Dry Hopping and IBU's plus adding Lactic to reduce PH when Dry Hopping

[The Baron]

I know this thread may be taken over by the scientists amongst you so apologise if I do not get too involved as I do not have the full inclination to dig deep on the subject but go for it as it could be interesting for some.
Right the question is I have been reading up on dry hopping adding bitterness/IBU's/Perceived bitterness and one of the things that came up was adding hops raises the PH of beer so in a unscientific experiment I have added a 40g dry hop and 3ml of Lactic acid to counter the PH rise hopefully to counter this rise and reduce the bitterness I sometimes suffer from when dry hopping.
It does seem that the old belief that DH does not add IBU's is now being thought not to be true by quite a few aficionado's of the brewing industry.

 

[dmtaylor]

Dry hopping does not add any IBUs. But it can add bitterness that is not measurable as IBUs. IBU is a measurement of isomerized alpha acid, which requires heating to happen. Otherwise the bitterness can still exist but it's not from isomerized alpha acid. Did you ever eat a hop cone? I have. It's very bitter, but the bitterness is not from IBUs. It's from other stuff and precursors that are still very bitter.

 

[The Baron]

From what I have read that is a technicality you are correct that it does not add IBU's as that is a measurement of Iso Alpha Acids(AA's that are acquired from Isomerisation which occurs on the hot side) but it does add Alpha Acids in some cases which are bitterness.
This is what confuses some brewers when they say it does not add IBU's which is correct but only because it adds cold side Alpha Acids which fall outside of the technicalities of how IBU's are measured so for all purposes in laymans terms it does add bitterness just not measured.
So the question many brewers ask is not answered correctly as far as the ordinary brewer they are just being scientifically correct.
Lets say then that Dry Hopping can make beers more bitter in some occassions which does not show on a recipe sheet and misleads many brewers who then get a beer more bitter than they expected

 

[Agentgonzo]

I tend to ignore IBU. add mentioned, you can get a whole lot of different bitterness from things that don't measure in IBU.

It's like trying to judge how nice a car is to drive by it's bhp alone. So much more happens than just the ibu

 

[The Baron]

What do you think of the adding Lactic to counter the PH rise when the DH is added do you think it is a possibility it will reduce some of the bitterness transfer as PH adds to it from what I have read?

 

[Agentgonzo]

What do you think of the adding Lactic to counter the PH rise when the DH is added do you think it is a possibility it will reduce some of the bitterness transfer as PH adds to it from what I have read?

Not a clue. I know that the yeast stabilise the pH during fermentation to what they want/need, but that's about the total of my knowledge on the subject. I'm a laissez-faire kind of brewer

 

[The Baron]

I haven't a clue whether it will work but lowering the PH when adding hops hopefully will slow down the extraction of Alpha Acids.
If it works I'll write a book on the thesis

 

[Benfleet Brewery]

I wonder if different hops provide different amounts of this perceived bitterness. The reason I ask is because my go to hazy pale ale is dry hopped with 20g of each Simcoe, Mosaic, Citra and Amarillo and it comes out great (well I think so anyway). However, for a change, I recently did the exact same recipe but instead dry hopped wit 20g each Rakau, Ekuanot, El Dorado and Taiheke but it came out tasting really bitter.

 

[The Baron]

It is something to do with Humulene oils that can have as much as 66% bitterness of AA's but can be released on the cold side unlike AA's.
I Think?

 

[RoomWithABrew]

I've listened to several podcasts on the craft beer and brewing and they mention acidifying the wort, seems to be that phosphoric acid is the acid of choice for this.
I do believe as well from various readings that dry hopping will add some IBU. This occurs because of the heating that occurs to the hops when they are dried and pelletised.
I add the phosphoric acid after the boil and before the whirlpool. It's a bit of a guessing game as to how much acid to add, but the water calculator can help if you input your pH post boil.

 

[The Baron]

I will measure the PH next time before adding acid prior to the DH. It will be interesting to see if it helps obviously I have not done anything scientific in this one.

