Why use corks for wine

And though new advances in winemaking technology mean that screw caps and artificial corks can work as well as the natural stuff, cork trees and their history are critically important, especially as climate change affects wine regions, growing seasons, and life cycles globally.

Like wine, cork comes from a living, breathing organism: Quercus suber, or the cork oak. Amidst the frenzied yearly cycle of the wine industry, these evergreen oaks move like sloths, slowly expanding and growing the bark, known as orange cork.

With an average lifespan of years, each tree can provide thousands of bottle stoppers when cared for properly.

The short version of the cork life cycle goes like this: Happy cork trees grow to age 25 in semi-arid forests surrounded by other animal and plant life on the Iberian peninsula and North Africa.

After that, skilled cork harvesters use axes to slice off the outer bark of the tree, leaving its inner wood intact and undamaged. Then, the planks of cork bark are dried, sorted, and processed. To make the bottle stoppers we know so well, slices of cork are boiled to remove impurities like the chemicals that cause cork taint and dried until they reach the optimum texture to be pressed into bottles. As a result, many vintners began abandoning cork in favor of alternative closures, like aluminum screw caps and plastic plugs, which also had the added benefit of lower cost.

Importing cork from the Mediterranean can be expensive, especially for wineries in New Zealand and Australia; by , most wineries in those countries had switched to screw-cap closures, which were also gaining prominence across the world. Though it has recaptured some market share in recent years, the cork industry is now fighting against the newly discovered appeal of plastic and aluminum. Screw caps are just easier to use. Plastic stoppers have also surged in popularity, now accounting for 10 percent of the wine-closure market.

A report by the Wine Market Council, a nonprofit association of grape growers, wine producers, importers, and other affiliated businesses, revealed that 65 percent of older Millennials over the age of 25 drink wine daily or several times a week; half of younger Millennials fell into the same category. Before cork taint frightened so many winemakers into abandoning cork, the material had helped to successfully preserve fine wines for centuries.

This feature allows a cork to be pressed into a smaller physical space and yet spring back to its original form when removed. Step after step, cork absorbs the pressure and then instantly springs back to its original form, no worse for the wear. Following the cork-taint scare, the cork industry set out to improve both its product and its image.

Cork producers invested in new equipment and worked to refine production techniques, contributing to a sharp decline in tainted wine. Screw caps can vary in price, depending on quality. Easy to open. Screw caps open with a simple twist of the wrist.

Negative environmental impacts. Screw caps are made from aluminum, which is often produced from a strip-mined ore called bauxite. Processing aluminum can be a dirty process, negatively impacting the air and water and generating about 70 million tons of waste annually. Their plastic liners, if not removed, can also make recycling impossible.

Some, like the California Office of Environmental Health Hazard Assessment, also consider it to pose possible health risks. Amcor, the company that makes Stelvin screw caps, recently released a PVDC-free range targeting countries like Germany which have restricted the material. Prone to reduction. The opposite of an oxidized wine is a reductive one , or a wine in which there is minimal contact with oxygen during the production process. However, the seal can prevent additives like sulfur from being absorbed into the wine the way a more porous cork would, exacerbating the effects.

Questionable aging ability. Cork versus screw cap aging has passionate advocates on both sides. Cork proponents say that the interaction between wine and oxygen facilitated by the naturally porous material is essential to the aging process of a cellarworthy wine.

Screw cap fans think otherwise, though neither side has proved their enclosure is better. Amcor has created multiple liners.

Synthetic corks can be made either from petroleum-based plastic or plant-based materials. Plant-based stoppers are made similarly, but use bio-polyethylene, a bio-based plastic made from ethylene, a byproduct of processing renewable raw materials like sugarcane. Synthetic corks are not prone to TCA taint. They provide predictable oxygen transfer rates and a tight, immovable seal. Synthetic cork can be up to three times cheaper than natural cork. Synthetic corks made from oil-based plastics are not sustainable or biodegradable.

Plant-based stoppers , however, use renewable resources and have a lower carbon footprint than their synthetic counterparts. Made from sugar cane, Nomacorc, produced by North Carolina-based Vinventions, are recyclable and carbon negative.

The company is also releasing a stopper made from recycled plastic. Hard to open and reseal. Many wine lovers groan at the sight of plastic-based synthetic cork, mainly because it tends to be the hardest wine closure to open, and some can be virtually impossible to put back into the bottle once removed.

Plant-based corks are often softer than plastic, making them easier to open. Chemical odor.