You may have heard the term “parti-gyle” before, but wasn't sure what it was, or it sounded like some new-fangled process to make all grain brewing more complicated. Well, in fact, it is a very old and traditional way to brew, dating back hundreds of years, and with some math and some practice it is a great way for you to walk away from your brew day with not one, but two beers in the fermenter(s).
Historically brewers would mash and lauter the same grain bill several times producing a batch of wort and subsequent beer with each individual mash. Most likely this is where the Belgians got their terminology for their Trapist ales; Trippel (highest alcohol first runnings), Dubbel (high alcohol second runnings), and Pater or Table Beer (low alcohol third runnings). And, in early American colonies beer was made for sale at taverns, but “small” beer was made from the second runnings which was consumed by workers and even children as to avoid drinking the water which was often considered unfit to drink. Since the total potential of the original grain bill was known as a “gyle”, the process of splitting or partitioning the runnings became known as “parti-gyling”
Today, the homebrewer typically just sparges the grain after the initial mash and combines the first runnings (mash) with the second runnings (sparge) producing a full gyle. So why do it differently? Well, because two beers are better than one, and if you don't think so, you are probably reading the wrong blog... And since you bought all that grain with your hard earned money, why don't you get the most out of it.
Practically speaking, there are a few different ways to use a parti-gyle brew day.
One: you can just keep sparging your grain until your runnings hit a gravity of 1.010 rather than to a specific volume size. Depending on the grain you are using you can maybe pull out double the volume of beer you would have got otherwise. But remember that if your grain bill was built for a 5 gallon batch of 1.060 beer, that will be the gravity of the first 5 gallons. If you run out another 5 gallons at say 1.020, then your combined 10 gallon gyle will yield a 1.040 beer. As you can see, there are lots of gravity readings required. This is impractical for a hydrometer. Get yourself a refractometer.
Two: Make a grain bill for your Imperial Stout/Porter/IPA etc, then continue to sparge until your runnings hit a gravity of 1.010 but make it a true pari-gyle and keep them separate. How you split it will be entirely up to you. Maybe split it in thirds for three similar beers but with varying alcohol, or maybe keep one an imperial, and the other a small session beer.
Three: After one of the partitions add some adjuncts or specialty grain to your mash for a different beer from your second (or third) runnings. Just add some roasted barley and flaked oats to your grain to turn what was an Imperial IPA first runnings into a small stout second runnings.
Pretty awesome right? Are you asking yourself, “why haven't I been doing this since I started brewing?” Well there are a couple of reasons it can be a hassle, and it isn't for everyone. Sorry extract brewers, I don't think your way is inferior, but you just can't play here. The next biggest hurdle is your ability to brew and ferment two beers (or three) at once? Two burners, two kettles, two fermenters. Otherwise you are looking at a tremendously long brew day. Fortunately for me I have my old extract equipment so I usually brew a 3 gallon Imperial on the stove top and my 5 gallons session beer on my regular equipment. The other downside is the math. It isn't rocket science, but once you figure out what you are doing it will still take some practice to get the process down to something you are comfortable with. I will provide some more detail in a subsequent post on the mathematics of a parti-gyle, but don't wait for me. Jump in with both feet and make a couple of beers during your next brew day. Don't worry, it will make beer. We are happy to help you with this in the store also.