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Brew in 90 Minutes - Modified Parti-gyle

Posted by TheBrewBag on 6/15/2015 at 12:26:14 AM


The parti-gyle, (the decision (parti) to split the brew (gyle) ) was/is literally used to make two or three beers of different strength from a single mash in different vessels, and was common practice until about 1725 when a new method of brewing was developed. It was called "entire" and meant that all the sugars from the mash were collected in a single vessel and boiled to create a beer of one strength. Most home brewers rely on "entire" brewing to create their beer and do not parti-gyle.

Sparge method brewers collect wort until they reach kettle / recipe / gravity volume, or the lowest accepted gravity, which is 1.010. The SOG (specific original gravity) is taken pre-boil - post-sparge and is the result of mixing what, in the days of yore, would have been the 1st, 2nd, and 3rd runnings, or the actual total sugar concentration in any given mash volume. Brew in a bag brewer's simply lift the bag and let the wort drain back into the kettle with the same result. 

Out of one mash there could be three separate strengths of wort. The 1st runnings contain the highest percentage of sugars and a resultant higher ABV. To create the 2nd runnings, the mash was again flushed with water (sparged) and drained into a separate vessel than the 1st runnings. If there were sufficient sugars remaining, (based on volume) a third flush was initiated which resulted in a very weak (1.010 to 1.025) wort. Depending on the class served and region the wort might be mixed to elevate, or balance one of the runnings to the intended gravity, or depending on profit considerations, left to stand alone. 

So, the topic of the blog is "How To Brew Beer in 90 Minutes." I'm going to assume that you know how to brew beer one way or another, and that you understand that this can not be accomplished using extract.  I'm going to further assume that you're using a fabric filter and one kettle to make beer. But, if you use a mash tun and transfer to the boil kettle, you're already set up to parti-gyle and the following steps, although in a two vessel system are more simple, produce the same results. I'll state ahead of time - based on proper temperature, pH, and sparging volume, tannins are not an issue. 

So, you're into your brew day, and as usual you think "what if I could transfer ALL the sugars left in the grain to the boil kettle -  there's beer waiting to be born!" And then you brew, clean up, have a brew, and realize you made 5 or 10 gallons in 3.5 hours (BIAB), or 6 hours (non BIAB), so you have another brew and forget about it. 

We know that no matter the method, there are residual sugars in the grain, and we also know that adding water dilutes the gravity of the wort. Progressive dilution, or sparging, creates target volume, but as the volume of water through the bed increases, the sugar concentration in the boil kettle decreases. In my opinion that creates a diminishing return, and again, in my opinion, is not worth the effort. That is a primary reason I BIAB - no time taken to sparge and the results in the boil kettle are comparable.  

Before your next brew day consider this. What if the residual sugar could be captured, added to, and used to create another 5 or 6 gallons of beer while only adding drain and boil time to the brew day? 

It can, and here's how it happens. Before you begin to brew, find a cooler, (or use your current cooler), or a vessel of some kind that you can insulate, and that will hold 10 + gallons of water. This is the parti-gyle vessel. You're not going to fill it with 10 gallons of water, but you need that volume for both the water and the grain.  A 40 to 50 quart cooler is great for this process, but any size that meets the volume requirements will do. You're going to keep the spent grain from the first mash, add fresh grist, and mash it all again. Adding fresh grains to the second mash creates the "modified" parti-gyle. Adding fresh grain will serve to boost gravity at a very low cost, and based on the additions, can create a completely different style of beer.

Before you begin, consider what you might add to any given grain bill to create a second style of beer. That might mean a basic Kolsch, or Amber, and then a Porter, or a Brown Ale and then a Stout. Make sure the fist grain bill does not have grains that will clash with the second beer (first wort hopping, dark grains, etc). 

Because of brewhouse efficiency differences, method, size of grain bill etc, you'll need to do some experimenting to determine how much grain to add to the second mash to reach your intended gravity, but that can be determined after you transfer the spent grain to the second vessel and have taken an initial gravity reading. Bear in mind that 1 gallon of water mixed with 1 pound of base grain will create a gravity reading of close to 1.036. Depending on what you're making consider adding candi-syrup, DME, or even extract. 

The following spreadsheet will assist with your calculations -

Let's assume that your first batch resulted in a SOG of 1.050. When using a brew bag, the spent grain when transferred to the parti-gyle vessel will carry the same gravity as the first mash and will be diluted by the parti-gyle water volume, so depending on if you squeeze the bag and how much you squeeze back into the first boil kettle, the gravity can vary in the parti-gyle vessel. Also, bear in mind that the "spent" grain has already absorbed its full measure of water and there will be no loss of water volume, so don't include it in the grain absorption loss calculations. In addition, the converted sugars in that grain bag, or tun, will be free to mix with the water immediately. This means you should stir well and take a gravity reading. This reading will provide the base information for how much additional grain you'll need to add to reach your modified part-gyle target. 

