Non-Alcoholic Wines at Their Finest

Theoretically, wine can also be dealcoholised using reverse osmosis or thin-film evaporation, but today producers work almost exclusively with vacuum distillation. Carl Jung from the Rheingau region of Germany discovered the principle over a hundred years ago: Applying a vacuum lowers the boiling point of alcohol or other volatile substances and causes them to vaporise at lower temperatures. Compared to back then, it is now possible to set and maintain a much lower vacuum. The required temperature is reduced and dealcoholisation is even more gentle on the sensory quality of the product. The boiling point of ethanol, for example, is only 30 to 40 °C instead of 78 °C under normal pressure when a vacuum of around 100 mbar is applied.

The problem: The wine also loses some of its volatile aromas through dealcoholisation, although ethanol also normally contributes to a complex bouquet. In fact, wine contains an estimated 1,000 or more flavourings. While the primary aromas mainly depend on the grape variety, the location and the climate, the secondary aromas develop during the refinement process. In this respect, a good wine should always be used as the basis for dealcoholised wines. Johannes Trautwein from the winery of the same name with headquarters in Lonsheim, Germany also emphasises this. The base wine - preferably as a cuvée - should have a moderate wine content of around 7 % by volume, be as rich in flavour as possible and rather low in acidity. Muscat or Muscatel varieties, for example, are well suited, he recommends. Riesling and Müller-Thurgau are also often used. In Trautwein's experience, freedom from faults is just as important: "The dealcoholisation process results in a slight concentration. This would bring out any wine faults and acidity notes more clearly." The winemaker also emphasises that the wine is more susceptible to microbial taste faults due to the lack of alcohol. It is therefore important to always ensure process hygiene. Under these conditions, non-alcoholic wines could easily be stored for three to four years, Riesling even for six years.

The vacuum rectification process used (rectification = separation of liquid mixtures) can be described as an optimised variant of classic vacuum distillation. Here the vapour is in contact with the liquid to be separated several times in succession in a countercurrent flow.

The winery has two large, modern and continuously operating systems with a capacity of 2,500 litres per hour and 1,500 litres per hour respectively. At a vacuum of 25 to 125 mbar, the base wine is fed into the central distillation column from above and flows downwards via open intermediate or rectification trays. The vapour from this, the “Brüden”, rises upwards in the countercurrent, taking the volatile alcohol with it. The vacuum applied is between 25 and 100 millibars, explained junior manager Johannes Trautwein during the presentation of the systems. With less than 0.5 % alcohol by volume, the resulting non-alcoholic wine can ultimately be drawn off in the lower part of the column. Even lower alcohol contents are possible if the system is operated appropriately. Continuous distillation in countercurrent reduces treatment times to one to two minutes. Short time and low temperature - both lead to the desired low thermal stress on the wine.
The distillate drained off at the top and liquefied via a condenser reaches an alcohol content of between 70 and 80 % by volume and can be further utilised. This is made possible by the partial condensation of the volatile components on the surfaces of the sieve, valve or bell bottoms inside the column. The flavour condensate could basically be traced back, adds Trautwein. However, it should be noted that this so-called flavouring water also contains alcohol and would increase the content in the product again.  

With sales of 36 million euros in the 2023 calendar year, the Rotkäppchen-Mumm Group is also the market leader in the non-alcoholic segment in Germany. The first products from the Eltville plant went on sale in 2009. Two spinning cone column systems from Flavourtech in Australia, with a capacity of 1,500 l/h each, have been in continuous operation since 2015.

At the centre of the SCC is an approximately three-metre-high round vessel made of stainless steel. Hidden inside: a rapidly rotating vertical shaft and a series of vertically stacked cones, each of which rotates with the shaft. Wine fed from above first runs downwards in a fixed cone into the next, rotating one. The centrifugal force causes the liquid to spread over the surface as an approx. 1 mm-thin film and pushes it upwards until finally it flows into the cone below. The whole thing is repeated several times. The process parameters with regard to temperature and vacuum are similar to those of vacuum rectification. However, the large, thin liquid surface and turbulence created by the protruding ribs on the underside of the moving cones make vaporisation much more efficient. At the same time, the contact time in the column is reduced to just a few seconds.
Production manager Thomas Krischke knows all about the details: In a first step, at a vacuum of approx. 40 mbar and a process temperature of below 30°C, the rising product vapour removes the volatile aroma substances from the wine film (regardless of the sensory characteristics) and traps them.

For the actual dealcoholisation, the returned partially dealcoholised wine passes through the column again - at a higher vacuum pressure and a temperature of around 38 °C. Ethanol escapes and is condensed out in a concentrated form.
Harmonisation takes place in a final third step. This means that the intercepted wine aromas are combined with the dealcoholised wine phase as a bouquet. If necessary, the product can be further improved with a shipping dosage.

The high investment in an SCC pays off in several ways: state-of-the-art control systems and automation, protection of the wine and recovery of an astonishingly similar flavour.