I’ve tried aging batches of cocktails in small, one-liter oak barrels — an apple brandy Old Fashioned and a Negroni — but it’s expensive. Those little barrels can cost more than $50 and they can only be used for so long. So I had a thought: what if I could just add the oak to a bottle?
Northern Brewer sells little oak cubes for between $2.50 and $4.00 for a 2 oz. bag. They come in American, French, and Hungarian oak with medium or heavy char. The cubes are around a quarter-inch, which is small enough to fit into the opening of a bottle. I bought three bags (partly just to justify the shipping cost, which rivaled the price of the oak cubes): an American medium, a Hungarian medium, and an American heavy char.
After some conversations with Joe Spiegel about aged Brennivin, the Icelandic aquavit that he’s started importing, I thought I’d found an excellent candidate for my first oak cube infusion experiments.
Northern Brewer’s description of the Hungarian medium char cubes sounded promising for the Brennivin: “Medium-plus toast Hungarian oak cubes impart a full mouthfeel with mild to moderate vanilla and background notes of leather, black pepper, and slight campfire/roast coffee.”
I poured about 12 ounces from my liter bottle into my infusion bottle and dropped in four oak cubes. I wasn’t sure how many I’d need for such a small test batch but Northern Brewer recommended 2.5-3 ounces of cubes for every five gallons of liquid. My entire bag of cubes was only 2 ounces and my test batch would be barely a tenth of a gallon. Four cubes was a guess.
By the end of the first day with the oak cubes the Brennivin, which started crystal clear, was tinted a pale amber. I shook the bottle about once a day when I remembered and tested it after a week. The flavor was odd. The oak seemed to suck up the natural sweetness of the Brennivin and leave the sort of bitter-sweet quality I associate with artificial sweeteners like aspartame. It also dulled the spice of the caraway a bit. Clearly, it needed more time. I wasn’t surprised — I had figured I’d need as many as six weeks — but with my rough guess about how much oak to use, I wasn’t sure.
By four weeks, all the sweetness and caraway flavor had returned, along with a hint of vanilla. By five weeks when I removed the oak cubes, it was even better, warmer. Brennivin’s natural coppery metallic edge was gone and I could almost imagine some orange and cardamom notes. It really took the oak well.
I tasted the oak-infused Brennivin next to Linie, the Norwegian aquavit that’s aged in barrels on ships that criss-cross the equator. Linie is lighter and slightly minty in comparison (it’s lighter in color, too; Linie has added caramel coloring, which is interesting given its aging). Side by side, I may actually prefer the aged Brennivin — at least for now.
Some conclusions: First, this is ridiculously easy and inexpensive to do. It cost me less than $20 for three bags of oak cubes and almost half of that was shipping. (Each bag has about 40 cubes in it, which is enough to do four bottles by my estimates.) If you have access to a good home-brewing supply shop, you can save the $8 shipping. Second, it was quite rewarding. I’ll be trying this with gin, tequila, and definitely mezcal. Why not just add 10 oak cubes to a whole bottle of something?