How to Get Two Beers from the Effort of One

Tricks for the Busy Brewer

by John Palmer (Brewing Techniques - Vol. 5, No.2)

A simple method enables any home brewer to make two beers as distinct as pale ale and Doppelbock in one brewing session.

Like many of us with interests and responsibilities outside of our favorite hobby — home brewing — I often find it difficult to schedule brewing time into my weekends. It seems as though there is always one more lawn chore waiting to be done, or it’s my turn to watch the kids, or other distractions beckon me away from my home brewery. If I am lucky, I can tell my family that come hell or high water I will brew next Saturday — and run out of the room before they can say “No!”

That being the case, I need to make every brewing session count. I need to brew enough beer to last me a couple months until I can manage to arrange more brew time. But who wants to spend several months drinking 10 gallons of the same beer? I want some variety, often a light and a dark that I can alternate depending on my mood, my activity, or the weather. My solution is to make two different beers from one brewing session.

The technique I describe in this article can be applied in all home brewing situations, whether you use 5 or 10 gallons as your basic batch size and whether you brew from extract, extract with steeped grain, or all-grain. The method is based on batch blending — brewing a generic wort for the bulk of the batch and then adding a small specialty wort (or two) to produce the final beers.

Common Denominators

Pick any two styles of beer, and they will have two ingredients in common: base malt and bittering hops. It doesn’t matter if the two styles are pale ale and Doppelbock or porter and Vienna, they can be made using a common base malt and at least one common variety of hop. In fact, many styles (for example, pale ale, steam, and Altbier) are very similar in terms of their grain bill. The critical differences lie in the yeast and fermentation schedule. Thus, a brewer can produce two different beers, even an ale and a lager, from the same wort, simply by pitching different yeast strains. A style purist, of course, will argue that to make a true porter you need to use British pale malt and to make a Vienna you need German lager and Vienna malts. Although this purist would be technically correct, no one will argue with the fact that you can make a perfectly acceptable interpretation of the style using North American two-row as the base malt.

The same is true for hops. People will say, “European lagers must use noble hops.” To which I reply, “Not necessarily.” I agree that using a finishing hop appropriate for the style is practically a necessity, but room definitely exists for an off-style bittering hop early in the boil. Consider, for example, the fact that many major breweries purchase hops from all over the world, regardless of variety and locale, solely for their “alpha” (alpha-acid content). Clearly, considerable room exists for innovation. This approach has its limits, however. You would not want to pick a hop that definitely clashes with a style you want to brew — Cascade hops for a Czech Pils, for example — but common ground can be found for just about any combination of styles, short of specialty beers such as Iambics or a very different beer such as stout.

Designing a Dual Recipe

Once you’ve picked the styles you want to make, the second step is to decide how you are going to brew them; here your equipment will influence the recipe. The third step is to formulate a recipe that will produce the beer styles you want using the equipment you’ve got.

The equipment limitation: When it comes to equipment, the limiting factor is the size of your boiling pot. I have the luxury of brewing in converted Sankey kegs using propane burners, which allows me to use full-volume boils for a 10-gallon batch. Most people use a standard 5-gallon pot, which limits the batch size that can be split. When conducting a concentrated boil, gravities above 1.090 become difficult to work with.

The first example given in this article (Example #1 — California Common and Porter) is for a 10-gallon batch, but all of the amounts in that recipe may be divided by 2 to produce an equivalent 5-gallon batch. With a 7.5-gallon pot (commonly called a Menudo pot), you can do a concentrated 6-galIon boil to produce a 10-gallon batch. I include an example for this case also (see Example #2 — Pils and Oktoberfest).

Ingredient selection: Once you have chosen your beers, examine the recipes for common ingredients. Usually this will be the lower of the amounts of base malt additions of the rwo recipes, and the minimum common hop profile.

Recipe formulation: The final challenge — here’s the fun part — is to create two worts that will combine to create the two final beers you want. For purposes of this article, let’s call these Wort A and Wort B. I usually make Wort A larger than Wort B. Often the recipe for Wort A will be complete for one of the desired styles (see Wort A in Example #1, for example). The specialty wort (Wort B) for the second beer is usually only 1–2 gallons and contains the added gravity, specialty grains, and/or hops to make up the remainder of the second style. The two different sizes are easily managed on the stovetop.