 

[dmtaylor]

What do you think of the adding Lactic to counter the PH rise when the DH is added do you think it is a possibility it will reduce some of the bitterness transfer as PH adds to it from what I have read?

I think this is an interesting idea, and it just might help.

 

[Sadfield]

Can we please spend a little time checking what we state as fact?

Many breweries are reporting that dry hopping does add IBUs, by the measurements they have been doing.

Here is a paper that discusses the tracking of IBU's through out the brewing process. It reports an increase in IBUs in beers with no hot side hops.

"IBU Increase from Dry Hopping High dry hop amounts resulted in an IBU increase (Fig. 7). IPA #8 had a 7.7 increase in IBU when it was dry hopped during fermentation and another increase of 14.9 IBU when it was dry hopped at terminal gravity (22.6 total increase in IBU). The Hazy IPA at Little Italy had a 13.2 rise with the first dry hop and a 19.3 increase with the second dry hop (32.5 total increase). This increase in IBU can be attributed to humulinones and α-acids introduced during dry hopping (1,10). We continued to study dry hopping’s contributions to bitterness at our R&D brewery, where we brewed two Hazy Session IPAs. We did not add any hot-side hops on brew day. Once both beers were at terminal, the temperature was dropped to 50°F and hops were added to the fermenter. Both beers were roused with CO2 for three subsequent days and then chilled. Hazy Session IPA #1 was dry hopped at 3 lbs/BBL with equal parts Amarillo, Cashmere, and Citra. Hazy Session #2 was dry hopped with 4 lbs/BBL of Centennial. The measured beer IBU for #1 was 26.6, while #2 was 42.9 (Table 7). "

Master Brewers Association.
Tracking IBU Through the Brewing Process: The Quest for Consistency

Same result at New Belgium.

https://beerandbrewing.com/rethinking-bitterness-in-dry-hopped-hazy-beers/

 

[Sadfield]

"IBUs: IAAs and ABCs
The IBU is a measurement of the amount of infrared light absorbed by a sample of processed beer [Thermoscientific; Anon.]. It is often (and incorrectly) reported that one IBU equals one part per million (ppm) of isomerized alpha acids (IAAs). However, as Val Peacock explains, the IBU was developed in the 1950s and 1960s to measure the combination of both IAAs and auxiliary bittering compounds” (ABCs) [Peacock, pp. 158-161]."

 

[dmtaylor]

Can we please spend a little time checking what we state as fact?

No, we can't.

In fact, we're learning more stuff everyday. Thank you for the facts that were new to us.

 

[matt76]

@The Baron I can add some thoughts based on my own experience with pH:

- Ultimately I think ones subjective perception of the finished beer is what matters most, overriding anything objective that you can measure (e.g. SG, pH, temperature), i.e. if it tastes right it is right.

- I think we tend to focus a lot on mash pH but put much less emphasis on pH of the finished beer at serving. This seems odd to me. A while back I got into the habit of checking the pH of the finished beer (most of the time) - not really with the intention of changing anything but just out of curiosity. Even if perception has the casting vote it still seems good practice to me to take measurements where possible, including pH.

- (Being of a curious mind I'd be interested in a Tilt-like device that measures the pH of the fermenting beer instead of SG, to see how it changes over time)

- I don't think it's a bad idea at all to add some acid (lactic or otherwise) to the finished beer if that makes it more to your liking, just do a bit of experimenting in the glass first as below before you overdo it at ruin an entire batch.

- I have from time to time done a bit of kitchen science, playing around with dosing the finished beer with a drop or two of lactic acid or CRS and comparing with vs. without, or a little vs. a lot. From here you can scale up and dose a keg if you wish - go under rather than over as it's easy to add more but hard to take away!

