Split batches are wonderful! They provide the opportunity to see (and taste) the changes that just one variable can make. They helps to cut through all the confounding batch-to-batch variables and identify what a single tweak is responsible for. However, with sour beers you always have to be cautious not to read too far into them as identical worts aged in identical barrels under seemingly identical conditions can diverge as the microbes compete. The beating of a bacteria’s flagellum can cause a proverbial hurricane of flavor!
These two beers started from the same mash, I pitched the same microbes (White Labs WLP665 Flemish Ale Blend, and dregs), and aged them in two third-use barrels from Balcones Distilling for four months. While most of each batch then went onto fruit (raspberries for the rum, cherries for the malt whisky) I reserved a gallon of each fruitless to taste the base beer. While I love fruited sour beers, I’m usually far more interested in the straight-up examples. They provide a truer expression of the magic of microbes, barrels, and wort!
Rum Barrel-Aged Sour Brown
Appearance – Clear, mahogany leather, dense off-white head.
Smell – Madeira-like, brandy-soaked raisin aromatics with a touch of oxidation. A brighter fruit candy note as well – SweeTarts perhaps. A tinge herbal as well, not what I usually pick-up in an old/dark sour.
Taste – Flavor leaves those darker fruit flavors behind for cherry-acidity flowing into cocoa powder. Dry, but still enough to support the malt and oak. Not distinctly rummy to my palate… but in comparison to the whisky-barrel it is surprising how much of that fruit is from the barrel!
Mouthfeel – No tannins or anything rough. The acidity helps to cover-up the lean body.
Drinkability & Notes – Somewhere in the nebulous realm between old ale and oud bruin, with the barrel playing a wonderful supporting role. While I enjoyed the jammy raspberry contribution, I'm glad I also got to taste all the nuance here that was obscured by the fruit.
Malt Whisky Barrel-Aged Sour Brown
Appearance – A twin, other than the slightly stickier head.
Smell – A cleaner more fresh-brown-liquor aroma. What I thought at first sip was dark fruit from the combination of fermentation/age/malt really seems to have been coming from the rum barrel. This one is more dusty-basement damp-oak. Coconut candy bar.
Taste – Acidity is tamer, but still firmly sour. The fruit is more plum than cherry, not as bright. The finish is a bit curdled milk, lingering in a not-entirely pleasant way. Likely more a result of the particular fermentation in this barrel rather than anything inherent to the wood/spirit themselves.
Mouthfeel – Similar, feels slightly richer, maybe just drinking it second a bit warmer and flatter.
Drinkability & Notes – It is a fine beer, but next to the Rumble-barrel it is missing that extra something that makes a great dark sour. Academically it is the same, but I’m tossing the last few sips and going back to the other bottle for the last few ounces!