Lactobacillus alcohol calculator?

[Rob2010SS]

Hey Guys. Started my cranberry sour ale last Thursday and finished up on Saturday afternoon and put it in the fermenter. Fermentation is going well but I do have a question.

On Thursday last week, when I finished the mash, my pre-boil gravity came in at 1.078. I did have to adjust manually because I've discovered my hydrometer is 8 points off. I need to get a new one but haven't done so yet. At 126*F, hydrometer read 1.06 which is 1.07 corrected for the temp and then added the 8 points that the hydrometer is off which puts me at 1.078. I pitched the Omega Lacto and let it sit for 43 hours, after which the pH was at 3.3. I performed the 60 minute boil and my post boil gravity was 1.044 (@ 68*F and 8 point correction).

My question is this: In trying to determine alcohol content of the beer, does the Lactobacillus Brevis work the same way as a normal yeast? Can I just plug in the starting gravity and end gravity in a calculator and get alcohol %? I think the answer to this is no, but if that's the case, then my question becomes how do I figure out alcohol with using lacto?

Thanks for the help.
:rockin::rockin::rockin::rockin::rockin:

 

[crane]

Lacto won't ferment that much of a gravity drop. You got a yeast infection during your kettle souring phase, so you would calculate the alcohol content as you normally would. However, since you boiled it at 1.044, all the alcohol that was in the beer turned to vapor and evaporated out of the beer. At this point 1.044 is your starting gravity to use for ABV calculations.

 

[Rob2010SS]

Hmmmm, really? I thought pre-acidifying the wort to 4.1-4.2 would have prevented the yeast infection? And I also read that lacto brevis ferments out some of the sugar. Is this not the case?

 

[Rob2010SS]

I reached out to Omega Labs and asked for their input. I ran through my process with the owner....

1. Mash for 60 min @ 152*F
2. Sparge and lauter to boil kettle to get 6.75 gallons of wort
3. Boiled wort for 10 minutes to kill any unwanted organisms
4. Added 3 tsp lactic acid to drop pH of wort to 4.2
5. Chilled wort to 95*F
6. Pitched Omega OYL-605
7. Covered top of kettle with plastic wrap and then foil on top of that.
8. Wrapped sides of kettle with 3 layers of foil to maintain heat.
9. Had kettle on stove to gently heat when necessary. Only had to heat once to bring temp from 80*F to 88*F.

After going through the process with the owner of Omega Labs, he feels the packet of bacteria that I purchased was contaminated with yeast, as I shouldn't have seen more than 1-2 points in gravity drop. He is sending me a new thing of OYL-605 and some "swag".

I have read that I can add some sugar to the fermentation to bring up the ABV a bit to make up for what I lost. Is there a known measurement out there of "X amount of sugar = Y increase in ABV"?

My ABV will now be in the 4.75% range...
Is it worth it to add the sugar knowing that I'm going to add 7lbs of pureed cranberries in secondary?

 

[mabrungard]

Most lacto strains don't produce much (if any) alcohol. Yeast is added after the souring stage to ferment the beverage to a desirable final gravity.

 

[Rob2010SS]

Yep, understand that now. Trying to decide if I should add sugar to this brew to bump up ABV or just leave it at a 5% sour after the cranberries are added...

 

[crane]

Hmmmm, really? I thought pre-acidifying the wort to 4.1-4.2 would have prevented the yeast infection?

If that were true then kettle souring would not produce beer at all. Pre-acidifying the wort prevents other bad bacteria from taking hold, but will have almost no affect on stopping yeast growth.