What is Cask? The real process behind real ale

BBF's Head Brewer, Tristan, has been going viral on Instagram with his tales from the brewery. As we’re celebrating being Cask Champions this Autumn, it feels like the season to ask Tristan everything we've ever wanted to know about cask, and dispel a few myths along the way!

So, Tristan, from the top: what is cask?

Simply, cask beer is real ale, it's real, it's cask conditioned.

Yes, but what does that mean?

It means it's gone through secondary fermentation.

With a keg beer, during fermentation we're going to fully ferment the beer out to hit our terminal gravity, which is the amount of sugar that we have allowed, that we've created for the beer to ferment.

With cask beer, we are going to leave a little bit of sugar in during that fermentation process, and we are going to leave some yeast in there. We're going to cool it down to below fermenting temperature, which for our yeast is around about 10 degrees C. And then we are going to package into cask. When we package into cask, we leave that little bit of fermentable sugar in there (about 1.5 gravity units) and we leave some yeast in there.  

When we fill the cask, we're at 6 degrees centigrade. And then when we cask condition our beer, we store our beer in our warehouse. And our warehouse is stored at 13 degrees centigrade, just like any pub cellar should be. This allows the yeast to wake up, to come out of its dormancy. And then it will have a little look around and it will see all those lovely sugars that we've left in there, those lovely fermentable sugars. And it will start fermenting. It will create the two things that fermentation does, which is it creates ethanol, which is of course alcohol, but it creates CO2.

The CO2, when we ferment in our fermenters, the CO2 escapes from the vessel. We don't want that CO2 to escape, we want to absorb that CO2 into the beer. So that's why we have an enclosed cask and the CO2 will dissolve into our beer and give us our lovely little bit of fizz, or what we call ‘condition’ in the brewing trade.

That’s the brewing covered! How can you tell the difference between cask and keg, just by looking at a line-up of beers at your local? 

Yeah, so when you're looking at a bar, you're going to look at those hand pulls and those keg lines. And the hand pulls are the old traditional centre of your bar hand pulls. They're connected to a beer engine and that beer engine goes into the cellar and it feeds into the tap of the cask.

To get the cask out, we're going to pull through with a beer engine and we are going to replace the headspace, the CO2 in the cask with oxygen. This is sort of what creates cask beer as such a great unique product.

The beauty of it is, it is a real product. This is why it's called 'real' ale; it has a short lifespan. Oxygen, when oxygen gets into the beer, when you're pulling beer out of the cask, that is actually going to start the degrading process. It's going to turn your beer flat, and then it's going to go as far as to introduce, create acetic acid, which is vinegar flavour, which is why we always serve cask within a few days once open. Fresh is best.

Ben Daley (BBF Sales Manager) says a pint of cask is as complicated and as artisan as a premium cocktail. The only difference is that the customer doesn’t see all the work the bar team are putting in to make the drink perfect. It all happens in the cellar.

Yeah, I'd agree with him there. It's not as simple as keg beer, and you've got the pub, the publican, the bar staff, who all must treat it with a bit more affection and a bit more knowledge. Temperature here is vital. You want a nice between 12 and 14 degrees centigrade. I personally like 13, but depending on the time of year. 

People are often put off by the misconception that cask is served warm. Is that not the case?

In our pubs we will adjust our cellar coolant temperature to get that cask where we want it. Maybe slightly colder in the summer to get that first quenching taste and then slightly warmer in the winter for a nice, smoother and more characterful flavour. Temperatures, lower the temperature, the less flavour you're going to get out of beer. 

How did Bristol Beer Factory become such an authority on cask?

Yeah, BBF's been built on cask beer from 2004 when we started brewing in South Bristol. We are a big on-trade brewer. We always will be and we always focus on pubs over anything, that community side of it.

And, of course, we currently hold the title of Champion Beer in Britain, the highly regarded CAMRA award for real ale, for Independence 4.6%.

What else makes BBF the so-called 'Cask Champions' of Britain?

Well, cask ale goes hand in hand with pubs and the traditional side of pubs. In the Southwest, I would say, it is very cask way inclined. People forgot about cask. And people moved away from cask, 10 years ago. We never did. And if anything, we pushed cask even harder than most brewers out there.

