Beer and Scobys

Ken writes:

As regular readers will know, I’m an avid homebrewer. Lately I’ve been thinking about how I might brew a very low alcohol beer (this way, I might be able to sell it at farmers’ markets and make the hobby pay for itself). The problem is that beer is a fermented beverage, and alcohol, along with carbon dioxide is a natural byproduct of fermentation.

One suggestion I’ve come across is to brew a beer as normal, or possibly brew a beer, but leave out the final aroma and flavour hop additions, and then once it has fermented out, boil it all again for half an hour, making sure to add the late hops that were missed out earlier, and adding just enough sugar to prime the beer, then once the beer has cooled inoculate with new yeast, bottle and cap the beer and there should only be enough fermentable material to carbonate the beer. The second boiling should drive off all the alcohol produced in fermentation and the bottle conditioning shouldn’t add very much alcohol (0.3% is an estimate I’ve seen), so that would be one way to do it, but it would be quite involved.

Lately I’ve wondered if it wouldn’t be possible to ferment the wort with a ginger beer plant or kombucha ‘mother’ instead. Proper ginger beer is a low alcohol drink made from fermenting ginger. Kombucha is fermented tea. These drinks differ from beer, however, in that the fermentation is carried out be a ‘SCOBY’, a Symbiotic Culture Of Bacteria and Yeast. The yeast converts sugars into alcohol and CO2, and the bacteria consume the alcohol. In the case of Kombucha, the bacteria convert the alcohol into vinegar, which I think would be unpleasant in beer. A mild sourness might be acceptable, and it might be possible to offset it if the wort contained a lot of complex sugars (dextrins and maltotriose, I think) that the kombucha fungus can’t digest but we can. I will have to investigate whether a malt kombucha produces anything worth drinking. It might produce a nice kombucha, but I’m rather doubtful that it will produce an acceptable substitute for a beer. I don’t know if the bacteria in a ginger beer plant also consume alcohol by turning it into vinegar. If they do, then the same reservations apply. Ideally, the bacteria would consume the alcohol and turn it into something the tongue can’t really taste. Only time will tell if there’s anything to this line of investigation.

First, however, I need to get my hands on some ginger beer and kombucha cultures.

p.s. it’s also possible to make ginger beer with brewer’s yeast, in which case you don’t have a ‘scoby’ and you don’t have a non-alcoholic drink. This might also be worth brewing, but it’s not my present aim.


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