Berliner Weisse - butyric acid

[Indoril]

Hi all,

I attempted to kettle sour a Berliner Weisse. After airlock activity stopped I took a gravity ready three days in a row to confirm fermentation was finished. The first two days there were no off smells or flavours but the third day it just smells and tastes like vomit. Now I'm wondering where I went wrong.

Here's my thoughts.
1. I kettle soured in a Grainfather and was not able to purge the head space with C02. But if it got infected at this stage I'm sure I would have smelled it then.
2. I have a fermenter similar to this with a lid on top and a tap on the bottom. I figured it was safer to pull samples from the tap rather than opening the lid. But what I failed to realise was that although I had sanitiser in the airlock, it also had become a little murky from a bit of a blow out. My guess is that this may have become infected and sucked back into the fermenter when I took samples from the tap.

I'd appreciate other's thoughts on this. Also if anyone has ever kettle soured in a Grainfather, is there a good way to purge with C02?

 

[Rob2010SS]

Hi all,

I attempted to kettle sour a Berliner Weisse. After airlock activity stopped I took a gravity ready three days in a row to confirm fermentation was finished. The first two days there were no off smells or flavours but the third day it just smells and tastes like vomit. Now I'm wondering where I went wrong.

Here's my thoughts.
1. I kettle soured in a Grainfather and was not able to purge the head space with C02. But if it got infected at this stage I'm sure I would have smelled it then.
2. I have a fermenter similar to this with a lid on top and a tap on the bottom. I figured it was safer to pull samples from the tap rather than opening the lid. But what I failed to realise was that although I had sanitiser in the airlock, it also had become a little murky from a bit of a blow out. My guess is that this may have become infected and sucked back into the fermenter when I took samples from the tap.

I'd appreciate other's thoughts on this. Also if anyone has ever kettle soured in a Grainfather, is there a good way to purge with C02?

So I guess my first thought is what did you use as your souring agent? I've done 3 kettle sours without issue before, and I don't purge with CO2.

A quick read on butyric acid tells me that if you pre-acidify the wort to a pH of 4.0-4.4, you should be able to avoid getting the contamination that causes butyric acid.

So I've never used a grainfather. How does it work? Did you do your souring phase in the grainfather as well as the main fermentation?

 

[mabrungard]

Both wort pH above 4.5 and any contact with oxygen (aka: air), will make it possible for spoiling organisms to out compete the lacto cultures. When making Berliners, I run my hot wort out of the tun into a corny keg and inoculate it with my culture after its cooled sufficiently.

 

[Renegade Brewer]

I think the higher PH may be a big part of your issue. An off flavor associated with an infected sour is indeed vomit.

When we kettle sour this is our process:

80% Pilsner malt 20% 2 row
Mash for 60 min at 152* F at 5.2 PH. We add 100ppm Calcium Sulfate, 50 ppm Calcium bicarbonate, and 40ppm Mag.

Fly sparge for 60 min after mashout at 168* F.

Boil for 10 min to kill anything on the grain and inoculate in the kettle with wyeast lactobacillus and hold at 98* for 48 hours. Add phosphoric acid to the kettle to drop PH to 3.4.

Boil wort for 90 minutes and add perle hops to equal 13 BUs.

Ferment at 66* F with US-05 at 5 liters and 8 liters of O2. Drop yeast out of conical at 1.007 and add raspberry purée for 3 days before pushing to brite tank.

 

[Indoril]

Hi all. Thanks for the replies.
Yes I think the high pH may also have been a problem because it was a new pH meter and I have a feeling it wasn't calibrated correctly.

Here was my process:

50% wheat, 50% pilsner
Mash for 60 min
Boil for 5 min to kill off bacteria
Cool to 44 C (111 F). Is this too high?
At this point I checked the pH and added lactic acid until it was down to 4.4 but as I said, I have a feeling my meter was not calibrated correctly.
Added a bag of uncrushed grain (about 200g), put the lid on the kettle and covered with plastic wrap and held for 48 hours (checking the pH a couple of times along the way).
Boiled for 15 minutes adding 20g Liberty hops.
Cooled, transferred fermenter and pitched Wyeast 1007 at 20 C (68 F).


I'd like to give it another go with a properly calibrated pH meter and probably a different source of lactobacillus from a probiotic or something. But is there anything else I can change to avoid infection again?

