December 15, 2013

Spontaneous Fermentation Project Part 2 -- Getting things organized for the brew day

I not-so-briefly explained my new sour beer project in Part 1 of this now ongoing series and today I'm going to walk through how I am going to get through the brew day and into fermentation. My goal here is to get as authentic to Belgian lambic production techniques as I can within reason. In putting this process together I relied on a combination of resources, including several homebrewing blogs, Wild Brews, Lecambre's 1851 brewing treatise, my own brewing experiences and a host of other sources too numerous to count.

Traditional Lambic Brewing, Briefly

Typical lambic brewing in Belgium employs pilsner malt plus unmalted wheat in a lengthy, historical mash process known as a turbid mash. Turbid mashes are long mashes that use a mixture of infusions and decoctions to produce a very starchy wort. The wort is then boiled with aged hops, which provide very little bitterness. They are instead used for their antimicrobial properties, although I suspect the flavors of the aged hops contribute something to the flavor of the beer. The boiled beer is then cooled on coolships, which are wide, shallow tubs that expose a high surface area of beer to the cool air, allowing the beer to cool to ambient temperatures overnight. While the beer is cooling, the exposure to the air allows native bacteria and yeast to descend into the beer and begin fermentation.

The cooled beer is then pumped into fermentors. It may go directly into barrels, where it will stay until packaging, or it may go into a primary fermentor (frequently referred to as a horny tank) and once krausen dies down it may be transferred to a secondary vessel, usually barrels, for additional aging. Within the barrels, bacteria and yeast (including brett) may continue to thrive and help add to the populations present in the beer during cooling. Over six months to several years the beer will develop sourness and funk, until it is packaged as either an unblended lambic, faro (a lambic sweetened with sugar and/or mixed with a non-sour beer), a fruited lambic, or gueuze.

And my process

I'll set up the specific details of the recipe in the next post, for now I'll leave you with the explanation of the process. The grain bill will be pilsner and unmalted wheat, using basically the same recipe as the lambic solera. I'm using RO water adjusted with brewing salts and I'll undergo a turbid mash. I don't have enough aged hops on hand for this particular batch (I am aging some Belma and EKG) so just as I have done with the lambic solera I will use just enough hops as a bittering addition to get to 8-10 IBUs, which is the least amount of IBUs you need in a beer to repress unwanted bacteria.

To cool the beer I am going to use vessels I have on hand, as unimpressive as that might be. It would be fun to build a functional coolship that I could pump beer into and out of but I have neither the technical expertise to build a metal coolship nor do I have the space to store it. You do not need a fancy copper coolship to make it "authentic". Although copper coolships have been considered the preferred vessel since the mid-nineteenth century, they certainly were not the only vessels used. Well into the nineteenth century, coolships were built out of steel, iron, copper, aluminum and even wood. In my case, the vessels I have on hand best suited for this purpose are baking sheets and pans. Like I said, not impressive. However, they are wide, shallow and have handles, which makes them functional and easy to use. I'm not entirely sure I have enough to hold five gallons of wort so I may not be able to coolship the entire volume.

I plan on leaving the beer in the baking pans and sheets as long as it takes to cool, plus some additional time. The wort will have to come down to around 130F before bacteria will start being able to survive in the wort and perhaps closer to 100F before yeast will take up residence in the beer. I want to make sure enough bacteria and yeast take residence in the beer to ferment it, so I'll need to leave the beer outside for some additional hours after it cools. Ideally I will start this beer very early in the morning so it can go into my backyard in the mid to late afternoon and I can move it inside before I go to sleep. I'd like to leave it outside overnight but I don't have a good way to protect the wort from bugs and animals that might wander by. We get a lot of stray cats in our backyard and I'd rather they not slurp up my beer or worse, decide to bathe in it.

The cooled beer will be moved into its one and only home, which will be a six gallon better bottle. I know, barrels are awesome and commonly used in lambic brewing. I chose not to go with a barrel for easy of use with the better bottle and most importantly, the ability to observe the transformation of the beer through the clear plastic and take pictures. Like the better bottle that houses my lambic solera, I plan on dropping some oak into this fermentor. I buy into the idea that the oak tannins and flavor compounds get manipulated by brett. However, since I don't have a well-used barrel to employ I'll have to make due with a small amount of unused oak. I have some left over oak chips soaking in Canadian whiskey (the same I added to the lambic solera last year) that I'll add.

The fermentor will go upstairs in the guest bedroom that I use for fermentation and brewing equipment storage. I'm going to let the beer ferment completely at ambient within my house, just as I do with the lambic solera. That room normally swings between the upper 60s to the mid 70s during the winter, depending on how much we run the heater. In the summer it can get as hot as 80F in the room, even with the AC running. It faces the late afternoon sun so it takes a brutal amount of heat during the mid-summer.

Most of my sensory review of the beer as it ages will be visual and olfactory rather than by taste or gravity readings. I don't like to expose my sour beers to the air more than necessary. The occasional removal of the stopper to get a whiff has a lot less impact than shoving a thief in and drawing out some liquid. Since I'm going completely spontaneous I have to assume there will be some acetobacter and that means preventing unnecessary aeration will be even more important than usual.

So that's it. Not a very different process from the usual brew day, except for the excessively long turbid mash. The beer itself isn't very exotic. It's an extremely basic recipe. However, the organisms within the beer will turn it into something exotic. Hopefully in a good way.

In the next part I will give the recipe and brewday. My goal is to get this batch brewed sometime this week or next week, depending on my work schedule.

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