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Some thoughts on bottle variation


Late word: At 11:02 a.m. tomorrow (Tuesday 7/21) I will publish the winner of the Murphy-Goode “A Really Goode Job” with pics and up close and personal background info.

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Interesting article by Dan Berger in last Friday’s Napa Register on bottle variation, a phenomenon rarely talked about by vintners because, frankly, they don’t want to talk about it. The most commonly understood (by wine consumers) reason for bottle variation is TCA — corkiness — but Dan points out another: lightstruck bottles (whether by direct sun or indoor flourescent lighting). I have to admit I’d never heard of this before I attended a tasting at Rubicon restaurant, years ago, at which Dan was present. He found some of the wines lightstruck.

There are other reasons for bottle variation:

– Transit. A bottle may have been exposed to excessive heat, say, in the back of a UPS truck on a summer day.
– Poor storage.
– The unequalization of production. Production of a wine is said to be equalized if all the barrels or tanks in which it was raised are blended together in one large tank. If this isn’t possible (and it’s often not), then you can have two different wines, both bottled with the same label.
– Time between tasting. Even if two bottles are identical, they can leave different palate impressions if tasted at different ages. Just a few months can alter a wine’s profile.
– Dishonest winery practices. Just because two bottles have identical labels doesn’t mean the winery didn’t knowingly put different wines in them. What, you think it never happens?
– Glass differences. The same wine, tasted in different glasses, will taste differently. This isn’t exactly “bottle variation,” but we don’t drink wine from bottles, we drink it from glasses.

I think bottle variation is the main reason why critical reviews of the same wine by the same critic can vary, when the wine is tasted more than once. It’s only reasonable for the public to expect perfect consistency from a critic, and certainly we critics ourselves would like to perform perfectly consistently. Unfortunately, consistency in anything is rare, and particularly in so subjective a practice as winetasting. Add bottle variation to the mix, and you have ample opportunity for scoring variation.

I once scored the same wine 9 points apart on 2 different occasions over a period of a few months. I don’t like saying that, but it’s the truth, and any critic who says it never happened to him isn’t being honest. Having said that, more often, when I accidentally re-review a wine (only to discover I’d previously reviewed it), my scores are either identical, or within 2-4 points of each other — a tolerable discrepency. I think that when I rate a wine differently over time, it’s because of bottle variation. I don’t think it’s because my judgment is at fault. But a wine reviewer always has to accept the fact that his judgment may be cloudy on any given day. I will say this: there is a strong imperative for critics to maintain rating consistency, which is the linchpin of our credibility. Imagine if, for instance, Parker started giving 72s to Lafite. Everybody would wonder if he’d lost his mind. That’s why he’s not going to start giving Lafite 72s.


I came across this John Cleese video on wine. It’s quite good, and I think you’ll enjoy it. Lots of familiar California faces.

On the Murphy-Goode contest

I spent the day today (Sunday) with the Top Ten and will blog Tuesday morning on my impressions and, more importantly, the winner. Will post a few minutes after the winner is announced by the winery.

R.I.P. Walter Cronkite

I met him once. I was on my first real job, as a sous-chef in a French restaurant in Massachusetts. Mr. Cronkite’s daughter was going to private school in the area; he was visiting with her. He dined alone, and after dinner, was hanging out in the bar. After I shut down the kitchen, he was still there, alone, nursing a drink. I got a glass of wine and asked if it was okay to talk with him. Of course it was. This was less than a week before Nixon resigned, so Watergate was obviously the focus of our conversation. I had the feeling Mr. Cronkite was happy to talk with me. He was so friendly, unpretentious, unphased by his fame. I was just a young, politically-oriented kid. He was a great newsman, a great reporter. The real deal. I hope his example of fair reporting lives forever.


  1. It takes time for (usually white wines) to become lightstruck.
    Also, one would think that bottle variation should be minimal since wines are transferred from barrel into a large tank for homogenization at the time of bottling and then the bottles are filled from the same lot. However, all you need is one organism in a bottle with some RS (which is common in CA wines) and one bottle can have Brett bloom, CO2, etc – while others don’t.

    Some wines evolve quickly, which is why I prefer two bottles as samples and I taste them about a week apart.

    But going back to what you and Joe Czerwinski have called “tasting room bias”: just as the shape and size of the glass can affect the way a wine shows, so can the ambient temperature, barometric pressure and humidity of the tasting environment.
    It is hard to control this – though you can achieve a fairly consistent environment. More than control, awareness of those factors at the time of tasting and understanding of how they affect the expression of the wine are important.

  2. Steve – thanks for bringing up an important point. Bottle variation is an issue we tend to avoid, because so little can be done to prevent it. There are cork-derived variations other than TCA, and very small imprerfections in sealing of alternative closures are also problematic. There are variations that arise from bottle contamination – ranging from cardboard dust to glass mold release compound (some of this could be dealt with by washing the bottles before filling, but many wineries don’t).