Thanks.

 

[Renegade Brewer]

I would up the boil to at least 10 min to kill bacteria. As I have seen with the grain father, it only gets to 212* and no hotter, so maintaining a true rolling boil is a difficult task.

Also switch from lactic to phosphoric acid to drop the PH. Lactic acid will taste like bile at over 200ppm where phosphoric has a flavor threshold of 400ppm.

A kettle sour should also be soured in the kettle, so add the lacto in the kettle and hold it at 98* for 48hrs. Then go into your 90 min boil, cool down, and add a sacramyces in the fermenter.

 

[RPh_Guy]

Using a lab culture for Lacto would be a huge help preventing off-flavors. ... certain probiotics, certain yogurts, Omega, Wyeast, etc. are all potential sources.
Pre-acidify wort (4 to 4.5) and bring to a boil after the mash. Purging with CO2 isn't necessary.

Add phosphoric acid to the kettle to drop PH to 3.4.

Huh? Your Lacto doesn't drop pH down past 3.4 @ 48h holding 98F ?!??
Do you not make a buffered starter to pitch an appropriate cell count? I'd consider making a starter or switch to a different Lacto species to get it done faster, especially since it sounds like you're operating commercially.

Using lactic acid to pre-acidify is perfectly fine. The bacteria will be producing the bulk of the lactic acid in the beer.

Cheers

 

[mabrungard]

Added a bag of uncrushed grain (about 200g), put the lid on the kettle and covered with plastic wrap and held for 48 hours (checking the pH a couple of times along the way).

OK, there is one of your problems. You do need to create a starter...especially when you're doing the natural bugs method. By creating a starter and keeping it warm and completely oxygen-free, you pass through the vomit stage pretty quickly and the lactic bacteria take over and acidify the starter to the point that the butyric bugs are killed or severely maimed. The handful of malt method definitely can work, but you need to 'proof' your culture to make sure it has the lactic character that you want. When I used Best Pils malt for the initial inoculation, I noted a funk in the starter's aroma for a day or so, but that gave way to a lovely floral, lactic aroma. Much better than I've noted from cultures from some yeast suppliers (they were too monotonic).

With that population of critters, you can safely inoculate your main wort with a mainly lactic pitch that will avoid the vomit issue. (of course, this souring step needs to be acidified to 4.5 or lower and be kept oxygen-free)

 

[mabrungard]

By the way, the wort coming out of the mash tun is at 165F or higher, so there is NO NEED to boil the kettle souring wort. However, I do briefly boil the soured wort to kill off my lacto before pitching the yeast. US-05 is a good choice for finishing a Berliner since it has decent acid tolerance and its clean profile doesn't interfere with the lacto flavors.

 

[Renegade Brewer]

Very sound advice from someone who obviously has done spurs successfully.

As for us dropping the PH to 3.5, yeah I do that because wyeast microbiologists recommend that strain be inoculated from a started at 3.5 and held for 48hrs at 98* degrees. I also prefer phosphoric acid to lactic because it has a higher flavor threshold at 400ppm vs lactic acid at 200ppm. Lactic acid will often accentuate the salty bile flavor when used too heavily. I can use phosphoric with no off flavors in higher ppm if needed.

Of course I want to kill that lacto culture before it hits my tanks, so we boil for 90 min when using over 50% pils due to DMS. I want to finish the clean fermentation with our house yeast (us-05) before adding the fruit purée.

As for boiling the wort off the lautertun, I will always kill whatever is on the grain before introducing any bugs. I will not rely on the bugs on the grains because the culture is too inconsistent, and I can’t be sure exactly what microbes are on that grain. I want a controlled lacto strain that acts and tastes the same each time I brew the beer. I can’t risk ruining a batch of beer by rolling the dice and hoping wild bugs on the grain do their job. I plate each sample after the sparge and boil to ensure nothing is living in the wort prior to pitching my lacto strain.

Our fruit sour we offer as a kit to our customers are presented as expert recipes with those exact directions and a snack pack of lacto. Never would I suggest to a customer to toss a handful of grain into his kettle not knowing the exact outcome; he might as well leave his fermenter open in the back yard for a couple days.

 

[Indoril]

Lots of things to consider. Thanks everyone.