Why are we not talking about booze on a Booze Tuesday post? This is just more of a curiosity thing for me. I figured it probably wasn’t a complicated process, but I never thought to do any research on it. So how do they remove the alcohol from beer?
The alcohol in beer is formed naturally by yeast during the brewing process, a process that also entails the formation of thousands of other chemical compounds, such as aldehydes and esters, which are essential to the flavor of beer. Accordingly, the fermentation step can’t really be bypassed if you want the final product to taste like beer. So, making nonalcoholic beer starts with the same raw ingredients as regular beer and uses the same basic method: Grain is cooked into a liquidy mash and then fermented.
There are two general approaches to making beer nonalcoholic: Either remove the alcohol from beer, or limit the creation of alcohol in the first place.
One Approach: Remove the Alcohol
The first approach, known as dealcoholization, can be done in various ways, but the most common is vacuum distillation. The alcohol in beer evaporates at 173° Fahrenheit under normal conditions; but in a vacuum, it evaporates at much lower temperatures. So, the alcohol can be “cooked off” from the beer without bringing it far above room temperature, thus avoiding the unpleasant off-flavors caused by heating beer.
Evaporating alcohol also evaporates valuable volatile flavor compounds from the beer, so those are captured at the start and added back into the beer after the alcohol has been removed.
Evaporation, even under a vacuum, can only reduce the alcohol content, but it can’t eliminate it completely. That’s why beers made with this method have that lingering half a percent of alcohol. In order to remove all the alcohol, other methods are used, commonly involving a membrane filter that selectively allows alcohol to pass through, thus filtering it out of the beer. Filtration-based methods can be more effective, but they’re also significantly more expensive.
A Second Approach: Brew Without Forming Alcohol
The other way to make nonalcoholic beer is to limit the creation of alcohol. Saccharomyces cerevisiae, the species known as brewer’s yeast, invariably converts sugar into alcohol, but it is possible to control the process so less alcohol is produced.
To do that, brewers start with a mash containing a smaller amount of fermentable sugar so that the yeast has less to work with. Fermenting this mash at a low temperature, just a couple of degrees above freezing, alters the yeast’s metabolism so that it produces a full complement of the tasty esters and other desirable flavor compounds, while producing scarcely any alcohol. (The same approach is used in bread recipes where the dough is refrigerated overnight or longer to allow the yeast to produce a lot of flavor but less carbon dioxide.)
The behavior of yeast can also be controlled by limiting the amount of oxygen in the mash (traditional beer making often involves aeration) and stopping the fermentation early, before the yeast produce much alcohol.
There are also methods that involve using entirely different species of yeast, which are unable to convert some types of sugar to alcohol. Fermenting with those produces a beer with the complexity of flavor of classic beer but without the proof.
The various methods are commonly used in combination, first biological approaches to limiting the production of alcohol, followed by physical techniques for stripping out the alcohol that’s present. The result is surprisingly good.
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