Sur Lie Aging

Lees are the deposits of dead yeast cells and other particles that precipitate to the bottom of a fermentation or aging vessel once fermentation is complete. The AWRI describes fermentation lees as primarily made up of yeast cells, tartaric acid salts, bacteria, phenolic material and remnant grape solids. Winemakers generally distinguish between gross and fine lees. Gross lees are the larger particles, including yeast cells and grape matter such as pieces of skin, stem and seed; fine lees are smaller, take longer to settle, and are the ones associated with a desirable impact on the finished wine. Gross lees tend to settle naturally and are generally separated from the wine quite quickly; Decanter notes that they can lead to the development of undesirable aromas and flavors. When wine is left on its fine lees, the dead yeast cells go through autolysis: their internal structures are destroyed by their own enzymes. This self-destruction releases a spectrum of compounds into the wine, including mannoproteins, polysaccharides, amino acids, and fatty acids. The AWRI notes that yeast cell components reach the wine through both passive transfer from the cells and autolysis, and names amino acids, polysaccharides, mannoproteins and fatty acids as the most important yeast-derived compounds for improving a wine's sensory properties. According to Decanter, mannoproteins reduce tartrate precipitation and promote protein stability.

• Gross lees are generally separated from the wine quite quickly; fine lees are the ones associated with a desirable impact on the finished wine.
• Fine lees are smaller particles that take longer to settle and interact with other compounds in the wine.
• The AWRI lists increased texture, greater oak, fruit and yeast integration, and more complexity among the reported benefits of lees contact.
• Mannoproteins reduce tartrate precipitation and promote protein stability (Decanter).

Autolysis is the breakdown of dead yeast cells by their own enzymes. In traditional method sparkling wine, WSET explains that the lees break down over time in this way, releasing aromas such as brioche, toast, pastry and cream. WSET notes that the longer a traditional method wine remains on its lees, the more intense and complex its brioche, toast, pastry and cream aromas become. Decanter names acacia, oatmeal biscuit, brioche, bread dough and toasted nuts as flavors telltale of sur lie ageing, and describes autolysis releasing sugars and peptides that contribute to an unctuous, buttery mouthfeel. Lees also protect the wine. The AWRI notes that lees can scavenge oxygen entering through the barrel staves and the bunghole, especially when they are stirred, which can mean lower concentrations of SO2 are needed to prevent oxidation. Decanter adds that lees serve as micronutrients for the lactic bacteria that carry out malolactic fermentation. How long lees contact lasts depends on the producer's preferred style: Decanter puts it anywhere from a few weeks to several years.

• The AWRI notes that lees can scavenge oxygen entering a barrel, especially when stirred, which can reduce the SO2 needed to prevent oxidation.
• WSET: the longer a traditional method wine remains on its lees, the more intense and complex its autolytic aromas become.
• Decanter lists acacia, oatmeal biscuit, brioche, bread dough and toasted nuts as flavors telltale of sur lie ageing.
• Lees serve as micronutrients for the lactic bacteria that perform malolactic fermentation (Decanter).

