So does lactobacillus produce alcohol? I understand it depends on the strain of lacto? I recently soured my wort with .5 lb of grains and my SG seemed to drop by a good 20 points. I was only measuring about 1.015 post sour and pre boil. I've used this method before and don't recall my SG dropping that much. Am I ok or should I add some DME? I was in a hurry when collecting wort and did not record initial SG. But I've got my system dialed in and usually right on.
Certain species can produce alcohol. Hottenroth from Bruery is fully fermented with just lacto. I don't know about a 20 point drop that quickly though. Maybe re-measure? Or your initial OG was high?
My somewhat limited understanding of lacto is that most strains used in brewing produce very small amounts of ethanol. I would suspect that you had a contamination (probably saccharomyces) somewhere along the way that caused the gravity to drop as much as it did. You should be okay adding DME to up the gravity.
I'll second @secondbase that it sounds like you have an infection with a sacc or Brett strain. Heterolactic metabolizers can produce small amounts of ethanol, but only small amounts...maybe a drop of 1-2 points, but definitely not 20! Here is a chart and link to some good info on lacto metabolism... http://www.milkthefunk.com/wiki/Lactobacillus#Metabolism
Yeah, it seems to be some sort of yeast contamination. It actually dropped about 25 points, went from 1.040 to 1.015 in 3.5 days. I didn't notice that active of fermentation though? Seems to taste ok... wouldn't I get some off flavors due to the 90F+ temps though? Come to think of it, how would yeast survive the higher temps from mash? Guess I'm still a little baffled by this.
The contamination likely came from your fermentation vessel, or any cold side plastic equipment that came in contact with your wort. You may want to check your cleaning and sanitizing regimen to be sure you're not missing anything that might invite unwanted bugs into your beers. As for the off flavors, maybe it's a strain that likes high temps (brew any saisons recently?).
I co pitch lacto and sacc at 120 for my sours and haven't had a problem/off flavor from pitching at a high temp or fermenting at 90-100. I reuse that yeast/bug cake for many generations as well and have never had issues.
You more than likely had a wild yeast on the grains you used that fermented. Lacto can't fully ferment beer wort.
Good to know. What a hobby! You can do this for years, and still learn something new! Thanks everybody. I think I'll try a different souring technique next time... maybe the Good Belly approach.
