Coffee Stout Update

A quick update on my coffee stout.

Appearance: Pitch black with a rich dark tan head almost the color of milk chocolate. Very little visible carbonation, though it’s present.

Aroma: Strong notes of roasted malts (chocolate, black patent, roasted barley), heavy coffee, some charred wood, and almost floral notes mixed with tart berry.

Taste: Extremely roasted flavor with strong coffee notes. Some charred flavors round it out nicely against some lingering sweetness. Faint bitterness of hops that quickly turns to an almost oaky espresso.

Mouth feel: Not too thin, not too thick. Mild carbonation on the tongue. Strong attack of charred grains gives the illusion you’re drinking something much heavier than it is.

Overall impressions: I’m happy with this one. The coffee and roasted grains are right in line with Péché Mortel though lacking the sweetness and strong floral tang of that brew.

Slow fermentation notes: As I mentioned previously, this brew just did not want to ferment with the initial pitch of yeast. I thought the yeast might have been either old or weak, but fermentation was still slow (though steady) after the second pitch of dry ale yeast. My friend Holland, who works with yeasts in a lab for a living, shared the following:

Yes, yeast is sensitive to caffeine. We use agar plates spiked with the drug in order to test growth of different mutants. The concentration I used last time I made media with caffeine was about 2 grams per 1.250 liters. My wild-type yeast didn’t grow in this concentration of caffeine, but some mutants did. Not sure exactly how the mutations changed the yeast metabolism in order to allow it to grow on that media, but it was kinda cool. Just thought you might find it interesting, your yeasties were probably quite sick 🙂

Since this batch had two full 12-cup pots of strongly brewed espresso roast added to it, I thought this would explain the slow fermentation. But Angelos then went against science and brewed a coffee beer that fermented rather violently right off the bat, while my brew that evening (yet to be blogged) puttered along. I think I’m just jinxed with slow fermentation cycles.


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