[NOTE: This is a very advanced topic.]

I've wanted, for a long time, to write a procedure for using the BIABacus to partigyle. One main problem is that I generally do not brew high gravity beers ([mention]Sarah[/mention] Sarah has forced me several times) and the grain bill on those done has not lent itself to being re-used for a lower gravity brew e.g. Cherry Chocolate Stout! Since tasting Rocky Ridge's absolutely beautiful Rock Juice, I now have the desire!!!

[mention]lukasfab[/mention] and I will brew it on Sunday week. Ricky from Rocky Ridge has already given Sarah a few tips and she'll drop in this Sunday to help with the recipe design. (She can't brew with Lukas and I as she's working ).

What is Partigyle Brewing? (Very Brief)

I'll use SVA (Single-Vessel All-Grain), i.e. pure BIAB, as the method although the same principles apply for MVA (Multi-Vessel All-Grain). When brewing high gravity beers, a lot of sugar remains in the spent grain. Partigyle started in days of yore to utilise this sugar, a second batch of beer was made from the left-overs of the first batch.

Think of it like this... clean a filthy bath towel in a 5 gallon bucket of water. Lift the towel out, give it a bit of a twist and then dump it in another 5 gallon bucket. Pull the towel out of the second bucket, give it a bit of a twist and then throw it on the floor. What you'll note are the following...

The first bucket of water will be really dirty and there will be a bit less in it because the towel soaked up some of the water and retained it.
The second bucket will be cleaner but will still be dirty and there will be more of it because the towel was already wet when dropped in the second bucket.

In the above analogy, we can think of the dirt as being sugar. The first batch yields very sugary water (high gravity sweet liquor) while the second yields a much lower gravity.

The Dynamics

There are many ways we can play around with our dirty towel and buckets. For example, what if we put the dirty towel in a 10 gallon bucket first and then put it in a 5 gallon bucket. Would both buckets be left with equally dirty water? Or, what about the opposite?

Old hands here know that the BIABacus is the first and only software that auto-estimates kettle efficiency. The existing algorithm is pretty good however it is a linear one whereas, in reality, at extremes, kettle efficiency changes rapidly. For example, put a dirty towel in 1 gallon of water, clean it and pull it out. What is left? A few dribbles of very dirty water. So, you have had almost zero efficiency in cleaning that towel. Put a dirty towel in 50 gallons of water and it is going to be pretty much as clean as if you had washed it in 200 gallons. Anyway until a mathematician puts their hand up we need to stick with our linear formula which does seem to be working really well.

Thinking through the Partigyle Plan Assuming you have come up with a grain bill that will work for both a high and low gravity beer (e'g' an IPA and an APA) the first thing to decide is which batch do you want to give priority too. There are three choices:

1. Aim for a full fermenter of the high gravity brew and get what you can for the low gravity brew.
2. Aim for a full fermenter of the high gravity brew and get what you can for the low gravity brew.
3. Play around with the BIABacus to find a compromise.

In the next posts, I'll explore the first options on how, using the same grain bill, I plan to brew:
- An Imperial New England IPA (9%ABV)
- An American Pale Ale (4.5%ABV)

With this option, when initially planning volumes and gravities of the partigyle, all we need to know are the

The High Gravity Batch Essentials (e.g. Imperial New England IPA)

In this scenario, the following information is essential for the initial plan....

- 9%ABV
- 19 L / 5 gallons - Volume into Packaging (VIP)
- An approximation of the amount of hops used*
*This recipe is massively hopped so there will be increased KFL (Kettle to Fermenter Losses) and FPL (Fermenter to Packaging Losses).

Setting Up the High Gravity Initial BIABacus

[Note: This file is an approximation of the hop amounts we'll be using - loads! (I'll post the finalised recipes later on.]

