Priming with flavorful sugars

Q. I want to add dark sugar flavors to an ale and am thinking about priming with muscovado sugar instead of corn sugar. This got me wondering, when using other types of sugar like muscovado, brown sugar, or maple syrup, is the addition amount always similar to corn sugar (I usually use ¾ cup of corn sugar for a 5-gallon/19-L batch). 
James Eaton
Via email

Mr. Wizard Says…

A. Using flavorful sugars and syrups for bottle conditioning is definitely a way to add flavor to beer. One helpful way to assess the contribution of these ingredients is to add a dose to chlorine-free water — distilled or reverse osmosis works well — at the same rate you would use for conditioning. In this sort of trial, mentally zero out the sweetness and focus on other flavors, aromas, and color, because those are the components that remain after the sugar is converted to carbon dioxide and alcohol.

The dosage rate of priming sugars, whether solid or liquid, is best measured by weight. And for accurate priming, beer volume is essential. Although it is possible to prime individual bottles using bottle volume in the calculation, this method is tedious and best reserved for small bottling runs unless you simply love the process. Whether you use a bottling bucket, keg, fermenter, or carboy for batch dosing, you must know the beer volume. While the exact carbon dioxide content of beer post-fermentation is also required, an estimate is sufficient for establishing a dosing range.

The first step is determining how much carbon dioxide you need to add. Most beers contain about 4.4–6.0 grams of carbon dioxide per liter of beer, which corresponds to roughly 2.2–3.0 volumes, but priming calculations are simplest in g/L, so we’ll stick with that. Most beers fermented atmospherically, i.e., without a spunding valve, contain 2–3 g/L of CO₂. This means we need to add between 1.4–4.0 g/L. For the examples that follow, I’ll use 3 g/L.

The second step is calculating the dry weight of sugar required to carbonate the beer volume. You must measure volume for anything more precise than an educated guess. Calibrated sight strips on translucent or clear vessels, dipsticks, or net weight (with known specific gravity) for stainless tanks are common methods. For this discussion, let’s assume 19 liters of beer are ready to bottle. The required dry weight of priming sugar is 19 liters × 3.0 g/L = 57 grams.

Here’s where things get approximate: You must know the moisture content of the sugar or syrup used
for priming. Cane sugar typically contains about 5% moisture, or 95% solids. To achieve 57 grams of sugar
on a dry basis, divide by 0.95. The calculation yields 60 grams of sugar from the bag.

Things get trickier with syrups because most do not list moisture content, so you need either a product specification sheet or online reference data. Even with spec sheets, you’ll find ranges. For example, Candico amber candi syrup from Belgium ranges from 78.0–80.5 °Brix. Using that range and the 57-gram target, you’ll need 71–57 grams of syrup. That narrow range contrasts with honey, which ranges from 70–88 °Brix — and therefore requires 65–81 grams to supply the same 57 grams of dry sugar.

Hope this information proves handy!