Here's a consideration - depending on the temp you mashed the first batch - switch to the opposite end of the acceptable conversion range for the second batch. This strategy works far better with a high range first mash and a low range second mash than the other way around. This is due to the majority of the sugars (70%) being produced in the low end scale, so the second mash will be a low-end weighted combination of low and high, with greater potential for higher gravity. If that's not what you're after, do what you like! 

So you have two vessels. The boil kettle will still be your primary mashing and/or boil vessel and the second vessel will be the parti-gyle mash vessel. Rather than heat full the volume of water twice, you can get the strike water temperature close enough in both to save time and heat energy by splitting the first kettle water.

Because it will sit in the cooler for the entire first mash and will lose 10 to 15 degrees (based on your vessel choice) heat the strike water past the parti-gyle temperature. With a little practice and some good notes, you can determine the heat loss and volume metrics and not have to adjust the parti-gyle strike water by much. 

The following steps are aimed at BIAB brewers, so if you sparge and drain to a boil kettle you'll still need additional water but it will likely come from your hot liquor tank. By replacing the braid or manifold with a fabric filter, you can mix the grains without fear of a stuck sparge. 

Step one: Knowing that you're going to take 6.5 gallons or so out, fill the first kettle with water. Heat the strike water to 20º above the parti-gyle strike temp you're after and transfer 6.5 gallons to the parti-gyle vessel.  Adding the 20º provides for heat loss because this mash water will not be used for 75 minutes or so. Close the lid, and / or insulate, and let it sit. Bear in mind that this vessel will need to be placed high enough to gravity drain (or be pumped) into the boil kettle. 

Step two: Check the temperature and volume of the first boil kettle so you can determine the amount of water to add to reach mash volume calculations.  Bear in mind that the water you'll add will be at a lower temperature than the water in the kettle and will reduce the temperature relative to the amount and temperature of both. So let's say you're going to add water that is 80º to the strike kettle water that's 170º. In any case, adding water will bring the temperature of the intended strike water target below 170º, and below your intended mash temperature -  so getting back to strike temperature will take far less time and energy.

Step three: Proceed with your normal brewing process for the first vessel. Depending on your set up and in some sort of coordinated fashion, think about how you're going to get the heavy grain bag into the parti-gyle vessel safely and quickly with no splashing (it's HOT). 

Step four: Check and record the strike water temperature in the second vessel - do not make any adjustments to this water until the grain has been added and well stirred! Place the bag with the spent grain in the parti-gyle vessel, stir well and take a temperature AND a gravity reading.

Assuming that you'll add 5 pounds of grain the water loss at 14 oz per pound is 70 oz, so if you started with 6.5 gallons, you'll drain about 6. If you boil for 60 minutes, evaporation will be about 1 gallon. Since you're after 5.5 or so in the fermenter, you can use the .5 gallon lost to grain to correct the temperature of the mash - add some water (hot or cold) and stir - add some more and stir. Use ice if that's easier, you're going to boil all this anyway.    

Because we all have different processes, the amount of sugars transferred to the parti-gyle vessel will vary, so this is where your attention is required. Take notes of every step the first batch or two. Really good notes - water volume, strike temp of both mashes, grains used, gravity of one compared to the other - everything!

Step five: Add the fresh grain, stir well, cover and insulate the second mash. Knowing that 70% or so of conversion occurs in the first fifteen minutes of mashing, stir well and take a gravity reading twenty minutes in. That will help you determine if you need to add more grain, or DME into the boil kettle, or whatever - remember, you have to wait until the boil kettle is available, so there's plenty of time to mash. 

Step six: Assuming the boil kettle is available - at 45 minutes - take a gravity and temperature reading - if the gravity hasn't changed since 20 minutes, proceed to drain. If it has changed, put the lid back on and wait another 15 minutes and take another reading. Once the gravity has stabilized, drain to the boil kettle and proceed as usual. 

Once you get used to adding these steps, the result will be 5 (or more) gallons of beer added to your inventory while only adding 90 minutes to your brew day.  

Rex Slagel is the founding member of Brew In A Bag Supplies LLC. in Plainfield, IL which manufactures The Brew Bag. He has brewed over one hundred batches, including over fifty using a fabric filter. As of this writing The Brew Bag is being used by brewers in fourteen countries and is also used by the nations largest cold-brewed coffee brewer. He can be reached at

Tags for this post: parti-gyle,brew in a bag,mash tun,first runnings,mash beer,make beer,home brewing

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