I, for one, am pleased that wine bottles are no longer closed with oil-soaked rags as in the 1600s. Over the centuries, closures have improved considerably in reliability and variety. Does the wine require aging or is it ready to drink? Is it meant to be consumed at one sitting or does it call for a reliable stopper for reuse? From natural cork to crown caps, the needs of the wine can now be met.
NATURAL CORK is a traditional closure used for approximately 70% of all wine bottles and 90% of fine wine bottles. Fine wines are often more capable of aging well and need the porous material to allow a bit of oxygen in to slowly interact. Half of the world’s cork supply is produced in the cork oak forests of Alentajo, Portugal. These trees have a lifespan of 200 years, take 25 years to mature for harvest, and can be harvested only every 9 years. Half of the bark of the tree is peeled off and cut into large sheets. Cylindrical pieces are stamped out of the sheet and cut larger and longer than the bottle top area so that when they are pressed in they shorten and widen to form the needed seal. The remains are ground for use in either agglomerated corks (cork dust and glue) or retail items such as coasters and cork boards. The positives are that cork is renewable, recyclable, and biodegradable. The negatives are natural flaws and the possibility of 2,4,6-trichloroanisole (TCA) contamination. Flaws, such as cracks in the bark, make the material inconsistent in the amount of oxygen it allows in. TCA is the result of interaction between several substances, such as fungi, bacteria, mold, and pesticides. It has a musty smell and can ruin the wine that it touches. It can occur on the tree before harvest or in damp storage facilities after being stamped into corks.
SYNTHETIC CORKS are designed to mimic natural corks and made from plastic compounds. The positives are numerous: little risk of TCA, predictable consistency for the amount of oxygen they allow in and are produced with various levels of permeability, and they are less expensive than natural cork. The negative is that they are not biodegradable. Also, some winemakers prefer to adhere to the tradition of natural corks.
CAPPED CORKS are corks with a plastic or wooden topper to keep out oxygen. They are most often used for spirits that are likely to be opened and closed many times, for instance a fine scotch that is opened for a pour every couple of months. These are also often used in tasting rooms since the bottle will be opened and closed all day long for small pours but also needs some cover during the day.
SCREW CAPS function like the caps on plastic water bottles. Some are engineered to allow a precise amount of predictable oxygen exposure to the wines and some fully shut out oxygen and are used for drink-now wines. New Zealand championed these a couple decades ago and uses them for the vast majority of their wine bottle closures. They have the positives of not being subject to TCA and are easy to open and close.
HERMETIC CORKS are reusable and airtight. They are perfect for recorking a sparkling wine bottle and they stay put, thanks to their included clip. Pressure of a sparkling would push a non-se cured closure out, pretty quickly rendering it flat.
VINOSEALS are glass closures. They are pricey to produce and not good for wines that age, but they are lovely. They are perfect for rosés, where beautifully styling the bottle is a big focus and aging isn’t needed. They are so pretty that I keep a bowl of them out as decoration.
CROWN CAPS are often seen on beer but sometimes wines. They are popped off with a bottle opener, keep aging at bay, and are meant for products that do not need to be recapped. They are often a stylistic choice in an attempt to make the product seem more accessible and casual.
Don't judge a wine by its closure by assuming things such as a wine topped with a screw cap is of a lesser quality than one topped with a natural cork. Sometimes they are, but sometimes they aren't. There are a variety of reasons for the winemaker's choice and I don't let the type of closure influence my wine purchases. I urge you to do the same.
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