What's that in my wine: tartrate crystals

A few weeks ago, we received the following email from a customer (edited to protect identity):

A couple of days ago we sampled a split of [Esprit de] Beaucastel Blanc at ... in ..., CA.  We enjoyed the wine until the moment we poured the remains of the bottle, and a glob fell into my glass, with a noticeable plunk.  The substance can best be described as several, 1 inch-long fuzzy-looking strands.  I have seen crystalline material and sediment in wine, but nothing like what plopped into my glass.  Needless to say, the restaurant did not hesitate to strike the cost of the wine from our tab.
I am just curious to learn what that substance could be.

Not the most pleasant of emails to receive.  And I'm sure that to the customer who wrote, the surprise at the end of the bottle colored his experience of the wine he'd been enjoying.  I was surprised, though, that the restaurant didn't have an explanation of what he'd encountered, because it's one of the most common things that can happen to a wine.  He'd encountered tartrate crystals that had precipitated out of a wine and settled into the bottle.

Tartaric acid is one of the three main acids found in wine grapes, and along with malic acid and citric acid provides the tartness in both grapes and wine.  Wine grapes are notably acidic; at harvest, their pH is typically between 3.25 and 3.5 at Tablas Creek.  While much or all of the malic acid is transformed to the softer-tasting lactic acid in the fermentation process, tartaric acid is relatively stable and is therefore responsible for the maintenance of a finished wine's pH and its resistance to various kinds of spoilage.  Still, much of the tartaric acid settles out of a wine during fermentation and aging as a part of the lees.

Tartaric acid's solubility is temperature-dependent.  So, when wine is chilled down, some of the tartaric acid drops out of solution as fine white powder or crystals and does not under normal conditions dissolve again.  For red wines, which are rarely subjected to cold temperatures and which may anyway be expected to throw a sediment over time as suspended color particles fall out of the wine, this is rarely a problem.  But for white wines, which are often refrigerated for days or weeks, and in which consumers aren't expecting to see any sediment, the tartrate crystals can be alarming.  We hear occasionally from customers who've seen these crystals wondering if they are shards of glass.  These crystals -- sometimes called, a bit romantically, "wine diamonds" -- are not glass, and are harmless.  In fact, they are largely potassium bitartrate, whose common name is cream of tartar and which can likely be found in your spice cupboard.  Nearly all commercial cream of tartar is harvested from wineries.

Most mass-produced wines are routinely stabilized in various ways, typically through sterile filtration (to eliminate any chance of refermentation in bottle), heat stabilization (for proteins that can cause a haze in a wine if it's exposed to high temperatures) and cold stabilization (for tartrate crystals).  The cold stabilization process typically involves chilling a tank of wine down around freezing for several days shortly before bottling.  This extended chill causes tartaric acid to drop out of solution in tank, and the resulting tartrate levels are then low enough that no more is likely to precipitate out in a customer's refrigerator or a restaurant's wine room.  Of course, like most interventions, cold stabilization has other less desirable consequences, and a lower concentration of tartaric acid in the resulting wine changes the wine's flavors somewhat and can impact its long-term ageability.

IMG00196-20110512-2145 How a wine is stored impacts whether a customer even notices tartrates in bottle.  If a cork-finished wine is stored upside-down, any tartrate crystals typically adhere to the cork and are removed with the cork when the wine is opened.  However, if a wine is stored upright, any tartrates that form are likely to be visible, and the last glass (like the one at right) will show the evidence.  And tartrates won't adhere to screwcaps, so no matter how a screwcap-finished wine is stored any tartrates will be visible in the bottle.

Coldstabilization At Tablas Creek, we prefer not to cold-stabilize the whites that we hope will have the longest aging curve.  These wines -- principally the Esprit de Beaucastel Blanc, Roussanne and Antithesis Chardonnay -- are also wines that we typically finish in cork.  It should not be surprising to see these wines throw tartrate crystals over time.  Of course, if they're stored upside-down, you may never notice unless you look at the underside of the cork carefully.  Our whites that we intend for earlier consumption, and our Rose -- all of which which are typically finished in screwcap -- do receive a light cold stabilization, like the one pictured to the right.  We would prefer not to have the tartrate crystals floating around in these bottlings, though it could still happen if a bottle is put in a cold refrigerator for a long period.

So, back to our initial customer.  What do I think happened?  I think that the restaurant likely stored the half-bottle upright in their white wine refrigerator for several weeks or longer, plenty of time for the tartrate crystals to settle out.  And neither the customer nor the waiter had seen enough minimally-processed wines to know that what they had encountered was normal.


Please DO sniff the Cork!

So, I've seen a proliferation of articles recently that promise to educate wine novices to not come across as novices.  Whether this is a good thing is debatable; wouldn't you want an expert to explain things to you if you didn't understand how they work? It's not always a great thing appearing more expert than you really are, as you miss out on lots of opportunities to educate yourself.  Still, even worse is when advice on how to appear expert is just plain wrong.  One recommendation I see again and again that I just don't understand is that sniffing the cork of a newly-opened wine will make you look like a novice, as it tells you nothing about the wine inside.  A quick search of Google shows 302 matches for the phrase "don't sniff the cork".


