Lees, Sur Lie and Bâtonnage

Bâtonnage; a delightful word you may have seen on the back label of some French wines. More likely you’ve come across Lees (stirring) or Sur Lie (aging), as these are the techniques used on white wines from just about anywhere to impart extra flavour and texture into a wine that may otherwise be overtly crisp, light or fruit forward.

Being somewhat OCD when it comes to my interests it was only a matter of time before I delved deeper into what actually goes on with these techniques and the theory behind them – should you be of a similar mind then read on (otherwise just skip to the videos at the end for a visual demonstration of Bâtonnage).
The spur for today’s piece of obsessive activity came from an innocuous paragraph in Matt Kramer’s “Why words matter” piece on Wine Spectator (which is worth reading in itself to understand the concept of texture and mouthfeel), when he describes heavy-toast oak and lees-stirring as maquillage, or “makeup”! Layers of lees

First to the lees itself. This is the general term used for all the particles that exist in the wine after the main fermentation process which, if left in there, would result in a cloudy (and probably spoiled) wine.
Gravity causes these to deposit naturally at the bottom of the tank or barrel, but they can be easily stirred up again so the process of clarification includes racking (transferring the liquid above the sediment to another container) and, later on, fining or filtration to end up with the clear liquid most of us expect to find in the bottle.
(For more details on fining have a look at the fun article “Something Fishy” from Australian blogger Rhiannon Stevens).

There are 2 types of lees referred to post-fermentation; Gross and Fine.

  • The Gross (Fr. Large) Lees is the heavy sediment in a tank or barrel which is composed of primarily of larger grape particles such as seeds, skin, stems and pulp, plus tartrates and dead yeast cells. These settle out in a few days or weeks.
  • Fine Lees are mostly dead yeast cells that take longer to settle down, up to several months.

Most wines are quickly separated (racked off) from the gross lees as they can rapidly result in the creation of sulphur compounds which can lead to spoilage. However, white wine-making techniques typically result in less of the “bad” gross lees components after fermentation.
If managed carefully leaving the wine in contact with the lees can add to the flavour and texture of the finished wine as the yeast cells undergo autolysis (effectively cell “self-digestion”).

Yeast autolysis is at the core of fine sparkling wine production, such as Champagne (where lees contact can be anything from 18 months to several years) but for most white wines the Sur Lie (Fr. on the lees) process is considerably shorter.
During this time the cell decomposition release enzymes and chemical compounds into the wine; sugars, amino acids, fatty acids and mannoproteins which all add mouth-coating textures, toasty aromas and nutty flavour complexity to the wine if managed correctly. It can also be used to take the edge off harsh tannins or acidity, improve resistance to oxidation and assist malo-lactic fermentation.

However, if handled poorly the lees sediment can lead to the production of sulphur compounds such as hydrogen sulphide (rotten egg aromas) and thiols such as mercaptan (the smell added to natural gas so we know when its leaking).
To prevent this the lees must be regularly stirred to ensure smooth and controlled autolysis and this is where bâtonnage comes in, named for the French word for stick it is the term used for the mechanical technique of mixing the lees (typically in barrel).

Along with spoilage risks the Sur Lie technique is not without its style compromises, as the wine tends to lose some of its primary fruit aromas and flavours. Therefore use of the technique depends on the grape variety, the post-fermentation characteristics and the final style intended.
It is common in filling out the light, acidic wines of Muscadet from the Loire; in Burgundy (and around the world) for preparing Chardonnay for its (hopefully) long, developed life; but also for other white varieties where barrel fermentation and ageing is used, including South African Chenin Blanc and some Sauvignon Blanc (not the typical New Zealand style though).

I also came across several videos which explain and demonstrate the bâtonnage techniques.
As they say, a picture is worth a thousand words;

  • Jordan Vineyards (Sonoma, CA, USA).
    Good explanation of the Sur Lie technique and the practicalities of using it.

  • Goosecross Cellars (Napa, CA, USA).
    Demonstration of classic technique using a perspex barrel-top to see the action.

  • River Road Family Vineyards (Sonoma, CA, USA).
    Also a perspex barrel-top, but using barrel rolling to mix the lees rather than the classic stick technique.

So next time you see the term Sur Lie on a bottle, or hear the word Lees used, you’ll have a better idea why and how it all fits into getting the wine into your glass – and if you’re feeling ambitious try sneaking bâtonnage into a conversation (good luck with that!)

Slainte!

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