First I looked at what gravity I would need to achieve 9.0% ABV:
- High gravity beers tend to attenuate less, so, in Section X, I have reduced the apparent attenuation to 70%
- I then adjusted my OG in section C until the expected ABV% in section A equalled 9.0%. The OG required is 1.100

My desired Volume into Packaging (VIP) is 19 L however, the BIABacus only allows the user to input a desired Volume into Fermenter (VIF) so:
- In Section B, I initially set my desired Volume into Fermenter (VIF) to 23 litres. In Section K, at the bottom, I saw that this would yield 21.3 L VIP. This is more than I need however...
- The current version of the BIABacus 1.3U does not auto-estimate for ridiculous loads of hops. Nor does it allow for the extra trub that occurs in high gravity beers* so, in Section X, I fixed the FPL to 4.0L. (The auto-estimate was 1.75L). This should be enough allowance and so we now have a VIP of 19L + KFL of 4L = VIF of 23L.
- For the same reasoning, I also need to over-ride the auto-estimate for Kettle to Fermenter Loss (KFL). The auto-estimate is 3.83 L however, I am going to increase that to 6L.
* I am working on the next version of the BIABacus which will aut-estimate these for us however, it's quite complicated to do as it requires a goal-seeking formula and, in the past, any time we have used macro formulas, they only work on some platforms unfortunately.

The above over-rides may be too high however, this is unimportant for the sake of this exercise. Although I'll need more grain than if I made the losses lower, if they are lower on the actual brew day, I'll simply get more beer.

Now that we have the High Gravity Partigyle set up, we now need to see what yield we'll get get for our Low Gravity Partigyle

The Low Gravity Batch Essentials (e.g. American Pale Ale)

For the Low Gravity Batch, the essential information we need to establish is, "How much sugar will be available from the High Gravity Partigyle spent grain?"

How Much Sugar Do We Have Available?

From the High Gravity Partigyle BIABacus, we know the following:

We have 14,587 grams of grist. (There is no need to worry about the fact that this grist is now wet.)
The BIABacus also tells us that the Efficiency into Kettle is expected to be 67.1% (Section P). This means that there should be 32.9% of sugars left in that grist.

Setting Up the High Gravity Initial BIABacus

Here's what I've done....

I've saved the High Gravity Partigyle BIABacus file as a different name and then changed the following:

- The name in Section A.First I looked at what gravity I would need to achieve 9.0% ABV:
- The OG in Section C to 1.050 (because, if possible, I'd like to get that gravity).
- I've changed the hop amounts to something more suitable.
- I've deleted the 70% attenuation in Section H
- I've deleted the KFL and FPL over-rides in Section X
- Also in Section X, I've changed the Volume Loss from Lauter to zero because our grist is already wet from our first brew.
- Finally, in Section Y, I've changed the FGDB to 26.32%* and the MC to 4%*

* The logic here is that our original grain bill assumes the grain held %80 sugar and 4% moisture however, the first batch has stolen 67.1% of that sugar. 32.9/100*80=26.32%. (The Moisture content we disregard.)

Seeing what we have so far...

The only thing we need to look at here is the right hand side of Section C. The BIABacus is telling us that we need 16506 grams of grist should we want 23 L Volume into Fermenter.



However, we only have 14,587 grams available. What I now need to do is keep lowering my Desired Volume into Fermenter in Section B until the right hand side of Section C says 14,578 grams. 20.45 L gets us pretty right.

What We Can Expect on Our Low Gravity Partigyle

In summary, we can expect to get 20.45 L Volume into Fermenter of wort at 1.050 Original Gravity and 18.94 L Volume into Packaging.



Things are looking good! As to what will happen in reality on brew day is yet to see
I'll let you know finalised recipes and actual results later.

[mention]Sarah[/mention] can now join us on Sunday as can [mention]sinkas[/mention]
Lost a lot of time this week* on some emergency call-outs. Finally had a few hours today to digest feedback from [mention]lukasfab[/mention] , Sarah and sinkas plus do some study on what is going to be a very expensive beer!

