Brettanomyces and Pale Ale

This is a question that's troubled me for some time: did long-matured Pale Ales contain brettanomyces?

Looking at it logically, it seems quite likely. I know many English pitching yeasts contained brettanomyces. In running beers, they wouldn't have been apparent as the beer would have been consumed long before they could have made their presence felt. But Pale Ales were Stock Ales, matured, as we've learned for up to 12 months in the barrel.Plenty of time to affect the beers flavour.

Then there are the union sets. A perfect place for brettanomyces to hide with all that wood and piping.Even if the pitching yeast contained no brettanomyces, there's a good chance a Pale Ale would have picked it up from the unions.

Then there are the descriptions of Pale Ale picking up its distinctive flavour only after a long maturation. You know what that screams at me? Brettanomyces. What else takes so long to develop?

I've lots of analyses of 19th century Pale Ales. But they aren't much help. Brettanomyces wasn't identified until just after 1900. So no hard evidence, just guesswork and supposition. And you know how keen I am on that as a research method.

Until a few days ago. When my latest book purchase flopped onto the doormat. "Onderzoekingen over het Gistgeslacht Brettanomyces" ("Investigations into the yeast species Brettanomyces".) As far as I know, it's the only book about brettanomyces. Weird that it's in Dutch. Luckily, that isn't a problem for me.

I found out about the book from "The Brewers' Journal" for 1940, which contains a review of it. You can probably guess what followed. I did a search in Abebooks and located a copy. (And there was only one, so bad luck if you'd like your own copy.)

I wondered if it would have anything about Pale Ale. I wasn't disappointed. That's putting it too lightly. I hit the jackpot. Not only was a Pale Ale analysed, but it was the most renowned of them all: Bass Pale Ale.

As already noted, Brettanomyces yeasts also play a role in the fermentation of English beer types "ale" and "Stout". Maturation does not, as with "lambic", take place in bottles but only in barrels. However, these are also bottled unfiltered. I examined samples bottled in this country of "Pale Ale" and "Stout" from Bass & Co., Brewers, Burton on Trent. For isolation of Brettanomyces strains from these samples a portion of the sediment was swabbed on malt agar and chalk plates and yeast-agar-glucose and chalk plates, which were incubated at 30° C.

After two days, several yeast colonies were observed, but which did not appear to form acid. After 7 days between these, very small colonies were visible, which dissolved the chalk around the colony. On the plates from the "Stout" two types of acid-forming colonies were distinguished, hard and soft. The majority were hard, and under the microscopic these were all found to be identical to each other. A hard and a soft colony tubes were scraped off into test tubes and then isolated into a pure culture in the way described for "lambic". The soft culture we will call for the time being St. I and the hard St. II.

On the plates on which were spread the dregs of "Pale Ale". only the hard acid-forming colonies could be isolated. These were apparently identical with St. II. In this context it should be remembered that the beers came from the same brewery.
"Onderzoekingen over het Gistgeslacht Brettanomyces" by M.T.J. Custer, 1940, page 27. (My translation.)

Did Bass Pale Ale contain brettanomyces? Yes it did.

But it's more interesting than just that. Did you notice that the Stout contained two different types of brettanomyces, but the Pale Ale just one. That implies that one of the types almost certainly wasn't in the pitching yeast. Unless the Pale Ale and Stout were pitched with different yeasts.

There were differences in the way Bass made their Pale Ale and Stout. Pale Ale was matured in carriage casks, Stout in vats. Had the Stout picked up the soft St. I type from the vats?

There are still lots of unanswered questions. But one thing we know for sure: Pale Ale did sometimes contain brettanomyces.