    Light-strike has been documented in some sparkling wines and still whites (as well as beers) and is dependent on the composition of the wine and the color of the glass. Some sources say UV light causes the change, but ordinary fluorescent light has no significant UV component and has also been implicated. I’ve never seen any evidence of ligh struck reds – anyone?

    As for 2-4 points? Believe me I think this is laudable precision! But it IS the difference between an 89 and a 91-93. Nine points? Fugetaboudit.

  3. Thanks for the insight into a critic, Steve. I see the pressures involved in consistent scoring and the antagonist you must find in bottle variation.

  4. Very interesting post, and an issue I wish would get more exposure. I think most of the time, except with the smaller producers’ wines that have excellent provenance, what the critic tastes is not what the consumer buys.

    I’ve seen it written that Robert Parker likes Brett in his wine, probably based on consumers buying a highly rated by RP wine that’s really Bretty. Maybe he does, but I bet the issue of Brett bloom in-bottle has a lot to do with this. Most critics taste wines in their youth, likely with near perfect provenance. Take a slightly leathery wine with a pinch of RS, let it sit above cellar temperature, and next thing you know, there’s some barnyard going on.

    I seriously doubt that French wines have less Brett, but between lower sugar levels and native yeast fermentations that consume complex sugars S. Cerevisiae can’t ferment, most of the Brett action probably takes place before bottling. I have a hypothesis that the high sugar levels and designer yeast fermentations typical in CA are a recipe for serious bottle variation via Brett.

  5. Steve, I was with Dan and the folks at Diam and our meeting prompted that piece. One big area that we’re not looking at is OTR or oxygen transmission rates which can be controlled by closure choice. Natural cork, because it’s natural has too much variation, so the discussion these days is about having consistent closures that affect post bottling chemistry. Winemakers can consciously choose how they want their wine to age. Europe is pretty far ahead of us on this discussion and I’m learning more. Cool piece here on the subject.

  6. @John Kelly

    I would think that since reds are put into green bottles, they are unlikely to be lightstruck.

    I was talking to an absinthe producer some time ago and he mentioned that absinthes can also become lightstruk – particularly the verte style, unfiltered ones.

    So my question would be: is the presence of some sort of colloidal suspension in whites (or a particular phenolic composition) coupled with clear glass bottles predispose them to being lightstruck?

  7. You guys, I would also like to hear your thoughts on how you can detect a lightstruck wine. What’s wrong with the aroma, flavor, texture? Is it slat, stale?

  8. Morton Leslie says:

    Never met Mr. Cronkite, but had the pleasure of watching him celebrate his birthday with family and friends at a nearby table at LeCirque. Like any other birthday dinner, lots of kidding and laughter, and wine. My waiter tapped me on the shoulder and drew my attention to a solitary diner (well, he was with two burly men) slipping out, saying good night to Sirio, face serious… ex- pres. Richard Nixon. Interesting that there was no acknowlegement that I saw between Nixon and Cronkite, yet they had to know they were both in the same room.

  9. Steve

    This is a referencesI found on Lightstrike:

    I am at a loss for the finer points distinguishing corked from lightstruck. Since the flaw comes about from UV-induced conversion of various aromatic compounds the flaw may be difficult to pinpoint or define as clearly as TCA (or TBA which seems to be indistinguishable from TCA).

  10. I think Kimberly has hit upon the dominate reason for bottle variation. The O2 permeability of Cork can vary 1000fold from cork to cork. When Patton Valley Vineyard made the move to screw caps we saw bottle variation decrease dramtically.

    I also think that bottle variation rates are inversly proportional to the degree to which wines are ‘manipulated’. The more a wine is ‘mucked with’ the less it will vary. This is extremely anecdotal.

    I suspect that light struck wine is not a signficant contributor to bottle variation, in terms of probability, most wines simply are not that poorly handled, especially wines finding thier way to the offices of wine writers.

  11. Arthur, well whatever the reason it can be said that these wines suck, which is really all that matters if you’re communicating to consumers.

  12. Yes, Steve, but don’t you think a wine reviewer should know what it is that they are communicating to the consumer?
    If lightstruck wines resemble corked wines, the implications are quite different for the whole production line.

  13. Arthur, I’ve wrestled intellectually with this point for a long time and come to this conclusion: My mind is not a fully-equipped laboratory capable of ripping a wine apart and analyzing its myriad details. If you want a detailed analysis of a wine, send it to Enologix or whatever lab you prefer. On the other hand the average consumer just wants to know, is the wine great, good, average, ageable, dry, sweet, etc.? or does it totally suck. If I say it has garbagey or moldy aromas and flavors nobody cares why that is, chemically. What they care about is knowing that it smells like garbage or rotting newspapers!