Today I also had some time to re-write a more realistic "High Gravity Parti-gyle" BIABacus for the upcoming brew and because of the huge amount of hops, we'll be looking at about:
31.3 L (8.26 Gal) Volume of Ambient Wort
24.5 L (6.5 Gal) Volume into Fermenter
19L (5 Gal) Volume into Packaging

Using 17 kgs (37.5 pounds) of grain and hops totalling 860 grams ( 30 ozs)
Efficiency into Kettle is looking to be 62% and into Fermenter 49%

Lower partigyle looking at 24.3 L (6.4 Gal) Volume into Fermenter at an OG of 1.055

*This batch is definitely not going to be as well planned as hoped. For example, we did intend to build up a big starter of London Ale III yeast but none of us have had time to buy it! It will certainly be a lot of un regardless of any poor planning

Was just tidying up numbers for tomorrow and on re-reading this thread noticed some errors. The result was right but I made a typo in my explanation. Fixed now. Hopefully there aren't too many more.

Met Hamish, the brewer from Rocky Ridge (lovely bloke) last night so scored some tips. Today also received more excellent advice from Dan Turley, one of my favourite brewers. And Lukas has been excellent in working out a lot of the tricky stuff too

Ran out of time to buy the correct liquid yeast for this style and make a starter so we'll use a combination of US-05 from a slurry currently in a fermenter and balance that neutralness out with some Windsor yeast. Big day tomorrow, have to transfer two fermenters into kegs so there is something to drink and still work out what to brew for the partigyle.

Late notice I know however, as always, anyone passing by East Freo is most welcome to drop in tomorrow. Just send a PM.

Pat

No need to bother reading this post unless you want a laugh and to get confused
The post following this will give a summary.

Just recovering from the 25 hour brew day . Had a week of being called out to emergency jobs (break-ins etc) so had very little sleep. All this meant that I managed to get 3 hours sleep before getting up at 5am to start the brew day.

For me, it's extremely important to be set up the day before brew day. No chance of that on this one. In fact, I spent the first three hours just getting my house back in order from the mess of jobs throughout the week. [mention]lukasfab[/mention] kindly took the day away from his family to come and help (thank the brewing gods) and was able to get here by 9am by which time things were organised to the stage that you could actually move around my place to a reasonable degree. First job was to transfer a beer from fermenter to keg as we needed some bits from the fermenter to start the day (a new bit of simple equipment I'm trialling). Finally got to weighing grain and doughing in. I won't bore you with the rest of the details, just try and bring you upt to the same level of confusion as experienced on the day

Dough In

Mashed in flaked oats and wheat at 40°C and then 50°C so they would have something to do while weighing out the uncrushed grain. Then doughed in at 67 aiming for mash at 66. I should have slowed down and used BIABacus strike temp calculator as this was a massive grain bill. So temp dropped to 60 C. No worries, just heat it up...

A Major Blow-Out!

So, I have brand new thermometer (with certification) plus a second thermometer. (I never use a single thermometer as occasionally, they will get stuck at a certain temperature and then suddenly jump.) So, both thermometers are matching each other nicely, I'm agitating the mash constantly waiting for it to get up to 66C - no problems and then, wtf???, the new thermometer suddenly jumps to 82C
The other thermometer stays at 66C and then about two minutes later it suddenly jumps to 79. By this stage, Lukas came from transferring stuff inside and shoved his two fermenters in and they are reading 82 or maybe even 84 (can't remember now) as well .

The Temperature Fix
There was 20L of cold water in the second kettle so we bagan a major transfer from Kettle 1 to Kettle 2 and then transferred back again to get the temp back down. In the frenzy, dropped kettle 1 back down to 60C which was fine by me and then gradually scooped as mcuh grain from Kettle 2 back to Kettle 1 and eventaully brought the temp up to 66C.
So we now had Kettle 1 back up to the correct volume but we also had 20L of somewhat sugary water in Kettle 2.
This meant that Kettle 1 would now be going into the boil with a weaker gravity than intended as it was basically washed in an additional 20 L of water.

