berliner (the cliff notes version)

I think Lacto strains vary in their ability to use all or part of the carbs in beer wort. And you inoculated with grains, so probably got a mixture of bugs.

No.

 

That means your Lacto strain was converting sugars to ethanol and CO2 in addition to lactic acid. The half hour boil likely chased out ~65% of the alcohol (according to this). pH doesn't have an effect on density as far as I'm aware. Homofermentative (without alcohol/CO2 production) shouldn't lower the gravity much because CO2 isn't being released.

 

Large drop in gravity means there was yeast present while you were souring. Lactobacillus (whether heterofermentative or homofermentative) are not capable of dropping the gravity of wort beyond 5-15% apparent attenuation on their own. This result isn't surprising given that you used malt as your inoculum, however. Malt harbors a plethora of organisms, including wild yeasts. If you're anywhere at 100F or below, the yeast will thrive.

 

I'm pretty sure this depends on the strain.

 

There is a debate raging about this topic at the moment (getting into how pure the commercial cultures are as well), I still haven't seen anything conclusive.

 

Here is what I did. I obtained the two Lacto strains from White Labs (delbrueckii and brevis) and Wyeast (buchneri and brevis), and the Omega L. plantarum strain. I grew them on AOAC plates (a Lactobacillus medium) supplemented with cycloheximide (kills yeast -- allows one-step purification of yeast-contaminated Lacto cultures, of which two of the commercial examples suffered straight out of the commercial packaging). Propagated the lacto in liquid AOAC at ~90F to maximum cell density (achieved in about 3 days). Pitched 200 mL of these cultures into 2 liters of autoclave-sterilized unhopped wort with a starting gravity of 1.036. Incubated for 2 weeks at 90F, periodically checking gravity and pH.

Final Results:
WL brevis: pH 3.24, 1.033
WL delbrueckii: pH 3.92, 1.033
WY brevis: pH 3.8, 1.033
WY buchneri: pH 3.74, 1.033
OYL plantarum: pH 3.26, 1.033

None of the cultures, whether heterofermentative or homofermentative, produced a significant gravity drop. None produced a krausen or obvious CO2 evolution.

And then there is the theoretical. The central metabolism of Lactobacilllus requires the creation of lactic acid. In other words, it is impossible to get Lactobacillus growth without lactic acid production. Thus, it is impossible to get significant wort sugar consumption by Lacto without dropping the pH. This is why you can safely assume, even without the aid of a microscope, that a significant drop in gravity without a drop in pH means that there is yeast present. This holds true for a heterofermentative Lactobacillus like brevis as well. In the heterofermentative pathway, a 6 carbon sugar molecule is broken into CO2 and xylulose-5-phosphate (a 5 carbon sugar). That xylulose is broken into a 2-carbon compound ultimately ending up as ethanol, and a 3 carbon compound ultimately ending up as lactic acid. In order to maintain redox balance, this is the necessary end result. In other words, Lacto cannot favor ethanol production at the exclusion of lactic acid because central metabolism would come to a screeching halt due to an imbalance in redox potential. Moreover, if a heterofermentative Lacto were to attenuate a 1.040 wort to 75% apparent attenuation, there would be 1.75% lactic acid by volume. Curious, I took some 1.040 wort and added lactic acid to a 1.75% final concentration. The pH measured 2.78. Lactobacillus cannot tolerate a pH that low.

Anybody out there that thinks they have done a 100% Lactobacillus beer that completely attenuated can feel free to send me a sample to be checked under the microscope. I will provide pictures of what I find.

 

is what your saying that my wort soured and fermented at the same time, and then i killed off all of the alcohol?
if so, am i looking at an alcohol free or super low abv beer now?
cuz that would suck

 

Yep, you made ~2.6% ABV boiled it down to about .9% ABV. Now you'll get another 2.1% or so assuming it gets down to 1.004. So 3% total, about right for a Berliner.

 

so i measure the final gravity against the post boil gravity of 1.020? is that right?
i thought i was shooting for about 4% but could be worse

 

My understanding is that the production of lactic acid has minimal impact on ABV calculations: http://www.themadfermentationist.com/2013/11/calculating-abv-for-sour-beers.html

It was 1.040 pre-souring, 1.020 post-boil. What was it Post-souring but before the boil?

 

Yea.. mine took quite a while to clear up. First few months it was hazy. Like @OldSock said it took a couple months in the bottle. Now the sediment has settled to the bottom of the bottles like a rock, and I do a gentle pour without disturbing the yeast and it's a nice clear yellow.

 

Neither would be accurate. You'd want to calculate the ABV created pre-boil (including the OG before souring and the gravity before the boil), adjust it down based on the amount likely lost during the boil. Add to that the amount of alcohol created using the gravity post-boil compared to FG. Or just guess, it doesn't really matter...

 

unfortunately i didnt take a gravity reading because i thought it to be inconsequential. i guess ill know better for next time.

as a side note, i pitched a whole packet of us-05 to 2.5 gallons of wort on sunday night, and i've yet to see any airlock activity. i expected more lag time than usual, but is this normal? its been about 36 hours since pitching.

 

cool, thanks.
what was your total fermentation time?