Sniffing The Cork, Screwcap Closures and the Facts About Wine Headaches

My brother says that the reason you smell the cork offered to you by the waiter at a restaurant is so you can tell if you should reject the wine in the bottle as being “corked.” Is that why people smell corks?  Do you need to do that or should you just taste the wine? Can I tell if a cork I want to use to bottle
my wine with is bad just by smelling it before it goes into the bottle?
Anna Diaz
Santa Fe, New Mexico

You are more in the right here than your brother; when buying wine at a restaurant you really just smell and taste the wine. If the wine smells and tastes fine to you, and you can’t pick up any cork taint, go ahead and approve it. Cork taint detection is very much as reliant upon our own individual sensory thresholds as it is upon the actual level of the “corked” compounds in the wine. Believe it or not, the “cork-taint” defect, attributable to, trichloroanisole (TCA) or related haloanisole compounds (molecules containing different numbers of halogen atoms, either chlorine or bromine), can manifest in the wine alone and may not actually be caused by the cork, or by the cork alone per se.

The haloanisole most commonly found in wine is TCA. It is widely known as the “cork-taint” compound, but contamination of wine during the production or cellaring process is also possible. There are other haloanisoles like PCA (pentachloroanisole) and TBA (tribromoanisole) which are biodegradation by-products of compounds that could be present in chlorine bleach, sanitizers, flame retardents and wood preservatives. Any of these can be present in the winery environment and though it’s unlikely that any of these things are getting into wine vats, mold spores that have interacted with these items could conceptually come into contact with the wine. These scenarios are quite unlikely but one that isn’t is the ubiquity of mold on barrels. Moldy barrels plus winery water that contains chlorine can be a TCA taint issue that is just waiting to happen.

Corks aren’t the only potential source of TCA in wines. The haloanisoles can be transferred into wine through a cellar’s atmosphere or by contact with contaminated materials from tank coatings, hoses, barrels, oak chips, filter pads, and additives such as bentonite. These smelly compounds (the haloanisoles which are often described as having “musty,” “moldy,” or “wet- cardboard-like” aromas) aren’t themselves transmitted from these sources into wine but are metabolic products of naturally-present fungi. For example, if certain fungus species come in contact with a chlorine molecule (in the winery’s water supply for instance) the fungus may metabolize (digest and spit out) trichloroanisole.

Interestingly, a cork may smell “tainted” and the wine below it might be just fine, or, better said the wine in the bottle may be below your TCA threshold. Especially in summertime, when warmer ambient temperatures mean that every aroma (good and bad ones alike) will be more apparent to your senses, be sure you sniff the wine itself, and not just the cork, to make sure you’re not buying a tainted bottle.

I notice these days that more and more wines on the shelves have “screw cap” metal closures instead of the more traditional cork. In this magazine I notice that you almost always talk about corks. I know some of your own wines are bottled under screw caps (I’ve had Garnet Vineyards and Layer Cake wines). Can you tell us why you make that choice, how do you think the consumer perceives screw caps? Are they still considered cheap? If you make the screwcap choice for your own wines why do you still write so much about corks here?
Maria Stange
Novato, California

Those are all great questions, let me see which order I’ll tackle them in. Firstly, we discuss corks for the most part on the pages of WineMaker Magazine not because they’re the only closure choice out there available to winemakers but because they’re simply the easiest closure for home winemakers, i.e. winemakers that typically bottle only a few cases of wine at a time, to use. You see, applying a metal screw cap (sometimes called a “twist-off” in the trade) requires a special machine as part of the bottling process that just isn’t available to the majority of folks making wine at home. Sure, if you know someone well in Wine Country and they have a small bottling line with a screw cap applicator machine in-line, you might be able to convince them to allow you to bottle your barrels, but it’s not a machine available at most homebrewing and home winemaking supply stores. If you make wine on a carboy-scale (5–10 gallons/19–38 L) there’s no way that it’s practical for you to put your wine through a winery bottling line — that volume wouldn’t get anywhere near to filling up the pipes leading to the filler bowl. Which is why, for small volumes we still talk largely about corks and not screwcaps as the bottling solution for our readers. Once a seal on a twist-off is broken, it’s not really completely 100% resealable. Small amounts of oxygen and spoilage microbes may enter your wine. For long-term wine storage, I would prefer to use a traditional cork than try to use, over and over again, a twist-off bottle. A couple of handfuls of good-quality corks and an analog no-electricity-needed hand-corker machine (which can be rented from your friendly neighborhood home winemaking store) are all you need.