Sur lie aging is most closely associated with traditional method sparkling wines, white Burgundy, and Muscadet. In Champagne, the process occurs in bottle following secondary fermentation. The INAO specification text for AOC Champagne (2019) does not allow disgorgement until twelve months after tirage, during which the wine must stay in bottle without interruption, and the Comité Champagne's 2025 appellation fact sheet gives minimum cellar ageing of 15 months for non-vintage and 36 months for vintage Champagne. Vintage Champagne requires a minimum of 3 years on lees; in practice, according to the Comité Champagne, vintage Champagne is nearly always matured for 4 to 10 years, and non-vintage for 2 to 3 years. In Cava, the ageing categories run from a minimum of 9 months in bottle for Cava de Guarda, through 18 months for Cava Reserva and 30 months for Gran Reserva, up to 36 months for Cava de Paraje Calificado, which Decanter describes as 36 months of lees aging. Franciacorta Riserva requires a minimum of 60 months on lees. For still wines, the INAO states that Muscadet Sèvre-et-Maine wines are aged on their fine lees at least until 1 March and until shipment, and reserves the 'sur lie' mention for wines bottled in the cellars where they were made before 31 December. InterLoire says the Muscadet Sèvre-et-Maine crus communaux, such as Clisson, Monnières-Saint-Fiacre and Gorges, are aged 18 to 36 months on lees. The INAO's 2018 specification text for the regional AOC Muscadet also provides for the 'sur lie' mention: such wines spend only one winter in vat or barrel and are still on their fine lees when bottled. The same text dates the rules for the traditional 'sur lie' mention to 1977. White Burgundy is aged sur lie in barrel: the AWRI notes that barrel lees contact is most commonly associated with Burgundian Chardonnay and Muscadet, and Decanter names Burgundy and Burgundy-inspired Chardonnays around the world among the wines that owe their identity to lees ageing, though stirring is not applied everywhere (see the bâtonnage section).

• Champagne: disgorgement no earlier than 12 months after tirage; release after at least 15 months (non-vintage) or 36 months (vintage) of cellar ageing.
• Muscadet Sèvre-et-Maine: on fine lees at least until 1 March after the harvest; 'sur lie' wines are bottled in the cellars of vinification before 31 December (INAO).
• Cava ageing categories run from 9 months (Cava de Guarda) to 36 months (Cava de Paraje Calificado); Franciacorta Riserva requires 60 months on lees.
• The INAO specification for the regional AOC Muscadet allows its name to be completed by the mention 'sur lie' for wines that meet the conditions set for it.

In traditional method sparkling wine, lees aging takes place inside the bottle. WSET describes a second fermentation inside the bottle, followed by ageing on the lees: as fermentation finishes, the yeast cells die and form lees. In Champagne, the Comité Champagne explains that the bottles are then taken down to the cellars where, undisturbed and protected from the light, they mature on lees. The yeasts die and decompose (autolysis), while minute quantities of oxygen enter the bottle and small amounts of carbon dioxide escape, leading to slow oxidation of the wine. The Comité Champagne describes a steady temperature of around 12°C as crucial for the best ageing conditions. Decanter notes that lees help limit oxidation and create a generally reductive environment, and that extended lees ageing in bottle (late disgorgement) is sometimes associated with greater ageing potential and more complex aromas, while also helping to preserve freshness for longer. At the end of the aging period, riddling (remuage) is used to consolidate the lees sediment in the neck of the bottle, after which disgorgement removes the lees before the wine is finished and sealed for release. WSET notes that a small amount of wine and sugar, the dosage, is added before the bottle is sealed again.

• Traditional method sparkling wines undergo a second fermentation in the bottle, followed by ageing on the lees (WSET).
• The Comité Champagne describes a steady cellar temperature of around 12°C as crucial for lees maturation.
• Riddling collects the sediment in the neck of the bottle; disgorgement then removes it before the dosage is added and the bottle is sealed again (WSET).
• Tank method wines spend little or no time ageing on lees, with the focus on preserving primary fruit and aromatic freshness (WSET).

Barrel lees contact is most commonly associated with Burgundian Chardonnay and Muscadet, and the periodic stirring of the lees in barrel, known in French as bâtonnage, is often performed, although the AWRI notes that the practice has pros and cons. Decanter says that by increasing the contact surface between wine and lees, bâtonnage encourages greater unctuosity and lees-derived aromas; it also ensures homogenous contact with the lees and prevents the accumulation of hydrogen sulfide. The AWRI adds that lees scavenge oxygen especially when they are stirred, but that excessive stirring can introduce too much oxygen, leading to the loss of SO2 and potentially the formation of acetaldehyde and acetic acid. Bâtonnage is not universal: Jean-Charles Thomas, winemaker at Maison Louis Latour, told Decanter that lees ageing and stirring give pretty much the same result, that the choice is essentially stylistic, and that no or very little bâtonnage is practised at Maison Louis Latour. In Champagne, the bottles mature undisturbed on their lees until riddling and disgorgement.

