Brewing with the Aurochs: Grain Bills for Homebrewing GlutenFree Beer
Above: Our team, brewing some glutenfree beer with our Aurochs
Hey there homebrewers. At Aurochs Brewing Company, we are constantly training ourselves on how to brew different styles of glutenfree beers. It’s fun–we’re home brewers at heart. Our flagship brew, the Aurochs White Ale, uses Millet and Quinoa. The recipe is completely from scratch and it is excellent; however, it involves a long brewing process with multiple mashing steps.
In today’s post, we’ll start a little simpler, and discuss how you set a grain bill and determine how many pounds of each ingredient to use in your glutenfree beer experiments. We are going to use a simple, hypothetical example with sorghum extract. Most home brewers start using extracts rather than grains because there is no mashing required, and the most widely available glutenfree extract is Briess Sorghum Syrup. Hopefully this blog will help you tinker with your formulas.
Calculating the Grain Bill
Step 1: Determine style and corresponding gravity and malt proportions.
First you need to determine what style of beer you would like to enjoy and the corresponding gravity of that style. In my example, I formulate the malt extract recipe for a hypothetical glutenfree ale. The target original gravity is 1.050. The base extract will be sorghum and we will use D45 Candi syrup to add flavor and color character.
The proportions we will use are 90% sorghum extract and 10% D45 syrup.
Step 2: Calculate total gravity.
Calculate the total gravity that is required to create your target recipe. To learn more about gravity, check out our post from a few weeks ago. In our example, the target gravity is 1.050. Here are the steps to get to the corresponding total gravity:
1. Convert target gravity to gravity units (GU’s). To do this, simply subtract 1 from 1.050 and then multiply by 1000. [(Target Gravity – 1) *1,000] = 50. The GU conversion is done to make future calculations more mathematically manageable.
2. Multiply GU’s by the total volume of beer you are brewing. In my example, we are using a 5 gallons system. So Total Gravity = 5*50 = 250
Step 3: Calculate the gravity that each fermentable will provide to your recipe.
Simply multiply the total gravity by the proportion of each extract that you are using. So in my example:
Sorghum extract total gravity in recipe = .90 * 250 = 225 of total gravity
D45 syrup in recipe = .10*250 = 25 of total gravity
Step 4: Divide the total amount of gravity for each extract by their respective PPG scores to determine how many pounds of syrup each are required. PPG stands for Points per Pound per Gallon. The score or ratio relates the number of gravity points contributed by one pound in one gallon of water. This information is usually available on the packaging of any malt extract or fermentable syrup. To determine how many pounds of each ingredient we need divide the total gravity provided by each by their PPG scores:
D45 Syrup 

Total Gravity 
25.00 
(a) 
PPG score of D45 
1.032 

PPG converted to GU’s 
32.00 
(b) 
Lbs of D45 required 
0.78 
(a)/(b) 
Sorghum Syrup 

Total Gravity 
225.00 
(a) 
PPG score of sorghum 
1.035 

PPG converted to GU’s 
35.00 
(b) 
lbs of Sorghum required . 
6.43 
(a)/(b) 
In summary, to achieve the required gravity target of 1.050 you will need 0.78 lbs of D45 syrup and 6.43 lbs of Sorghum syrup (note that this calculation assumes 100% efficiency, which is typical for brew kettle additions). This is just the beginning, however. There are many other steps required to brew your own glutenfree beer, and many other ingredients to choose from. We’ll work our way through these topics, and more, in our future posts.