Dealcoholisation methods Membrane techniques
MethodReverse osmosis
Pressure and a dense membrane: ethanol and water cross as liquid. Not osmotic distillation. Diafiltration is a step, not another method.
- 1 Pressure Wine is forced against a 0.1–1 nm membrane.
- 2 Permeate Ethanol and water leave; acids and tannins stay.
- 3 Wash RO water is added and the pass is repeated (diafiltration).
| Driving force | High pressure against a dense filter |
|---|---|
| What leaves | Ethanol and water as liquid (permeate) |
| What happens to water | Water has to be put back (diafiltration) |
| Heat | No boiling; sometimes cold (Ariel below 13 °C) |
| Type | Method Part of Membrane techniques |
|---|---|
| Developer | Generic membrane technique, no single owner |
| Volume loss | Low if volume is put back; water leaves with the ethanol |
| Final ABV | As low as <0.5% with repeated diafiltration |
| Wines known to use it | Ariel (California); WIN (Spain), for partial removal |
| Best for | Delicate wines where acidity and phenolics must stay intact, and aroma can be recovered in a separate step. Also 1–2% cuts. |
What it is
Reverse-osmosis membranes do not boil the wine: they push it under high pressure against a semipermeable filter (pores of 0.1–1 nm). Ethanol and water go through as liquid; acids, tannins and colour stay. That is the point when structure matters and heat is off the table. Aroma and texture still need watching.
Nobody owns it. Regulation (EU) 2021/2117 covers it under “membrane techniques”, alongside nanofiltration and osmotic distillation. Those three are not interchangeable.
How it is not osmotic distillation
In reverse osmosis, liquid flows through a dense hydrophilic membrane, driven by hydraulic pressure. In osmotic distillation the wine does not cross the membrane: ethanol moves as vapour through the pores of a hydrophobic membrane, at ambient temperature and without high pressure. Putting volume back is different too: here water leaves with the alcohol, so it has to be restored; there you lose only the volume of the ethanol you took out.
Diafiltration and nanofiltration
RO water is added back to the retentate to wash out more ethanol and restore volume. Filter then dilute, and ABV can fall below 0.5% without heat. That is diafiltration: a step in the recipe, not a method of its own. One pass is rarely enough.
Nanofiltration is the looser cousin in the same pressure family: it holds back fewer small molecules and runs at higher flux, at the cost of letting through more than ethanol and water. In the cellar it is used mainly for cuts of one or two degrees, often then coupled to osmotic distillation of the permeate (the Memstar scheme). It does not, on its own, take wine to 0.0% as cleanly as repeated RO.
Upsides and limits
The matrix is treated gently: it protects exactly the acidity and phenolics a thermal process puts at risk. The nose can fade unless aroma is recovered somewhere else. The energy bill comes from high pressure and membrane area, not from heat.
Wines that use it
Ariel, among the earliest recognised no-alcohol brands in the United States and best known for its Cabernet Sauvignon, is made on a patented “cold filtration” route: reverse osmosis with the wine held below roughly 13 °C (55 °F) throughout.
WIN, from Bodega Win, uses reverse osmosis for partial dealcoholisation of Matarromera whites and reds, and spinning cone when the target is 0.0%. A useful reminder that the two families are not mutually exclusive.
Reverse osmosis and nanofiltration membranes are also well documented in peer-reviewed work as an effective if imperfect route to low- and no-alcohol wine. Across the trade they remain the everyday tool for small alcohol adjustments of a degree or two, not only for stripping wine to zero.