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brettanomyces bruxellensis

January 26, 2012

Alternate title: Wild Yeast Starter Theory
Alternate alternate title: Caution, Entering Beer Nerd-dom 

I mentioned in a previous post that I had ordered a vial of Brettanomyces Bruxellensis. Surprise, surprise – they were out.  Actually, I was kind of surprised.

Anyways, it gave me an idea and an opportunity to have one of my favorite beers – Orval (Brasserie d’Orval, Belgium).

Background, idea, etc after the jump..

Alright.  For the uninitiated (which is most normal human beings), beer is sugary water that has been fermented by yeast.  Traditionally, that yeast is some variant of saccharomyces cerevisiae.  From my understanding, these “strains” have been highly modified over hundreds of years of brewing, and aren’t necessarily “naturally occuring”.  Similar to the way we breed dogs to develop certain characteristics, these yeast strains are purpose built.  They’re domesticated.

While there are a huge variety of grains, hops, spices, syrups, adjuncts, etc – nothing makes beer what it is more than the yeast used.  I once read (and don’t quote me – I’ll have to go back) that there are something like 90 compounds in beer that contribute to the taste, and 80+ of those come from yeast.  It gives the beer its personality.  That banana and clove flavor you love in a Hefeweizen – those are phenols and esters, created by the yeast (hefe is wheat, malted barley, hops and yeast – nothing else).  The delicious, peppery Saison you tried last night?  Yeasties.

So anyways.  Saccharomyces C (henceforth S.C.) is your friend.  Brett Brux is also your friend, and he actually kind of sounds like he has a human name, even though he’s an untamed, single-celled organism.

I’ll hold the details for a later post, but the sugars that S.C. is fermenting come from steeping (“mashing”) crushed malted barley in hot water.  Depending on the temperature, you’re going to get some mix of maltose, fructose, glucose, dextrins and other sugars.  S.C.’s primary function is to convert these sugars into CO2 and alcohol, but there are some it can’t handle.  

Dextrins are long-chain carbohydrates that are too complex for S.C. to convert.  All beers have Dextrins in them – they give them a lot of their (residual) sweetness and “mouthfeel”.  That’s where Brett Brux comes into play if you want it to (and sometimes if you don’t, if you’re unlucky).  Brett can convert Dextrins to alcohol (and CO2).  It also leaves a unique flavor behind.  In my opinion, the classic Brett “funk” is desirable in the right beer.

A great example of this is Orval.  This is me, finally getting to the point.  Orval is fermented with S.C. but when those Monks bottle it, they add – you guessed it, Brett Brux.  Orval goes through a secondary fermentation in the bottle, which – if you’ve ever had it, is why the glass is thick and the beer is apt to foam over.  The sediment at the bottom of an Orval bottle has both S.C. and Brett Brux in it.  I want to capture this (still living) Brett B so I can reuse it in the future.

A lot of brewers will just dump the dregs right in their homebrew and give it time to do its thing.  I also do that on occasion, but I want to build a little cadre of Brett that I can use on a moments notice.  Normally the way you do this, is by making a starter, which is just a little mini batch of beer, that you add your yeast to.  The yeast will multiply, grow and strengthen as they ferment that little bit of sugar.  When you “pitch” that into your homebrew, you have lots and lots of yeasties, ready to rock n roll.

I read some articles and forum posts on creating a starter from Orval dregs, to do just this.  The first thing I heard a lot of, is that because many people age Orval, the Brett may be dead.  My bottle was filled on 10/3/11, so I think I’m safe.  There’s also a lot of “no point – S.C. grows faster and will ferment it all out before the Brett can grow and do its thing”.  OK, fair enough.  In my case, I do just want the Brett to grow and multiply, I dont want or need the S.C.  

As I mentioned before, Brett takes over where S.C. leaves off – with the dextrins.  So what if my starter was already fermented by S.C. – leaving only dextrins for the Brett to feed on, so only Brett will grow and ferment?

That’s my theory, and that’s what I’m trying out.  Two days after pitching the dregs into a small starter of already-fermented wort, I’m starting to see some bubbling activity and am getting the classic, bready, funky Brett Brux scent.  It seems to be like its working as I thought it might.

I’m curious if anyone else has tried this and agrees or disagrees with my theory.  Your thoughts?  Do I have all my facts straight?

Saison yeast starter that I’ll be using this week.  I stole a bit of the fermented liquid and added to a sanitized bottle for the Orval dregs to start doing their thing..


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