LAB and hops.

Kinda dead in here these days, but I’ve got some more data that might drive a bit of discussion.

Read any information provided by the various yeast/bacteria supply companies on the lactic acid bacteria that they supply and you will see something about the IBU tolerance of the species or strain they provide. The Milk The Funk wiki does a good job summarizing much of the available information ( http://www.milkthefunk.com/wiki/Lactobacillus). But I think only talking about IBU misses a big part of the story.

I’ve shown you before data indicating that the LAB we use in the brewery is able to handle a fair bit of iso-alpha acid. So we were somewhat surprised when wort we made with a sub-inhibitory level of iso-alpha acid didn’t sour the way it should have. But there was a key difference here: IBU testing was done with iso-alpha acid extract, and the wort derived its IBU from hops added to the kettle, specifically late in the boil or in the whirlpool.

So, there are (at least) two possibilities for whats going on here:
1) We could be off on our WP add math (We assume 5% utilization during our 8 min WP and 15 min stand)
2) There is something beside iso-alpha acids inhibiting the LAB

I lean towards option 2, for a variety of (fairly obvious) reasons, a few of which include:
- The use of high beta acid hops as antimicrobial
- The commercial use of beta acid extract for decreasing contamination in large scale fermentation vessels
- The use of "0" alpha acid hops in lambic brewing

So to test this I set up a couple small scale LAB fermentation experiments. What I did here was to take 10P wort and add it, while still hot, to flasks with measured amounts of hops (I used a varietal with 9.8 alpha and 5.9 beta). I let them sit hot for 20 min (to simulate our WP and rest) before cooling it down. To account for the presence of the hop material in the flasks, I also "dry hopped" cold wort with a few different levels as well. I then added a 3% v/v pitch of our house LAB and incubated between 70-72 degrees F, taking pH measurements when I had time.

I’ve included the previous data as well for the sake of comparison



A few things jump out right away
-Adding WP hops really hurt this LAB, even at levels that (theoretically) produce far less iso-alpha acid than is inhibitory.
-"Dry hopping" the cold wort is also inhibitory. There is a decrease in the pH after a few days, but as anyone who has worked with hops can tell you...they are not sanitary. The hot wort added to the other flasks was sufficient to pasteurize the hops, the cold wort...not so much. As a result, I saw fermentation activity in the "cold" experiments which could account for the pH drop. I’d like to try this again and add cyclohexamide to stave off any sensitive yeast.
-Comparing the earlier data with these

I was told I had 6 characters remaining. Fix the post tab Joet!

In any case, here’s part 2:

A few things jump out right away
-Adding WP hops really hurt this LAB, even at levels that (theoretically) produce far less iso-alpha acid than is inhibitory.
-"Dry hopping" the cold wort is also inhibitory. There is a decrease in the pH after a few days, but as anyone who has worked with hops can tell you...they are not sanitary. The hot wort added to the other flasks was sufficient to pasteurize the hops, the cold wort...not so much. As a result, I saw fermentation activity in the "cold" experiments which could account for the pH drop. I’d like to try this again and add cyclohexamide to stave off any sensitive yeast.
-Comparing the earlier data with these new data, it sure seems like pre-acidification of the wort helps a lot, both in terms of rapidity and final pH. This is something other people have reported, and that we have anecdotal evidence from the brewhouse batches on. I plan to test this more carefully in the coming weeks as time allows.

The idea that dry hoping and/or beta acids is inhibitory to LAB isn’t a new idea (I know of at least one Youtube video supporting these observations) but I think it’s important to have more data to help us determine best practices for LAB use.

As a final thought, I really think that this behavior is the rule and not the exception. We have experience with (very) mixed cultures in barrels where a large WP addition (calculated to yield 20 IBU) will acidify to 3.8, whereas that same culture will take wort with a 75 min 25 IBU addition to 3.4 or lower in the same amount of time. I’m keen to use late hop additions to dial in the pH of batches for blending and such. We will see where that goes!

Cheers

Caleb

So this is the forum to post dick pics in, as no one reads it I guess. No snark from HornyDevil even, this was a perfect example to tell me to get a FB account and log into MTF

Sorry man...I know this forum doesn’t get much traffic, but I for one appreciate your research!

This comes at a great time for me since I’m brewing an IPA this weekend with a big whirlpool addition. My plan was to run a couple gallons off from that and add LAB to do a sort of "sour wort" beer. Maybe that’s not such a good idea since it looks like whirlpool hop additions may be more inhibitory than early kettle additions....

