I recently tried to oak age a Russian imperial stout that I brewed – Pagan Dog’s Moddey Dhoo, named after the Manx version of the spectral black dogs of the British isles.
Oak aging can be done a number of ways – traditionally it’s obviously done in barrels previously used for wine, bourbon, or some other exciting non-beer liquid. The previously occupying liquid would lend some character to the aged beer in addition to that of the wood itself. Oak always adds a unique ‘oaky’ character, partly because of the high concentration of tannins. So, I bought and tossed in some oak cubes, little chopped up pieces of an oak stave or barrel.
What I failed to do first was boil the cubes or soak them in ethanol to leech out some of the tannins. Unfortunately for me this meant that my fancy new stout tasted like I was munching on the end of a board. Yum. Honestly, it’s not really possible to overstate HOW astringent this beer was. I looked around a bunch for a solution, and most brewers I talked to suggested whipping up a second batch and blending it. It occurred to me that people who make wine probably deal with oak more commonly, so I looked around a little more widely for ideas. Lucky for me, I found some suggestions that protein fining agents such as gelatin work great for removing tannins, as they will bind with the larger tannin molecules most responsible for astringency and help precipitate them out of solution.
Most brewers seem to agree that gelatin works better at cold temperatures, so I cold crashed a gallon of beer, mixed 1/4 tsp of gelatin with 1/4 cup of water at 150F, and added it. After leaving it for 3 days, I pulled a sample of the fined beer. I also pulled a sample of the unfined beer to compare them. I didn’t manage any kind of real experiment here, but the difference was really obvious on a taste test. The massive astringency of the original had settled into a tasty, although still strong, oakiness.
And there we go! I’m testing the cold crash alone now, since I thought it might be possible that the cold crash itself could precipitate out a sizeable amount of tannins. I won’t be stepping this up to the level of the awesome exbeeriments, but I’m going to get someone to blind me to the options after the cold crash is over to see if I can tell the difference.
Helpful references:
https://winemakermag.com/715-using-fining-agents-techniques
http://www.bertusbrewery.com/2012/06/how-to-clear-your-beer-with-gelatin.html
Eli Swanson 