December 16, 2008 |
What's up with screwcaps?
One of the questions that I am asked most often is why don't you use a cork? My answer is always, because corks are not as good for wine.
It is really tempting to choose a seal based on aesthetic appeal and familiarity. Corks are nice. The seal has a direct impact on minor little things like quality, stability, longevity, etc. The truth is that the choice of closure can play as much of a role in determining wine quality as winemaking techniques and viticultural practices since a cork-affected wine makes all of your hard work pointless.
There are four main conditions which must be satisfied to create a successful wine closure. It must:
- offer a reliable seal
- present an inert substance to the wine
- be easily removable
- be available at a low cost
Against these criteria, the screwcap has proven to be the most dependable closure currently available. Here are 20 reasons for choosing a screwcap thanks to Tyson Stelzer from his book Taming the Screw: a manual for winemaking with screw caps.
- Screwcaps remove the risk of cork taint which spoils an average of somewhere between 5% and 15% of cork-sealed wines - that's like one bottle in every case. Cork taint or TCA is created when the bark from the cork oak comes in contact with chlorine. The effect on the wine is gross - moldy, wet cardboard, or wet dog characters. It suppresses the fruit and shortens the length of the finish of the wine. When it it is really subtle, TCA has a slight dulling effect on the nose and palate. Low levels (as low as 1 part per trillion) oppress fruit characters by 45%, and at the other extreme, high levels make a wine nastily unapproachable. It is the frustration with cork taint that has been the primary motivation for the uptake of alternative closures across the wine world in recent years.
- Screw caps remove the threat of sporadic oxidation. The cork can be an awesome wine closure when it works exactly like it's supposed to. However, corks are natural and natural variation in corks dictates that inconsistencies exist, such that only a small percentage of corks actually achieve this ideal. After cork taint, the most significant problem with corks is that of sporadic oxidation, aka 'random oxidation'. It involves arbitrary bottles which develop more rapidly as a result of ingress of oxygen through or around the cork. The result is premature browning (in both white and red wines), maderized characters, loss of primary fruit, a general flattening of flavors, a shortening of the length of finish and, at its most extreme, a vinegar or bitter taste. Driven closures such as corks and synthetics rely on the elasticity of the closure to provide the seal between the closure and the glass. This seal can be corrupted by imperfections in the closure or bottle. While good natural corks can produce a good oxygen barrier, their inherent variation means that many corks do not provide a good seal. Natural corks contain large holes, which are often adjoining, cracks, and insect holes which can allow oxygen to pass through or around the cork.
- Screwcaps avoid flavor modification.