Oxidative Aging Without Flor (Oloroso, Madeira Canteiro Method)

Oxidative ageing is one of the two types of crianza carried out in the Jerez region: the wine is stored and developed in wooden butts, where it undergoes slow, physico-chemical development influenced by surrounding conditions. Legally, it is the type of crianza in which wines age without velo de flor and exposed to the direct action of the oxygen in the air. It contrasts with biological ageing, in which a film of flor yeast protects the wine from oxidation by preventing direct contact between the liquid and the air in the butt. Beyond Jerez, Madeira's canteiro is oxidative ageing in cask, and gradual exposure to air shapes older Tawny Port.

• Fortification to 17% ABV or more kills any flor yeast, committing the wine to purely oxidative development
• Butts are not usually filled to the top, and because the wood is permeable to oxygen, it admits a gradual but continuous dose of oxygen into the wine.
• Oloroso ranges from rich amber to deep mahogany in colour, and the darker the wine, the longer it has been aged
• Oxidative ageing can be done statically, without blending wines of differing ages, but the traditional system in Jerez is the dynamic criaderas y soleras system

Several changes run in parallel while the wine sits in cask. Acetaldehyde levels increase as wines age due to chemical oxidation of ethanol, and above 125 mg/L acetaldehyde can impart sherry and nut-like characters. Over years in cask the wine is also enriched by subtle, specific contributions from the wood of the butt, which is thoroughly wine-seasoned before being put into service. In Madeira, heat plays a further role: estufagem, used for inexpensive wines mostly made from Tinta Negra, is artificial heating that caramelises the sugars and, in one wine magazine's phrase, lends something of a 'maderised' taste. In Jerez, evaporation through the butt, known as merma, accounts for losses of 3 to 5 percent per year of the total wine stored, and because the loss is essentially water, the wine's other components are continually concentrated.

• The sensory characteristics of oxidation include sherry-like and madeirised aromas, and for some wine styles, such as sherry, oxidation is deliberately encouraged
• Oloroso can reach alcohol levels even above 20% simply as a result of long ageing, because the cask lets a good amount of water evaporate, concentrating the alcohol and the other components
• In Oloroso the content of both alcohol and glycerine increases over time, giving smoothness and a certain unctuousness on the palate
• Biological ageing works the other way: the flor consumes glycerine and volatile acidity and brings a substantial increase in acetaldehydes

Oloroso ranges from rich amber to deep mahogany, with a predominantly nutty bouquet of walnuts, toasted, vegetable and balsamic notes reminiscent of noble wood, golden tobacco and autumn leaves, and spicy, animal tones suggestive of truffles and leather. On the palate it is full flavoured, powerful and full bodied, smooth from its glycerine content, with an elegant dry finish. In older Tawny Port, gradual exposure to air concentrates and intensifies the original fruit, with honey and spices touched with aromas of dry peaches, hazelnuts and vanilla.

• Oloroso analytical profile: 17 to 22% alcohol by volume, under 4 g/L sugar, 4 to 6 g/L total acidity and 8 to 10 g/L glycerine
• Under the 2026 Pliego, Oloroso is old gold to dark mahogany, with aromas of nuts and wine-seasoned noble woods, possibly with caramelised or varnish notes, and a dry, balanced taste
• Amontillado ranges from pale topaz to amber with hazelnut and plant aromas; those aged longer under flor are paler, while in others the spice and wood of oxidative ageing predominate
• 20 Years Old Tawny is more developed and concentrated because the wine was aged in small oak casks, with aromas reminiscent of toasted vanilla and dried fruits

The solera and criaderas system in Jerez involves tiered scales of barrels: young wine enters the top tier and is progressively blended downward, with the floor-level solera being drawn for bottling and replenished from the criadera above. The withdrawal of wine is called the saca and the topping up the rocío, with the youngest scale refreshed from the añada system. Under Jerez norms, the total volume of a solera system divided by the volume withdrawn from it each year must be greater than two, with the aim that no sherry reaches the market with less than two years of ageing. Madeira uses two ageing processes, estufagem and canteiro. Canteiro wines, named after the wooden beam supports (canteiros) on which the casks rest, age in cask, normally on the upper floors of the lodges where temperatures are higher, for a minimum of two years, and may be sold only after at least three years counted from 1 January of the year after the harvest. In estufagem, the wine is placed in stainless steel tanks heated by hot-water coils to 45 to 50 degrees Celsius for no less than three months, followed by a rest of at least 90 days at ambient temperature, and estufagem wines are mostly blends.

