of the bouquet that comes with age. To be honest, I've never quite understood why that reaction should proceed at all since there is no appreciable energetic benefit. Perhaps over that time scale, however, the desolvation of the alcohol is the driving force...
I have heard that a small reduction in acidity happens as tartaric acid reacts with any calcium and potassium in the wine, precipitating as tartrate / bitartrate.
I have also heard that tartaric acid and alcohol react to produce esters.
"'What is truth?' said jesting Pilate..." Great opening line, right up there with "Cogito ergo sum" and "Call me Ishmael" and on a more obscure note "...to wound the autumnal city." See my other post in this thread for a serious answer to your question, Mike.
Am I alone in thinking same doesn't really seem true with reds? Acidic Chiantis or Burgundy from an acidic vintage ('93 or '96) always seems acidic to me (not a complaint, if you know my palate). This was one of the side points that got lost last year in my (stupid) battle with the Collectors Recork Wines/Europeans All Have Wine Knowledge guy. But was maybe the most interesting question of the whole debate. I can't think of a reason that whites' and reds' acids would age differently. Dale
Another chemist friend of mine has the same problem with the concept of this organic reaction going in an essentially aqueous solution. He mentioned once that he'd heard of so called "lethargic reactions" that could account for the phenomenon, but the mechanism wasn't clear to him even then.
le/on 04 Jun 2004 20:43:16 GMT, tu disais/you said:-
Well, I'd claim that reds certainly _do_ lose acidity, yes.
Chuckle. Pity Max wasn't around at the time. I wonder how he'd have had us treat him!
Simplist answer, Dale. "They start differently".
What I mean by this is that I don't feel red wines are just white wines with red pigment "added". They usually - even in the softest examples - have tannins, which are pretty active, chemically, for example. It's a truism that for red wines to live a long time, they need to have plenty of acidity, plenty of fruit and plenty of tannins. By the time they are "ready", they've lost all three, but the original fruit driven flavours have been replaced by complex (secondary or tertiary) flavours.
It's equally a truism that for whites to live a long time they need plenty of fruit and acidity and they in turn THEY lose both fruit and acidity and gain in complexity. I have no idea whatsoever of the chemistry of these processes, my knowledge is in part from my own experiences, and more perhaps from reading.
I'd think that most would have that same reaction: esters placed in aqueous acid tend to hydrolyze, and the reverse reaction (what we're talking about here) occurs only when the water is removed from the reaction. BUT, it's not clear to me that either reaction -- as usually conducted in the lab -- ever reaches equilibrium. Over 15-20 years, the system may come to an equilibrium that favors the formation of the ester, though the only reason I can think of to rationalize that would be the removal of ethanol from water, thereby allowing the water to assume a more stable structure. (This explanation accounts for a lot of biochemical energetics, for instance)
What I am accustomed to hearing about, and seeing played out in wines for many years, is the co-importance of acid content (along with tannins) as preservatives permitting the "fruit" to evolve to other flavors. Probably that is very familiar stuff to many of you. One experienced expert in the
1970s characterized tannin and acid as ropes of a "hammock" supporting the fruit in its patient rest as the wine ages. In that view, acid in youth is essential for the long term. (And not always appealing in youth. I wonder by the way how many serious 1988 red Burgundies are yet drinkable? Patience has been required of their owners.)
But both "tannins" and "acid" tend to fade over time. (-: Dale maybe you should wait longer to open your 93 and 96 red Burgs. Or if you don't like them, sell them to me.)
I think the first thing that needs to be established is if acid content really decreases much over time as would be determined by chemical analysis as the wine ages. The human sense of taste is easly fooled when you have a combination of acid, sweet, bitter, and salty as well as strong smells and mouth feel. For example, some rather sour tasting lemon juice in water can be made to taste much less acid and quite sweet by adding enough sugar. Development of various tastes and smells as the wine ages could well tend to make the wine taste less acid. I think most of us would agree that many wines taste less acid as they age. The question is are they really less acid, or is some sort of masking effect caused by components produced as he wine ages causing the reduction in acid taste.
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le/on Sat, 5 Jun 2004 02:38:36 -0500, tu disais/you said:-
Grin!! You noticed my caution then.
I can't think of any wine off hand which I've followed through from youth to maturity where this hasn't been true. So instead of "many" I'd say "almost all", in case someone comes up with a (slightly nitpicking) exception to invalidate "all" on it's own. :-)))
Exactly, and without doing chemical analysis over a (say) ten year period, for a white, I don't think there's any way of knowing. As you rightly say, there are many ways in which our perception can change. Mind you - in the real life situation in a bottle, and taking one of the commonest ways of changing our acid perception, I can't believe that sugar content increases! In fact it's pretty well documented that in Sauternes, perceived sugars decrease too with age.
Hmm, I always thought of 1988 as more a tannic vintage in Burgundies than an acidic one.'88 DRC RSV still has quite ample tannins.
