One of my big beer-related interests is brewing with “alternative” grains, partly because of curiosity but also because my wife has celiac disease and likes beer. For the unfamiliar, the treatment for celiac disease is to avoid all gluten-containing foods, whether they are made with gluten-containing ingredients (barley, wheat and rye and their derivatives) or potentially cross-contaminated with remnants of gluten-containing ingredients. This can be a lot more complicated than it seems (partly due to not being taken seriously, thanks to fad dieters and health food nuts co-opting your involuntary, medically-necessary diet, but I digress…) and the consequences of not doing so are serious, far, far beyond than the stomach discomfort most would associate with it.
Conventional beer is out of the question as it is made with at least one of the three problematic grains. Filtering and/or enzymatically breaking down the leftover gluten in beer is possible — beers like Estrella Daura or the Omission line are made this way and are tested for safety. Levels below 20ppm are held to be safe for celiacs, and done well these treatments are effective. But this is at the very least unreliable at the homebrew level since we can’t test the gluten content in the finished product short of sending samples to a lab.
Fortunately, we can “simply” malt and brew with other grains and pseudocereals, like millet, rice, sorghum, maize, buckwheat and quinoa, all of which are naturally gluten-free. Since hops are naturally gluten-free, wort production is taken care of–although often with much more difficulty than barley beer and with a distinct flavor from each of the different grains.
That brings us to yeast. Commercial liquid yeast manufacturers use barley wort as the base in their growth medium, and the finished product ends up containing some. The levels are low, low enough that we can ignore it: about 120ppm for Wyeast, and an extremely low 12ppm for White Labs. When diluted in several gallons of wort, that gluten content is surely under the aforementioned accepted maximum of 20ppm. That is great, for sure. Some celiacs are fine with that level of assurance. But we are not perfect (or perfectly rational) beings, and while we may know it is not going to be a problem, sometimes whatever doubt lingers in our minds is enough to ruin the experience of having a nice beer.
To fully eliminate any apprehension, we can use dry yeasts from (at least) Danstar, Safale and Mangrove Jack’s that don’t use barley wort as their medium. At least for Danstar and bread yeast manufacturers, molasses is the sugar source in growth medium. But that is further restricting due to the limited number of strains available. Not that they aren’t good, of course, but there are just so many good liquid ones that it is too important to ignore.
The good news is that yeast ranching with gluten-free media is trivial. In fact, I have mostly used only such media from day one and use them exclusively on all slants. This opens up the entire world of liquid yeast for gluten-free brewers, because we can culture the yeast taking essentially nothing but the cells themselves from the original tube/pack. Plating and further culturing is then done on gluten-free media and the resulting beer is 100% free of any contamination, provided standard hygiene is practiced.
Potato-based media are completely fine and require no changes. But even malt-based media are easy to adapt. Briess white sorghum syrup, which is made from unmalted sorghum grain that is enzymatically mashed (and thus totally different from sorghum cane syrup/molasses), is a 1:1 replacement for LME. Most malt medium recipes call for DME due to its ease of use, but we can swap in LME and thus sorghum grain syrup by accounting for the 20% water content. Some might call into question the lower FAN content of the Briess syrup relative to standard LME (as indicated by Briess’s spec sheets) but I have not found that to be a problem, and end up using yeast nutrient in starters anyway. So, that’s pretty much all there is to it.
Part II will contain a few concrete recipes and go over a few of the idiosyncrasies.
DC Yeast Lab 