Yogurt smell, low FG

[Nathan Buckner]

I brewed a Porter and it's been fermenting for 2 weeks. OG was 1.070, I took a gravity reading today and it's around 1.030. I noticed a slight funk smell a couple days previous but as I looked up posts about it, they said that's pretty normal. Especially when using chocolate malt. I added cinnamon (in vodka for 5 days) a few days ago and now it has a cinnamon yogurt smell. Everything I have read said let it go since it's a green uncarbed beer.
I'll try to give as much info as I can to get a faster more accurate answer
Grain bill:
2.5lb Maris Otter
.5lb Victory
.5lb crystal 120
.5lb flaked oats
.5lb brown sugar
.25 chocolate malt
1oz Crystal hops at 60 min boil
Yeast: 6g of US05

I'm using a 2 gal Mr. Beer fermenter
It only made a thin krausen line around the edge of the beer and has been a really mellow fermentation the whole time.

Any ideas/ explanation? Should I agitate the yeast? Dump it for fear of lactobacillus infection?

Thanks

 

[IslandLizard]

The yoghurt smell is probably from the yeast. I'd let it be, what you got to lose?

As long as your cleaning and sanitation regimens are spot on, infection should not be an issue.
Now for 2 gallons of 1.070 wort half a pouch of US-05 is a bit skimpy.

Although you do have a lot of crystal in there, a gravity of 1.030 is way high after 2 weeks.
Did you measure it with a refractometer perhaps?

 

[Nathan Buckner]

I've done 1.080 with half a pack and no trouble hitting target gravity. Those were IPAs though.
I used my hydrometer for both OG and gravity reading this morning.
I sanitized everything before putting it into the fermentor. I used Io-star to sanitize the fermentor then rinse it with star san (I always make a solution of star san to keep equipment sanitized so I just rinsed the fermentor with it just to make sure all the Io star was out).

 

[IslandLizard]

How did the sample taste? That would be your guide.

IO-Star, then Starsan. Not much will get past that!
Those Mr. Beer "barrels" do need some close attention when cleaning, they have tight corners and threads. Also that spigot.
IO-Star at 25 ppm is also no rinse, whatever clings to the surfaces is fine. I do prefer to drain it thoroughly, though. Or rinse with Starsan, as you do.

Lactobacillus is not harmful. Most things that grow in beer aren't, except for molds, but they're rare.

 

[Nathan Buckner]

I appreciate the feed back! The taste sample tasted better than it smelled but there was still a noticable flavor that tasted like the smell. Milky, yogurt, buttery. The buttery flavor makes me think diacetyl, which would make sense with the 1.030. That tells me that yeast stopped and wasn't able to clean up diacetyl. That is 100% assumption, I have no idea.

 

[IslandLizard]

I appreciate the feed back! The taste sample tasted better than it smelled but there was still a noticable flavor that tasted like the smell. Milky, yogurt, buttery. The buttery flavor makes me think diacetyl, which would make sense with the 1.030. That tells me that yeast stopped and wasn't able to clean up diacetyl. That is 100% assumption, I have no idea.

Did you detect any sourness? Or other off flavors and aromas, aside from the ones you mentioned?
Those would point to a (slight) infection. Pediococcus is a heavy diacetyl producer. It lurks in tight places, like inside (kettle) valves, spigots, etc. It's fairly heat resistant too.

If the beer is still cloudy, that could be yeast, and you would taste it too.

Cinnamon can play games with your sensory system. Has anyone else tasted it?
Brown sugar contains molasses. When it ferments it leaves a metallic taste to me, so I never use it anymore. Instead, I make sugar syrups, from light to fairly dark (D-90+) and use those instead. Much better.

1.030, huh? Did you mash high?
What was the projected FG from the recipe?

You could try to pitch more yeast, but I would make a small starter first and pitch it at high krausen to optimize the chances of resuming the job, if there's anything to be resumed.

