“The Industry Has to Produce Wines Specifically That Are Easily Dealcoholized”

Ms. Kunz, you’re a full-time wine taster. Do you have a particularly good sense of taste and smell?

Lisa Kunz: Well-trained senses are definitely part of my daily work. We actually go through olfactory training regularly. It’s like learning new words. My “vocabulary” has expanded a lot when it comes to smell and taste, though as someone from the region of Rhineland-Palatinate known for wine making, maybe I do bring a certain natural talent. Of course, we don’t drink the wine we taste [laughs]. When you’re tasting professionally, you spit it out – otherwise, we’d soon be unfit for work.

You study how alcohol-free wines can be made to taste better. What is it about this that attracts you?

Above all, that it’s such a new and current field. I wrote my bachelor’s and master’s theses on aroma chemistry and found the crossover with sensory analysis very exciting. It is really about deciphering aromatic particles but also about understanding their effects on human senses. That combination can be easily applied to dealcoholized wines.

Wine “without the kick” only has a market share of about one percent so far, whereas with beers, it’s seven percent. Why is that?

I think that the dubious reputation of alcohol-free wines rests on negative experiences. The differences between good traditional wines and dealcoholized wines are indeed quite substantial – twelve percent or more of alcohol by volume is missing. This changes the body of the wine and the sensation within the mouth, as alcohol-free wine feels thinner. A portion of the aromas also evaporates during the process of alcohol removal; for instance, the fruity or flowery notes. This results in, primarily, the more slowly dissipating notes remaining perceptible, which then appear overcooked rather than fresh and fruity.

How is the alcohol actually removed from the wine?

There are two processes for this. The usual one is vacuum distillation, where the wine is warmed to 30 degrees Celsius under negative pressure so that the alcohol evaporates at this relatively low temperature. Alongside the alcohol, however, volatile aroma particles will also vaporize away, and because of that, the dealcoholized wine tastes different from the original wine, often less expressive. The second method uses membranes that only allow the penetration of very small molecules, such as ethanol. The drawback to that method is that it’s barely possible to achieve the legally required alcohol content per volume of below 0.5 percent.

How does your research help to improve this process?

Above all, we’re trying to create aroma-richer wines through targeted wine production so that the aroma loss through dealcoholization won’t matter as much. We use gas chromatography to reveal more precisely how the aromas change during the process, and that way, we can measure which aromas, in which amounts are in the wine – both before and after dealcoholization. Then we combine these analyses with our results from the sensory analysis. Our tasters also evaluate the wines both before and after the vacuum distillation, which helps us better understand which wine components are important for a better or a less good flavor.

How does gas chromatography work?

You inject the extracted evaporated wine aromas into the gas chromatograph and convert them into the gaseous phase at 250 °C. Then, alongside a carrier gas, the aromas flow over a separation column. The separation column has a different affinity for different molecules. You can picture it as if you started off with a mix of red, green and blue marbles that get held up at different points along the column. In this way, they are separated and selectively arrive at a detector that reads which individual substances are in the gas stream. In the case of the gas chromatography-olfactometry process, the gas doesn’t stream into a detector, but rather into the nose of a person trained in sensory analysis, who sits in front of the device and writes down the components they perceive.

How do your findings help winemakers in the production of alcohol-free wines?

When I’ve identified a component through the analysis that heavily affects the base wine and no longer appears in the dealcoholized wine, I can decide how to preserve that component. For example, there are scent particles that are bonded to larger molecules, like sugar. Through fermentation at cooler temperatures during wine production, more aromatics remain bound to those larger molecules, and consequently, they will not evaporate and thus survive dealcoholization unchanged. In alcohol-free wine, these can then be released by the acidity of the wine and develop their beneficial flavor. Another example: I could experiment with different yeasts to emphasize certain aromas in the base wine. After dealcoholization, a balanced amount should remain. At least in theory – in practice, it’s not so easy.

What do winemakers have to do to make non-alcoholic wines popular?

There’s a growing awareness in the industry that wines have to be specifically produced which can be easily dealcoholized – you shouldn’t just take any old wine lying around the cellar and put it to different use. We also work with wineries that implement our measures on a greater scale and give us feedback. Such a qualitatively top-tier alcohol-free wine is easier to market, simply because it tastes better.

How would you, as a winemaker, go about producing the best alcohol-free wine possible?

It makes sense to work towards that goal starting in the vineyard. Bouquet grapes like Muscat or Scheurebe grapes are especially suitable because they carry a lot of powerful aromas, many of which are preserved even after the dealcoholization process. It’s also very important to harvest the grapes when they’re at their ripest and most aromatic. In principle, a base wine could be produced with such strong aromas that it would be too rich as an alcoholic wine but would be a good product as an alcohol-free wine.

Which wine do you currently enjoy drinking?

I actually like to drink alcohol-free or sparkling wine in the summer because I don’t enjoy alcohol in the heat. Where I live in the Palatinate region of Germany, the traditional Riesling region, alcohol-free wine has enjoyed a surprisingly good reception. An alcohol-free Riesling spritzer was very popular at the big wine festival in Bad Dürkheim last year. That motivates me to keep researching tasty alcohol-free wines.

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