This article has been written by Dr Jose Piornos, Researcher at the INRAE, Dijon.
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.
“Do you have any alcohol-free beer?”
“Wait, what? Why are you ordering that? That’s not beer! You better just have water…”
What is ‘beer’
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 there is no fermentation”. This is incorrect; to use the definition of “beer” we indeed need fermentation.
What is alcohol-free beer
Then, what is an alcohol-free beer? There is no universal definition of these products. To call a beer ‘alcohol-free’ the maximum alcohol content in a beer 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).
Companies produce Alcohol-free beers 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.
Evaporating alcohol to make alcoho-free beers
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. Panelists sometimes describe this flavour 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, it is important to separate these fruity aroma compounds from the ethanol and reincorporated back into the de-alcoholised beer.
Biological methods to remove alcohol from beer
The biological methods don’t do any better. The most common ones are based on the restriction of the fermentation. The yeasts cannot form ethanol from the sugars present in the malt. We can do this thanks to fermentation, with temperature as low as -0.5°C (like for the cold contact fermentation method) or by stopping the yeast activity once you reach the desired alcohol content. You cool the product quickly and remove the microorganisms.
Under these conditions, the yeast can’t do much to produce ethanol, but neither can’t they degrade the malty and honey aldehydes. Yeasts at normal fermentation conditions, can transform these aldehydes into fruity higher alcohols and esters. However, here they are not and they impart a potent malty and honey aroma to them, not fruity. The unfermented sugars from the malt are untouched. What we get is beers with a sweet malty flavour, similar to the wort (the sugary liquid that after fermentation, is converted into beer). The responsible for the body in bears are some sugars like maltotetraose and maltopenaose. These constitute one positive characteristic of these beers.
So, we have very watery beers but with the flexibility to add the beer aroma extract back to them. On the other side, the very malty sweet beers but with better textural characteristics. Due to this, it common to see alcohol-free beers produced by mixing beers from different methods. This aims 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