By Jen Blair
“Gyle” is a word used to describe a batch of wort as it proceeds through the brewing process. While it is Dutch in origin (“gijlen” = to ferment[ii]), the term is most frequently associated with British brewing methodology. Homebrewers are probably the most familiar with the word as it pertains to the practice of parti-gyling, which is discussed below.
What is Poly-gyle?
We, however, are talking about the practice of poly-gyling, which involves mashing with wort rather than water through multiple mashes. Poly-gyling is not a new concept—records show it was used as early as the 16th and 17th centuries in Elizabethan England.[iii] Back then, brewers were forbidden from brewing strong beers because they were considered wasteful. Nowadays, employing a poly-gyling regimen is an effective way to achieve higher gravity beers while saving mash tun space. Poly-gyling may also be referred to as reiterated mashing or double mashing.
Poly-gyle vs Parti-gyle Brewing
When I mention doing a poly-gyle, people inevitably ask if I mean parti-gyle. I do not. A parti-gyle is the term used to describe running the wort from a single mash into several kettles.1 A parti-gyle consists of one mash being used for several batches of beer with progressively lower gravities. The same mash is lautered multiple times. The family of Scottish ales is a good example of how one mash can create a style such as Wee Heavy, then a lower gravity Scottish Heavy, and finally an even lower gravity Scottish Light. A poly-gyle, on the other hand, is making concentrated wort with the purpose of achieving a higher gravity.
How to Poly-gyle Homebrew
Like many things with homebrewing, there is an in-depth, technical (but easy to follow) method for poly-gyling, and then there is the quick-and-dirty method. The quick-and-dirty method is what I’ll describe here, as it’s the one with which I have the most experience. For an excellent primer on the technical method, please see Chris Colby’s influential article outlining his procedure for reiterated mashing.[iv]
Poly-gyling will extend your brew day, as you’re doing two (or more) mashes to create your concentrated wort, but the time spent is on par with the time it takes to do an extended boil. The first step in poly-gyling is dividing up your grain bill. For the quick-and-dirty method, there a couple of options for doing this. First, you can weigh out and mix your entire grain bill together and divide it into roughly equal batches. Second, you can prioritize mashing your base malt in the first mash along with any specialty malt your recipe contains in the remaining mash tun space and then conduct your second mash with the remaining grain. I’ve done a poly-gyle using both methods and both worked fine for reaching my intended gravities. Sometimes a poly-gyle is a well-planned step in my brew day process, and other times it’s a gameday decision when I realize, as I’m attempting to mash in, that my grain bill is too big for my mash tun. If this approach is too willy-nilly for you, I really can’t recommend Chris Colby’s extremely detailed and thoughtful article enough.
You’ll conduct your first mash as normal. Aim for a mash temperature of 150–152°F (66–67°C) and a mash time of 60 minutes. Recirculate your wort until it runs clear and then run off the wort—your brew kettle is the perfect vessel for the runoff. Your aim in running off this first mash is to get your pre-boil volume of wort needed for your entire batch. Because the grain will absorb some of the water, you will need to sparge your grain bed until you collect your full pre-boil volume. Next, heat your wort up to strike temperature. While your wort is heating, clean the spent grain from your first mash out of your mash tun.
For my fellow brew-in-a-bag homebrewers, I typically add all of the water I’ll need to achieve my pre-boil volume during the first mash. This is usually a function of the aforementioned realization that my grain is not all going to fit in my mash tun as I’m already mashing in. While the wort is heating to strike temperature, I clean the spent grains from my brewing bag (and wish that I had remembered to buy a second brewing bag) and then fill it with the grains for the second mash.
You’ll conduct your second mash as you normally do with the exception of using your strike-temperature wort from your first mash instead of water. Run your wort from your kettle back into your mash tun and mash in, again aiming for a temperature of around 150–152°F and a mash time of 60 minutes. Once your second mash is complete, you’ll recirculate, lauter, and sparge as usual into your boil kettle.
After completing your poly-gyle, your brew day continues on as usual!
As mentioned, the above method is the quick and dirty method I’ve employed several times with success. Water chemistry and appropriate pH are the concerns I hear the most often with poly-gyling. When developing my water profile for a poly-gyle, I will typically aim to keep the pH of my mash in the mid to higher end of the recommended 5.2—5.6 pH range for efficient enzymatic activity. My poly-gyle batches have also been comprised of base and crystal malts, with no roasted malts. If you’re interested in trying a poly-gyle with a grain bill that includes roasted malts, my suggestion is to either add your roasted malts during the last few minutes of your second mash, or make a roasted malt hot steep and add the resulting tea to the last few minutes of your boil. Alternatively, you can invest in a pH meter and monitor the pH of your second mash, adding calcium or carbonate as needed to adjust.
Poly-gyling is not just a great way to brew high-gravity beers with the equipment you have, but it can also be a great way for homebrewers making smaller batches <5 gallons) to brew medium- to high-gravity beers, such as Dunkles Bock or Double IPA.
Poly-gyle Homebrew Recipe
Old Wives Tale Barleywine
- Original Gravity: 1.120
- Estimated ABV: 13%
- Color: Deep copper
- Bitterness: 52 IBU
- Yeast: Alcohol-tolerant English ale
Ingredients for 5 gallons:
- 21 lb (95%) Maris Otter pale malt
- 0.5 lb (2.5%) Victory malt
- 0.5 lb (2.5%) Crystal 120 malt
- 1.5 oz Target hops, 11% a.a. (60 minutes)
- 0.5 oz East Kent Goldings hops, 5% a.a. (20 min)
- 0.5 oz East Kent Goldings hops, 5% a.a. (flameout)
Divide the grain into two equal parts. Conduct your first mash at 150-152 °F for 60 minutes. Vorlauf until wort is clear and then run your wort off into your boil kettle. Sparge as needed to reach desired full pre-boil volume. Heat wort up to strike temperature (at least 158 °F but will vary). While your wort is heating up, clean the spent grains out of your mash tun and get it ready for your next mash. Repeat your mashing regimen and sparge to collect desired pre-boil volume. After your poly-gyle mash is complete, your brew day continues as normal.
About the Author
Jen Blair is an Advanced Cicerone and National BJCP Beer Judge. She is the co-host of False-Bottomed Girls, a podcast about beer and brewing. Jen can be found at underthejenfluence.beer or on Facebook at Under the Jenfluence and Instagram at @underthejenfluence.
[ii] Wiktionary, s.v. “Gyle,” accessed April 10, 2022, https://en.wiktionary.org/wiki/gyle.
[iii] Mosher, Randy, Radical Brewing: Recipes, Tales, & World-Altering Meditations in a Glass (Boulder, CO: Brewers Publications, 2004).
[iv] Colby, Chris. “Reiterated Mashing: Multiple Mashes for Massive Brews,” Brew Your Own, December 2007.