OG drop during sour mash

[bshaf]

So I've been having some success sour mashing berliner weisses (actually sour wort since I'm throwing in a handful of grain after sparging)..

But this batch I let go a little longer than normal (almost a week) and after boiling it I realized my OG was down to 1.016. After sparging it was 1.036.

Was this just the lactobacillus taking out too much sugar? Was it a wild sacch that partially fermented it (and if that is the case did I boil off the alcohol during the 30 min boil?)?

I pitched K-97 and it never actually started (it's almost been a week).. I'm thinking about adding some DME at this point to the carboy with packet of safale 05

At least I have a decent tasting sour soda right now if there isn't any alcohol in it..

Any thoughts on if I have alcohol right now or not?

 

[marvaden]

Well, you definitely got something that ate the sugars (lacto and other wild critters including probably some brett). If you boiled it after the sour mash, you did lose some of the alcohol (~173*F is alcohol's boiling point). Since alcohol and a lot of the other chemicals produced by bacteria and yeast are lighter than water, it will be hard to say exactly how much sugar there is left in there for the sacch to eat. When I sour mash, I tend to add extract to bring the gravity back up a bit, but this also causes it to not be quite as sour as it could have been.

Another method would be to do a sour mash, pasteurize at 150-160*F (adding any hops for flavor and mild bittering here), cool to fermentation temps, then pitch yeast into it. You'd end up with a very low IBU, but would most likely be delicious nonetheless. This should also reduce the likelihood of infecting your equipment.