Brewing of an Oud Bruin Part 3 -- So It Begins - Brain Sparging on Brewing


Sour beer, saisons, farmhouse beer, homebrewing, ramblings

January 14, 2011

Brewing of an Oud Bruin Part 3 -- So It Begins

Making the Starter

A week and a half ago I added a small amount of Orval dregs to a small amount of starter wort as is normally the case when one bottle harvests yeast. I waited...and waited. Nothing. A few days in I realized that brett usually functions in an acidic environment and I needed to drive down the acidity to give it a hand. The only food grade acid I have in the house is vinegar, which contains small amounts of acerbic acid. Then I waited some more. Nothing. I added yeast nutrient and yeast energizer in small quantities each day. Nothing. Then I added some more vinegar. The only thing I could get to grow were strange white blobs on the sides of the flask where my aeration-swirling had left grain bits and residue on the walls. Very disheartening.

God may have rested on the seventh day but brett decided to start working on the seventh day. I came home from school to find the starter full of saccharomyces-like krausen. It smelled fruity, somewhere in between a saison yeast and a Belgian abbey strain. It was a start, for sure. After several days the krausen died down. I decanted the liquid and added more wort. This was followed by about a day of inactivity before a new krausen formed. This krausen was different. It was filmy and full of balloon-like bubbles. The smell is best described as musty dates. Sounds gross, I imagine, but it actually smells quite good.

Looking in the bottom of the flask, I have a very thick layer of yeast. I hope most of that is brett, rather than sacc. The only thing that half-concerns me is that the white spots seemed to have moved over to the top of the pellicle-like krausen. I suspect it is lacto or brett being funky. It reminds me a lot of what got into the cherry beer I made last year. I'm only half concerned because getting some lacto in an oud bruin is more a positive than a negative since oud bruins are typically dosed with both lacto and brett.

Sour Mashing

I decided to sour mash half of the total pale ale volume. The reason I chose to do so much is because the brett starter would only function in a very acidic environment and that is exactly what the sour mash creates. I would rather the pale ale come out way too sour and make the brown ale sweeter than risk brett being a secondary player. I want the brett to take hold before saccharomyces can.

I sour mashed the half gallon in a half gallon growler with some foil over the lid. Ultimately that will make the sour mash slightly less than half because I will need to compensate for boil off in the other half, but it's close enough. I forgot how much of a pain in the ass sour mashing can be. Brewers don't normally mash in glass because it has zero insulation so you lose heat very quickly. During the day I have had to keep it in a sink and add small amounts of boiling water to keep the temperature up so the bacteria will work quickly. I don't have a heating blanket or an aquarium heater; both would make it a lot easier. Without heat, who knows what bacteria would take hold and what kinds of nonsense it could do.

The strain of lacto generally found on plants is L. brevis, which is like the badass of lacto strains. It is hop resistant, it doesn't fear alcohol and it is heterofermative so it can ferment both aerobically and anaerobically. I believe (and I may be remembering incorrectly) when it ferments anaerobically it produces a small amount of ethanol. Since this is the strain generally found on plants it is also the strain that normally makes its way into sour mashes by way of the grain. Commercial versions of lacto are typically L. delbruckii, which is a more gentle strain that is homofermative (so it only ferments aerobically) that tends to produce more desired flavors in beer. I haven't seen my sour mashes form a pellicle, which is often the hallmark of L.debruckii. Instead, the sour mash gets foamy and pushes out a thick brown goop. Rather than tart it smells very much like creamed corn, which is probably a sign of DMS. The brown goop is like krausen but without any bubbles.

I will most likely let the sour mash go two days, possibly three. I really want to get this as sour as realistically possible without it tasting like total piss. Once the sour mash is done I will mash the other half, add the sour mash to the boil kettle and finish it all up. I will post that section as soon as the sour mash is complete.

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