It's as close as you'll come to getting a brewery tour without going on one, and embedded in it are a ton of illustrative points about technology and beer. Reading through it, I hope you have the reaction I had listening: there are just so many factors that go into a batch of beer. It's technical and fine-grained for the average fan, but I think geeks will appreciate it. Mostly, it just felt too interesting to keep secluded on my hard drive. I've slightly cleaned up the language so it flows. Enjoy.
Fergus Fitzgerald: When we want to start a brew, then, we select a recipe, and [the brewery] weighs out the right amount of malt and it will put in specialty malt, whatever you’ve loaded into those silos. From there it goes into the malt hopper and below that then is the mill—and this is what’s called a wet-conditioning mill. So basically the malt sits up here [gesturing to the computer screen] and in this little chamber here we spray it with a small amount of water. What happens then is the husk of the barley takes up that moisture so when it goes through the mill--these two big rollers--the husk is a bit more pliable so it doesn’t break up quite so much. This is important for two reasons, because the husk is what does the filtration when it’s in the lauter tun—the more intact you keep that, the better filtration you get. But also, you can leech a lot of harsh tannins coming out of there; so the more intact you keep it, the less of those tannins you leech out into the beer.
We add water at this stage. The water we use is town’s water. Like most breweries, at one stage we would have had our own well, but that got contaminated with salt water in about 1940 and since then we’ve been on town’s water. We put it through the carbon filters and then we Burtonize it. Again, because of the age of this brewery, when we started making the majority of the beer, the beers coming out of Burton on Trent would have been the iconic beers of the age. And like lots of breweries we Burtonize our water to try to give it that sort of hop [clarity].
From there into the mash tun, which is this vessel out here. Jonathan Adnams, from later, during the tour: As [the malt] comes out from the bottom of the mill, in goes the brewing liquor to eliminate oxygen from the grist right at that point of exiting the mill. And then it literally flows up underneath [into the mash tun] so there’s no splatter splatter. It’s very important in bottled beers to eliminate oxygen right at an early stage. FF: The less oxygen you create at this stage, the less oxidative reactions you’ll get in the kettle. You don’t want to add oxygen and heat together because that’s going to give you staling compounds later on. Everything’s filled from the bottom to try to keep that out.
Fergus Fitzgerald: [There are] steam jackets on the outside and a big stirrer. All the mash goes in, sits in there for about an hour. We can temperature program mash so we can do protein stands and bring them up to 65, 66 degrees [149-151 F]--which is something we could never do on the old system. We basically put it in at one temperature and it got gradually colder after that.
Typically after an hour we check that the starch is all gone and then it goes into the lauter tun. It's fairly well automated; we take all the first wort off and then we sparge and then we take some second wort off. All that wort is then going to a pre-run tank, which is really just a holding tank. [Jeff: how big are your vessels?] In terms of grain capacity we can go up to about seven and a half ton and down to about two ton, so it’s got a reasonable turn-down ratio. In terms of volume, we’re between about 100 and 300 barrels. That’s quite a good turn-down for that size brewhouse. So, lauter tun usually about three hours.
[Next, it goes to a "pre-run tank", which is] basically a holding tank and then it goes on into the kettle. We boil for about an hour. We have four dosing vessels over here, so we load three of them with hops and those hops go in at different stages—obviously bittering, aroma, and some really late aroma hops. And then one of them we use for copper finings [Irish moss/carrageenan]. So those get dosed in at different times, which is really quite an advanced form from where we used to be. They all used to be added by hand, so there was a bit of variation, particularly on the aroma hops. With this system it gets added at exactly the same time every time—which gives us greater control over the consistency of the beer.
One of the major advances we put in was the energy-recovery system. In the old brewhouse all the steam just went up into the atmosphere and made some nice, fluffy clouds. Whereas here, we can capture all the steam going up off the kettle, use that steam to heat a hot-water tank, which we call our energy-storage tank, and on the next brew, as the wort’s traveling from this pre-run tank into the kettle, it goes through this heat-exchanger which picks up the heat from that energy-recovery tank. Typically we can heat up from 72 degrees to about 93,94 degrees [162 to 199-201 F] just using the steam that previously would have been blown away in the wind.
Jonathan Adnams adds We’re the only brewery in the UK that can do this kind of energy-store, capture-and-storage system, bringing it back at a later date. So even for the last brew on Friday we can hold that energy to first thing Monday. And we can do the same thing with cold energy, too.” FF “We can still get up to 88, 89 degrees Celsius [190-192 F] on the first brew Monday.
Fergus Fitzgerald: So it boils in there for an hour. We control the amount of steam we put in. In the old brewhouse we had basically two big steam controllers that we could open by hand. JA adds “We’re evaporating at about five percent" and then FF takes over We’re now at five percent; we used to be anywhere upwards of ten—not because we wanted to do, just because we had very rudimentary control of how much steam we put in. It was a quarter of a turn for a gentle boil an three quarters for a big rolling boil. So you had big variation between one person’s quarter turn and another person’s quarter turn. It’s also a whirlpool, so at the end of the boil we do the whirlpool stage and then from there through the wort cooler and then into the fermenting room.
We aerate either with air or oxygen depending on the gravity of the beer style—higher gravity stuff we use oxygen, lower gravity’s air. We have cooling capacity, too. There’s this two-stage cooler: part of it’s cooled just using mains water, off the mains, and part of it’s cooled using chilled water tank. At different times of the year we use more—obviously if the water from the ground is running colder we have to use less of the chilled water.
Jonathan Adnams It's a highly automated brewhouse, switches itself on at four in the morning, there’s no one here, it literally runs—I mean, the first thing we do is take an iodine test. The manpower now is mainly about monitoring the process, taking samples, taking back to the lab to analyze. The computer’s running the kit so you get repeatability time after time. All the recipes are in the computer; they can load up the recipes for the week and the computer will run. We generally run two to three brews a day. So three brews go through in 16 hours, so you can have three brews in this brewhouse at any one time.
PHOTOS: Fergus Fitzgerald at top, Fergus and Jonathan Adnams below.