Is Brett Predatory?

statseeker · 09-12-2011, 06:54 PM

This is a two-fold question:

1. Does brettanomyces only feed on dead and decaying yeast?

2. Do you think that brett would eventually become the only yeast in a yeast cake of a Sacc. strain and a brett strain?

The reason I ask is that I have a yeast cake (plus about 1 inch of stout) of 9097 Old Ale yeast and now it has a pretty nice pellicle on it after I've left it for about a month without washing. I have a feeling the pellicle is from the brett feeding on the dead yeast and maybe some left over unfermented sugar. I want to rewash this yeast and maybe add a portion of the washed blend to a Sacc. fermented brown later on in its life.

jmo88 · 09-12-2011, 07:09 PM

I don't believe that's the issue. More likely the pellicle is a result of oxygen being introduced to the beer after racking.

hopsalot · 09-12-2011, 07:11 PM

too my knowledge, NO, brett does not feed on dead/dormant saccharomyces. Brett can consume much smaller sugars, therefore left over, that Saccharomyces cannot. Brett can eat unfermentable dextrins as well. Brett is chowing down on the left over fermentables not saccharomyces.

I do not think that brett would eventually become the only yeast in a yeast cake of a Sacc. strain. I will do some research though

strat_thru_marshall · 09-12-2011, 07:26 PM

1. No
2. No

For sure no to both questions.

The pellicle forms to protect the yeast from oxygen, when you transferred the beer out of the carboy, the added air in the headspace caused the yeast to form the pellicle.

Wernerherzog · 09-12-2011, 07:27 PM

Brett does indeed eat dead yeast cells, or rather nutrients left in their dead "bodies", see pg. 166 in wild Brews. Also, pg. 174 where Sparrow compares the different Brett character in Flanders and Lambics by the fact that the production of Flanders beers involves racking off the original Saccharomyces relatively early on and the fact that Lambics continue to sit on the original yeast cake, providing more nutrients to the Brett when it starts to run out of residual sugars/sugars unfermentable by Sacc.

To answer your question, barring other variables, the life of Brett will be much longer than Sacc. since it can eat a lot more things than Sacc. can. I don't know whether this means it will totally take over a cake though.

ReverseApacheMaster · 09-12-2011, 09:13 PM

I think it would take a very long time before the brett would completely consume all the sacc. If you repitched on the cake under more normal circumstances the sacc would wake up, reproduce and eat sugars, reestablishing its population in the cake.

**smokinghole** · 09-12-2011, 10:07 PM

1. Brett doesn't only consume the dead yeast but it will consume nutrients that remain in the dead cell walls and what was released when they died.
2. I highly doubt all the sacch would be dead leaving only brett. I think that would be more pH dependent than based on food availability. You have to remember that yeast have been extracted and used from pieces of hardened amber.

Brett is better suited for survival in already fermented beverages like wine and beer. I think in the laboratory brett has been taken up to 12%abv but has been found in wines higher than 14%abv (can't find the paper that has the data). So it can survive in fairly low pH where sacch would surely be dead.

statseeker · 09-12-2011, 10:17 PM

Cool. Most brewers and yeast scientists say not to repitch on a brett blend because the funk will be magnified. I dont know if I mind that so much in THIS case just by the smell of the yeast cake. It smells sort of lightly like cherry pie and stout. Tells me the Brett strain is likely lambicus. A brown will be delicious with the blend. I was just curious if there was any evidence the Brett feeds on the dormant yeast. By the answers here, it doesnt, which is good with me.

ryane · 09-12-2011, 10:38 PM

Quote:

Originally Posted by statseeker

Cool. Most brewers and yeast scientists say not to repitch on a brett blend because the funk will be magnified. I dont know if I mind that so much in THIS case just by the smell of the yeast cake. It smells sort of lightly like cherry pie and stout. Tells me the Brett strain is likely lambicus. A brown will be delicious with the blend. I was just curious if there was any evidence the Brett feeds on the dormant yeast. By the answers here, it doesnt, which is good with me.

If I remember right, contrary to what it seems the brett in 9097 was confirmed to be brux

statseeker · 09-13-2011, 06:31 AM

http://www.wyeastlab.com/hb_yeaststrain_detail.cfm?ID=147

http://www.wyeastlab.com/PC4Q2010.cfm

That's from Wyeast's website. I'd be surprised if it's brux. The character of the smell alone is way off. If it is though, maybe I stressed it into producing those characteristics. Worth trying again I think.

These questions beg another question for me:

If I were to make a starter with only dextrins and sugars that Sacc. couldnt eat, do you think it's possible to isolate the brett strain from the sacc. strain just from fermenting with those dextrins? It would seem to be slow but I think it would work. I dont think the Sacc. would be activated by the starter and would likely sink to the bottom just dormant. But the brett might come out and eat.

This seems like a time for an experiment.