Vitis & Winemakers managing director Paul Baggio explains in the latest edition of Grapegrower & Winemaker Magazine, how electro-membrane technology is changing tartrate stabilisation and the role of refrigeration in the winery.
For decades, wineries across Australia and New Zealand have relied on a straightforward trade-off for tartrate stability: cool the wine, hold it cold for long enough, and remove the crystals that form.
Contact-and-hold cold stabilisation is proven and widely used. But it is also one of the more energy- and resource- intensive processes in the winery, drawing on refrigeration capacity, tank time, water and labour, often with consequential impacts on wastewater systems. It also has a limitation: calcium tartrate instability, an increasingly recognised issue in some wine styles, is not addressed in the same way as conventional cold treatment of potassium bitartrate instability.
Electro-membrane technology, commonly referred to as electrodialysis (ED), offers a fundamentally different approach. Rather than chilling wine to force nucleate crystals, it uses an electric field to selectively remove the ions responsible for instability, continuously and at ambient temperature, without relying on a large refrigeration load.
What’s changed in recent years isn’t the underlying science. It is the economics, scale, reliability and accessibility of the technology.
There is, however, a bigger change occurring. Electro-membrane tartrate stabilisation is only one part of a broader technology shift across the winery. Processes that historically created significant refrigeration demand, from juice clarification through to post-fermentation clarification and tartrate stabilisation, are increasingly being reconsidered through continuous, ambient-temperature process technologies. The result is a narrowing range of winery operations for which aggressive cooling steps are strictly necessary.
Cation- and anion-selective membranes have been used in Australian wine applications for around 25 years. Early systems were specialised, membrane stacks were expensive, water consumption significant, and the overall economics difficult for many wineries to justify.
Much of that has changed. Global investment in desalination and industrial water treatment has dramatically expanded the use of the same underlying technologies, membranes, membrane stacks, electrical systems, controls, skids and pumping systems, broadening the supply chain, increasing manufacturing scale, and progressively reducing equipment and membrane costs. Systems that were once difficult to justify commercially are becoming increasingly accessible to wineries.
The modular architecture of modern systems also allows processing capacity to be scaled: a winery can install a system around its current production requirements and expand membrane capacity as throughput increases.
How the electro-membrane process works
Wine passes through a stack of alternating cation- and anion-selective membranes under an applied electric field. Potassium and calcium ions migrate through the selective membranes into a separate concentrate stream, leaving a treated wine stream that continues to storage or further processing. Rather than precipitating crystals in a tank, the process changes the wine’s ionic balance so that it no longer supports crystal formation under defined stability conditions. Treatment can be controlled against conductivity and/or analytical targets, allowing it to operate continuously and inline.
This is fundamentally different from contact-and-hold stabilisation. The wine does not need to be taken to sub- zero temperatures and held for weeks to achieve the desired result. Because the process manages ionic concentration rather than temperature, it can address both potassium and calcium stability within the same treatment regime.
The refrigeration question is becoming much bigger
The discussion around winery refrigeration has traditionally centred on how much cooling capacity is required. A more relevant question for the modern winery may increasingly be: how many winery processes actually require refrigeration at all?
This is where several technology developments converge. Continuous and static flotation have reduced the industry’s historical reliance on prolonged cold settling of juice, the objective of removing solids and producing clarified juice remains the same, but the process no longer necessarily needs the extended cold storage and settling once considered standard. Advances in post-fermentation clarification are having a similar effect. Bucher Vaslin's Flavy FGCM technology, for example, provides a membrane-based clarification platform that can operate without the cooling traditionally associated with certain clarification processes.
The significance isn’t that any one process can now run at ambient temperature, it’s that several are moving that way at once. Continuous flotation, static flotation, improved centrifugation, membrane clarification and electro- membrane stabilisation each address a different part of the traditional process chain. Individually, each removes a fairly specific refrigeration requirement; collectively, they begin to challenge the assumption that a modern winery needs to carry large refrigeration infrastructure to support a series of processes that have traditionally been temperature dependent.