Pre-Boil Volumes and Gravities on the High Gravity Partigyle

I have no idea how long we mashed for although it is probably buried in amongst a flurry of hand-written notes and clacs that still surround my desk. Interestingly though, The BIABacus predicted there would be 42.31 L at 1.076 SG going into the boil. Tose of you who know about "sugar points" will know that we can do some simple maths (42.31 x 76) to see the prediction was for 3,215 metric gravity points. Here's what we got...
Kettle 1: 44.06L at 1.060 = 2,644 metric gravity points
Kettle 2: 18.81 L at 1.033 = 621 metric gravity points
TOTAL = 3,264 metric gravity points (about 1% more than predicted)
[EIB estimated was 62%. Actual = 62.2% - I also in Section X had -2 for Adjust Auto Kettle Efficiency as it was such a high gravity brew]

The Volume/Gravity Fix on the Brews

For the High Gravity Brew: Just decided to boil for longer so as we'd get the right gravity but less volume. (We lucked out a bit here as final numbers show)

For the Low Gravity Brew: Just topped up the 18.09L already in Kettle 2 to the 40.55L of TWN (Total Water Needed.) However, predicted VIB and GIB were 39.7 L at 1.040/9 but the actual was 44.06L at 1.060 (66.5% EIB instead of anticipated 81.6%). So decided to do the same as for the high gravity brew - boil for longer.

Volume and Gravity of Ambient Wort End Results

Seeing as I haven't had a chance to even clean the kettles since Sunday, I better go and measure the KFL before writing further. Hold on a minute ...
Okay as far as I can tell four days later
High Gravity Brew = 2.48 L of KFL + 24.5 L VIF = 26.98 @ 1.097 (=2,617 metric gravity points)
Low Gravity Brew = 4.17 L of KFL + 22.7 L VIF = 26.87 @ 1.048 (=1,290 metric gravity points)

Double-check on the Sugar Points

High Gravity Brew began with 3,264 metric gravity points.
621 of these points were "given away" to the second kettle leaving this brew going into the boil with 2,643 gravity points.
It finished with 2,617 gravity points so....
We have a nice double-check on there.

Low Gravity Brew began with 1,322 metric gravity points.
It finished with 1,290 gravity points so....
We have a nice double-check on there.

In the next post, I'll draw some conclusions...

Please remember, you can never draw conclusions from a single brew.

Despite the mess and disasters mentioned in the post above, it's nice to see that the "sugar points" pre and post-boil match. This double-check on measurements and their matching gives us confidence that there probably weren't any errors made in our measurements.
As a matter of interest, instead of taking volume measurements as the boil starts, I take them at mash temp and multiply them by 1.02. This avoids the almost impossible ability to measure at boiling point when the wort swelling and jumping dramatically.

The "Sugar" Result...
High Gravity Partigyle Estimate and Actual Matched
Low Gravity Partigyle Actual "sugar" Extracted was almost 20% Less than Expected

On the Low Gravity Partigyle, my estimate was 81.6% Kettle Efficiency (that's EIB and EAW in Section P of the BIABacus) however, we only achieved 67.5%.
Or to put it another way, I estimated getting 1,5560 metric gravity points but only obtained 1,290 metric gravity points.

Some Theories (and the problem with "theories"

It's actually not a bad result for such a messy, unprepared brew day that included such a major thermometer disaster and a tad of stress .
When I recover from this brew day, I'd like to repeat it. (Put a note in your calendar for around 2024 )
Although the second mash was constantly agitated from 66C to mash-out (about 15 minutes) maybe a longer soak could have made a difference?
Or, maybe, if the same results were to occur again on a second brew, we need to look into the logic of the way I calculated the partigyle?

Another way I could have worked out how much "sugar" could be expected on the partigyle would be to look more at how much water the grain was going to be washed in. The process of doing this is too fiddly for me to work out how to write clearly today, however, I did just try it and it tells me that we would score 3,877 metric gravity points. Of those, we need 2,600 for our high gravity partiglye. This leaves 1,277 for our low gravity partigyle.
That, surprisingly matches our actual results!!!!

For me, (probably no one else , that is quite interesting!

What the Hell Happened with the Thermometers?

This totally baffled me. Here is what I think happened though. I had both thermometers on one side of the kettle, one floating in a pierced container and the other held close to it. This was a bloody thick mash and, although I agitated all around the kettle continuously for probably fifteen minutes, including where the thermometers were, it is possible that both were stuck in a clump of dough sitting high on that side of the kettle. Possibly the doughball then collapsed in two stages.
We checked all four thermometers soon after in boiling water etc and they all read the same.
That is the only thing I can think of. Just when you've seen it all!


