Partial Mash, Palmer Method, and Hop Utilization

[TheCache]

Yesterday I did my first partial mash after a couple years of extract/steeping. From the numbers everything appears to have gone well and the beer is fermenting away at the moment. I have a question regarding hop utilization, IBUs and extract additions, but here is process I stitched together from a few sources:

Mashed the following in 5qts of water for 60 minutes at 152 (held pretty steady between 148-154˚ in a nylon bag, in a 3 gallon kettle on a gas stove).

2.25 lbs (2 row) pale malt
1.25 lbs Crystal 80L
6 oz Chocolate Malt (420srm)
1 oz Black Patent malt (500srm)

At 60 minutes I moved the bag into a 5 gallon pot with another 5 quarts of 168˚ water for 15 minutes (I did not maintain temp in this pot so it cooled down to 152 or so). After 15 minutes I poured a final 2 quarts of 168 degree water over the bag and then removed the bag and poured the wort from the 3 gallon kettle into the 5 gallon kettle. At this point I had approximately 3 gallons of wort in my 5 gallon kettle which measured 1.040 gravity.

I brought the wort to a boil and made the following hop additions:

1 oz East Kent Goldings @ 60m
1 oz Willamette @ 11 minutes
1 oz Mt Hood @ 11 minutes

When the 60 minute boil was completed, at flameoff I added 4.95lbs Briess Golden light DME and stirred for about 10 minutes until it was dissolved. Then I cooled to 68, added another 2.5 gallons of water and pitched a decanted 1.5 liter starter of London ESB 1968 (about 500ml went into wort). OG ended up at 1.056 and 5.25 gallons in the fermenter.

Here is my question:

The flameout DME addition is something Palmer mentions in the partial mash section of How to Brew. He basically extends his Palmer Method to work with partial mash by using grains up front and extract at the end. But Jamil and several others mention adding the extract at the start of the 60 minute boil. I played around with Beersmith and noticed that changing the timing of the DME addition had a pretty big impact on the IBU and I'm not sure I understand why:

From Beersmith using above ingredients:

DME addition at start of 60 minute boil: IBU 21.9
DME addition at 5 minutes (from end): IBU 28.4
DME addition at 1 minute (from end): IBU 31.4
DME addition at 0 minutes (Whirlpool): 32.3

I assume 0 minutes at whirlpool is the same as saying right after flameout. Also, I noticed that if I chose 0 minutes in the boil, the IBU dropped back to 21.9, but this may be a Beersmith bug because .1 minute stayed near 31.4.

Can someone help me understand why the IBU (I assume this relates to Hop utilization) changes so much as I move the DME addition time further towards flame out. I've read a lot of threads over the last day or so and still don't fully grasp what is happening. I do like doing late extract additions, particularly for partial mashes, but I want to be sure I understand how the grains, hops, and extracts are working together. If the answer is too long, point me toward a good source.

Thanks

 

[robfar]

Higher gravity has a negative effect on hop utilization. Adding DME late is usually done to prevent darkening of the extract by boiling, but a little improvement in hop utilization is a benefit. DME does not need to be boiled beyond getting it dissolved.

 

[TheCache]

Ok so the later I add the DME, the longer the gravity stays low and thus the better the hop utilization and the higher the IBUs. Correct?

I guess I was a little surprised at the difference - 10 IBU change just by changing time of the extract addition.

And I understand the color issue, although i primarily use DME which is apparently less susceptible to darkening and since this particular recipe is a dark brown beer anyway, color was not really an issue.

Thanks for the input.

 

[Beernik]

That is correct.

pH, gravity, vigorousness of boil, boil size, and amount of break material all impact how many IBUs you’ll get in the final wort.

 

[hottpeper13]

There's a chart in Palmers book that shows the utilization at different gravity, page 58 in my edition.

 

[BeerAndTele]

I used the process you described on the path of moving from extract to all grain. In addition to the change in hop utilization, I found that adding the DME at the end of the boil helped to reduce that extract "twang" you get when adding all of your extract at the beginning of a concentrated wort boil. Palmer describes it as being due to the maillard reactions that occur in the sugars during the boil. I tried to save the proportionate amount of DME for the end; in other words, if my boil was 1/2 of a full volume boil, I would try to save the amount of DME that accounted for half the sugars.

 

[TheCache]

So the utilization at different gravity levels is likely what Beersmith is using to calculate its estimated IBU's, I think part of what got me confused is that when I changed the DME late addition time on the boil category to 0 minutes the IBU level reverted to the amount of a 60 minute DME boil (21.xx), but when I kept it at .1 or switched it to 1 minute in the whirlpool category the IBU's came back to 31.xxx.

It just made for a strange spike in the graph that I could not account for other than to say Beersmith was just confused about my entering 0 minute boil for a flameout addition. Moving the DME addition to the whirlpool category smoothed out the IBU graph according to what you all are saying.

