Behind the Numbers — What’s in an Oyster Stout?

Behind the Numbers — What’s in an Oyster Stout?

"What does the 'Oyster' bit mean in the 'Oyster Stout'?" asks the man at the bar, half-way through asking every question he can think of about the beers on the board behind me.

"It means it was brewed with oysters" I reply. His eyes widen. His questions have found a focus.

" the beer?"

"Yes. Actual oysters are actually put into the beer during the brewing process!"

"… Does it taste of oysters?"

"Not really, a slight fruitiness, a subtle minerality and a little briney quality, but that's about it."

"Can I have a taste?"


"Oh yeah, lovely! I'll have a pint of Session IPA please."

I mean, it is a strange sounding beer. There aren't any other beer styles that I know of that involve actual molluscs (Snail Pale, anyone?). But this bivalve-brew is steeped in more history than anything featuring Citra hops, which have only been around since 2008!

A brief history of the Oyster Stout

oyster-historyIt was hard work being a porter. When their day's work was done they weren’t interested in any piddling pale ales, and the stronger IPAs were exclusively for the trip to the East Indies (now Southeast Asia). No, they like dark beers with all the extra calorific goodness that comes with those richer malts. Over time, these beers come to assume the name of their most popular patron and the Porter is born. And for those bigger blokes who like their beer with extra body, the Stout Porter is close to follow.

When they drank their favourite beer in those bankside taverns, there was only one bar snack cheap enough to session on - the then bountiful Thames Oyster. The salty minerality of the shellfish cuts through and compliments the bitter richness of the stout. Admittedly these guys probably didn't discuss the tasting notes, but they knew they were onto something.

Eating oysters with stout is nearly as old as the beer itself. It's even something a certain Irish brewery made clever use of in its advertising. It was good for you, after all. But when did people start brewing with them?

The history on this matter is murkier than the Thames. My favourite theory is that the words were used so often in the same sentence that people just thought that was how the beer was made, and so did it themselves; something of a "self-fulfilling myth". There's perhaps more credence to the suggestion that crushed-up oyster shells were used as finings (which checks out scientifically), and certain pioneers just took it one step further.

Either way, the oyster stout emerged over the 20th Century with a view to achieving that beautiful combination of flavours in the beer itself.

Cue the Craft Beer Revolution and for innovative brewers with a penchant for the alternative, the oyster stout was an option too interesting to ignore.

How we made our 08 Oyster Stout

Nowadays it's still a rare style, with people understandably unwilling to brave the hard sell that is shellfish in a beer. Also, there is no established methodology for getting this right. Some only use the shells, some use the flesh too. When are they added? In the mash? In the boil? Is it supposed to taste of oysters? Or is it just supposed to have subtle minerality or saltiness?


With our emphasis on experimentation, we at Brew By Numbers have always jumped at the opportunity to be one of the few breweries in the country daring to brew this style.

I was invited to help out on the last brew day and I can report back that our immensely talented team have found some answers to the questions posed above.

This is now our third oyster stout in as many years, the process being refined with each iteration. This time we started with a robust stout malt bill. Then, with the help of our friends over at Wright Bros., we dropped a veritable beach’s worth of Lindisfarne oyster shells into the late stages of the mash, and then 1.5kg of oyster flesh into the whirlpool. This last bit was particularly entertaining as the oysters were first packed into two pairs of tights so as not to clog up the transfer. The result looked like some Cronenburg monster. There was actually a discussion on the type of tights to be used. We settled on a trusty pair in XL Skin Tone.

We also worked with a new variety of English Ale yeast this time round. It’s lower-attenuation has left us with a wonderfully silky and full-bodied beer: a real homage to those original ‘stout porters’.

The release saw us pouring and chatting all things oyster alongside the The Wright Bros. team. They brought a spread of fabulous oysters to taste alongside the stout. And, most excitingly, there was an oyster master providing an informative talk about the oysters that went into this startlingly-storied drink.

The tasting presented an unrivalled chance to experience this pairing, just down the road from where it all started.