Ageing fizz: crown cap or cork?

Sur-lie ageing is an imperative step in Champagne production, though the nuances behind how it’s done remain aplenty.
Recently, numerous Champagne producers have begun eschewing secondary fermentation/ageing under crown capsules and replacing them with cork closures. Although costly – and labour intensive – for many, the decision to use corks is one worth pursuing, despite the upfront investment.
We spoke to three local vignerons about the intricacies of ageing Champagnes under cork, as well as how doing so affects final wines.

The benefits of micro-oxygenation

Juliette Alpis, winemaker at Ludes-based Domaine Les Monts Fournois, chose to age her first batch of estate-produced Champagnes – which have yet to be released – under cork, thanks to the influence of her cousins’ estate, Champagne Bérèche et Fils, which has been implementing the practice for multiple generations.
“The cork stopper allows micro-exchanges between the oxygen present in the air and the wine in the bottle,” she explains, stating that the chemical reactions carried out during the wines’ ageing period will be significantly different from bottles aged without oxygen exposure. Alpis finds that these micro-exchanges with oxygen ultimately result in Champagnes with more aromatic complexity, as well as a finer mousse characterised by smaller bubbles.
Cédric Moussé, winemaker at Cuisles-based Champagne Moussé Fils, echoes this point, emphasising that the quantity of gas exchange through cork ageing is starkly different from that of a crown cap – and, moreover, this exchange changes over time.
“The cork is very tender in the beginning, so there is more gas exchange,” he explains. Moussé notes that as time goes on, the corks become more like wood, and can ultimately provide a tighter closure than those provided by crown caps. “With crown caps, the [minimal] gas exchange is always the same.”

Prolonging micro-oxygenation

For winemakers like Alpis, who vinify their wines in barrel prior to bottling, ageing wines under cork creates an even more consistent exchange with oxygen throughout the entire vinification and ageing process.
All the musts at Domaine Les Monts Fournois are fermented entirely in barrel (450L or 600L), which introduces the wine to oxygen interaction from the beginning. “In this way, the wine has learned to live and exchange with oxygen from its earliest days,” she says, describing the act of ageing under cork as a “logical continuation” of the vinification process.
“It is important for me to carry out a linear vinification,” she says, emphasising the consistency that ageing under cork provides. “My wish is that the wine does not have any [stark] jumps in ageing conditions and temperatures,” she says, affirming that a gentle and steady ambiance is ultimately better for the wine.

Additional labour – and cost

However, prolonged labour – and supplies – come at a premium. Winemaker Etienne Calsac (of his eponymous, Ludes-based estate) reiterates that the cost of a regular Champagne bottle is already higher than that of a standard wine bottle, plus factoring in the additional costs incurred from using corks over capsules.
“Additionally, one needs to use top-quality corks to avoid contamination with the taste of cork at this stage in vinification,” he says.
With regards to TCA, Alpis states that the risk is very low, as cork makers have recently been able to identify traces of TCA, for example using Amorim’s NDTech screening.
Moussé notes that the production cost of ageing under cork generally adds €2-3 per bottle, depending on the corks used, though this doesn’t include the cost of added labour.
“The disgorging of bottles corked with crown caps can be mechanised, though those aged under cork must be disgorged individually by hand,” explains Alpis, citing the rate of mechanical disgorging as 1,400 bottles per hour, versus just 400 per hour when done by hand. “Of course, this manual disgorging takes time, and is more expensive, but it’s worth it for the qualitative gain,” says Calsac.
Similar to Alpis, Moussé cites that disgorging by hand takes him around four times as long as when done mechanically, but the outcome is worth the output. “The pleasure in this is that you touch each bottle, taste the mousse from each one. I love that!”

Time gained under cork

Although ageing under cork incurs additional labour and expenses, the process can actually end up saving time.
“Traditionally, the ageing under cork is often reserved for vintages intended for a long ageing in the cellar – think seven or eight years or more; personally, I use cork for those with shorter ageing, such as two or three years,” says Calsac, who explains that the strong exchange with oxygen in the first few years helps to “erase the ‘yeast’ side of young wines”, which ultimately yields clean aromas after a shorter period of time.
“I’ve done numerous trials and found that ageing my Clos des Maladries cuvée aged under crown cap for four years is no more interesting than when aged [for shorter periods] under cork, so the shorter ageing period equally brings the benefits that I’m looking for,” he says, adding that cork ageing also renders the wines creamier and more accessible.
Similarly, Moussé finds that having higher levels of oxygen during the prise de mousse period creates a more complete final wine (often with less residual sugar), as well as lengthens its ageing potential.

‘Champagne aged under corks will be fresher and have more tension’

Alpis notes that the aromatic complexity found in Champagnes will be perceptible and more accessible in those aged under cork versus crown cap. “The sensation of reduction notes after long periods of sur-lie ageing are less noticeable in wines aged under cork versus crown cap,” she says, citing fine and delicate bubbles as an additional benefit.
Additionally, Alpis shares that post-disgorgement, new cork stoppers (“shipping corks”) are added prior to market release – and surprisingly, one can actually tell if a Champagne was aged under cork upon opening it. “If this is the case, the bottle will have a square ring with pronounced [ridges], intended to allow stapling [to secure the cork],” she explains.
Though above all, the quality and complexity offered by the method speak for themselves, and Moussé sums it up best: “Champagne aged under corks will be fresher and have more tension – and the ageing potential becomes wonderful!”

This article was originally published by our friends at Wine-Searcher.