Vignette 37: Stephen Kilcullen, Guinness
The only photo I have of Stephen is a still from a video I shot. Here he is at the Open Gate Brewery at St James Gate.
This series, picking up after a couple years, features the words of brewers as they discuss the beer they make. I visited Guinness in Dublin just after they started sponsoring the blog in 2016. Stephen Kilcullen was overseeing brewing operations at St. James Gate at the time. See past posts in the series here.
Guinness is a famously secretive brewery, and I was surprised to find that Stephen was more anxious discussing fermentation than any other part of the process. The beer is defined by the bitterness that comes from the barley roasted on-site, but the brewery is happy to discuss that process. The yeast? Not so much.
“[The yeast] is extremely important to us. It’s a unique strain that we use. We absolutely nourish it like a baby. It really is a superb yeast, and it contributes a huge amount to the flavor and aroma of stout. It’s quite a robust yeast, and we probably ferment a lot higher than a majority of breweries. We free rise it two or three degrees [4-5F], and then we maintain that temperature for a period of time. We store it at 5 degrees [C], but as far as pitching temperature, we don’t talk about that [laughs]. That’s a trade secret.”
“Maturation takes a number of days as well. And that really is the essence—that we do not talk about [laughs]. I’ve told you too much already—I might get sacked over this [still laughing, but clearly speaking a truth of the brewery].”
“Diacetyl is actually a key flavor aroma and attribute of Guinness Foreign Extra Stout. So that’s what makes it different. We actually allow the yeast to produce diacetyl and maintain that. It’s beautifully balanced. In Draught we don’t want any diacetyl. What we’re relying on for Guinness Draught in terms of flavor profile is the sweetness of the malt, it’s your roast barley that’s giving that lovely roast character, and then it’s the bitterness on the back of your tongue. Then you get the creamy mouthfeel as well. In the aroma, you’re getting the roast character; you’re also getting some slight esters as well.”