Lees ageing
A version of this article first appeared in Wine and Spirit in 2007, since merged into Harpers Wine and Spirit.
Even when those little gods of wine, the yeast, have done their fermentation job, they still do good work on wine, adding flavour, aroma, body, structure texture, weight, complexity, even petillance (that’s a faint sparkle, not a petulant little wine), and both protein and tartrate stability.
It’s important to discuss the right lees. Wine should always be taken of the gross lees (from the French for heavy), which in wine terms are gross (from the English for gross). It is only the fine lees that are potentially good for wine.
sur lie means ‘on the lees’
Essentially lees comprise dead yeast cells, and maybe some bits of grape skin and pulp that settle to the bottom of the vat at the end of fermentation.
This technique of leaving wine on fine lees mostly applies to white wines, but increasingly reds too are left on the fine lees for several months. The classic white wine example is Muscadet ‘sur lie’, from the Loire valley in France. ‘Sur lie’ means simply ‘on the lees’, So this style should have a bit more weight, substance and character than a straight Muscadet.
Lees ageing is taken to its apogee in traditional method bubblies, such as Champagne, Cava, Franciacorta from Italy and Cap Classique from South Africa.
Yeast autolysis (auto-breakdown of yeast cells by their own enzymes), as it’s called when used with bubblies, confers rich flavours of biscuit, brioche, white nuts such as almonds and macadamias, toast, even marmite notes which add depth, breadth and savoury character to the wine. Flavour crudely depends on the length of time the wine is in contact with the lees. So a Cava that has had the minimum nine months on lees will taste more of the original fruit than vintage Champagne, with at least three years on lees. Autolysis is also argued to give fineness and persistence to bubbles. And some argue that a greater integration of bubbles occurs with longer lees ageing.
stirring the lees lessens the risk of reductive conditions
Stirring the lees (battonage) in the barrel or vat is done to increase the effects of lees contact. This obviously cannot be done with traditional method bubbly, although some producers practise the art of poignettage where bubbly bottles are shaken to mix the yeast cells into the wine again, for example Gosset Champagne and Recaredo Cava. Stirring also minimises the risk of reductive flavours (think stink bombs and rotten eggs) occurring, which can develop under a thick layer of yeast cells. But slightly reductive conditions are good to help preserve primary fruit character, so it is a delicate balance to get the best from fine lees.
Mannoproteins are released naturally during lees contact. It is these that create a creamy, silky smooth mouthfeel, and a richer texture to the body of the wine. They are also important for wine stability.
A good, if expensive, comparison would be to choose a non-vintage and a vintage Champagne from the same producer.