Beer is coming along nicely now, I expect it to be a good. And I have to admit, realizing that my nice dark 1.040 gravity wort came straight from grains with out added extract (until later) was pretty exciting. I made beer!

Thanks for the input

 

[BeerAndTele]

I think part of what got me confused is that when I changed the DME late addition time on the boil category to 0 minutes the IBU level reverted to the amount of a 60 minute DME boil (21.xx), but when I kept it at .1 or switched it to 1 minute in the whirlpool category the IBU's came back to 31.xxx.

Yeah, that’s weird.

 

[CascadesBrewer]

The flameout DME addition is something Palmer mentions in the partial mash section of How to Brew.

What edition of "How to Brew" are you using and where is partial mashing covered? I have the 4th edition and could not find any coverage of partial mashing.

 

[BrewnWKopperKat]

I have the 4th edition and could not find any coverage of partial mashing.

The idea of doing a partial mash for "wort a" is mentioned briefly in chapter 20 (p 315 in the eBook).

 

[TheCache]

The idea of doing a partial mash for "wort a" is mentioned briefly in chapter 20 (p 315 in the eBook).

Sorry, just getting back after a few days away. In the paperback of the 4th edition it is in the inset on pg 319. One sentence:

"Wort A will consist of base malt and most of the specialty grains, and wort B will be malt extract, although a portion of the specialty malts could be used (steeped) there as well, such as roast malts." (How to Brew, 4th ed. pg 319).

And his "Wort B" addition is done at the end of the hour after the last hop (if a 0 minute hop) and when the heat is off. He allows the hop to steep for 15 minutes and adds the final extract addition during this time (pg 14, steps 7c and 8).

Jamil covers Partial Mash in appendix C of Brewing Classic Styles, although he puts the extract addition at the beginning of the boil. So I merged Jamil's and Palmer's instructions. Also, I read through Homebrewing.org's page on Partial Mash Brewing. On this page, they describe heating the second 5 quarts of water and then sloshing the bag (after removal from the wort) in this second kettle before adding the wort into it. I used that method because it seemed efficient, although I think their temperatures are wrong since they heat the second kettle to 180-190˚. Everything else I have read says that the sparge (or slosh in my case) should be 165-170˚. So that it is the temp I used both for the second sloshing and then the final 2 quarts of sparge (final rinse of the bag).

 

[BrewnWKopperKat]

Jamil covers Partial Mash in appendix C of Brewing Classic Styles, although he puts the extract addition at the beginning of the boil

It looks like the process in Brewing Classic Styles is a full volume boil.

With the "wort a/b" approach, there's an interesting refinement for adding the DME at the end of the boil - dissolve the DME in some of the "top up" water before adding it to the kettle (link). I've used it a couple of times and found that it works well.

 

[TheCache]

It could be a full volume boil, but....

Brewing Classic Styles discusses partial boil methods for extract on pages 34-36. The discussion includes adding some extract at the beginning along with steeping grains to reach the target boil gravity. Then adding late extract and more water to reach target volume/gravity.

In appendix C the instructions are to add 1.5 quarts per lb of grain and then 2 more gallons at the end of the mash for sloshing/sparging the bag before both volumes are moved into the boil kettle. I assumed that these instructions would yield around 3-3.5 gallons of wort (pre-boil) at close to target boil gravity. Then late extract and more water could be added at the end.

It seems like the book leaves the door open for a partial mash, partial boil, w/late addition extract or a full boil with extract added early on. He does explain the calculations to work with extract/grain gravities as does Palmer, so I think I am going to have to dig in and study mash math a bit more....

 

[CascadesBrewer]

@TheCache: I think your overall process sounds solid and probably pretty close to what I would expect for "best practices" for a partial boil + partial mash brew. I don't have lots of insight to the IBU calculation part. I think part of what John tries to fix with the "Palmer Method" is keeping the gravity of a partial boil in check...vs throwing it all in and boiling a thick 1.100 gravity wort. I am mostly an all-grain brewer, but I did my first partial mash recently to learn more about it.

It is a little debatable how much improvement in quality you will get with a Partial Mash consisting of Pale Malt with Crystal, Chocolate and Black malts. All 3 of those are specialty grains that can be steeped and don't have to be mashed. On the other hand, a Partial Mash does open an "extract brewer" up to lots of other grains and malts like Rye, Vienna, Victory, Honey Malt, Flaked Oats, etc. Also potentially to more flavor contributions from base malts like English Pale Ale or German Pilsner or grains from a wide variety of maltsters.

I am curious to hear how your beer turns out and what you think about it compared to your prior extract-only batches.

