Parti-Gyle brewing is a method for making more than one batch of beer from a single all grain mash. parti-gyle brewing is one of the oldest tricks in the book. Originally, it wasn’t actually a trick, but an inherent procedure in old brewing methods. It offers tremendous flexibility since you can brew two beers of different gravities, and also add different hops and yeast to create distinct beers from one brewing session.
So how can this technique help the homebrewer? This technique lets you make the most out of your big beers—if you are brewing a barley wine or any other high gravity monstrosity, using this technique will allow you to actually get two batches from the same grain bill. Perhaps you are limited for brewing time and just want to brew two different beers on the same day without doing two mashes, then Parti-Gyle is for you.
Parti-Gyle brewing is not a new method. The method goes back hundreds of years, and many modern sub-styles are examples of light and heavy versions made from a single mash. Examples include the various weights of English and Scotch Ale, various grades of Bock, and even variations of Trappist ales. In the 1700′s and 1800′s it was very common to create a strong beer from the first runnings of the mash and a lighter common beer from the second runnings of a mash.
The Parti-Gyle Method
The standard method for Parti-Gyle brewing is to make two beers from a single mash. Typically a fairly high gravity beer is made from the “first runnings” of the mash, and the second runnings are boiled separately to make a lighter beer. Often different hop additions, boil additions and yeast are used to create distinct styles from the two runnings depending on the brewer’s preference.
It should be no surprise that the color of the two batches in a parti-gyle will be darker for the first runnings and lighter for the second in most cases.
After the Mash
Once you have mashed your parti-gyle beer and taken the two runnings, the rest of the brewing process is the same as with any other beer. Obviously the two runnings are boiled separately so you either need two boil pots and heat sources or a sterile way to store one of the runnings for a few hours while you boil the other.
One of the great features of part-gyle brewing is the ability to change the character of the beer in the boil and fermentation. By adding different hop additions, yeast, spices or steeping additional grains prior to the boil (much like an extract brew) you can dramatically change the character of the two beers produced. With a little imagination you really can create two distinctly different beer styles from a single brewing session.
For design purposes it is usually best to treat the two runnings as separate beers at this point, and the usual rules for estimating bitterness, final gravity and fermentation apply. The design possibilities are nearly endless. You could create a strong ale and bitter, a wheat bock and weizen, a brown and pale and many other combinations from a single mash.
For The Eggheads
I just touched on the basics of this technique, if you need more eggheadery and want to look at complex mathematics and stuff on how to figure the gravity and color—then you should look elsewhere, because I just want to give this a try by the seat of my pants and leave the calculations to someone who cares…Great minds drink alike!