There isn't a whole lot of info out there on how to make good extract-based gluten-free beers, and let me tell you that just boiling up six pounds of sorghum extract and calling it good will NOT make a great beer. With over 30 brews under my belt, all of which have been recipes of my own devising, I thought I'd share a bit of my experience in how to make good extract beers (since not everyone wants to fuss with enzymes, decoction mashes, self-malted grains, etc.). It is perfectly possible to make extract-based gluten-free beers that rival and even exceed the commercially-available stuff! Check out these tips after the jump.
Tip #1: Maltodextrin
Typically derived from corn, rice, or tapioca (I've yet to find non-gluten-free maltodextrin), this unfermentable carbohydrate is my biggest secret weapon. I add it at the start of the boil, at a rate of 4 to 8 oz per 3-gallon batch.
What maltodextrin adds is mostly body and head retention--and boy howdy, does it ever help with the latter! If your gluten-free brews suffer from non-existent or soda-pop-like head, maltodextrin is what you need. It also really helps in hoppy beers like IPAs by giving the beer a much-needed body to balance the strong hop presence.
Tip #2: Whirlfloc Tablets
Tip #3: Candi Syrup
Not to be confused with candi sugar, which is a rock-like crystalline substance that comes in various shades of darkness, candi syrup is absolutely essential in brewing darker gluten-free beers or beers that require a bit of caramel malt character. D-45 is an excellent addition to amber ales, American-style IPAs, British bitters, and of course Belgian styles. D-90 is twice as dark and contributes some smooth chocolate and dark fruit notes, and is appropriate in porters and some stouts (or in smaller quantities in brown ales and Belgian dubbels). D-180 has a roasty coffee-like character that I rely upon heavily in my darker beers, and it pairs well with roasted grains or chestnuts used for steeping.
One word of caution: I've found that candi syrup can thin the body of a beer considerably, and in large amounts it does leave a lingering caramel sweetness. I've really pushed the envelope with it in some of my beers, but my current view on it is that it's better when used with a little restraint (and a lot of maltodextrin!)
Tip #4: Raw, Varietal, Unfiltered Honey
Note also that while many brewers insist that honey dries out a beer and adds very little honey flavor, my own experiences are so far at odds with this I have to wonder what everyone else is doing wrong. I add between 4 and 12 oz of honey to a 3-gallon batch, always after I turn off the flame, and with the more heavy-handed additions, my beers come out tasting almost like mead when young. Honey flavor has dominated many of my beers, and only after several months of aging has the honey flavor relaxed and blended with the grainy flavors of the extracts.
Another neat trick with honey is that you can "burn" it in your brew kettle to get some nice dark color and roasty flavor. It's easy to over-do it, though; I don't recommend burning more than a pound of it in a 5-gallon batch. Lighter honey seems to work better for this, as darker honey can develop some earthy or bitter off-flavors. It's easy to do, but potentially messy—using a big 5-gallon pot is crucial. Just crank up the heat, add the honey, and stir with a looong metal spoon. Cook it just until it darkens for a caramel flavor, or keep going all the way to tarry blackness for a sharp roasted marshmallow flavor that adds TONS of color, and then add boiling water—SLOWLY—after taking of the heat to re-dissolve the honey for the boil.
Tip #5: Exotic Sugars
Take a cue from Randy Mosher's Radical Brewing and hit up some Asian, Indian, Mexican, or Middle Eastern markets for some flavorful alternatives to the usual brown sugar. Jaggery, piloncillo, coconut palm sugar, date sugar...all of these sugars can add interesting flavors and nuances to a gluten-free beer. I've personally had some good successes with palm sugar, using a little less than 1/3 of a pound per gallon of wort; the resulting beer had a light toffee-like note to it that was unmistakeably contributed by the sugar.
For added complexity, you can also caramelize these sugars by dissolving them in water and boiling them until they start to darken a little bit (adding a little di-ammonium phosphate helps the darkening by contributing the nitrogen necessary for maillard browning reactions); for basic instructions to make caramel, check out this link, and for info on how to use DAP to enhance browning, see this post on homebrewtalk.com.
Tip #6: Teas and Herbal Tisanes
For more noticeable flavor contribution, I've had phenomenal success with chamomile, used in anything from a summer cream ale to a strong and heavily-bittered IPA. Chamomile can be added directly to the boil, and even if added right at the start, its flavor will be prominent in the finished beer. However, the contribution it makes is somewhat unlike its flavor when steeped as a tea: in a beer, it has a coconutty/marshmallow quality as well as its characteristic sweet hay-like aroma.
Rose also makes a nice addition; I did a rose blonde last year with palisades hops that was quite delectable (if a little perfumey), and this year I have a rose stout in the works. Putting an herbal or floral note very forward in a beer allows the drinker to focus on something other than the lack of a strong barley malt flavor. For those that really like to feature herbal, floral, or spice flavors, gluten-free beers can actually be a superior platform, particularly because gluten-free extracts have such mild tastes.
Caution is advised, however: bitter or strongly-flavored teas can overpower and ruin a beer if not used judiciously!
Tip #7: Yeast Nutrient
Some Ingredients to AVOID
I've tried a whole lot of wacky ideas, and while most have been successes, a few have proven to be anywhere from lackluster to terrible.
Avoid #1: Blackstrap Molasses
It might be possible to get good results with light molasses or sorghum molasses, but blackstrap? Forget about it! I thought this stuff would be great for adding color and deepening the flavor, and while I was right on about the color, the flavor contribution was a strong minerally-metallic flavor that amplified the familiar sorghum "twang" to unbearable levels. Even in low doses—4 oz in 3 gallons—it still came through, and even dominated when the beer was young.
Avoid #2: Carob
I thought carob would add both fermentables and a nice chocolate flavor. What it added instead was an intense diacetyl "buttery" character, replete with slickness in the mouthfeel. The guys at Harvester Brewing noted the same thing when they tried a version of their Dark Ale brewed with carob. Stick to raw cacao nibs added at secondary, or chocolate flavor extract or liquer at bottling, if you want a chocolate flavor in your beer.
Avoid #3: White Sugar/Corn Sugar
Barley brewers often utilize this stuff to "dry out" or "thin the body" of high-ABV beers that would be cloyingly sweet and thick otherwise; we gluten-free brewers just do not need to do this, EVER. Sorghum extract and rice syrup are already very thin, and in fact regular brewers could just as well use rice syrup instead of corn sugar to lighten the body of their brews. If you brew a big high-alcohol gluten-free beer, DO NOT take a cue from barley brewers and add corn sugar or white sugar, because you will end up with a thin, hot-tasting mess (which probably also tastes over-hopped, too). Save this stuff for bottling time.