 

[hotbeer]

Since I know very little about IBU's I've been watching this thread to gain some insight. But haven't really found any more insight here. IBU's are just a way to estimate the bitterness of a brew aren't they? And the earlier you add hops the more you have to add to get the same ending IBU because during the boil, things are going on with the hop compounds.

Depending on a lot of stuff, that's why some beers get a lot of hops at the start and no other additions. And some get staggered timings for hop additions. Many being different hops.

So I'm curious if you didn't realize that hop bitterness decreased with boil time or am I the one that is wrong on that? Or am I not understanding at all what your original question was?

 

[TheCache]

So I'm curious if you didn't realize that hop bitterness decreased with boil time or am I the one that is wrong on that?

My understanding is that bitterness actually increase with boil time, up to a point. That point being between 45 and 90 minutes with most of the isomerization occuring in the first 45 minutes. So hops that go in at the beginning of the boil produce most of the bittering, while later additions produce aroma, but also add moderate bitterness.

My original question was mainly trying to lay out my partial mash process and understand what impact a late extract addition would have on bitterness (@robfar answered that pretty well right away - higher gravity has a negative impact on hop utilization, so less isomerization). As @CascadesBrewer said, this is something Palmer tries to address with his method of splitting extract additions to keep the boil gravity in check. I'm trying to to incorporate that method into my partial mash process as well as understanding why it works the way it does.

Hope that makes sense...


btw, @CascadesBrewer , yeah I figured mashing mainly two row pale with a lesser amount of steeping grains was really not tapping the depths of mashing, but I figured it was a simple replacement for DME+Steep and would give me some practice with mashing. And it was a chance to really dig into Beersmith, trying to understand how it interacts with partial mash recipes.

And thanks for the comments on the process, always appreciate any insights there...

 

[BrewnWKopperKat]

It is a little debatable how much improvement in quality you will get with a Partial Mash consisting of Pale Malt with Crystal, Chocolate and Black malts. All 3 of those are specialty grains that can be steeped and don't have to be mashed.

I suspect that the quality of the steep depends on the mineral content of the water. The wort a/b process in How to Brew, 4e, chapter 1 steeps in wort, not water: "Steeping the grains in [hot] wort as opposed to plain water improves the wort pH ..." (p 13).

I brewed the 1st of a couple of "test" batches around this idea this weekend. I didn't steep in wort, but went down a different path. One note worthy item: I found that Brewers Friend's "Water Chemistry Advanced" calculator provided a good estimate for the pH of the steeped wort.

 

[TheCache]

I am curious to hear how your beer turns out and what you think about it compared to your prior extract-only batches.

Just to follow up....

The beer turned out great. Just just the right balance of malty sweetness and hop but not overpowering either way. Nice roasty coffee and chocolate notes as well. So far everyone who's tried it is very happy, myself included.

As far as a difference between this brew and my extract only brews...

It's hard to say without comparing the same beer brewed both ways, but I do think this beer is one of the richest, fullest tasting beers I have made. It almost seems to have a greater warmth than some of my previous dark brews, but I could not tell you if that is the recipe or the method or both.

Also, doing the partial mash was so easy and pretty fun to see and smell the wort forming from a bunch of grains. Yes it was somewhat longer than extract with steep, but still an enjoyable brew day. In fact it was so simple that I bought a smaller 3 gallon fermenter and am going to try stove top all grain. I know that I'll have a lot to learn re: PH and water chemistry, but I'll start with some strong stouts and IPAs where those factors may not be as much of an issue and get started on a new learning trajectory.

Thanks for all the input. Cheers.

 

[BeerAndTele]

In fact it was so simple that I bought a smaller 3 gallon fermenter and am going to try stove top all grain.

My path exactly. I went from all extract beers with a little steeping to partial mashes to all grain BIAB batches in a 3 gallon Fermonster. Not only do I like my all grain beers better, but I also found that I prefer the 2.5 gallon batch size much more. As much as I love a good beer, I'm not a high-volume beer drinker, so I was finding it hard to get thru my 5 gallon batches before wanting to brew something different. And, with the exception of a few neighbors, I don't have a slew of beer-drinking buddies to help the cause. So now my turnover is quicker, I'm brewing more often, and trying different styles more often. Good times.

Cheers.

 

[CascadesBrewer]

In fact it was so simple that I bought a smaller 3 gallon fermenter and am going to try stove top all grain. I know that I'll have a lot to learn re: PH and water chemistry, but I'll start with some strong stouts and IPAs where those factors may not be as much of an issue and get started on a new learning trajectory.

Nice! I am a huge fan of stove top BIAB! I just brewed a batch of an NEIPA this evening after I finished work. Where I often have to plan for a chunk of time on a weekend and pray for decent weather to brew a 5-gallon batch, I can whip out a 2.5 gallon batch in my kitchen just about any random evening.