Which is not to say that corks are without their problems. As I’m sure you know, corks can be a source of “cork taint” (trichloroanisole) contamination, which smells swampy and in high levels can ruin a bottle of wine. Which is one of the reasons more and more winemakers in the commercial space (as I have with the Garnet Vineyards wines I make) are bottled with a twist-off closure.

It’s not just your imagination that you’re seeing more twist-offs on the market shelves. I recently read an article that stated 38% of US wineries are using screw caps for some or all of their wine, “up from a mere 4% in 2004.” Especially in whites, pink wines, and Pinot Noir (which may have more to do with perceived consumer acceptance and conservative marketing than actual wine aging dynamics) screwcaps are to be found everywhere and in every price point. Flavor and aging-dynamic wise, I like how a screwcap is predictable and consistent for wines. Corks are nothing but a plug of tree bark, with all the good (“traditional” visuals and marketing signaling), bad (uneven expansion into bottle necks which can mean premature oxidation and bottle variation), and ugly (possible TCA). Far from signaling cheapness, quality twist offs actually are right up there in cost with corks. Twist offs have other benefits besides being TCA-free. They can be fully recycled along with your glass wine bottle, they don’t require a corkscrew (what other consumer product that you know of requires a specialized tool to access it?) and they can be easily sealed up again. I believe in quality and convenience, and evidently so do a lot of other winemakers, which is why I like to use twist-offs for Garnet Vineyards. I worked for Bonny Doon Vineyards for about five years during the time when that innovative winery was switching over from corks to twist-offs so I gained a confidence with this closure. However, best-quality corks are still simply the easiest closure for smallest-scale winemakers to find, buy and utilize.

I saw an article on Facebook about a tool that reduces the amount of sulfur dioxide (sulfites) in a glass of wine. Their claim is you could then drink wine without getting a hangover or “wine headache.” Do you think this is legit?
M. Alice Waymack
Poughkeepsie, New York

I’ve seen a few of these kinds of articles (ahem, I mean advertisements) floating around on the internet and it always results in an epic Wine Wizard “facepalm” upon reading.

For starters, sulfur dioxide doesn’t contribute to hangovers. This has been proven time and time again, so much so that I sometimes feel like a broken record when I talk about it. There are indeed people with a true “sulfite allergy,” i.e. they lack the digestive enzyme sulfur dioxide dehydrogenase and know to stay away from wine, beer, deli meat, dried fruit, and any number of other food products that contain sulfites. However, they constitute less than 0.10% of the population in general.

Indeed, there is no such thing as a sulfur dioxide-free wine as yeast cells naturally produce 10 ppm or even more during a natural yeast fermentation cycle. Dr. Linda Bisson from UC-Davis, a source I often consult about these kinds of issues, wrote as part of a response to me, “People do not realize that we make grams of SO2 per day in our own bodies and those folks who are sensitive (to sulfites) have an enzyme deficiency.”

Dr. Andrew Waterhouse, also of UC-Davis, further elaborated, “Most studies of sulfites overlook the fact that we produce almost a gram of sulfites in our cells every day. Thus a few milligrams from a glass of wine, etc, is hardly going to overload our natural systems for breaking down  the sulfite.”

It is so tempting to blame sulfur dioxide (SO2) for hangovers. After all sulfur has always had something of a devilish reputation. Unfortunately, for those touting SO2-free wine as being headache and hangover-free — the facts say otherwise. Most evidence suggests that the true culprit of the “red-wine headache” (aside from the obvious dehydration and effects of ethyl alcohol, the largest hangover culprit) is actually naturally-occurring histamines that are products of fermentation. Histamines are histidine-derived amine compounds found in many foods and all fermented drinks. Some people are more sensitive to them than others. They are particularly associated with red wines because these are made using the grape skins, and it is probably no coincidence that more people seem to get red wine hangovers and headaches than those drinking white. In fact white wine typically contains more SO2 than red.

For anyone to suggest they are marketing a tool or gadget that will prevent hangovers and enable you to drink as much alcohol as you like, consequence-free, is irresponsible. Removing sulfites in wine (even if their tool is effective as advertised) will not remove biogenic amines and ethyl alcohol, the two main contributors to the negative “morning after” effects of drinking.