January 23, 2012

Stacking the Deck...

Spontaneous fermentation is achieved by exposing the wort to the air. Everywhere around the world there is yeast and bacteria in the air, so why does spontaneous fermentation seem to only work in Belgium? Some believe the ambient air in Belgium has more good yeast/bacteria in it that undesirable microbes.  While this may be true, the brewers of Belgium also have had hundreds of years to refine their barrels.  After a beer sits in a coolship to pick up some ambient yeast, it is then put into a barrel to ferment.  That barrel had been used to previously age lambic, so there are plenty of resident microbes to guide the fermentation process.  If a barrel did not produce good lambic, they would throw it out (or burn it to heat the brewery).

Here, we have not been doing this for hundreds of years.  We can still open the beer up to the wilds of the air, but for my first barrel I want to emulate the effects of the barrel already having aged lambic.

To do this, I am basically diluting desired yeast with water and adding it to the barrel (see follow up post).  The oak will absorb the water and the yeast will become resident to the barrel.  I will be priming with the Cantillon Gueuze culture I built up and will now wash.  I siphoned off the beer until just the yeast cake at the bottom was left.  Give that a good swirl and dump it into a growler.  After the growler sat in the fridge for a few minutes it had already started to settle.

Since this yeast is not left over from a complete brew cycle, there will be no hops sediment at the bottom, and I don't expect to have much of a protein build up.  I am going to work under the assumption that what I have is nearly all yeast, so my efforts here are not to separate out the yeast, but rather concentrate it and remove the "beer" from it.

I let that sit over night to further settle, and then siphoned off the liquid on top.   With a concentration of yeast left, I added water that had been boiled and cooled.  I will let this settle (if necessary siphoning of the liquid on top) and add this to some water.  That diluted yeast mixture will then be poured into the barrel and rolled around to coat the walls.


Anonymous said...

How long did you allow each starter to build up? When you used the mason jar did you fasten an airlock to it or just poke some holes in the top and cover it with foil? That's how I did mine and it's been going for about three weeks like that. Is that too long?

Levi said...

Tin foil over the top of a mason jar is fine, no need to poke holes in the lid. I go in 3 stages. Mason jar, growler, and 5 gallon pail. Once I step up, I wait for fermentation to kick in. This can take 1-3 days, and then I let it work for 2-3 weeks and then step it up to the next stage. Unless you have a stir plate, you should be shaking up the yeast every day. I don't worry about washing the yeast at each stage either, just dump everything into the next vessel.

For a MUCH more technical and scientific method of building up yeast, read this: http://trilliumbrewing.blogspot.com/2010/10/yeast-hunting-update.html

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