How to avoid lactobacillus infection

[Nathan Buckner]

Hey all,
I recently made a cinnamon vanilla brown sugar oatmeal raisin porter. During fermentation I brought this up here because it had a yogurt smell. Got great advice and as per usually most said let it go and see what it's like when it's ready. Well I've been drinking on it for a couple weeks now and it's still sour. Not horribly. I read an article on how original porters were a bit sour but this is a bit more than subtle. So I'm thinking it got a lactobacillus infection because of how it smells and tastes.
I'm going to post the ingredients I used and see what I could change to prevent it from happening again. The flavor beyond the sour was amazing but unfortunately it over powered the beer.
I used:
2.5lb Maris Otter
. 5lb Victory
.5lb Crystal 120
.5lb flaked Quaker oats (I had a bag for over a year in the pantry)
.5lb Dark Brown sugar
.25lb Chocolate malt
1oz Crystal hops 60min boil
This was a 2 gal batch.
In brewers friend it estimated an abv of 7.5% and IBU of 31.92
Its OG was 1.070 but FG was 1.030. I added more yeast and waited another week but the gravity stayed at 1.030.
I mashed at 150F for 60 min and did a 60 min boil. Pitched US05. I noticed the yogurt smell after a couple of days and it never went away even after pitching more yeast. I didnt dry hop.
Any suggestions or idea why lactobacillus flourished in this batch?
Thank you!

 

[MaxStout]

It might be an equipment sanitation issue on the cold side. Plastic and tubing are particularly susceptible to harboring bacteria.

 

[Nathan Buckner]

It might be an equipment sanitation issue on the cold side. Plastic and tubing are particularly susceptible to harboring bacteria.

Could the bacteria affect the yeasts attenuation?

 

[MaxStout]

Could the bacteria affect the yeasts attenuation?

Not sure. I do know that bacteria compete with yeast and will consume some of the sugars. But I don't know if bacteria will cause under-attenuation or otherwise prevent the yeast from reaching its attenuation levels. My experience with infections has been the opposite--gusher bottles because the bugs attenuated it even more. There are some people on HBT who have a much more solid understanding of microbiology. @RPh_Guy - maybe your thoughts on this?

In any case, it's good to develop a solid sanitation regimen, so you don't find yourself at that point again with the next beer. Using a good sanitizer like Starsan or Iodophor on anything that will touch wort or beer on the cold side is key. And sanitizers do no good if the surfaces are not clean first. Disassemble valves and clean/sanitize, replace plastic tubing, make sure other plastic items aren't scratched (harbors microbes), etc.

 

[RPh_Guy]

maybe your thoughts on this?

I'm famous! Thanks for mentioning me. Happy to help.

cinnamon vanilla brown sugar oatmeal raisin porter.

We seem to be missing some info.
How did you add all the other spices/adjuncts?
Did you add any lactose?

I'm thinking it got a lactobacillus infection because of how it smells and tastes.

It does sound like it might have lactic acid bacteria (not necessarily Lactobacillus).

Any suggestions or idea why lactobacillus flourished in this batch?

Contamination can occur at so many points in the process. Every piece of equipment that touches the wort/beer after chilling increases the risk of contamination exponentially. Unpasteurized ingredients added to the fermenter are also highly likely to carry wild microbes. Wild microbes even float around in the air.

As @MaxStout said, sanitation is completely dependent on proper cleaning. I suggest a warm/hot PBW soak for all cold side equipment.

Can you describe your typical cleaning process? Many times it's not new brewers that get contaminations, but people that have a dozen or more successful batches under their belt and start to let sanitation slide.

Could the bacteria affect the yeasts attenuation?

The short answer: Yes.
The long answer: Attention depends on a large number of factors. The acid produced by lactic acid bacteria is of similar density to the sugar it replaces, so soured beers often have FG a few gravity points higher than a similar non-sour beer. Acidity has also been known to slow down or potentially stall fermentation.
There are also other non-acid-producing microbes that may cause a slow or stuck fermentation.

For what it's worth, I have good attenuation from US-05 in my intentionally sour beers, which I'm sure have much more acid than your current batch. Most yeasts are generally pretty acid tolerant.
I suspect your beer is probably not acidic enough to affect the yeast. The low apparent attenuation is likely due to some other factor.

Hope this all makes sense.

 

[S-Met]

Silly question, but what are using to take your FG? If a refractometer, are you correcting for alcohol?

 

[Miraculix]

When did you add the cinnamon and vanilla? If you added it after cooling the wort, it's most likely the source of your contamination.

As us05 is also regularly used in sours, I doubt that the contamination and the lowered ph led to underattenuation. I guess it's more related to the mash, or did you use lactose?

 

[Pappers_]

Moved from "Introductions" to "All Grain" forum, since this is a technical brewing question. I don't have anything to add to what has already been said. Well, maybe one other item - enter it in a competition and see what the judges anonymously think the off flavor you're perceiving as yogurt might be.

 

[Vale71]

Any suggestions or idea why lactobacillus flourished in this batch?

Here's a few:

cinnamon
vanilla
raisin

Any crap you add cold-side will introduce bacteria and then it's just a question of whether they will flourish or not.

 

[Nathan Buckner]

Thank you all for your insight and moving this thread to the appropriate location.

For raisin, I just used .5lb of Crystal 120 thinking that would be enough to get the raisiny flavor in a 2 gal batch.
I made a tincture of cinnamon an one of those small bottles of vodka. In total I used 1/2 of a teaspoon of cinnamon. 1/4 tsp @5 min boil and 1/4 tsp in tincture. I added vanilla right before I was going to bottle, should have checked gravity before that to see if I needed to add more yeast. I used a sanitized dropper and put in 10ml of vanilla extract which only had vanilla in 41% alcohol.
No lactose was used. Only grains, vanilla extract, cinnamon during boil and cinnamon tincture. Sorry for not including those in the beginning.

 

[bracconiere]

For raisin, I just used .5lb of Crystal 120 thinking that would be enough to get the raisiny flavor in a 2 gal batch.

8oz's of 120 would be a lot for my 10 gallon batches.....

not too much, but a lot....

 

[Vale71]

Alcohol extracts can obviously be ruled out as a source of infection. Specialty malts as fruit adjunct substitutes can be ruled out too, unless you rubbed them on actual raisins to enhance the aroma...
If it is indeed an infection then you just need to look at your general cleaning and sanitation practices. Lacto infections are unfortunately the most common as lactos are basically everywhere.