• The preferred and most widely used Jerez cask is the 600 litre American oak butt, also called a bodega butt; the 2026 Pliego limits ageing casks to 1,000 litres
• In solera wines aged non-biologically, the oxygen introduced during decanting operations accelerates the oxidative processes of maturation
• Blandy's ages canteiro wines in American oak casks in the warm attics of its lodge and uses the method for wines of a superior quality
• Madeira is fortified by stopping fermentation with wine alcohol at 96% vol, timed to the sweetness sought, giving dry, medium dry, medium sweet and sweet wines

Oloroso is the Jerez wine of fully oxidative ageing: the 2026 Pliego classes it as a wine of exclusively oxidative ageing after the initial velo de flor disappears. Palo Cortado is also aged oxidatively; its young wines were first fortified to 15% for biological ageing and later refortified to 17%. The aged categories are over 12 and over 15 years, plus VOS (over 20 years) and VORS (over 30 years), and a bodega must keep at least 20 litres in the ageing system for every litre of VOS it sells, and at least 30 litres for every litre of VORS. In Madeira, Blandy's, founded in 1811 by John Blandy with his brothers Thomas and George, ages its wines in lodges whose layout, shape and structure create a combination of temperature and humidity conditions stretching from the cellar up to the highest attics. For Port, the wood-matured Tawny style covers Tawny Reserve, 10, 20, 30 and 40 Years Old Tawny and Colheita.

• Oloroso: fortified to 17% by volume, it ages in constant contact with oxygen as it descends through the criaderas and solera system
• Palo Cortado: similar to Oloroso but with a lighter structure, its alcoholic strength usually between 18% and 20%
• Madeira canteiro: oxidative ageing in cask that develops intense and complex aromas, with wines aged in cask for anything from five to 50 years at ambient temperatures in warm lofts
• Colheita Port: single-vintage Tawnies aged in cask for a minimum of seven years

Jerez producers use one grape variety, Palomino, to make five different types of wine, and the amount of fortification alcohol determines whether ageing will be biological or oxidative. Wines classified for Fino and Manzanilla are fortified to 15% by volume, enough for flor yeast to form but intolerable for other micro-organisms; the flor then covers the wine and prevents its oxidation. Wines for Oloroso are fortified to at least 17%; above 17% not even flor yeast can survive, so the wine loses the film and begins a slow but inexorable process of oxidation, seen in its gradually darkening colour. Amontillado bridges the two: it ages first under flor, then the flor begins to disappear and a second, oxidative stage gradually darkens the wine and enhances its concentration and complexity.

• Fino and Manzanilla: fortified to 15% by volume and protected from oxidation by the flor; the 2026 Pliego sets Fino at 14 to 17% alcohol
• Oloroso: fortified to at least 17%, exclusively oxidative ageing, old gold to dark mahogany
• Amontillado: biological then oxidative ageing, pale topaz to amber; the 2026 Pliego sets it at 16 to 22% alcohol
• Glycerine: the flor feeds on alcohol, any unfermented sugar, glycerine and oxygen, while in Oloroso the glycerine content increases over time

Primary sources (Consejo Regulador Jerez-Xérès-Sherry, IVBAM, IVDP, AWRI, Blandy's): https://www.sherry.wine/documents/597/21052026_Pliego_Jerez_1wBQg8y.pdf, https://www.sherry.wine/sherry-wine/production/ageing, https://www.sherry.wine/sherry-wine/production/fortification, https://www.sherry.wine/sherry-wine/dry-sherry-wines/oloroso, https://www.sherry.wine/sherry-wine/dry-sherry-wines/amontillado, https://www.sherry.wine/sherry-wine/special-categories, https://www.sherry.wine/sherry-cask/types-of-sherry-wine, https://www.sherry.wine/news/abc-fortified-wines-jerez, https://vinhomadeira.com/o-vinho-madeira/vinificacao-e-envelhecimento, https://www.ivdp.pt/en/wines/port-wines/special-categories/, https://www.ivdp.pt/en/wines/port-wines/the-winemaking/, https://www.awri.com.au/industry_support/winemaking_resources/sensory_assessment/recognition-of-wine-faults-and-taints/wine_faults/, https://blandys.com/en/about-madeira-wine/, https://blandys.com/en/about-us/. Secondary source: https://www.decanter.com/premium/understanding-the-different-madeira-styles-413857-413857/. Last verified 2026-10-04