Alcohol Reduction: Spinning Cone Column and Reverse Osmosis
Two precision cellar technologies that let winemakers lower ethanol content post-fermentation while preserving the aromatic and structural character of the wine.
Spinning Cone Column (SCC) and Reverse Osmosis (RO) are the two most widely adopted post-fermentation dealcoholization technologies in the wine industry. SCC uses low-temperature vacuum steam distillation to selectively strip and then reintegrate aromatics before removing alcohol, while RO passes wine under high pressure through semi-permeable membranes to separate ethanol and water from larger flavor compounds. Both methods are approved under OIV guidelines and EU regulation, and have become key tools for managing climate-driven alcohol elevation.
- Flavourtech, headquartered in Griffith, New South Wales, Australia, was established in 1987 and commercialized SCC technology originally developed by Australia's CSIRO for sulfur removal from grape juice
- The SCC process takes approximately 20–25 seconds of product residence time in the column, operating under vacuum at temperatures between 28°C and 38°C across its two-stage process
- SCC uses a two-pass approach: the first pass at around 28°C strips delicate aromatics, which are condensed and stored; the second pass at around 38°C removes the bulk of the alcohol before aromas are blended back
- Reverse Osmosis forces wine through semi-permeable polyamide membranes under high pressure, typically 25–35 bar, allowing ethanol and water to permeate while retaining larger molecules such as polyphenols, pigments, and sugars
- The EU first permitted partial dealcoholization via physical separation techniques in 2009 under Commission Regulation (EC) No 606/2009, originally capping reduction at 20% of original alcohol content
- OIV Resolutions OIV-OENO 394A-2012 and 394B-2012, adopted in June 2012, further defined and expanded the permitted use of SCC and membrane techniques such as RO across member countries
- RO operated in diafiltration mode, where water is added back to replace the permeate volume, can achieve deep ethanol reductions but the addition of water is restricted or prohibited in some wine-producing regions
What These Technologies Are
Spinning Cone Column and Reverse Osmosis are mechanical dealcoholization technologies designed to lower wine's ethanol content after fermentation is complete, without the thermal damage associated with traditional distillation. The SCC, commercialized by the Australian company Flavourtech from 1987 onward, is a vertical stainless-steel column containing alternating rotating and stationary cones attached to a central shaft. Wine is fed in at the top and forms a thin film as it moves down the column under vacuum while steam rises counter-currently to carry off volatile compounds. Reverse Osmosis is a pressure-driven membrane process in which wine is forced through semi-permeable polyamide membranes; ethanol and water pass through to the permeate side while larger flavor-active compounds are retained in the concentrate, or retentate.
- SCC was originally developed by CSIRO in Australia and first applied commercially for sulfur removal from grape juice before being adapted for alcohol reduction
- RO membranes, often made of polyamide, allow ethanol and water to permeate while rejecting larger molecules such as polyphenols, organic acids, and sugars
- Neither technology requires chemical additives; both rely entirely on physical separation principles
- Both methods are now recognized and permitted under OIV guidelines and have been approved in the EU since 2009
How Each Process Works
The SCC alcohol reduction process operates in two distinct stages. In the first stage, wine is fed into the column at a low vacuum pressure and temperature of around 28°C; the centrifugal action of the spinning cones spreads wine into a thin film, and the most volatile aromatic compounds evaporate and are condensed and stored for later reintegration. In the second stage, the dearomatized wine is processed at a slightly higher temperature of around 38°C to remove the bulk of the alcohol. The recovered aromas are then blended back into the dealcoholized wine. The entire residence time in the column is approximately 20 to 25 seconds, minimizing heat exposure. In Reverse Osmosis, wine is pressurized against a semi-permeable membrane at typically 25 to 35 bar. Ethanol and water molecules are small enough to pass through to the permeate side, while larger compounds including tannins, pigments, and most flavor-active molecules remain in the retentate. The permeate, containing alcohol and water, can be processed to strip the ethanol, and the water fraction is returned to the wine. When operated in diafiltration mode, water is continuously added to the retentate to replace the permeating volume and sustain the concentration gradient.
- SCC first-pass temperature of around 28°C is low enough to protect delicate aromatic compounds from degradation
- RO operates at ambient or near-ambient temperature, avoiding any thermal impact on heat-sensitive volatiles
- RO in diafiltration mode can achieve deeper reductions but adding water back to wine is regulated or forbidden in some appellations
- Multiple RO passes or varied membrane selection can be used to fine-tune the degree of ethanol removal
Effect on Wine Style and Quality
When carried out within modest reduction targets of 1 to 2% ABV, both SCC and RO can preserve the essential aromatic, structural, and chromatic character of a wine. The SCC's two-stage approach, which captures and reintegrates aromatics before removing alcohol, is designed specifically to minimize aromatic loss. However, research has shown that some aromatic loss during the alcohol-removal pass (particularly the second stage of SCC) is unavoidable, and the degree depends heavily on operating conditions. RO studies have demonstrated that modest reductions of around 2% cause minimal changes to phenolic composition, while deeper reductions of 4% or more can affect flavan-3-ols, anthocyanins, and volatile esters. Alcohol contributes body, warmth, and texture; larger reductions risk thinning the mid-palate and shortening the finish. Aromatic white varieties and lighter reds are particularly sensitive to over-treatment.
