Are you going to be roasting malt? If you want to add complexity to the flavor of your gluten free beer, you may consider roasting some of your gluten free malt. This is assuming, of course, that you have made some gluten free malt. Roasting malt can change the aroma, taste, and color attributes of the malt. Any changes to the characteristics of the malt will translate to changes in the final beer.
When roasting your gluten free grains, you should consider the following:
1. What do you hope to achieve by roasting the malt?
Are you trying to add some color? Is there a particular flavor characteristic you're trying to impart in the beer? If you're new to this, you may need to roast a very small amount of your malt to varying degrees to get an idea of the flavor and color profiles you can obtain from your particular gluten free malt. You also need to consider what portion of your malt you want to roast, and to what level of roasting you need to go.
2. Does your malt have a decent diastatic power?
What is "diastatic power"? This is basically a way of measuring how well a particular malt will be able to covert it's starches to sugars, which depends on the inherent enzymes of the malt. Unfortunately, gluten free malts tend to have a low diastatic power, which often means that other sugars of some sort must be added to the wort or the necessary enzymes must be added to the mash phase of brewing. You probably won't be able to measure your malt's diastatic power in the home brewing setting, but unless it's millet you can pretty much assume it has moderate to low diastatic power. If you have a malt with a decent ability to convert its starches to sugars, you'll want to be careful with the temperatures and timing while roasting malt. If the malt has a low diastatic power, you won't have to be as meticulous while roasting malt since you probably won't rely on the enzymes in the malt anyway.
After considering the two aspects above, and potentially doing some small batches to practice roasting malt, you'll be ready to start roasting malt to whatever level you desire. You can also roast un-malted grains and pseudo-grains for use as adjuncts. If you'll be using amylase enzymes you can slightly increase the amount of sugars that can be fermented by adding lightly crushed un-malted roasted grains or pseudo-grains. Regardless of what you're roasting, you'll need at least a standard home oven and some pans. Ideally, you would use a convection oven because the circulating hot air in these can help you to more evenly roast the grains. A counter top convection oven or large convection toaster oven can work great.
Remember that amylase enzymes are sensitive to higher temperatures. It might seem like roasting malt would destroy these enzymes, but there's a way to approach roasting malt that minimizes the impact of the heat on enzymes. The key is to gradually increase the roasting temperature in steps. The enzymes are able to better survive a roasting malt regimen that allows adequate time at each jump in temperature. This gradually removes the very small amount of moisture that may be in the malt, and the dryer the malt the better protected the enzymes will be.
The first step is to make sure you're starting with well dried base malt, which will still have a moisture content of about 10% by weight even though it seems dry. Spread the malt out on baking pans while being sure to keep the depth of the malt at no more than 1 cm. If using a standard oven, preheat it to 250 degrees F. If you're using a convection oven, preheating won't be necessary. Roast the malt at 250 degrees F for 1 hour in a standard oven or 50 minutes in a convection oven. This is sufficient roasting to achieve a light toasted malt with some mild nutty flavor, though the flavor will vary for different malted grains. At this point the moisture content of the malt will be even lower than the dry base malt. You can stop roasting at this point or you can progress to the next level of roasting malt.
Since the malt will be very dry and the enzymes are better protected, you can get a little more aggressive in roasting malt after the initial roasting phase. You can now crank the temperature up to 350 degrees F. Roasting malt at this temperature for anywhere from 15 minutes to an hour will darken the malt more and can add more complexity to it's flavor qualities. You should mix and redistribute the grains on the pan about every 15 minutes if using a standard oven or every 30 minutes in a convection oven. You definitely don't want to burn the malt. Try crunching a few pieces of malt to see what color the inside of the malt has reached. You can also taste a few pieces to get an idea of the flavor it may contribute to your beer.
When the roasting malt reaches the level you desire, let it cool for about a half hour. Once cooled, you'll want to transfer it to large paper bags and fold over the top of the bag or bags a few times. You'll want to keep the roasted malt in the bags for at least 2 weeks. The paper bag allows some of the harsher and more intense or sharp aromas to escape which might be a little too strong or harsh in your final beer. Store the bag or bags in a dark place at room temperature during this time period. You need to add an extra week or two if you roasted your malt at higher temperatures.
There are some more complex roasting methods that involve adding water to the base malt and roasting the moistened malt for an hour or several hours. This is usually done with barley malt to create what's called a caramel malt, which tends to have a slight sweetness in its flavor. Roasting malt can certainly be done in other ways as well. The most important part is to start the roasting with a dry base malt that is under 10% moisture, and allowing the malt to slowly roast at a temperature under 250 degrees F for about an hour. Also, as mentioned earlier, this initial roasting period isn't as important if you're planning to add amylase enzymes and/or sugars in the brewing process. You now know the basics of roasting malt in your home.
As the last article in the series on making gluten free malt, we want to take a moment to thank you for your interest and to remind you to be careful of cross-contamination with traces of gluten. This is very important if the gluten free beer is being made for someone with celiac disease. This may not be a concern if you live in a gluten free home. However, if gluten containing foods are prepared in your household, be sure to take steps to minimize any chance that traces of gluten may get into your gluten free malt and gluten free beer. Baking pans can have traces of baked-on gluten, so you may need to line the trays with foil. Also, be sure to keep gluten containing foods away from your work area to prevent small crumbs or bits of gluten from falling into your gluten free malt and beer.
We hope you enjoyed this series on making gluten free malt. Good luck with your gluten free brewing endeavors and thanks for your interest.