PP

A person with one thermometer is certain of the temperature,; with two thermometers, he is never sure.
You have to carefully calibrate your hand, but I have learned that I can keep my own hand on the outside of my kettle for 5 seconds if it is below 60 degrees C. Above that, it is HOT. Heating water to strike temp exceeds my human thermocouple pain threshold. Mash temp is pretty close. “Handy” But you have to know when NOT to use it, too. If checking whilst applying heat, you’ll know if your other device(s) have wandered off.
If your mash temp went so high, how is it that enzymes were not denatured? You lucked out on that part.

Bob. The denaturing thing has always had me stumped when you consider decoction mashing. I mean how does that work? In a decoction mash, a form of step-mashing, you are scooping out thick parts from the mash, bringing that "stiff portion of grist/water) to the boil in a second vessel and then returning it to the original vessel. This brings the main mash to the next step temperature. This is repeated for each temperature step. Wonder if there is any quality info on why that doesn't halt the enzyme activity?

I think it is due to the enzymes being dissolved in water (liquid) not the grains.
Therefore, when you boil the grains, you are denaturing some enzymes, but not the bulk of them, as they remain in the "unremoved" part.

Well, seeing as I was, "up at cyclists," I thought I'd do dome study. [I used to use the term, "up at sparrows," which is when you wake with the birds merrilly singing. Being up at cyclists is when you wake with the aggressive screaming of a plague of passing sporting cyclists. In my street, being up "up at cyclists," means being awake two to three hours earlier than being, "up at sparrows."]

My study began with the usual scour of the internet before my brain began working sensibly and I dragged out my two volumes of Malting and Brewing Science. I scanned about 70 pages, beginning at about Page 100 but it needs a full day of study on that section I reckon bu someone who understands chemistry far better than I do. ([mention]ShorePoints[/mention]?)

I suspect this is another area that has been bastardised over the net from the original but I'm not absolutely sure on this after just the skimming I've done this morning on the net and in the book. Here's what I think [mention]mally[/mention]

How Decoction Mashes were Originally Done

The decoction does pull out both grist and sweet liquor from the main mash, a very thick mix. It is a very long process because (and this is where I think the misinformation is) the decoction itself, is actually rested at steps in the sendond kettle before it is boiled. In other words, it is not simply just thrown in a second kettle and brought immediately to boiling. This explains why decoction mashing (done this way) does not affect the overall fermentability/denaturing of the entire mash.
You'll the read that the decoction is "boiled for some time." The variance of this time depends on what colour is desired for the beer. In other words, the maillard reactions caused by the boiling of the thick decoction bring in the colour.

The decoction mash was originally performed for several reasons...
1. to deal with unmodified malts
2. add colour to the beer
3. create a mechanism of bringing the main mash to the next temperature step.
[Note also that many different ways of doing the concoction were used in order to achieve the desired wort for the style being produced.]

These days we don't need to do it...
1. We don't have to deal with unmodified malts.
2. Specialty malts now bring flavour and colour to our beer.
3. Direct heating of commercial mash tuns is now available so the temp step can be easily applied. (Without this, using normal step mashing by adding hot water to the mash at each step means the thickness of the mash has to be super-thick to begin with and then becomes thinner with each addition of hotter water. In fact, unless the mash tun is huge, the mash tun will end up over-flowing.
[Note with single-vessel all-grain (SVAG / pure BIAB), we don't have that last problem as we have the advantage of a large mash-tun and a heat source.]

You'll find many other interesting things in Malting Brewing and Science but it is a vary hard read

OK, Pat. I'll take a look at Malting and Brewing Science. Thanks for the link. It may take me a few days, though.

Decoction is interesting and a bit weird to me. My experience in batch processing of pharmaceuticals frowned upon returning anything to the mother liquor (yes, that's what it was called) after removal and different treatment/conditions. But then, my focus was tracking impurities. It makes my head hurt to think of newly created intermediates combinig with a host of reactions already underway.

