Cork. It’s more than a detail.

Susan R Lin is a Master of Wine and a Master of Fine Arts in Classical Piano and Musicology. She is the Head of Wine Expertise for San Francisco-based boutique fine wine retailer Belmont Wine Exchange, where every wine sold happens to be sealed with a cork.

Susan was named Master of Wine in 2021 upon the publication of her dissertation ‘Influences of Classical Music on the Perception of a Brut Non-vintage Champagne’.

Corks grace the bottles of many of the world’s most renowned wines. It’s no wonder: cork’s sustainability throughout the centuries and its ability to allow wine to age make it an invaluable asset. With the proliferation of alternative closures, how does cork compare? After studying numerous peer-reviewed scientific papers, I was struck not only by the contrasting influences of various closures on a wine’s sensory characteristics but even more so by the comparison of sustainability implications. The aggregated findings showed compelling reasons as to why cork has been, and continues to be, the world’s preferred wine closure.

Cork provides clear benefits as a wine closure. It does not impart off-flavors, as it does not aid the desorption of undesirable volatile compounds into wine. The small amount of controlled micro-oxidation from corks allows wine to maintain a trajectory of natural maturation. The oxygen is inside the cork cells – oxygen is not permeating from the atmosphere. The wine is thus allowed to evolve without risk of oxidation or reduction.

The exchange of gasses explains why studies of oxygen ingress show that bottles with natural cork “pick up” a small amount of oxygen over the first 6-9 months of aging.  After that, oxygen ingress is no longer significant. Artificial closures provide oxygen ingress primarily through permeation.  Oxygen passes directly through the closure from the outside air.  This can happen at a controlled rate, but unlike diffusion, the permeation does not stop.  Oxygen continues to enter the bottle at whatever rate is determined by the closure. A permeable closure is fine if you know how much oxygen you want to introduce and you know how long it will take for that to occur.  In the absence of that control, a natural cork is a preferable solution. Natural cork introduces a small amount of oxygen over the first 6 to 9 months. After that, additional oxygen ingress is virtually nonexistent, and if stored properly the wine will develop without reductive or oxidized flavors. – Source CQC

Strides in research have rendered cork taint moot in high-quality corks thanks to innovations such as industrial gas chromatography technologies to screen corks for TCA, providing the means to seal wines for the long term safely.

Alternative closures have their merits and can serve specific purposes. But when it comes to our impact on the earth as wine lovers, our choice in wine closures matters. The increasing frequency of extreme weather patterns makes it unequivocally clear that the longevity and viability of our world hangs in the balance. Using cork helps fight climate change by preserving some of the world’s largest oak populations from deforestation while providing viable jobs for agricultural workers. Nearly 7 million acres of these powerful carbon sinks retain up to 14 million tons of CO2 each year, a significant contribution to reducing greenhouse emissions that cause climate change. By supporting the use of cork, we support the protection of our world: cork oak trees are not cut down, instead, they are harvested and allowed to regenerate.

Even better, the harvesting, production, and afterlife of corks equate to zero waste. Every bit of cork harvested is used in countless ways. Even the dust resulting from cork production can be used to generate energy. Think about that: cork dust energy! And as cork is entirely natural, the environmental risk of its production and use is minimal. It’s recyclable and compostable.

As the wine industry seeks ways to reduce its carbon footprint, whether through recycled packaging or the use of lighter glass bottles, cork has captured the spotlight through its proven sustainability. When we use 100% Cork we not only promote a wine’s flavor profile and aid its longevity, we also help save the planet. I am grateful for all the scientific research conducted about different closures and their impact on wine quality and sustainability. We now possess even deeper insight as to why cork has been wine’s best friend for centuries. May this friendship endure.

CORK FACTS:

• Cork is a perfect balance between environmental preservation and sustainable development. As a foraged and not cultivated material, cork bark is a 100% renewable natural resource.
• The net effect of producing 1,000 natural wine corks is that you remove around 250 pounds of CO2 from the atmosphere, making it the most sustainable closure for eco-conscious wine drinkers.
• Compared to others, plastic closures take 9 times more greenhouse gas emissions to produce, while aluminum screw caps take 24 times the emissions to produce than natural cork. Both Aluminum and plastic closures take four times the non-renewable energy to produce, compared to natural cork stoppers.
• Until now, only the natural cork stopper has been able to provide this perfect balance, allowing for the consistent, slow oxygen transfer to enable the correct evolution of wine and the formation of tertiary-aged characters
• By using natural cork in your wines, you are an active participant in the fight against climate change.
• Cork is the ONLY sustainable closure.
• Sustainability does not end in the vineyard, it must be carried through to packaging as well.
• The cork oak forest is one of the world’s 36 biodiversity hotspots and can retain 14,000,000 tons of CO2 per year. It is estimated that for every ton of cork produced, cork oak forests capture 73 tons of CO2. The harvesting of cork does not damage but improves the health of the cork tree. After the harvest, the bark regenerates for the next 9 years until the next harvest, while continuously removing CO2 from the atmosphere. A single tree can be harvested up to 20 times and capture 20 tons of CO2 over its 200-plus-year lifetime.
• A new study by the Cork Quality Council (CQC), which evaluated the life cycle assessment of the three major closure types found that an average wine cork has a negative carbon footprint of -5 grams. But the net amount is -276 grams per cork when the biogenic carbon cycle of the cork oak forests is taken into account, as is specifically allowed by EU Product Environmental Footprint Category Rules based on Life Cycle Assessment standards established by the UN.
• The net effect of producing 1,000 natural wine corks is that you remove around 250 pounds of CO2 from the atmosphere, making it the most sustainable closure for eco-conscious wine drinkers.

by Susan R Lin MW for 100 Percent Cork/Colangelo & Partners – December 2022

Susan R Lin is a Master of Wine and a Master of Fine Arts in Classical Piano and Musicology. She is the Head of Wine Expertise for San Francisco-based boutique fine wine retailer Belmont Wine Exchange, where every wine sold happens to be sealed with a cork. In her independent consultancy, Susan focuses on the experience of music and wine by specializing in musical branding, pairings, and events. She is also a wine judge, speaker, educator, and writer.

Susan was named Master of Wine in 2021 upon the publication of her dissertation ‘Influences of Classical Music on the Perception of a Brut Non-vintage Champagne’. Her joy is to create memorable experiences through wine and the performing arts.