The Bastard Ale and the Bastard Barrel

Starting off this blog, I hope to share something that is a little bit different.  Inspired by Lars Marius Garshol's blog, Larsblog, I brewed a Raw Ale (Norwegian farmhouse brewing term for "no boil"), which was mash hopped with debittered hops, racked directly from the mash tun into a 6 gallon Vadai Hungarian medium toasted oak barrel, and allowed to cool in the barrel over night.  The next morning I pitched a packet of Safale T-58 Belgian dried yeast into the barrel.  I allowed that to ferment for around 3 days before topping the barrel off with 1 gallon of my house sour solera beer which contains an unknown assortment of Brettanomyces, Lactobacillus, and Pediococcus.  I am half expecting to dump this beer, but it's been a while since I've taken a big risk in my homebrewing.

Barrel fermentation with Safale T-58

I know what you are thinking, "What the f*** is this guy doing?"  If you're not thinking this, here is why you should be:

1. Shouldn't I be concerned about DMS?
2. Debittered hops smell like feet (and citrus).  This is isovaleric acid.  Isovaleric acid is an off-flavor, and boiling it off is a good idea.
3. Cooling over night without boiling the wort first is asking for contamination from thermotolerant bacteria!
4. What about access protein from not boiling?
5. Small oak barrels impart too much oak flavor and tannins, and allow too much oxygen to pass through into the beer. 

Let's go through these one at a time:

1. A lot of people have had luck with no boil Berliner Weisse beers.  In addition to this style, many farmhouse beers in Scandinavia were not boiled (see the Larsblog link above).  What's going on here?  First of all, S-methylmethionine (SMM) converts to DMS starting at around 80°C (176°F) (see links to references here).  My wort only got up to around 160°F from the first runnings plus batch sparge.  Secondly, on a homebrew scale, I have never tasted DMS in a beer.  Brulosophy contributes at least one data point that shows that a 30 minute boiled beer did not have any DMS in it.  Perhaps maltsters these days, thanks to science, are just that badass at their jobs.  Perhaps DMS on a homebrew scale is less of a concern than it has been made out to be (similar to hot side aeration).  
2. Isovaleric acid boils at 176.5°C (350°F), so I don't believe that boiling debittered hops removes the isovaleric acid from solution.  I am not a chemist, so perhaps I am wrong.  Isovaleric acid, however, is esterified into ethyl isovalerate, a fruity, berry ester by Brettanomyces.  My only experience with IVA as a brewer has been when letting sour beer sit for a long time on fruit.  IVA developed in one of my raspberry sour beers after being on raspberries for about 8 months (Brettanomyces can also produce IVA).  By the time I blended and bottled that beer, the IVA had disappeared.  
3. This one was a concern to me.  However, I think that ~12 hours of cooling won't give the beer spoilage bacteria/fungi enough time to spoil the wort beyond repair.  People generally get off-flavors in kettle sours when the wort sours for 2-3 days.  The longer the wort sits without full attenuation, the more time unwanted microbes have to multiply and produce off-flavors like butyric acid.  If I do get some off-flavor development, I am hoping that the Brettanomyces in my house sour blend will be able to clean it up (this thinking is admittedly a large gamble).
4. I talked to Lars a bit on MTF regarding protein and shelf stability of Raw Ale.  I believe it's a complicated subject.  Lars told me he has had good Raw Ale that was 6 months old, so stability issues due to proteins may not be a factor in all cases of Raw Ale.  Regardless of the unknowns, I don't think I will have an issue with this since the Brettanomyces and Lactic Acid Bacteria in my house culture can continue to consume those proteins, and Brettanomyces plays a large role in keeping sour beers shelf stable for years and years due to it's ability to stay alive in sour beer and metabolize oxygen.    
5. The barrel volume is my biggest concern.  Both Devin Bell from MTF, and James Howat from Black Project Spontaneous & Wild Ales have warned against using small barrels for sour beer.  Howat admittedly has no experience with smaller barrels himself, but his science brain tells him that the surface area to volume of a small barrel will allow too much oxygen to permeate the barrel walls, which will be metabolized by Brettanomyces into acetic acid (green apple in small amounts, vinegar in large amounts), and then into ethyl acetate (pineapple in small amounts, nail polish in large amounts).  Bell's experience has been an over extraction of oak in just two weeks; his 5 gallon barrel ended up becoming a coffee table.  Other MTF members like James Sites recommend aging a non-sour beer or wine in smaller barrels first to try and strip some of the oak character; too much oak character in a sour beer can easily overwhelm the beer.  My problem is that I don't make wine or non-sour beers.  To try and combat these issues by first not leaving my beer in the barrel for longer than 6 months (Shawn McBride from Fermentation Nation has had success aging sour beer for ~3 months in small barrels), and also by soaking my barrel with boiling water.  I did this by filling the barrel completely with boiling water, and allowing it to cool over night.  The heat from the boiling water allows the pores in the oak to open, absorbing the water faster and deeper, and the cooling creates a vacuum which pulls that water out of the wood and back into the barrel.  I did this four times. I then soaked the barrel for two weeks with citric acid and metabisulfite while I dealt with a small leak issue on one of the heads.  By the end of that soak, the water coming out had almost no brown color to it at all.  Also, in my experience, fermenting on oak strips a lot of the oak character.  My last line of defense is having a non-oaked sour brown ale sitting around that I can blend with.  

Swelling one of the heads of the barrel

Recipe

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Batch Size (fermenter): 5 gal  
OG: 1.072 SG
Estimated Color: 20.8 SRM
Estimated IBU: 0.0 IBUs
Boil Time: 0 Minutes

Ingredients:
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Amt                   Name                                     
6.00 g                Calcium Chloride (Mash 60.0 mins)            
2.00 g                Gypsum (Calcium Sulfate) (Mash 60.0 mins)            
15 lbs                Pale Malt (6 Row) US (2.0 SRM)       
1 lbs                  Brown Malt (Crisp) (65.0 SRM)        
1 lbs                  Carapils (Weyermann) (2.0 SRM)        
8.0 oz                Carafa I (Weyermann) (320.0 SRM)
8.0 oz                Acid Malt (for ~5.3 mash pH)
4.00 oz              Aged Lambic Hops [0.00 %] - Mash hopped      


Mash Schedule: Single Infusion, 153°F, 1 hour
Batch sparged

Notes: Collected 5 gallons in a 6 gallon barrel; chilled over night in the barrel.  

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