Sniffing a cork may tell you nothing about whether a wine is oxidized, or tannic, or whether it smells like cherries, or whether it's ready to drink, but it does tell you a lot about whether a wine is corky.  I open thousands of bottles of wine each year, at tastings here and around the country, as well as in a more relaxed setting at the dinner table.  I always sniff the cork, not because it's a guaranteed indicator of whether a wine is corky or not, but because it's a warning flag.  Sure, it's possible that a wine whose cork is suspect might taste fine, but in my experience, at least 90% of the wines that taste corky have corks that smell corky.  And, the more I open and taste wines, the more convinced I get that even if it isn't apparent at first, wines with suspiciously musty corks usually are flawed.

Another interesting factor is that most sound corks have an appealing smell, like a fainter version of a new oak barrel.  Wines under those sweet-smelling corks are nearly always in good shape.  You do get the (very) occasional false negative, where a cork smells fine but the bottle is slightly tainted.  And, of course, there are plenty of flaws that have nothing to do with the cork (oxidation, reduction, and refermentation are probably the most common).  So, it's not a foolproof test and everyone should taste as well as sniff a newly-opened bottle.  But, I don't see what good it does consumers to be denied a fairly reliable indicator of when they should at least be suspicious their bottle of wine might be bad.

Have any readers out there had experiences where people have looked down on you for investigating the cork?  Or been fooled by a bottle (either with a nice bottle under a musty cork or a bad bottle under a sweet-smelling cork)?  If so, please share.

Sulfites in Wine - What's Causing my Headache?

In my recent post on lessons I've learned from blogging I recommend that bloggers write about the questions they find themselves asked all the time.  Following my own advice, I realized I've recently answered several questions about sulfites in our wines.  There are two phrasings to this question, both getting at the same issue.  One phrasing runs along the line of "oh, you farm organically.  Does this mean that your wines are sulfite-free?"  The other phrasing is "I get headaches from the sulfites in wine.  Does the fact that you're organic mean I can drink your wines?" 

Just the other day, I got pulled in by a discussion on organic wines and sulfites on the excellent blog 1 Wine Dude.  As I was writing the response, I realized that this is exactly the sort of issue I'm recommending that others address.  The confusion surrounding the issue would be farcical if it didn't negatively impact the acceptance of organic wines in the marketplace.  The punch line of the joke (which no one I know really finds funny) is that sulfite sensitivities don't typically cause the headaches that most people who believe they suffer from sulfite allergies describe as their principal symptom.  Those who report headaches are far more likely to be reacting to the histamines (or, more rarely, the tannins) in wine.  Or the alcohol.

As for us, yes, we use sulfites.  If we didn't, our wines would be unstable to a degree we're not comfortable with, and we're making wines for aging over the long term.  We do what we can to minimize the concentration to under 100 parts per million (the average American wine is about 350 ppm).  Still, I am not aware of any top winery anywhere in the world who omits sulfites entirely from the winemaking process.  And, sulfites have been used since Roman times in wine.  The fact that (unlike in other countries) United States regulations prohibit us from calling our wines organic is an unfortunate consequence of the widespread fear in America that many, many people are allergic to sulfites.  Fortunately, sulfite allergies are quite rare, and wine contains minor quantities of sulfites compared to other common foods.   

Important fact #1: If you (other than wine) eat quite normally, and wine (particularly young, red wine) gives you headaches, you almost certainly are not allergic to sulfites. 

Sulfur occurs in many foods, including (according to WebMD):

  • Baked goods
  • Soup mixes
  • Jams
  • Canned vegetables
  • Pickled foods
  • Gravies
  • Dried fruit
  • Potato chips
  • Trail mix
  • Beer and wine
  • Vegetable juices
  • Sparkling grape juice
  • Apple cider
  • Bottled lemon juice and lime juice
  • Bottled Tea
  • Many condiments
  • Molasses
  • Fresh or frozen shrimp
  • Guacamole
  • Maraschino cherries
  • Dehydrated, pre-cut or peeled potatoes

Particularly common sources of sulfites are dried fruit, potato chips and french fries, and condiments.  Three ounces of dried apricots, for example, contain 175mg of sulfur dioxide.  By contrast, a four ounce glass of Tablas Creek (at 100ppm of sulfites) contains about 12mg.  Even a glass of wine with average sulfite levels would contain about 40mg of sulfur dioxide.  You'd need to drink half a bottle to get the same sulfites as that handful of apricots. 

The FDA estimates that about 500,000 people in the United States have sulfite allergies (about two-tenths of one percent of the population).  Those who do need to be very careful about what they eat and drink, as exposure to sulfites can cause respiratory reactions.  Six people have died in the last 30 years in the United States due to sulfite reactions (none traceable to wine).  The reactions to a sulfite allergy are typically wheezing, coughing, hives, abdominal pain, and difficulty swallowing, the same reactions you'd expect from, say, a medical allergy (and, in fact, those with allergies to Sulfa drugs are much more likely to have other sulfite allergies).

