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D - 38: Corks from Sardinia

Updated: Mar 26, 2021

When sailing along the coast of Sardinia, we probably won’t see the Oak forests, which cover around 90’000 hectares of the island or 4% of its surface. They grow in the mountains to the east on an altitude between 500 – 900 meters. But we will definitely hold the bark of these trees in our hands when we open Sardinian wine. Cork Oaks - Quercus Suber, a species of the oak tree family – love granites and moderate climates. The eastern part of Sardinia is an ideal home. They have always been native to Sardinia and were already there when the Phoenicians arrived.

Corks as we know them today

Cork Oaks can actually be found around the entire Mediterranean and were known by many cultures. Cork, the bark of the Cork Oak, was used as floaters for fishing nets, as material for sandals due to its shock absorbing nature and for building homes since it isolates so well. It has a unique honeycomb cellular structure with lots of empty cells, which makes it light. A Cork Oak takes about 20 years to reach full height and for the bark to be thick enough to be harvested. After the first harvest, the process can be repeated every nine years. The trees produce usable bark until they reach the age of 150 years – so the locals say. Today, about 70% of the global cork production is used for making wine stoppers.

Old English wine bottle before glass blowing became industrialized

The use of cork to seal wine bottles is a relatively recent innovation. As seen in previous blogs, Greeks and Romans transported and preserved wine in wax-sealed amphorae. Glass bottles – invented by the Phoenicians - were already in use since 400 BC. Not to store wine but to distribute it from the amphorae to the tables. Neither Greeks nor Romans could fully solve the problem of wine oxidation, meaning their wines turned inevitably into vinegar. But since alcohol killed bacteria, it was consumed nonetheless. We all remember the story from the New Testament when Roman soldiers gave Jesus a sponge with vinegar to quell his thirst. What I once thought was particularly cruel turns out to be the Legionnaire’s daily drink. They had an allocation of 1 liter of wine per day – am sure it was vinegar like.

The problem was not solved in the Middle Ages either but it was less pressing then. Wine was not consumed on large scale anymore and replaced by beer. The main consumer of wine was the church - I know you now think of drunken monks – but it was needed to celebrate Holy Mass. Produced mostly by monasteries – without monasteries wine cultivation would not have survived in Bordeaux – the wine was as sour as vinegar and the difference between the two was probably gradual. The best way to store wine was the oak barrel invented by Gallic people during Roman times. An oak barrel was easy to seal and wine could be protected for a short time. But it was not satisfactory. That bottles were not used was also reflected in the medieval tax code. Wine was taxed by barrel.

One of Madame Pompadour's refined quotes. The popular version is "La vie sans bulle est nulle"

The people who complained loudest about sour wines were the nobles who had the money to buy it and wanted good quality on the table. A market with customers eager to pay for a solution existed. But - as always - technical progress was needed.

Low and behold, it arrived. Not from where you think. It required the early industrialization of England to provide a solution. The key challenge for sealing wine was the individual shape and size of glass bottles. Everyone was manually produced and thus different. Compare once your manually blown champagne glasses at home and you will discover that they all look slightly different. Sometimes in the early 18th century, English glass makers cam up with the idea of a standard mold, which allowed them to blow glass bottles to standard size. This was particularly important for the production of Champagne, which required standardized, strong bottles to mature into the fizzy drink we love today. Dom Perignon is usually credited with the invention but it was not him – he produced white wine not Champagne. Never found out who was the first English producer of standard glass bottles – would be interesting to know but is beyond today’s blog.

Once standardized bottles were in available, corks as a standard wine stopper could be used. It was squeezable and would hold tight. Today, the opening of a wine bottle is 18.5 mm wide – I guess you never thought about the fact that all corks are of the same size. They have to be in order to make the bottling process efficient. Imagine you would have to cut every single cork individually before you could insert it! You would seal a few bottles a day only.

Manual corking machine from 1870

Selling Champagne in bottles caught on during the reign of Louis XV. – his mistress, Madame Pompadour, was from the Champagne area. Doing what a king does best, Louis XV changed the tax code. From now on, wine and Champagne were taxed by the bottle.

Using cork as wine stopper and seal is not the perfect solution. A tiny bit of air still gets into the bottle. But it was so much better than anything else before. From the 19th century on, wine could be kept for years instead of weeks. Also, it could be easily shipped and sold to markets, which were completely out of reach before. There would not be a global wine culture without standard bottles and corks.

Sardinia’s Cork Oaks got a new lease of life. Demand for it grew almost exponentially 200 years ago as the new technology spread. Even with today’s screw caps and plastic corks it is still high. Whether the industry is going to survive is to be seen. But I know many people who refuse to drink a fine wine when the bottle comes with a screw top or a plastic cork.

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