Significant Attenuation in 48 hours from Lacto Starter?

[hasbrew]

Hi all,

Just started dabbling in Wild Brews and ran into an unexpected hiccup:

Background Info:
I tried to make a Quick turnaround Oud Bruin based off on this blog post: http://www.themadfermentationist.com/2010/07/sour-old-ale-quick-oud-bruin.html

I did step up my lacto starter (innoculated from grain and kept around 100 for 4 days) up to 2 liters and had a really nice sour apple smell and an impressive lacto pellicle on the starter.

I performed a normal mash (152 for an hour) ran off into a pail fermenter and pitched the lacto starter once the temp dropped to 118. Gravity was 1.061 (per a refractometer), about 12 hours later I peeked into the fermenter and had the same pellicle as the starter.

48 hours after pitching I decided I would boil, hop, and pitch some brett b to finish things off. Taste was tart, not crazy sour, and smell was ok but not the sour apple aroma the starter had.

During the boil (60 mins to get a nice hot break) the smell coming off was an absolutely horrible vomit smell that diminished as the boil progressed so I'm thinking I must have had a bit (or maybe a lot) of butyric acid in there.

The Problem:
Before dumping the concoction in the kettle I thought I might take a quick gravity reading using my rarely used hydrometer. I got a reading of around 1.024 and I'd estimate the liquid was around 90F.


I expected the gravity to be just a few points shy of the original 1.061 (per the blog link above) but was just confused by the reading I got. I wrote it off thinking maybe lactic acid specific gravity was significantly lower than that of alcohol or water and proceeded with the boil on my original plan.

I ended up adding 1.5 lbs of DME and a lb of Belgian dark syrup to try to boost the gravity, just in case there really wasn't much sugar left for the Brett.

Today, 3 days after pitching the Brett (a 2 L stirred starter) I'm thinking there really wasn't much sugar left as the brett fermentation started off quickly but never formed much of a krausen, and seems to have dropped off by day 3.

What I'm wondering:

• Did I have some other wild yeast or bacteria in my starter that attenuated that much or can lacto actually do this on its own?

If it was a wild yeast that attenuated that much, I assume I boiled off all the alcohol/butyric acid. What might that other organism be?

Anyone else experienced significant attenuation in such a short time from a supposed lacto starter?

 

[spearko520]

when you use grain there is no way to be certain that all you have is lacto. It is probably unlikely that that will be the case. That doesn't mean that the results can't be pleasant, though. I have had a very difficult time getting consistency with the grain method. if your numbers are right, something was definitely working - maybe clostridium butyricum.

 

[hasbrew]

when you use grain there is no way to be certain that all you have is lacto. It is probably unlikely that that will be the case. That doesn't mean that the results can't be pleasant, though. I have had a very difficult time getting consistency with the grain method. if your numbers are right, something was definitely working - maybe clostridium butyricum.

Definitely lesson learned about using a pure culture. I expect I did have some clostridium or competing bugs in the starter but was fairly confident with the correct growth temps, indications, and smells that lacto had a good foothold in the starter.

What were your experiences with attenuation from a grain inoculated stater?

 

[spearko520]

The attenuation was pretty spotty- along with the results, which is why i buy cultures (for now). The best grain innocculated one that i had took off like a rocket and dropped into the low 20's in four days- but i am certain it was infected with something, as there are some banana and juicy fruit flavors that weren't from the lacto. I have had other starters that seemed like they didn't move but got very sour. my most recent problems have been something getting in and producing copius amounts of acetone. Some people seem to have really good results with the grain method, so don;t give up. it seems like i always have a starter of one sitting on heating pad, while i pray.

 

[bigljd]

The sour mash method sounds very similar to the Zymurgy method I posted a while back ( https://www.homebrewtalk.com/f127/berlinner-weisse-question-293924/index6.html#post3979714 ), except you didn't boil the wort to kill off any competing bugs.

Next time I'd recommend the same starter process, but after sparging bring the wort to a boil for 5-10 minutes, then cool to ~110 and pitch the starter. If possible keep the wort in a cooler during the souring to keep it ~ 100. Then 12-24 hours later it will be fully sour and ready to boil again without the vomit smells.

What probably happened is some other bugs/yeast took over and started fermenting the sugars - they had 2 days to work, so it's likely the wild bugs converted a lot of sugars to alcohol (which would have been boiled off when you boiled the wort).

If you follow the Zymurgy method and have a good sour starter, you should have pretty consistent results each time you sour mash (no need for praying for your wort to sour correctly LOL).

Edit: removed comments about refractometer, since you didn't use one to measure - it was a hydrometer. I just can't read LOL