Put a Cork In It

Most people only think about the cork in a bottle of wine when there is something wrong with it. The dreaded “it’s corked” comment, which frequently encompasses a range flaws that may not be the fault of the cork, often comes up. When the cork works well, we barely think about it.

Screwcaps: Not Just for Cheap Wine

The screwcap closure, often known as the Stelvin, used to be associated with only the cheapest of wines. A lot of time and effort was invested by its adherents to change the minds of consumers, helped in no small part by the success of Australian and New Zealand wines. These were, at least to the North American market, the first significant wine-producing countries to wholeheartedly embrace the screwcap.

Screwcap supporters trumpeted its ability to preserve freshness and maintain the integrity of the wine — it was going to taste exactly as the winemaker intended, with no chance of corked flavours or other imperfections. This is not entirely true, but a screwcap is still better than a plastic or latex cork, at least when it comes to midterm or longer storage and consumer acceptance.

These are good arguments, but I think it’s worth mentioning that it would cost an awful lot of money to ship a lot of cork to that part of the world.

Faults from Closures

The problem with screwcap wines is that the closure forces some changes and if not closed properly, the wine can be reductive when opened. The winemaker needs to control things such as hydrogen sulphide presence (a by-product of winemaking) and a few of the stabilizing compounds.

A cork is able to absorb the compounds that cause problems because they allow a tiny bit of breathability and are slightly porous. A screwcap doesn’t have the same breathability and the stabilizing compounds can cause a wine to become flat, deficient or to develop a rotten egg character. Most wineries are pretty good about controlling reductive faults in their wine, but it is not a failsafe closure.

Cork Taint

Cork is a renewable resource and a tree will be harvested for its bark 15 or so times over a lifespan of up to 200 years. Wine closures are the top value-added product for cork producers (corkboards, insulation, shoe soles, baseballs and other products provide much lower value,) and producers spend a lot of time, money and resources trying to fix the cork problem of 2,4,6-trichloroanisole (TCA,) which is the cause of that infamous fault.

Cork (TCA) taint has received a fair bit of press over the last few years and for a while, it seemed to be the nail in the coffin for cork producers. Producers have tried bleaching, microwaving and boiling corks in order to get rid of this compound. Unfortunately, its properties (thermal and acoustical insulation, its compression and its resistance to fluids and gas transfers) make cork taint very hard to prevent.

Amorim and Sustainable Corks

Amorim produces about a quarter of the 12 billion wine corks consumed globally each year and about one third of the total corks produced. I had a chance to visit the cork producer on my recent trip to Portugal.

During my visit, I learned that Amorim is very focused on sustainability. They told us that the production of plastic closures emits 10 times more carbon dioxide than cork and the production of aluminum screwcaps emits 24 times more carbon dioxide than cork.

Cork is a sustainable product, however it is not easily compostable or biodegradable. Many wine corks are slightly coated to make them easier to extract from the bottle and some of the composite corks are produced with food safe glues that don’t compost very well.

Cork recycling programs are in the works, but they are mostly slated for shredding and repurposing into products like shoe soles. If you are looking to compost your wine corks at home, fair warning, it may take a while. Shredding might help, but don’t blame me if you get in trouble for using the coffee grinder or blender to chop up your corks.

What do I do with all my corks? Like any good wine geek, I have a couple…hundred corks floating around the house — special bottles, old bottles, neat corks, etc. But they get thrown out when I’m not looking.

Happy composting!

Photo: Matti Mattila