Pat,

The first thing I noticed is that the publisher is CRC Press - that's the Chemical Rubber Company! The book is wonderful. I recognise their logo from long ago when I used the CRC Handbook of Chemistry and Physics. So I start out respectful of the source. My wife now uses my old CRC Handbook to press flowers.

Jumping to 4.2 on page 88 for decoction mashes I note that there are several possible procedures involved using multiple vessels and pumps. The amount of mash and its thickness that gets moved are also factors selected by the brewer. Talk about recipe integrity! One has to know lots more details beyond ingredients and crush size in order to try to reproduce a partigyle batch; time & temp ramps & holds, flow rates, solids/liquid ratios coming and going, stir rates, mixing, air exposure, etc. Could things be more complicated while supposedly trying to achieve consistency? How about a double mash and adding another vessel? Automation of a complex process starts to look good since there are so many things to do and monitor. Decoctions recover a bit more than one infusion mash...therefore, one should acquire more equipment... somebody is selling something.

Did you know that the shape of the paddle of an overhead stirrer can impact the process along with stir rate? How many different stir blades are there? It never ends.

As Pat said under These days we don't need to do it: Modern highly-modified malts reduce the need for decoction. Yet some beer style recipes seem to still benefit from flexible decoction mashes (p. 90). Whatever floats your boat. You can use as many tricks as you want to brew your beer. Keeping accurate notes on every detail of every step in the process is the only way to plan to reproduce a batch. You will get beer, just not the exact same thing as before.

Decoction aliquots of a quarter to a third of the mash that are boiled and returned do not denature all of the desirable enzymes at play in the entire batch, so they still work. If decoction adds something special to your final results, fine.

BIAB, single infusion, full-volume mash for 90 minutes, stirred at the beginning and once with a potato masher at the halfway point, when the Temperature is checked and heat applied if more than 2 ºC low, no mashout, pull the bag and let it drain back to the kettle. Even that is getting to be a long list of activities, but it is so much simpler. That works for me.

Recognise that many, if not most of the variables are beyond your control. Adapt. The choices are yours.

I'm not trying to be snarky. I admire those who build their equipment and automate things. That's a different goal from mine. I'm going back to reading more of the book and having a beer.

Brew Update

Transferred both these beers to secondary on Thursday for their last hop addition. Then crash-chilled to -1.5 °C. Should get a chance to keg them on Tues or Wed although they could be done now; you can see the trub has settled out already. Some numbers for you. (High gravity beer / partigyle)

VIF and OG: 24.5 L (6.47 Gal) @ 1.097 / 22.5 L (6.0 Gal) @ 1.048
Final Gravity: 1.025 / 1.012
Apparent Attenuation: 73.2% / 78.5%
Primary Fermenter Trub: 5.2 L* (1.37 Gal) / 1.1 L (0.29 Gal)
Likely Secondary Fermenter Trub: 1.35 L (0.36 Gal) / 1.1 L (0.29 Gal)**
* This was a visible layer in the fermenter (see pic). New "BDI" transfer system (not published on the site as yet) managed to get all the clear beer out which is pretty cool.
** Had to dig out my "non-pail" fermenters as I haven't done a secondary for ages. Also needed both of them to sit on one level. My normal pail fermenters are too wide. You should be able to see the secondary trub in the pic. Left brew is the partigyle, right brew is the high gravity one.

[mention]lukasfab[/mention]: Was so looking forward to having a relaxing brew day with you. This week was a bit like the week before brew day, people ringing up for me to come and do a job that "will only take 5 mins." I am so gullible . Place is slowly getting back to normal (organised etc) and, can't wait to taste the brews with you maybe later this week or on the weekend? I won't taste them until then. Man, they smelled terrific during the transfer to secondary!

[mention]ShorePoints[/mention]: Lol on your, "A person with one thermometer is certain of the temperature,; with two thermometers, he is never sure." Totally missed that before . Nice job on having a wade through "the book." I just had another quick scan then and from what I'm seeing, a decoction is not commenced until the main mash has spent significant time at "normal" mash temp. So, enzymes have done their job by that time anyway. (And thanks for the, as always, good read )