Headaches, on the other hand, are not mentioned in the literature on sulfites, but are common reactions to an excess of histamines.  Many more people have sensitivities to histamines, which are common in pollen as well as many other plant materials.  Reactions to histamines include headache, itchy eyes, runny nose and flushed skin... the common effects of hay fever.   It's less well known that histamines are also common in the skins of grapes.  This explains why many people are sensitive to only red wines (which spend time in fermentation next to grape skins) or only to young wines (histamines break down over time in bottle).

Important fact #2: as with seasonal allergies, sensitivities to the histamines in wine can be treated with an over-the-counter antihistamine such as Benadryl or Claritin.

So why does the government mandate that wines display "CONTAINS SULFITES" on the back of nearly every label, but make no mention of histamines, when histamine reactions are much more common than sulfite allergies?  Essentially, histamine reactions are not particularly dangerous.  Inconvenient, sure, but not life-threatening.  However, from the number of questions I get, it's clear that the government-mandated warning has convinced lots of people that they're allergic to something they're not, and obscured the easy steps people could take to minimize their reactions. 

I've already written about how the fact that American wines with sulfites are prohibited from being labeled organic discourages vineyards from farming organically, so I won't go into that again here.  It's just another example of the unintended consequences of even well-intentioned government.

Corks and Screwcaps: Not an open and shut case

I came back from a tasting today (the always excellent Central Coast Wine Classic) having again had my third discussion in a week with a consumer who was confused as to why we bottle some of our wines in Stelvin screwcaps, and others in cork.  She asked if it was because the wines in screwcap were less expensive than those in cork (they weren't).  We do our best to match up the wine with the closure that best allows it to age and evolve gracefully, and the answer is not the same for all wines, any more than a one-size-fits all prescription for winemaking would be.  Tell a winemaker that he must choose either 100% barrels or 100% stainless steel tanks for everything in his cellar, and you'd have a revolt.  And yet most accept such a prescription for sealing their wines without question.

Spectator_cork_screwcap I guess I can see how consumers would find this difficult to understand; most of the coverage of alternative closures is terribly reductive, either taking the position that anyone who stuffs a piece of tree bark into a bottle of wine deserves the contamination they're likely to get, or in talking in mushy language about the romance of opening a cork-finished bottle of wine.  Probably the most public debate of this sort was played out in the March 15, 2005 issue of the Wine Spectator, where James Laube and James Suckling shared cover space with dueling articles entitled "Why I Hate Cork" and "Why I Love Cork".

It is undeniable that  a percentage of all natural corks are tainted by TCA, a chlorine compound that makes the cork (and any wine in contact with it) smell and taste musty.  Industry estimates range from 3% to as high as 10%.  Even at 3%, this is a terribly large number of bottles that are ruined each year.  For a winery of our size (our production of about 16,000 cases per year) this would mean that we'd send out over 5000 bottles that would be compromised.  If we were lucky, the consumer would recognize that this bottle was corky and would request a replacement.  If we're unlucky, the consumer just decides that he must not like Tablas Creek (or at least that particular bottling).  It's easy to see why so many winemakers are passionate advocates of alternative closures.

At Tablas Creek, we have bottled samples of the same wines, finished in both cork and screwcap, since 2002.  We have tracked their evolution to get some of our own impressions of what the various impacts of both options are.  When we taste the wines, we do it blind, and ask ourselves (and anyone who joins us for these tastings) to describe what we taste.  Matt Kramer included his experience in such a tasting in a thoughtful piece in the Wine Spectator in August 2004. 

We (and everyone who's joined us) describe consistent differences between the cork-finished and screwcapped wines, and have noted these differences as early as 3 months after bottling.  Wines bottled under screwcaps taste fresher, higher in acid, younger, tighter, and more mineral.  Wines bottled under cork taste softer, sweeter, richer, more open, and more evolved.  Which is better is not a simple question, and it depends on what we want out of the wine.  For an aromatic white, or for our Rose, we like the brightness and freshness that the screwcap provides, and feel that the screwcap will have the additional benefit of keeping these wines (which are typically meant to be enjoyed young) tasting youthful longer.  But those same characteristics do not benefit most of our reds, and they do not benefit our Roussanne-based whites, all of which we want to develop that softness and sweetness that time brings to wines meant to age.

There is logic to this.  Corks come from the bark of cork oaks, and have a flavor (if untainted) similar to gentle oak from a barrel.  In addition, they provide a measure of oxygen exchange with the wine (even if they provide a perfect seal between the wine and the outside air, corks contain oxygen in their pores and share that with the wine).  Screwcaps provide a better seal, but don't provide either the flavor exchange or the oxygen exchange that a cork does. (New models of screwcap allow a tiny oxygen exchange with the air outside, but are new enough that we haven't felt comfortable experimenting yet.)

So, next time you hear a winery declare that they've switched entirely to screwcap, or a writer rhapsodize the ceremony of opening a cork-finished bottle, I hope you resist the suggestion that things are so simple.  Rarely in life do either of two options, each with passionate advocates, have a monopoly on the truth.  The debate between cork advocates and screwcap advocates is no different.