Attenuation in sour wort?

[chillaxis]

Hi all,

Yesterday I made my first expedition into brewing with lacto. Following approx the process of http://www.themadfermentationist.com/2010/07/sour-old-ale-quick-oud-bruin.html, I collected two gallons of 1.040 OG wort from my mash tun into a small bucket with an airlock and pitched a vial of WLP677, Lactobacillus delbrueckii, at 120*. Today there's been a lot of airlock activity, and just now I took a sample and found that it has an SG of 1.025. I didn't think that lactobacillus could attenuate a wort nearly that much, but maybe I'm wrong? Or maybe, could some wild yeast living on the grains survived mash temperatures and made it into the wort? I didn't boil the wort before pitching the lacto.

If it's relevant, the wort temp has gone down to about 90* (I have a fermwrap keeping it warm but I haven't insulated it). I had a small taste of the sample and it had a faint sourness but nothing strong. I don't have a way to test pH unfortunately.

Finally, any ideas what to do with this since it doesn't sound like the original plan of boiling and pitching sacch makes much sense? Any safety concerns w/r/t botulism or other nasties?

 

[dantheman13]

Sounds like my experience with WLP677. Some folks have found Saccharomyces contamination in vials of WLP677 from a few months ago, so that is perhaps what you are experiencing. Supposedly, WLP677 is heterofermentative (this is what WL says), but normally L. delbruekii is not heterofermentative, so that is why some folks wonder if these WLP677 vials are pure or if WLP677 is misidentified.

I would do a short pasteurization at 170°F for 5 minutes to avoid boiling off too much alcohol, and then pitch your yeast as planned. You shouldn't have any issues with botulism since the wort pH is most definitely below 4.5 at this point.

 

[Calder]

WLP677 is heterofermentative, so it prodices lactic acid and alcohol, so you will get a drop in gravity. I don't think you have any contamination, and you should keep the temp up around 100 F for another couple of days.

I had a berliner drop from 1.038 to 1.012 before adding yeast.

Do not add yeast until it is sour enough for you.

I would not advise boiling, or you will boil off all the alcohol. The low ph and alcohol will prevent anything from taking hold in it. And for that very reason, when you eventually pitch yeast, pitch big ....... I mean really big as the environment is also hostile for yeast.

 

[Agate]

I had a similar experience from my latest grain lacto culture. The wort attenuated from 1.034 to 1.011 while trying to kettle sour over 2 days. Oops! I pasteurized at 160f, trying to minimize the ethanol loss, and now it's finishing up with us-05.

The silly thing is, I made a culture of lacto plantarum from probiotics, but at the last minute I pitched that and the culture I made from grain. Next time, it'll just be the plantarum culture as it doesn't produce any ethanol.