Electrodialysis and the Rathfinny Style

INNOVATING FOR SUSTAINABILITY IN ENGLISH SPARKLING WINE

In 2023, the Winery team at Rathfinny set up an experiment. In the Cellar, they sat two sets of 2022 Classic Cuvée side by side, one marked ‘Cold Stabilised’ and the other ‘ED’- short for electrodialysis. The bottles stayed there for three years.

The purpose was to explore new ways to innovate and improve the stabilisation process which ensures the wine doesn’t ‘gush’ or erupt when you open it. It’s energy-intensive and we’ve always been keen to find more sustainable methods of winemaking, in accordance with our B Corp values.

This is where electrodialysis steps in, using just 4% of the energy that the cold stabilisation requires while achieving almost identical results. But how does it impact the final wine?

The experiment reached its conclusion in September 2025. After 27-months in our temperature-controlled cellar, our winemakers sat down to taste the difference between wines.

In this blog, Production Manager Alex Rabagliati reflects on our experience using electrodialysis and shares a surprising discovery about how it shapes the taste, texture and profile of our wines.

WHAT IS ELECTRODIALYSIS IN WINE?

Electrodialysis is a modern method of wine stabilisation that uses a series of charged membranes to selectively remove ions: the tiny, charged particles that can later cause crystal formation in the bottle, creating a “gushing” effect on opening

Most sparkling wine producers use what is called “contact seeding” to remove ions and prevent crystals forming in the bottled wine. This energy-intensive process involves chilling and holding wine in-tank at sub-zero temperatures, and “seeding” it with finely-ground crystals to encourage the formation of larger potassium bitartrate crystals which can then be filtered from the wine. While effective, this process requires huge amounts of energy to chill and then maintain the wine at a low temperature. It also strips out delicate compounds that contribute to texture and taste.

The electrodialysis technique to achieve cold stability has the same effect with a tiny fraction (just 4%) of the energy for contact seeding. That makes it one of the most promising decarbonisation technologies in winemaking, and one highlighted in Wine Australia’s national sustainability strategy. In the UK, Rathfinny has pioneered the use of electrodialysis to achieve cold stabilisation, reducing our environmental footprint and ensuring the stability of our sparkling wines.

A MORE SUSTAINABLE APPROACH

Sustainability isn’t only about the Vineyard. It’s about every decision made along the journey from grape to glass.

Because electrodialysis works without deep chilling, which requires vast amounts of energy to bring large tanks of liquid to low temperatures, it dramatically reduces our energy requirements – typically saving us 18,000 kilowatt-hours a year – and carbon footprint, a key part of Rathfinny’s wider sustainability goals.

However, the benefits go beyond reducing our footprint. By avoiding extreme cold, we also preserve more of the polysaccharides and polyphenols that shape the structure, mouthfeel and ageing potential of sparkling wine. These are the compounds that give Rathfinny wines their creamy texture and long, refined finish.

HOW ELECTRODIALYSIS SHAPES THE RATHFINNY STYLE

In September 2025, the Winery team came together to conduct a detailed trial and tasting comparing the two treatments of our 2022 Classic Cuvée: one stabilised through electrodialysis, the other using the traditional contact seeding method.

In the lab, the electrodialysis wine showed higher acidity and lower volatile acidity. We could also taste a difference in the glass: the electrodialysis wine had a brighter, more fruit-driven expression with a crisp, refreshing profile.

The contact-seeded sample, by contrast, showed a deeper colour and broader palate with oxidative and nutty notes, a profile more typical of older, tertiary sparkling wines.

These initial tastings have shone a light on how electrodialysis supports the pure, elegant and aperitif-style structure that defines Rathfinny’s Sussex Sparkling wines. We’re excited to continue exploring and understanding how it impacts our wines.

A STYLE SHAPED BY AUTOLYSIS, NOT OXIDATION

A long lees-ageing process gives all traditional method sparkling wines their distinctive character, but it’s important to understand where that character comes from.

• Autolysis is the gradual breakdown of yeast cells, releasing mannoproteins and polysaccharides that contribute aromas of brioche, cream and biscuit while enhancing texture.

• Oxidation and Maillard reactions, on the other hand, produce deeper colours and flavours of nuts, caramel and honey, which are often mistaken for autolytic notes but are in fact driven by oxygen exposure and catalysed by metal ions such as iron, copper, magnesium and manganese.

Because electrodialysis removes many of these metal ions, it naturally inhibits oxidation and Maillard reactions, allowing autolytic complexity to shine through.

Our sparkling wines therefore show the elegant, biscuity characteristics of extended lees ageing, without the heaviness of oxidation.

SCIENCE IN SERVICE OF STYLE

By carefully managing ions in the wine, electrodialysis refines everything from pH balance to aromatic freshness. The result is a wine that retains its precision and energy for longer.

• Lower pH and brighter acidity enhance freshness and longevity.

• Reduced volatile acidity creates a purer, more defined fruit profile.

• Reduced metal ion content slows the development of tertiary aromas, preserving freshness.

• Preserved polysaccharides ensure a silky, mouth-coating texture.

PIONEERING A CLEANER FUTURE FOR ENGLISH WINE

Adopting electrodialysis is part of our ongoing commitment to innovation and sustainability. As one of the few UK producers using this technology, we see it not as a novelty but as a necessary step forward for English winemaking.

As part of the production team, my goal is simple: to craft world-class Sussex Sparkling wines while doing all we can to reduce our footprint. Electrodialysis allows us to do that, reducing energy use by over 90% at this stage of production while creating delicious and unique sparkling wines.