And by doing that, we created 30 to 40 different cask beers per annum, with some returning and some not, all of them being everything that we stay true to: every beer passing the three-pint test and being crystal clear and full of condition, which are our ideals of what a great cask beer is.

Why is BBF's cask such a cracking pint?

Bristol Beer Factory beers have a higher CO2 level on our cask than I would say the average brewer does. The publican might get a bit wet when they hit their first spiling - venting the cask with a wooden peg in the cellar ~24 hours before serving - but it really translates to when that beer gets poured over the bar. You're getting a lot bigger head and a lot creamier character than a traditional old flat Bass, for example.

And our sessionability, I would say, and that comes down to the roots of our brewing, our love of cask.

Explain the ‘three-pint test’ and the NPD process...

We don't want to make a great half pint; we want to make a beer that is great after three pints. We intentionally keep our beer down, around the low 4% ABV mark.

And we have a lot of experimentation with your newer hops. With flavour coming back into it, you'll be able to get more character from the flavour of the hops at a lower rate, which is then a lot cheaper to produce than a big DIPA.

And you can focus a bit more on the malt as well, I would say. There are plenty of different malts. Malts sort of gets overshadowed by the hops in the brewing industry. So yeah, playing around with the likes of your ambers and your reds and then moving into your stouts, yeah, really lets the malt shine through.

Yeast is very important. We have our own house ale yeast strain, which is a really good workhorse. It's a really good flocculent, which means it will settle out quickly and ferment at a good rate. Not too fast for off-flavours, but fast enough to push beer through and get good secondary fermentation on our cask.

Is cask beer inherently better for the environment because it's a real product?

Yeah, absolutely. We use no CO2 in the production of cask ale because you have that cask conditioned in secondary fermentation to give your beer the fizz. So we don't have to introduce any more CO2. It is. Yeah.

And better for you, do you find even anecdotally, do you feel better? Like, sometimes I feel quite gassy if I have loads of keg in a night, but cask, I don't. What's different?

100%. I would choose cask over keg 9 times out of 10. And one of the things is the sessionability of cask beer because of the lower CO2, so the lower fizz, allows you to consume more and potentially, as you say, maybe don't get bloated like what maybe a lager is doing to you or a big hoppy IPA on keg is giving to you.

How do you like your cask? Do you like it with sparkler? Do you like a handle glass?

I like my cask with a sparkler. I like my cask in good condition. I'll happily take cask out of gravity, so straight out of the cask. But yeah, a nice big swan neck. Personally, I like the Gates glasses...

Tulip?

The tulip, thank you. That's my personal go-to. But in the winter months, yeah, give me a dimpled handle any day and I'll be super happy.

And what's your non-BBF pint of choice when it comes to cask?

I got many, but I would say some of the big guys, there's a reason why some of the big guns do so much cask and they're so prominent in the pubs around the country and that is your Timothy Taylor Landlord and your St Austell Tribute. Yeah.

I love a Proper Job.

Yeah, I like a Proper Job. You just can't session too much with a Proper Job!

Back to BBF, do you know how many casks we do a year, roughly?

30, 40, 50 different new beers with alterations of hops.

How do you keep it interesting?

There are always new hops coming out and we always love to trial new hops. What we love to do is we quite like to do a single or a dual hop to really let those hops express their characters rather than doing a 5 or 6, 7 hop beer. Let the hop shine through.

On a nice easy malt base always helps. Keeping it sort of simple on that side. Just a touch of wheat and a bit of dextrin, a bit of Cara and then yeah, really let the hop shine through.

Bitterness, I would always like to talk about. Bitterness is a little bit Marmite for people. Everyone's got different palates and everyone's got different flavour thresholds. But what bitterness does to a beer is it actually claws you back in for more. So that is the beautiful thing about bitterness, you take a sip and then you go, oh, I want another sip of that beer. So getting the bitterness right is always, in my eyes, is difficult.

How many to date, do you reckon?

It'll be over 250, I bet.

Yeah?

I reckon for sure. 250 and counting.

Finally, what's next for BBF cask?

It's quite interesting with the new power series that we've done. We've been using hop oils. So again, that's sort of evolved our cask ale. It's never standing still, and there's plenty more that we can do, play around with, and test.

Thank you, Tristan. Now, to the pub for a well-deserved pint from a handpull!