The real cost of conventional cold stabilisation
The refrigeration bill is only part of the picture. A typical contact-and-hold cycle involves holding tank capacity for extended periods, cooling and maintaining the wine at the required temperature, crystal accumulation and the subsequent tank cleaning it demands, additional wine movements, potential wine loss through lees and cleaning, water consumption, labour, and downstream loading on wastewater and trade-waste systems.
Potassium bitartrate removed from the wine ultimately has to go somewhere. The resulting deposits and cleaning streams add solids and ionic loading to winery wastewater systems and settling ponds. None of these costs appear on the refrigeration electricity meter, but they contribute to the actual cost of achieving stability.
The structural cost of the refrigeration ring main
There is another cost that’s often overlooked. Many wineries run glycol or ammonia refrigeration systems with a ring-main temperature set primarily to accommodate the most demanding cooling duties, including cold stabilisation. That means the entire refrigeration infrastructure can effectively be shaped by one of the winery’s most energy-intensive processes, even though it may only run for a relatively limited part of the production cycle.
Fermentation temperature control generally needs a much narrower range. If cold stabilisation can be removed from the refrigeration load, a winery can potentially run its primary refrigeration system around fermentation and general cellar requirements, rather than designing the plant around deep-cold stabilisation. That distinction matters most when a winery is weighing up a major refrigeration replacement or expansion, where the real question is whether to build the next plant around historical processes, or to first remove the processes that no longer need refrigeration.
Water, membranes and automation
Water consumption was historically one of the criticisms levelled at electrodialysis. Modern systems have improved this considerably: process water can be recovered and reused through an integrated reverse-osmosis system, substantially reducing make-up water requirements under suitable operating conditions.
Membrane economics have also changed. Stacks are now designed as replaceable components with predictable maintenance requirements rather than prohibitively expensive assets. Indicative membrane life is in the order of five years or more, depending on wine composition, operating conditions, cleaning regimes and pretreatment, with longer service life achievable where predominantly white wines are processed and well clarified before entering the membrane system.
These systems are also highly automated. PLC-based control manages the process, while automated regeneration, de-scaling and CIP cycles, typically around two hours a day, reduce the need for continual operator intervention. The technology does, however, remain dependent on appropriate wine preparation: turbidity, suspended solids and other feed characteristics need to stay within defined operating parameters, so good prefiltration and clarification remain important parts of the overall process.
From a refrigeration-dependent winery to a process-dependent winery
Historically, refrigeration has been an enabling utility across a broad range of winery processes. Increasingly, technology is allowing the process itself to perform the function that refrigeration once provided, a meaningful shift in how future wineries may need to be designed, and in how much refrigeration capacity they actually need to carry.
A different way to think about refrigeration investment
Perhaps the more useful question for a winery isn’t “what does cold stabilisation cost per kilolitre,” but “how much of our refrigeration infrastructure exists because of processes that technology can now perform without refrigeration?” If tartrate stability can be managed through an ambient electro-membrane system, and juice and post-fermentation clarification can increasingly be managed through flotation, centrifugation and membrane technologies, the refrigeration plant can potentially be designed around a much smaller number of genuine cooling duties.
For an existing winery, that may mean reducing peak seasonal refrigeration loads. For a new winery, or a major plant upgrade, it raises a more fundamental question: should refrigeration capacity be designed around historical winery processes, or around the processes the winery of the future will actually require?
Where this leaves the conversation
Electrodialysis itself isn’t new. What has changed is the technology ecosystem around it, lower membrane and equipment costs, improved automation, modular system design and global investment in membrane technology have made electro-membrane stabilisation increasingly relevant to commercial wine production. At the same time, advances in f lotation, centrifugation and ambient clarification are removing refrigeration requirements from other parts of the winery.
Taken together, these technologies offer more than a replacement for cold stabilisation, they offer the chance to rethink the role of refrigeration throughout the winery. The future winery may still need refrigeration, but for a much narrower range of applications. The question worth asking is no longer simply how much refrigeration a winery needs, but which processes genuinely require it, and which technology can now remove from the load altogether.
Contact Paul Baggio via email: paulb@vitiswinemakers.com or phone: 0412 251 975