sourdough beer

[Algonzo]

I've started brewing with my sourdough culture. This was my first proof of concept with DME and fermented at room temperature on my kitchen counter. Only 500ml for a single bottle - in the snap-top jar for 3 weeks and then primed & bottle conditioned 3 weeks. The rest I'm leaving in the jar and opening/shaking every once in a while to see if I can get some vinegar happening.

I read that most strains of yeast in sourdough cultures are not capable of fermenting maltose so I'm posting this mostly to encourage others to try as mine attenuated 1.046 --> 1.011 (76%) within 3 days.

It is moderately sour but not puckering, tastes strongly of grape juice (I think due to warm fermentation esters) and has a woody character which I find very interesting - is it possible that my culture contains brett and it would have produced this effect in only 6 weeks?

I've got two other experiments running presently. I brewed a flanders red type wort (15% munich, 13% crystal-40, 4% special B, OG 1.051] on Oct 3 - it fermented cool (17c), also attenuated 75% and I'll leave it for a year. My third one is a raw (unboiled) lambic type wort (6% munich, 18% all purpose wheat flour, 8% oats, OG 1.052) which I also pitched some grains in for a 24h sour-wort before pitching sourdough - it is presently roaring along in primary fermentation and I will also leave that for a year.

 

[ColoHox]

Sourdough is sour because of Lactobacillus bacteria. Also, I am not sure what you read, but most strains of Lactobacillus in sourdough bread ARE capable of fermenting maltose. So your attenuation makes perfect sense.

 

[Algonzo]

I see some seemingly contractdictory info but milkthefunk says that most (commercial) lacto strains are not capable of fully fermenting (>70% attenuation) wort:

http://www.milkthefunk.com/wiki/100%_Lactobacillus_Fermentation

Whereas oldsock's book says that the bruery has a berliner weisse of "low alcohol" which is fully fermented with lacto (pg. 55-56 I think). But my wort was 1.046, which I don't think qualifies as "low alcohol".

Anyhow sourdough is mix of yeast & lactobacillus and I was saying that most of the strains of _yeast_ commonly found in sourdough can't ferment maltose. The most common is C. Milleri due to its acid tolerence but it doesn't ferment maltose nor do other common sourdough yeasts Saccharomyces exiguus or Candida humilis.

 

[Agate]

Algonzo, you must be thinking of hottenroth? It's been confirmed by a reliable source that it does indeed contain brettanomyces, which accounts for the attenuation.

This article may be of interest, as the author references some lacto strains found in sourdough bread:
http://phdinbeer.com/2015/04/13/physiology-of-flavors-in-beer-lactobacillus-species/

If your culture does contain l sanfranciscensis, it does appear that it can make a little more ethanol than some of the other strains, but nothing like the attenuation you're seeing. That's a sure sign of yeast in there. But that doesn't make it any less awesome!

 

[Algonzo]

Thanks for that article, Agate. The most salient point I took from it is that some species of lactobacillus create succinic acid which has a wood flavour. This is maybe what I had in my beer and my culture may give me some of the benefit of wood aging without the barrels. This is indeed exciting!

 

[ColoHox]

Fermenting enough maltose to sour some sourdough is different than fully fermenting wort.

Type 2 sourdough contains maltose-fermenting S. cerevisiae, along with many maltose-fermenting species of Lactobacillus. Do you know the source of your culture or is just an amalgamation at this point?

Did you pitch the actual dough? That's a fun experiment.

 

[Algonzo]

I made the culture from robin hood white flour in toronto about 8 years ago and it's since lived in 2 other countries with me (england & france) so been fed a variety of flours and made around 1000 loaves of bread. My bread is not considerably sour although this depends a lot on technique.

Yep, I pitch the dough directly in the wort! The flour seems to just sink to the bottom but I figure that having this starch in the wort could be a benefit for long term aging (food for lacto or brett).