Calculating How Much to Add

So how do you decide how much of which ingredients to use in preparing Worts A and B? You can look at this process as if you were solving a puzzle. You’re trying to come as close as you can to the desired recipes/styles while maximizing the common ingredients. You’ll see in my sample recipes that this is not an exact process; there are no hard-and-fast rules that will guide you to certain success.

For example, while both recipes call for caramel malt, they each call for different roasted malts. I had to do some fudging using caramel 40 and 80 to arrive at the desired gravity for Wort A. I also compromised on the hops to achieve the proper bitterness level. Everyone handles problem-solving differently, and you will need to find your own solutions. A willingness to compromise is a must.

The blending equation: The following equation will help you figure out the blends. It describes the blending of solutions of differing concentrations.

V_aX_a + V_bX_b = V_cX_c

where V = the volume of the two worts, V_a + V_b, = V_c, and X= the specific gravity of the worts (works for bitterness, too).

Before going any further, I would like to add one quick note about accuracy and home brewing practice. The relationship expressed in the equation above assumes that the solutions are “ideal”; that is, that volume remains constant as the amount of stuff dissolved into it changes. We know this is not true for sugar solutions, where the volume does change as the sugar dissolves. Likewise, the basis for calculating bitterness is a “best approximation” of the relationship between gravity and boiling time. On the surface, then, it might seem ludicrous to apply any kind of expectations of accuracy to a combination of nonideal solutions. But, there is method to this calculation madness. If you consistently apply accuracy to your approximations, then your approximations will be more consistent and your brewing will be more accurate.

Calculating the gravities of combined worts: If you combine two worts of different gravities — for example, 3 gallons of 1.064 with 2 gallons of 1.034 — the equation becomes

(3 x 64) + (2 x 34) = 5 x X_c

When we finish the math, the gravity of the resulting beer (X_c) is 260 ÷ 5 = 52, or 1.052.

*The recipe on the opposite page calls for the steeping of Munich malt, which normally should be mashed. In this case, the brewer is trusting to luck that some conversion will take place (Munich malt has some diastatic power). Here the malt is being used more for its flavor components, which can be extracted to a large degree by steeping. The resulting beer will probably be a bit cloudy due to unconverted starch.

You could also work backwards from the desired gravities of the two beers to determine what the gravity of Wort B should be. Plug in numbers for different volume ratios until it works. The work may be minimal, as in the steam/porter recipe, where many ingredients were common and the gravities were the same. If you have large gravity differences, however, as in the sample Pils/Oktoberfest recipe, you may need to play around with adding water to dilute to achieve the desired results. You just plug different quantities of water in as the “B” value (specific gravity, of course, is 1) until the resultant gravity is close.

Calculating the bitterness of combined worts: Once you’ve determined this ratio, the equation may also be used for combining the IBUs of two batches. Keeping our earlier example using a 3:2 ratio, for example, 3 gallons of 58 IBU wort combined with 2 gallons of 9 IBU wort becomes

(3 x 58) + (2 x 9) = 5 x X_c

The combined IBUs (X_c) are 192 ÷ 5 = 38.4, or 38.

Calculating original ingredient amounts for the two worts: The nice thing about simple algebra is that you can work it forward and backward. Our equation can be worked backwards from a desired combined gravity or IBU to determine how much of the various ingredients to add to Worts A and B.

Suppose you want the second of the beers to have 40 IBUs and you have designed Wort A to have 45 IBUs. You already know that because of the malts and gravities you’ve decided on, you need to combine Wort B with a 3:2 ratio. You now need to figure out how hoppy Wort B should be to arrive at the desired result. Plugging the known values into our equation, we find that

(3 x 45) + (2 x X_b) = 5 x 40

and

The good news is that once you have your blends down, you can easily play with them, varying the parameters for different effects.

Diversity and Uniqueness from Common Ground

Producing two stylistically different beers from one brewing session is a nice way to vary the inventory in your cellar when brewing time is hard to find. Most beer styles share common ingredients; often the yeast and fermentation schedule make the crucial difference in the final products. By identifying the commonalities and assessing their relative attributes, you can produce a base wort and a blending wort that will produce two different beers with relatively little added effort. The blending equation presented in this article enables you to design a combined recipe that will closely target your intended beers.

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