Sokol Blosser Wine Blog

First, let me say that I hate corks. They definitely can have an impact on the wine. Corks are generally acknowledged to be responsible for causing taint in anywhere from 2-5% of wines bottled with them. The taint is caused by the presence of the chemical trichloroanisole (TCA), which is formed by the activity of the microorganisms that cause mold. The chemical may be present in the cork bark when it is still on the tree and can also be formed during the processing that converts the bark into wine stoppers. TCA, if present, may migrate from the cork into the wine and alter the flavors and/or aromas, but it is important to understand that there is absolutely no actual mold or fungus in the wine, and there is no health risk at all. And TCA, again if present, may be there in incredibly small amounts -- it is detectable in levels as low as two parts per trillion in white and sparkling wines and as low as five parts per trillion in red wines. One part per trillion would be the equivalent of one gallon in a trillion gallons. It's difficult to conceptualize such a miniscule concentration, but it would be analogous to a teaspoon in a couple of thousand olympic-sized swimming pools or one second in 32,000 years.

In some cases the taint is severe enough that it is obviously the cork causing the problem, and the consumer realizes that. Although I hate that, I actually prefer it to the scenario in which the cork taint is very slight – just enough to depress the fruit or make the wine taste a little off. In that case the consumer might not be aware that the cork is the problem and will just think that the wine is not very nice. The severe cork taint bottle is infuriating to both the producer and consumer, but hopefully the consumer will contact the producer and the bottle can be replaced. In the case of the insidious low-level taint bottle, the consumer will probably just decide that he or she doesn't like the wine and never contact the producer.

Even though I hate natural corks because of the spoilage potential, we have made a very conscious decision to continue with them because of our strong commitment to sustainability. Our core values compel us to examine every step in the winegrowing and winemaking process. We have to care as much about how we make the wine as the wine itself.

Having already addressed the major negative issue with natural corks, here are the positives:
• Most cork comes from Portugal where the trees are a protected resource, subject to a code of good practices to ensure sustainability. Many of the forests are managed organically. Cork oak forests are one of the most successful examples of sustainable agroforestry in the world.
• Cork oak forests provide valuable habitat for in incredible diversity of species, especially endangered birds like the rare black stork.
• Cork is a renewable resource. The bark is stripped from the tree about every nine years, after which it grows back. Cork oaks can live for hundreds of years.
• Cork is recyclable. Wine corks can be collected and remanufactured into numerous other products. There is a growing worldwide movement to collect and recycle corks.
• Cork is biodegradable. A cork that goes into a landfill will eventually degrade and dissolve.
• Cork is lightweight, chemically inert, moisture and rot resistant.

Here are the reasons we haven’t switched to synthetic (plastic) corks:
• They are a petroleum-based product and are not recyclable on the consumer level. A plastic cork that ends up in a landfill will be there essentially forever.
• They are not proven for long-term storage and have, in some cases, been found to contribute plastic flavors and/or aromas to the wine.
• Maybe most seriously, the wine would be in contact with the plastic, potentially leaching out carcinogenic plasticizers.

Aluminum screw caps are currently the most promising alternative, but they also have issues. Here are the reasons we haven’t switched to screw caps:
• Aluminum is not a renewable resource and is not biodegradable.
• It takes a tremendous amount of electricity to manufacture aluminum, and many (if not most) of the caps would probably not be recycled.
• There is a plastic liner in contact with the wine, so again there is the plasticizer extraction potential.
• Recent findings have raised questions about the aging of the wine under screw caps. It seems that the guarantee of an absolutely airtight seal can cause the wine to develop differently. In the absence of any oxygen, the wine can become what is chemically called “reduced�; that is, it can form sulfur-based compounds like hydrogen sulfide (the smell of rotten eggs) and mercaptans (a skunky smell). Proponents of screw caps acknowledge this possibility and say that winemakers may simply have to adjust their winemaking and bottling protocols. This is a new issue and not yet well understood.

There is just now another new alternative closure emerging – a glass stopper (like the top of a decanter). This could snap up some market share, since it is a much more upscale concept than the screw cap (which has cheap, jug wine connotations). However, it uses a silicone (plastic) gasketing system to make the seal, and requires an aluminum capsule over it to hold it in and ensure tamper resistance. So again, plastic and aluminum.

As synthetic corks, screw caps and other alternative closures become more widely used and the natural cork manufacturers see their market share decreasing, they are all working like mad to come up with a solution. Over the past few years they have made some progress (the percentage of tainted bottles has dropped), but they have still not solved the problem. They may be getting closer – there are new methods for removing TCA using everything from supercritical CO2 extraction to gamma ray irradiation.

Since there is still no perfect closure at this time, we continue to opt for the natural cork, the most sustainable choice.