A friend asked recently if I could brew a gluten-free beer for her sometime: a porter since she likes dark beers. Naturally this got me to thinking about various gluten-free (GF) brewing options for homebrewers, and I thought it might be useful to record some of my (initial) thoughts.
Commercially, most gluten-free beers I’ve seen use sorghum as the base: sorghum is not only gluten-free but it is the fifth most important cereal grain in the world (used primarily in Africa—sorghum beer is commonly brewed in Africa also). Accordingly my local homebrew shop carries sorghum extract syrup in 7-pound containers along with regular barley-based malt extracts. So, theoretically you should be able to brew an extract GF beer pretty easily by substituting sorghum extract for the regular extract in your recipe.
Of course, to add any additional character, mouthfeel, and color to the beer, we need to use specialty grains: the problem is, you need to know what grains are gluten-free. Here’s a list (besides sorghum):
- Montina (Indian rice grass)
- Rice (white/brown)
- Wild rice
(Barley, wheat, and rye all contain gluten.)
A quick check through the available grains at the Brew Shop reveals the only gluten-free ones they carry are flaked corn and flaked oats—I suppose they could do special-order grains, but at the same time you can actually find many of these from other sources (grocery stores, specialty marts, etc.). For most extract beers you’d typically steep the specialty grains but in the case of GF beer you’d probably need to do a mini-mash to get the character you wanted from them. However the problem with mini-mashing is you’d need to find a GF grain that has enough diastase to convert the starches to sugars, which is ordinarily something you need barley or wheat for.
(Interesting corollary: it seems oat malt would do it—it has enough diastatic power to convert itself and some additional grains. This could be a viable GF beer base, but oat malt is pretty specialized and rare these days. It might make an interesting exercise to buy raw oats and try malting them yourself.)
For a GF porter, I’d think about using oats and maybe wild rice as grain additions. You could use rolled oats and toast them up in the oven, and for the wild rice I believe you’d have to cook it beforehand to gelatinize it. I might even consider adding both directly to the boil though I’m not sure how that would turn out.
Of course sugars and syrups should all be fairly safe to use in a GF beer—various shades of brown or raw sugars, molasses, honey, maple syrup, and so on. Molasses would be my first thought for a porter, adding color and strength to the beer; and to preserve the aromatics and more subtle character add it towards the end of the boil, or even to the secondary.
Other flavor components to consider: licorice is the first that springs to mind here, though I see no reason you couldn’t use coffee, chocolate, or more exotic flavorings and spices like juniper berries and chili peppers.
Part of why I’m thinking in terms of “flavoring” is that in my experience, most of the GF beers I’ve tried have a distinctive plastic, band-aid type character to them: I suspect the sorghum is the cause (since I’m pretty sure every one of those beers was sorghum-based), so you definitely want to try to temper that character. Of course, it’s entirely possible that the fermentation characteristics of sorghum (temperature, certain yeasts) cause this and finding the right combination could eliminate it. That would be worth looking into.
I’ll try brewing that GF porter soon and I’ll post the recipe and notes online. In the meantime, any brewers out there have any thoughts they’d like to share?