 

[Nathan Buckner]

Any sour flavor came from the yogurt flavor I think. The beer is still fairly cloudy. I'll have my wife taste it to see what she thinks.
When I added the brown sugar I took some of the wort and brought it up to boiling, turned off the heat then added the brown sugar to that to dissolve then added the mixture at the end of the hop boil.
I mashed at 150f and the FG was supposed to be around 1.014
Could you explain your comment about pitching at high krausen? During initial fermentation only a thin line of krausen formed around the edges of the beer, it never coated or became thick at all.

 

[IslandLizard]

Don't tell your wife what you're after, let her taste and give her report. Then talk about your experiences.

Look up "shaken-not-stirred" starters.
Use good sanitation of course.

In short:
Make a pint starter using DME (DME:water @ 1:10 by weight). Boil, then chill to room temps. Pour into a fairly large, closeable mason jar or jug, like a 1/2 gallon clear wine jug, or so. Shake it up well to create lots of foam. Add the rest of that yeast package, and let it rehydrate itself for half an hour. Cap loosely.

Tighten cap and shake it up as much as you can to create lots of foam. Repeat every 30-60 minutes or whenever you can, letting fresh air back in each time before you shake. After 4-8 hours you should see a good layer of foam on top of the starter. That's high krausen. Pitch the whole lot into your fermenter. That's the most viable yeast you can get, ready to chow down on anything left that it can.

 

[Qhrumphf]

Yogurt or sour milk character does make me think lactic bacteria contamination. Fortunately many lactic bacteria are *extremely* hop sensitive, so it hopefully won't get worse than that (not a guarantee though). But presence of diacetyl does suggest pediococcus, which tends to be more hop tolerant than lactobacillus.

 

[Nathan Buckner]

Wife described it as grainy yogurt. This was unprompted. I just asked her to drink it and she reluctantly did based off the smell. She didnt like the flavor too much either.
Before tossing it I will definitely make a starter and pitch more yeast.
To Qhrumphf, what can I do about that other than toss it?

 

[Qhrumphf]

Toss some Brett at minimum but ideally a broader sour culture (and/or viable bottle dregs, there's lists of who's wild beers have viable dregs) and embrace it. If you're not getting offensive phenols or enteric notes then hopefully its a good indication you'll end up with a tasty sour beer down the road (though if it's a spontaneous contaminant you're still gambling with unpleasant). I'd also rack it to glass (as small a carboy as possible to minimize headspace, use sanitized marbles to fill the rest and make the headspace virtually zero).

Otherwise, dump it. You could potentially try and kill the bugs but it won't fix the yogurt character even if successful.

Though whether you keep or dump, anything that's touched it should be treated with funky beer protocol from here on out. If you don't intend to brew wild beer in the future the easy/safe answer is discard any and all cold side plastic/rubber that touched it.

And then you probably wanna revisit your cleaning and sanitizing practices. Your fermenter probably wasn't cleaned/sanitized properly, especially if it has trouble points as indicated above.

 

[Nathan Buckner]

Greatly appreciate the feedback.
So that I can get better at sanitation, I usually fill my fermentor to the 1 line mark and put 45 ml of io star in it, shake and let sit for 5 min, then rinse it with starsan. I run star san through my siphon, hose, hydrometer, yeast pack, scissors and keep stirring utensil in star san when I'm not using it. Any points that need improvement or alteration?

 

[Qhrumphf]

Although, if you want to try other things like pitching more yeast, do that first before you dump it. If you're gonna dump it anyway, it can't hurt. Just in case you're describing a different character than I think you are.

But yeah, if it's indeed a LAB contamination, there's no way to make it "better" (ie reverse it)

 

[Qhrumphf]

How is it cleaned? And if there's a spigot are you breaking that down? Spigots, threads, and ball valves are MAJOR homebrew contamination points that often don't get the attention they deserve.

You can't sanitize a dirty surface.

 

[Nathan Buckner]

That actually didnt occur to me. That dang spigot. I didnt run anything through it since I siphon it into bottles so I didnt think to take it apart. I'm still going to let it run its course and bottle, but if its still bad I'm going to through it all out and start using the 5 gal brew bucket I just got in preparation to scale up.