This month I (Nick) wanted to take the O’Connor’s loyal fan base on a journey into the world of parti-gyle brewing. Math warning! This is a bit in depth and technical, and I am doing my best to get my scattered thoughts onto paper.
First, a little background on the subject at hand. Parti-gyle brewing is an age old method of using your first runnings for a beer (that is higher in gravity) and using your second or third runnings for a beer that is lighter in gravity. For the best example of this process, we need to look at the Belgians. It was typical in medieval times to brew first batch Golden Strong or Trippel Ales with the first runnings and then a Single or Dubbel from the second and third. Coincidentally the batch we are working with today is partially a Belgian beer. To start, most of the info out there on parti-gyle brewing is geared towards knowing what the Original Gravity of your full volume of beer is. This number would be given to you by Beersmith or whatever program you were using to do your brewing calculations. This is not that method. You can read about that from Randy Mosher and other home brewing demi-gods elsewhere (it basically involves separating the batch into ⅓ High Gravity ⅔ lower gravity wort).
The method I am utilizing today allows me to use two mashes for two different beers at the same time but with dramatically different results. I wanted a dark beer and a beer that had no black or caramel malts. More specifically, I wanted to get a higher gravity beer with a lot of caramel and black malts in it and a lower gravity second runnings beer that was the color of a Pale Ale to Hop burst (most of the hops near the end).This method also requires me to steal a buddies mash tun…oh yeah.
1st Batch: Belgian Quad: Total grains = 25lbs
2nd Batch: Hop Session: Total grains (2nd runnings) =18.5lbs
When you mash in on a beer like this your water to grain ratio determines your maximum extraction. For a really great read on this stuff you can hit the website http://braukaiser.com. I utilized the chart on potential first running gravity available here: http://braukaiser.com/wiki/index.php?title=File:First_wort_gravity.gif.
For the Quad I mashed in all the grain:18.5 lbs of non-colored grain in one cooler (without any of the caramel and dark roasted malts) and the remaining grains in the second cooler. In the second cooler with the remaining grains I made sure to have some highly modified base malt in there to convert it. Since I wanted to just use the first runnings from both mash tuns I was able to calculate the volume I needed (8 gallons-ish) and dial in my pre-boil gravity using the sheet from Braukaiser. With our system you can usually count on a grain absorption of about a half quart/lb of the mash so total I needed a little more than 10 gallons to mash. This volume of water ended up being a 1.6-1.7qt/lb water to grain ratio. With a higher water to grain ratio the conversion is a little slower, so I ended up mashing for 90 minutes to ensure I had maximum conversion. Once I was done recirculating, I collected from both tuns at the same time until I was at my desired volume in the first kettle. I measured my preboil and it was on the mark (I usually live if its within 4 gravity points this ended up higher than my estimate and hit 1.080)
While the Quad was getting up to a boil I reloaded the mash tun with base grains in it with an additional 7 gallons of water for my second runnings beer and let it set up for a half an hour. I got the Quad to a boil and did its one hop addition. Now it was all about the second runnings beer. I recirculated until the line ran clear and collected the 7 gallons of wort. It ended up being about 1.042 for the pre-boil gravity. I then did a one hour boil and bursted it with 6 oz of Nugget hops right at flameout. I cooled both and ran them off into two different fermenters. The Hop Session was on tap at my house in less than two weeks, and the Quad went from primary to a carboy to age and finally into an oak barrel spiked with Makers Mark before it found its way into the keg. Not a bad couple beers for my first brew day with my newborn son!
I hope you get the chance to play around with your home brew the way I do and remember, malt hops and yeast with a little water pretty much always ends up becoming beer so just try to make make it fun and relax, it’s just science… I mean… it’s just home brew.