- RO at low transmembrane pressure causes minimal phenolic changes at 2% ABV reduction targets
- Studies show RO results in significant decreases in total acidity, volatile acidity, and some organic acids alongside ethanol removal
- SCC aromatic losses are most pronounced during the alcohol-removal stage, even with prior aroma capture
- Post-reduction aging can help re-integrate wine components and partially restore perceived complexity
When and Why Winemakers Use These Tools
The primary driver of SCC and RO adoption has been the steady rise in grape sugar levels caused by warmer vintages and climate change, which translates directly into higher finished alcohol. Winemakers in warm-climate regions where Shiraz, Grenache, and Zinfandel routinely reach 15% ABV or more often deploy these technologies to bring wines into balance after achieving full phenolic ripeness. The technologies are also used by producers seeking to enter markets where high-alcohol wines attract punitive excise duties or by those targeting a food-friendly style without sacrificing ripeness in the vineyard. SCC and RO can also be applied to rescue overripe lots in hot vintages. In Europe, these methods were used covertly for years before the EU formally permitted them in 2009; anecdotal evidence suggests widespread use in Barolo and Barbaresco as early as the mid-1990s.
- Most commonly applied to Shiraz, Grenache, Zinfandel, and other warm-climate varieties where 15%+ ABV is routine
- European producers used spinning cones informally before EU legalization in 2009 under EC Regulation 606/2009
- High excise tax thresholds in some markets, such as the 14.5% duty point in some countries, incentivize modest alcohol reduction
- Premium producers often deploy these tools quietly as a safety net in hot vintages rather than as a standard production step
Commercial Adoption and Industry Context
Flavourtech, based in Griffith, New South Wales, is the principal commercial manufacturer of the Spinning Cone Column and has sold systems to producers across more than 60 countries. ConeTech, established in 1991 and based in California, is a major toll-processing provider of Very Low Temperature Distillation services to wineries in the United States that do not own their own SCC equipment. The technology spread from its origins in Australian and Californian winemaking into European regions, including Piedmont and Bordeaux, where it became a hotly debated topic in the early 2000s during the modernist versus traditionalist controversy in Barolo and Barbaresco. Both SCC and RO services are now also available via toll processors, making the technology accessible to smaller producers without capital investment in equipment.
- Flavourtech was established in 1987 in Griffith, Australia, and commercialized SCC technology originally developed by CSIRO
- ConeTech, a California-based toll processor, was established in 1991 and pioneered commercial alcohol-removal services for US wineries
- Toll processing makes both SCC and RO accessible to smaller producers who cannot justify the capital cost of dedicated equipment
- The use of spinning cones in Barolo and Barbaresco was reportedly widespread in the mid-1990s, predating EU legalization by over a decade
Regulation and Transparency
The European Union formally permitted partial dealcoholization using physical separation techniques, including SCC and RO, through Commission Regulation (EC) No 606/2009. Initially limited to generic wines and subject to a cap of 20% reduction from original alcohol content with a minimum final level of 9% ABV, the rules were subsequently refined through OIV Resolutions OIV-OENO 394A-2012 and 394B-2012 and later EU CAP reform legislation. EU member states retain the right to impose stricter rules for wines with protected designations of origin, meaning that individual appellation regulations may effectively discourage or prohibit these practices even where EU-level rules allow them. In the United States, both methods are permitted as oenological practices. The addition of water during RO diafiltration remains a regulatory complication in some wine-producing countries and regions where adding water to wine is explicitly prohibited.
- EC Regulation 606/2009 first formally authorized dealcoholization by physical separation in the EU, originally with a 20% reduction cap and a 9% ABV minimum
- OIV Resolutions OIV-OENO 394A-2012 and 394B-2012 further codified the use of SCC and membrane techniques internationally
- EU member states may impose stricter rules for PDO wines, meaning appellation-level restrictions can effectively prohibit use even where EU rules permit it
- Adding water during RO diafiltration is prohibited in some regions, limiting the depth of reduction achievable without regulatory issues
A wine where alcohol has been reduced by 1 to 2% ABV using SCC or RO typically retains the varietal aromatic character, color intensity, and tannin structure of the original wine. The SCC two-stage process is specifically designed to preserve top-note florals, fruit esters, and spice by capturing and reintegrating aromatics before the alcohol-removal pass. Well-executed modest reductions are often imperceptible in blind tasting. Larger reductions of 3% ABV or more carry a measurable risk of reducing mid-palate warmth, thinning body, and shortening the finish, as alcohol contributes significantly to texture and the perception of richness. Acidity may also appear more prominent once the softening effect of ethanol is reduced.