• Bâtonnage increases the contact surface between lees and wine, encouraging greater unctuosity and lees-derived aromas (Decanter).
• Stirring prevents the accumulation of hydrogen sulfide and helps lees scavenge oxygen (Decanter, AWRI).
• Excessive stirring can introduce too much oxygen, with loss of SO2 and potential acetaldehyde and acetic acid formation (AWRI).
• At Maison Louis Latour, no or very little bâtonnage is practised; its winemaker calls the choice between stirring and resting essentially stylistic (Decanter).

Lees ageing can lead to unwanted volatile sulfur compounds (VSCs); the AWRI says they are more likely to form in wines fermented in tank, because of the relatively lower oxygen concentration, or when insufficient oxygen is introduced by stirring. That is why, according to the AWRI, lees ageing is most commonly performed in small oak barrels. For tank-fermented wines, the AWRI says the problem can be largely negated by storing the lees in barrels for a few days and later recombining them with the wine. Other risks the AWRI lists include 'leesy' and 'cheesy' sensory characters, and acetaldehyde and acetic acid when stirring and topping introduce excessive oxygen. In a study of Chardonnay kept on lees for 180 days, cited by the AWRI, tyramine and histamine concentrations were higher than in the same wine stored in barrels without lees, particularly when the wine was stirred. Stylistic fit matters too. Where the aim is primary fruit, as in tank method sparkling wines, lees time is short: WSET says tank method wines spend little or no time ageing on lees, the focus being on preserving primary fruit and aromatic freshness. In a barrel-fermented Chardonnay trial by Brajkovich (2008), cited by the AWRI, the wine that was neither stirred nor topped was preferred after four months and described as fresher and with more varietal definition. Decanter adds that ageing on the lees requires technical knowledge and an acknowledgment of the desired style of wine.

• Unwanted VSCs are more likely to form when initial juice solids are above 200 NTU or when stirring introduces insufficient oxygen (AWRI).
• Lees ageing is most commonly performed in small oak barrels; lees from tank-fermented wines can be stored in barrels for a few days and recombined with the wine (AWRI).
• In the Brajkovich (2008) Chardonnay trial, the wine that was neither stirred nor topped was preferred after four months as fresher and with more varietal definition (AWRI).
• Tyramine and histamine were higher in a Chardonnay kept on lees for 180 days than in the same wine without lees, particularly when stirred (AWRI).

Primary sources (the Australian Wine Research Institute, the Comité Champagne, the INAO, InterLoire and WSET): https://www.awri.com.au/industry_support/winemaking_resources/winemaking-practices/winemaking-treatment-lees-contact/, https://www.champagne.fr/en/about-champagne/how-champagne-is-made/maturation, https://extranet.inao.gouv.fr/fichier/PNOCDCAOC-Champagne-20190619.pdf, https://www.champagne.fr/system/files/2025-09/FICHE%20AOC%20CHAMPAGNE%20EN%202025.pdf, https://www.inao.gouv.fr/node/37679/printable/print, https://extranet.inao.gouv.fr/fichier/CDC-Muscadet-PNO.pdf, https://www.vinsdeloire.fr/fr/vins-loire/muscadet-sevre-et-maine, https://www.wsetglobal.com/knowledge-centre/blog/2026/a-guide-to-sparkling-wine-production-methods-and-regional-styles. Secondary: https://www.decanter.com/learn/what-is-sur-lie-ageing-and-what-does-it-do-to-wine-ask-decanter-465202/, https://www.decanter.com/learn/advice/what-are-lees-in-wine-ask-decanter-377513/, https://www.decanter.com/learn/advice/lees-ageing-batonnage-taste-353099/, https://www.decanter.com/sponsored/is-this-a-bottle-of-d-o-cava-513546/. Last verified 2026-09-28