This article has been written by Dr Jose Antonio Piornos Martinez who is a Researcher at the INRAE, Dijon.
You can find him on Linkedin, he will be happy to answer your questions and curiosities.
“Do you have any alcohol-free beer?”
“Wait, what? Why are you ordering that? That’s not beer! You better just have water…”
Many people who have ever made the bold choice of ordering an alcohol-free beer at a restaurant or a bar might have experienced this reaction from their loved ones who care about their social reputation. And I will try to explain to you why these beers don’t taste like their alcoholic equivalents.
So, first of all, it is essential to define what beer is. In France, where I live, beer is “a drink obtained through the alcoholic fermentation of a wort prepared from malted cereals, (…) hops, (…) and drinking water”. And it is essential to start with this because alcohol-free beers are commonly defined as a sub-category of beer and not as a product by themselves. And for this reason, it must be fermented. Some people think “it doesn’t have any alcohol because it’s not fermented”. This is incorrect; it must be fermented to be called “beer”.
Then, what is an alcohol-free beer? There is no universal definition of these products. The maximum alcohol content in a beer to be called “alcohol-free” varies from one country to another. In France and Italy, this maximum alcohol content is 1.2 %ABV (alcohol by volume); in Spain, 1 %ABV, whereas in Germany and the Netherlands is 0.5 %ABV. This answers to another recurrent question about alcohol-free beers. Do they contain any alcohol at all? They do, but these amounts are comparable to the naturally-occurring alcohol in grape juice, vinegar, and even bakery products like bread! (Gorgus et al., 2016).
Alcohol-free beers can be produced following two different strategies. We can either brew a regular alcoholic beer and remove the alcohol from it or modify the process so that the yeast won’t produce enough alcohol to exceed the legal limits for the “alcohol-free” designation. These are the physical and biological methods, respectively (Brányik et al., 2012). These processes all have pros and cons, no matter the strategy followed.
The physical methods are based on the separation of the alcohol in the beer by evaporation (for example, distillation at low temperature and pressure) or by membrane process, like reverse osmosis. These processes are widely used at industry scale, but they show two important flaws.
The first one is that those de-alcoholised by evaporating the alcohol usually have a “cooked beer” flavour to them due to thermal damage. This flavour is sometimes described as “burnt biscuits” or “burnt bread”; I even had a student who described it as “liver pâté” flavour, and to be honest, he was not so wrong, I think! A common flaw to both evaporation-based and membrane-based beer mutilating processes is the absolute lack of fruity flavour after de-alcoholisation. The very appreciated higher alcohols (in brewing science, “higher” alcohols are those other than methanol and ethanol) and esters formed by yeast during fermentation are stripped out along with the alcohol during the de-alcoholisation processes. For this reason, these fruity aroma compounds must be further separated from the ethanol and reincorporated back into the de-alcoholised beer.
The biological methods (spoiler alert) don’t do any better. The most common ones are based on the restriction of the fermentation, so the yeasts cannot form ethanol from the sugars present in the malt. This is usually done by fermenting at very low temperature (as low as -0.5°C like for the cold contact fermentation method) or by stopping the yeast activity, when the desired alcohol content is reached by cooling down very fast and removing the microorganisms (arrested fermentation). Under these conditions, the yeast can’t do much to produce ethanol, but neither can’t they degrade the potent malty and honey aldehydes. These aldehydes should be transformed into fruity higher alcohols and esters by yeast at normal fermentation conditions, but they are not and they impart a potent malty and honey aroma to them, not fruity. Moreover, the unfermented sugars from the malt stay untouched, and this way what we get is beers with a very sweet malty flavour to them, more similar to the wort (this is the sugary liquid that after fermentation, is converted into beer). One positive characteristic of these beers is that precisely some sugars, like maltotetraose or maltopentaose, are responsible for the body in beers.
So, in one side, we have very watery beers but with the flexibility to add the beer aroma extract back to them and in the other side, the very malty sweet beers but with better textural characteristics. Due to this, it is not rare to see alcohol-free beers in the market which have been produced by mixing beers from different methods aiming to get a more balanced final product. In the last decades, scientists and brewers have put much effort into improving these beers, but, as we researchers always say to end a paper, more research is needed (so we won’t lose our jobs).
Here I leave some interesting articles and scientific papers for further info:
Steady drinker: Quite an interesting blog about alcohol-free beers, product reviews, and other alcohol-free beer interesting stuff.
Brányik, T., Silva, D. P., Baszczyňski, M., Lehnert, R., & Almeida e Silva, J. B. (2012). A review of methods of low alcohol and alcohol-free beer production. Journal of Food Engineering, 108(4), 493–506. https://doi.org/10.1016/j.jfoodeng.2011.09.020
Gorgus, E., Hittinger, M., & Schrenk, D. (2016). Estimates of ethanol exposure in children from food not labeled as alcohol-containing. Journal of Analytical Toxicology, 40(7), 537–542. https://doi.org/10.1093/jat/bkw046