I guess I could run off at the end of the boil before the hops are added. Would you be interested to hear my results if I tried to sour with the whirlpool addition in there? I was going to use one of the Good Body probiotic drinks. I think it’s planatarum...

Yeah, please post the results! Even if you just pull a couple hundred ml after the WP addition you could try to add a small amount of the plantarum and compare the final pH to the pre-WP addition wort. It would be really neat to see how another strain stacks up!

Thanks for posting, CLevar! I have no knowledge or experience to discuss this further, but I find it an interesting read.
Did I just press the ’like’ button?

Originally posted by CLevar
Yeah, please post the results! Even if you just pull a couple hundred ml after the WP addition you could try to add a small amount of the plantarum and compare the final pH to the pre-WP addition wort. It would be really neat to see how another strain stacks up!

Originally posted by CLevar
So this is the forum to post dick pics in, as no one reads it I guess. No snark from HornyDevil even, this was a perfect example to tell me to get a FB account and log into MTF

Feel free, just attribute please.

Of note, the sugar beet industry has been using beta acids for years (since at least 1994, see https://betatechopproducts.com/wp-content/uploads/2015/09/Application_acids_sugar_industry.pdf), and you can buy beta acid extract from a variety of companies (see http://www.hopsteiner.com/)

This is why we really need to stop thinking about these types of beers as "Art and Magic". The science and technology are out there, but we, as an industry, need to stop perpetuating myths about how this stuff works (IBU is king, Brett sours, no need to use aged hops, etc)

Ok, so this experiment was somewhat botched by me (as usual) but I think the results still give some decent intel. Here’s the scoop...

Brewed a 1.062 SG wort and then diluted four gallons with sterile water down to 1.034 (I was brewing a double batch. The other half was an IPA) The grist was:

50% Pilsner malt
26% White Wheat
11% Rye Malt
10% Flaked Oats
3% Carafoam

It was a 90 minute boil and I added .25 ounces of Polaris (18%AA) at 60 minutes for around 7 IBU’s supposedly under the threshold for lacto, especially a hardy strain like Plantarum.

The other half of the batch was whirlpooled with 2 ounces of Simcoe, 3 ounces of Galaxy and 3 ounces of Citra at 165 degrees F for 30 minutes... supposedly below the temperature at which alpha acids are isomerized, but oils are certainly extracted. I canned about 8 ounces of this wort to use for the lacto experiment to see how the pH drop would compare to the main batch with no whirlpool hops. This also had the 60 minute addition of Polaris. Also of note was that this sample was not diluted, so it remained at 1.062 SG.

Here’s where I jacked up. I wanted to adjust both the main batch and the small sample of whirlpool hopped wort to around 4.5 pH with lactic acid, but I miscalculated and ended up adjusting both to a pH of 4.0. Another reminder of why its good to undershoot at first to see where it lands.... Live and learn.

I pitched most of a 32 ounce carton of Good Body probiotic drink (tropical something or other) to the main batch without the whirlpool hops and added a little to the 8 ounce container WITH the whirlpool addition. Both were incubated at 100 F.

After 7 hours, the main batch without the whirlpool hops had dropped to 3.8 pH and the whirlpool hopped batch hadn’t dropped at all. Still at 4.0 pH.

After another 7 hours the pH of both remained the same. 3.8 for the main batch and 4.0 for the hopped sample.

10 hours later.... the same result. No change on either.

12 hours later.... same results. No change in pH on either sample.

36 hours later... pH of the main batch was the same, pH of hopped sample was 3.7... Honestly I wasn’t very careful with sanitation on the hopped sample at this point in the experiment since the point had already been made... I’m pretty sure a wild yeast had contaminated it, explaining the sudden drop in pH.

So, any thoughts? I’m not sure if my over-acidifying the wort before pitching the plantarum had an effect on the souring. Could this be a factor in why I didn’t get pH drop I expected? I’ve used the Good Body probiotics before with good results, but that was on totally un-hopped wort. Maybe the 7 IBU’s was too much after all?

In either case, the whirlpool hopped batch saw zero pH drop in the first 36 hours. It held steady at 4.0 at 100 degrees F for 36 hours...A good case for hop oils restricting the activity of lacto plantarum. Or maybe it was the 7 IBU’s....but the main batch with the same amount of IBU’s (but no whirlpool hops) dropped .2 pH in the first 7 hours and then stopped.

Any thoughts on this? There were several miss steps in the process e.g. adding a 60 minute addition of hops and then over-acidifying with lactic acid, but it seems like hops in any form certainly inhibit lacto... even below isomerization temps.