Actually, I like them fine. Acidity (in balance) doesn't bother me. The recent '93s I've tried were mostly pretty close to peak- but these were regional and village level wines (though from good producers like Lafarge, Chevillon, etc). I have no plans to open the Drouhin Clos de la Roche or CSD or the Chevillon
1ers for a while.
I'll still maintain that there seems to me to be little appreciable drop in apparent acidity in most reds. I've in last couple years had some '88 & '90 Chiantis- great wines, for folks like me who like acidity. I love '85 Bdx - but don't know any I'd characterize as fat. One would think that if acids faded that riper low-acid vintages like '82 would be undrinkably flabby after 22 years. While '82s are not my favorite vintage (a little more opulent than my preferred style), certainly most of the better classed-growths are drinking quite well.
There are several factors that need to be considered in respect to acids during wine aging. First, the esterification of organic acids will be addressed. Acid is partially converted to its ester form during wine maturation lowering the perceived wine acidity (Edwards et al. 1985). Due to the high proportions of tartaric acid and ethanol, ethyl bitartrate is the predominant ester that forms (Boulton et al.
1998 p.....). In a study which examined the effect of aging and ethyl bitatrate formation in wine (Edwards et al. 1985), it was found that it improved the "mellowness" of the wine and lowered it's apparent harshness. This was attributed to loss of wine acidity. The author then went on to note that the benefits of wine aging also included making the wine more "harmonious, less harsh and more integrated or balanced". Esterification rates of the organic acids are different, with lactic and acetic acids having the highest rates (respectively) followed by succinic acid then malic acid, with tartaric acid having the slowest rate (Shinohara et al. 1979). The authors also suggest "that wines containing large quantities of organic acids will form the bouquet and the odor well with the formation of large amounts of ethyl esters during aging". It should be noted that the ethyl bitartrate ester at least, has no direct effect on the wine flavor (Boulton et al. 1998). This change in acid proportions could also possibly contribute to the change in sourness of a wine with age in addition to acid "loss". Due to this esterification process, if a wine is to be aged for a long period of time then it needs to have a low pH and high acidity in order to retain sufficient sourness or tartness for consumption (Boulton et al. 1998).
It has been noted (Marais, 1978) that different pH levels in wine during aging would result in different ester concentrations due to different rates of hydrolysis. When the author examined this and the effect on wine quality, it was noted that acetate and ethyl esters concentrations correlated significantly with wine quality in four month year old Colombar wines, with the loss of these esters being associated with the mature bouquet development. It was also noted that wine quality tended to improve with the two lower pH concentrations used, which also correlated with bottle maturation bouquet development. It should be noted that specific wine quality parameters were not defined in this paper.
Acid-catalyzed hydrolysis can be thought to be an important factor with aroma/flavor development in wines during aging. It should be noted that acid hydrolysis yields different compounds as compared to enzyme hydrolysis (Zoecklein et al. 1999). Compounds that this might attribute an effect too are those that are glycosides, including monoterpenes, aliphatic residues, sesquiterpenes, norisoprenoids and other glycosidic compounds (Williams et al. 1995). Acid-catalyzed rearrangement of glycosylated and non-glycosylated norisoprenoid compounds (Winterhalter et al. 1990) is another potential contributer to aroma development in wine aging. One important consideration is that "not all volatile compounds released from grape glycosides have a desirable effect" (Zoecklein et al. 1999), such as TDN which is said to be responsible for a kerosene-like odor in aged Riesling wines (Simpson, 1978). Acetate and fatty acid esters are lost due to acid hydrolysis, this will be addressed in the esters segment and will not be discussed further here as these are not thought to contribute to wine aroma development during aging.
This leads to the discussion of development of varietal aroma during the wine aging process. In a report (Francis et al. 1996) acid and enzyme-catalyzed hydrolysates were compared in Semillon wines. Enzyme-catalyzed hydrolysis was found to not contribute to wine aroma whereas "acid-hydrolysis products produced significant aroma and conferred similar sensory properties to those of bottle-aged wines". This supports the proposition that slow acid-hydrolysis of grape glycosides, such as during wine aging, is a process which produces varietal aroma in white wines (Francis et al. 1996). In another report (Francis et al. 1999), the contribution of glycoside precursors to cabernet sauvignon and merlot aroma was examined. Acid-hydrolysates, which were produced from skin and juice extracts conferred varietal aromas of young wines of these varieties. These results do not directly suggest what may happen as far as aroma development with long-term aging is concerned, but as the intensities of specific wine aromas could be correlated with the concentration of specific compounds, it can be suggested that further acid-hydrolysis/rearrangement reactions would also affect red wine aroma during aging.
From this discussion it is proposed that a low pH and high acidity is required for long term aging of wines to match the length of time required for the flavor development reactions to take place (acid-hydrolysis/rearrangement and esterification reactions) and to achieve a balanced and integrated wine. This is so that when a wine is consumed it will have the appropriate sensory level of tartness to match the wine style.
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