Acrid smell

[TMVBW]

Recently brewed 3bbl of brown ale with WLP080.

OG was 1065 and took about 48 hrs to start fermentation. Maybe because i under pitched with 4 new vials from WL. Any way fermentation started going pretty good every thing tasted and smelled great. fermentation started to slow around 1032 and stopped at 1028. its been stuck at 1028 for 6 days now.

day1 1065 62F
day2 1065 62F
day3 1057 64F
day4 1048 62F
day5 1042 62F
day6 1036 64F
day7 1032 64F
day8 1031 64F
day9 1029 63F
day10 1028 63F
stuck at 1028 for 6 days

So first question.
i know the cream ale is a mixed ale and lager yeast and takes time. ive read this yeast like temps between 60-70 but when do i drop the temp and let the lager yeast finish out? After how much attenuation?


Next question. (Which has me worried)
About 5 days after the fermentation stuck i noticed this Sharp faint sour smell
today the smell has become very acrid. Almost like a very sharp vinegar but not a pleasant vinegar smell. i pulled a sample and there is a unpleasant bitterness forming.
Now all along there has been the normal sulfer smell associated with yeast like this, but it is now replaced with this new acrid smell.

has anybody smelled this before?


Help!

[Brew Chef]

Sounds like all the classic symptoms of an infection...possibly from the long lag time and underpitching. We've had a problem with it before on our pilot system. The only thing we do differently to prevent it is be very careful to sanitize everything well, pitch plenty of yeast, and be sure the yeast we're pitching is healthy. We once had a bad batch of dry yeast that infected our hefe for several batches before we determined it was the yeast itself out of the package. It was sour sour sour.

Let me know what you find out. We're always trying to discover every possibility of a good beer gone bad.

[Moonlight]

I agree that is soulds like a classic infection. However, even with an infection you should have seen lowering of the gravity if your yeast pitch was happy. It seems not to be. Commonly the first pitch should be at a higher than normal temperature to help them grow more vibrantly. Underpitcing and under-aerating could be the most likely reasons. That is to assume proper ferm temp and that the culture was not abused before pitching.

The greatest chance of spoilage comes from a pitching yeast that doesn't get started quickly enough to out-pace common low-level infections.

Basically, if you have a vinegar aroma/taste, it is acetic acid which comes from an acetic acid bacteria and a source of oxygen.

[dereknobleluke]

yup. Acetobacter would be my guess. If you can see a white film on the top that would be indicative.

At this point you can try and get it going again, but it is a sour ale at this point....
sorry man...

[BigWilley]

When you say you pitched 4 vials into 3BBl are you referring to the little homebrew vials? If so you were extremely underpitching. One of those is barely adequate for a 5 gallon batch.

[TMVBW]

Yeah i figured some sort of infection.....its just such a distinct sharp smell and i haven been able find any info on it.
We have been brewing ales with out any problems. just seemed to happen with the long fement times for the wlp080.

We still want to use this yeast in the future, so im thinking..
1. Yeast nutrient.
2. Pitch much more.

Any advice on this yeast?
im curious about temp range. i understand 60-70 is good for first part of fermentation but when do i drop the temp? after how much attenuation?

We are fermenting in 3bbl open unitanks