  14. Ok
    I get your point Steve.
    BUT if you have a full shipment of wines that are light struck, they will ALL have the flaw.
    The flaw is said to resemble TCA taint.
    You get only one bottle of the wine.
    If you can’t determine if it is corked or lightstruck you can’t tell your readers if only the particular bottle was screwy and they are likely to have a decent wine or if the whole lot is worthless and they should not waste their money and time.
    I want to know how to be able to make this distinction. it’s not a matter of being an enological laboratory but being and informed, skilled and trained olfactory assessor or wines – for the benefit of the readers. After all, its about them. We are supposed to serve them.

  15. Second thoughts:
    I also appreciate what the average consumer wants.
    Average is a sticky category.
    An average doctor, lawyer, wine critic, wine enthusiast, etc…
    Maybe it’s time to raise the average?
    We can do this by raising the bar for ourselves and our readers.

  16. Giving Lafite 72s is a compelling thought and I see no reason to be too pessimistic that it could actually happen. Parker isn’t getting any younger and many a dementia has begun long before his current age. This business is full of surprises.

  17. lol

  18. A few years ago, my wife and I poured a single red wine at a charity auction. The wine was, as I recall, about six years old, from a large (but not the largest) Washington winery, designated from a well regarded vineyard, and signed by the winemaker, so it was at the higher end of a broad product range. The bottles were from sealed cases, and all of the same vintage. We did not know the source (winery or distributor) or storage history.
    We had recently taken a class that included examples of several wine faults, including cork taint, brett, acetification and the like, so we felt some confidence tasting each bottle before serving. And it was good that we did, because we ran across a bad bottle early on, and so we were careful to taste and spit with each new bottle.
    A couple of more bottles were set aside, but what we took away from the experience of testing through about two and half cases of merlot was that we would have been less surprised had they been mixed-brand bottles. There was that much variation. The wines we served weren’t bad or dead, just surprisingly different, and because I trust my wife’s palate a lot, we tended to both taste most bottles, and came to a shared conclusion.
    I’ve told this story to local winemakers I respect, and the best answer is just that wine is a living thing. My guess is that bottle variation increases with age, even with little or no obvious faults, so that down the line the same wine could be sublime, great, or average, even from the same cellar, and consumed at the same time. I have no other evidence for this claim, so will stand by it until proven wrong.

  19. A few facts about lightstruck wine. First of all, the cause is light energy activating riboflavin as a reducing agent, and causing in white wines a cascade reducing reaction which is quenched in reds before it gets going, but in whites quite quickly (five minutes is enough in bright sunlight)produces a mix of sulfide compounds, mostly familiar like H2S (rotten eggs), ethyl mercaptan (diesel or onion), and diethyl mercaptan (canned asparagus), but also some exotic ones like ethyl methyl mercaptan, which smells like wet wool, almost a mothball odor and quite different from TCA.

    Many dark bottles don’t offer much UV protection — it takes a special UV coating which much cheap glass is less likely to use in these days of Chinese imports.

    It is extremely rare that a shipment of wine is lightstruck. It usually happens on the retail shelf or after purchase.

    In my view, the most important sources of bottle variation are environmental influences of light and heat. Given perfect handling and storage, however, the cork closure is the main culprit.

    Still, the way a wine is perceived in reaction to the environment in which it is serve — not just the food but the music, the mood, the lighting, the background aromas — have much to do with creating an harmonious experience or a dissonant one in which the wine shows us its best, and these influences are almost never discussed.

    That does not mean we should taste and judge wines ganged into groups in the sterile environment of current vogue. Nothing could be further from the consumer experience.

  20. The warmer a bottle of wine, the faster aging reactions will take place.

    Corks vary widely and are highest on my list as culprit for bottle variation. Changes in temperature will cause thermal expansion and contraction of the wine. I suspect that will cause changes in pressure in the headspace of the bottle and more (gas) transfer through the cork.

    Unfiltered wines treated only with SO2 can have many types of survivors, including Saccharomyces, Brett and lactic acid bacteria. Likely, they will not be in best of health. Unhealthy organisms can do some stinky things.

    Wines seem to go through phases over time. Perhaps, Steve’s example wasn’t bottle variation?

  21. I think BradK makes an excellent point:

    Bottle variation would be the phenomenon of several bottles of wine tasting differently at *exactly the same moment in time*.

  22. Arthur, that would be definitive proof. But it doesn’t mean that bottle variation can’t occur over time. It just makes it more complicated to prove, as someone could always say that the taster was the variable, and not the bottle.

  23. Very interesting article, thanks for pointing this out Steve. I’ve heard about bottle variation, but only when it comes to beer. Either way I usually like to stick to bottles that are darker and don’t allow too much light to penetrate.

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