- I used to add CRS and gypsum to my hoppy beers, but lactic acid and CaCl to my malty beers. I often found the former a bit flabby and after doing a bit of kitchen science as above found that I preferred the result with a slightly lower pH. I don't recall exact numbers but we're probably talking something like pH 4.2 vs. 4.4. Nowadays I simply use lactic acid and CaCl in all my beers and in general I'm happier with the results. I can't say if this is purely down to pH, flavour impact of CRS vs. lactic acid or of gypsum vs. CaCl. But I'm getting a bit more "zip" from my beers which I prefer.

- A more recent change I've adopted is dumping all the kettle trub into the FV. A result of this is that I'm seeing a touch more attenuation and a touch lower pH, again it's like pH 4.2 vs. 4.4. The beers seem crisper and drier which is sometimes good, sometimes less so, depends what you're after. I'm not sure if the attenuation causes the lower pH directly or if it's down to something else such as the presence of the trub.

- Something else to consider is the flavour impact of different acids. At the moment I'm fermenting an American wheat beer - I added lactic acid to the mash water as usual, but also added citric acid at the end of the boil, not to go full-on sour beer but just to add a lemoney-citrusey kick. Honestly I think I might have overdone the amount of citric acid but you could certainly taste it in the wort at pitching. If you're interested, the pH at pitcing was about 4.0 vs. 5.2 or so for a "normal" beer. However, whereas the pH of a "normal" beer might drop from 5.2 or so down to 4.2-4.4, the forced ferment I did only dropped to about pH 3.8 (though as part of that comparison we do also need to consider the meaning of pH with regard to the logarithmic scale and the number of H+ ions).

 

[The Baron]

Some really good info coming out of this thread.
Guess what Matt I did just that and added a couple of drops of lactic to a pint of beer and this may be perceived but it did smooth out the bitterness but is it just a mind trick.
I will give it another go when I have a pint tonight or tomorrow.

 

[Brew_DD2]

"IBUs: IAAs and ABCs
The IBU is a measurement of the amount of infrared light absorbed by a sample of processed beer [Thermoscientific; Anon.]. It is often (and incorrectly) reported that one IBU equals one part per million (ppm) of isomerized alpha acids (IAAs). However, as Val Peacock explains, the IBU was developed in the 1950s and 1960s to measure the combination of both IAAs and auxiliary bittering compounds” (ABCs) [Peacock, pp. 158-161]."

Thanks for the links. This is really interesting stuff. I hope we can see new measures of IBUs becoming more mainstream. To the best of my knowledge, I think a lot of this is perpetuated by the most common ways that IBUs are calculated in brewing software. Would be good to see some of this stuff being incorporated into how IBUs are estimated going forward.

It's currently a bit of a crapshoot trying to work out the level of perceived bitterness in Hazy IPAs. I get that a single number doesn't tell the full story, but it's better than where we are currently.

 

[Sadfield]

To the best of my knowledge, I think a lot of this is perpetuated by the most common ways that IBUs are calculated in brewing software.

https://beerandbrewing.com/dictionary/eej03p6ZUI/

Agreed. This is an interesting read. I think it goes back to the 50-60's, whilst IBUs can be measured, predicting them was impossible. An Iso-Acid based calculation was deemed close enough for the brewers of the time. Now it's assumed that only those IBU's that can be calculated actually exist, despite brewers adding a shed load of measurable IBU's into a beer via dry hopping.

 

[Brew_DD2]

https://beerandbrewing.com/dictionary/eej03p6ZUI/

Agreed. This is an interesting read. I think it goes back to the 50-60's, whilst IBUs can be measured, predicting them was impossible. An Iso-Acid based calculation was deemed close enough for the brewers of the time. Now it's assumed that only those IBU's that can be calculated actually exist, despite brewers adding a shed load of measurable IBU's into a beer via dry hopping.

I've certainly been guilty of assuming that. I think we've all known for some time that IBUs are of limited value, given the number of variables at play, but if there is a more accurate way of estimating bitterness that is more applicable to more modern hopping techniques, then the measurement will certainly be of more utility than it is currently.

That, coupled with BU:GU, will surely give a better level of predictability to recipe design.