Before anything else, I should make it clear that I am a US brewer that hasn't had a pint in the UK in over twenty-five years. Take everything that I write about UK ales with a substantial pinch of salt. I'm a US-based admirer of UK ales, not a UK brewer. I'm hardly an expert.
I recently started using Jasper Yeast's version of the Fullers strain and, although I only have two pitches under my belt, I'm excited enough about my results that I wanted to post my results as early as possible. We're all familiar with WY1968/Pub: it makes unambiguously UK-esters, is easy to work with, and it floccs like a lead ball. It's the UK's version of the Chico strain or 34/70, it wants to make excellent beer and you have to screw up spectacularly to keep it from doing so.
Nevertheless, WY1968 and Pub have a reputation for pulling up a bit short in the attenuation department, especially when you compare it to the wild attenuation rates described by Ron Pattinson's amazing blog. I certainly recall reading a few frustrated posts about this in the past and I've absolutely experienced it myself. Pub will eke out a few more points than WY1968, but both of them punk out around 75% on their best days.
Enter Jasper Yeast. As mentioned above, I only have two pitches under my belt and only one keg in my fridge with this strain, but it's already clear that Jasper's take on the Fullers strain is a more aggressive attenuator. On the first and second generation pitches (an ordinary bitter and a dark mild) Jasper's JYO-37 has hit 79% attenuation. Wow!
Jasper's take on the strain delivers the esters and, like '68 and Pub, it makes an unambiguously UK ale that has those big, fruity esters. Jasper's esters are just a bit more restrained, maybe because the greater attenuation cuts into the sweetness that helps define the concept of "fruity?" That greater attenuation also allows your water adjustments to cut through a bit more cleanly, which is really nice and might also contribute to the slightly restrained esters.
You don't get all that for free: Jasper's take on Fullers is fractionally slower to hit TG compared to '68 or Pub--but that's still blazing fast. Both my pitches hit TG in four days. It's also more reluctant to flocc, but that makes sense given its higher attenuation rate. More bothersome, it seems to hang around much more persistently in the serving keg than '68 or Pub. Nah, it's not chill haze: you can taste the yeast in the ale. On the plus side, it's a very pleasant yeast taste, nothing bitter or bite-y. It plays nicely with the hops, malt, and water salts. I'm a stickler for clear beer, but my tongue does not object to its presence.
Going forward, I'm really eager to put this strain to work on some UK IPAs. The Thames Valley strains have never impressed me, but I think the Jasper strain might get the job done in spades. Its propensity to clear the way for your water salts makes that a no-brainer. I also think this will excel in stouts and porters where it's drier finish will highlight the dark grains and clear a lane for them to play a bigger role in the ale's finish.
I'm very excited about this strain and, like all Jasper strains, it's a bargain. Their pitches are packaged for 10gal batches and they cost the same as Imperial or Omega. RIP White Labs and Wyeast.
Here are the fermentation curves for the first two pitches:
Ordinary Bitter that is kegged an pleasant.
Dark Mild, crashed today no flavor impressions yet.
I recently started using Jasper Yeast's version of the Fullers strain and, although I only have two pitches under my belt, I'm excited enough about my results that I wanted to post my results as early as possible. We're all familiar with WY1968/Pub: it makes unambiguously UK-esters, is easy to work with, and it floccs like a lead ball. It's the UK's version of the Chico strain or 34/70, it wants to make excellent beer and you have to screw up spectacularly to keep it from doing so.
Nevertheless, WY1968 and Pub have a reputation for pulling up a bit short in the attenuation department, especially when you compare it to the wild attenuation rates described by Ron Pattinson's amazing blog. I certainly recall reading a few frustrated posts about this in the past and I've absolutely experienced it myself. Pub will eke out a few more points than WY1968, but both of them punk out around 75% on their best days.
Enter Jasper Yeast. As mentioned above, I only have two pitches under my belt and only one keg in my fridge with this strain, but it's already clear that Jasper's take on the Fullers strain is a more aggressive attenuator. On the first and second generation pitches (an ordinary bitter and a dark mild) Jasper's JYO-37 has hit 79% attenuation. Wow!
Jasper's take on the strain delivers the esters and, like '68 and Pub, it makes an unambiguously UK ale that has those big, fruity esters. Jasper's esters are just a bit more restrained, maybe because the greater attenuation cuts into the sweetness that helps define the concept of "fruity?" That greater attenuation also allows your water adjustments to cut through a bit more cleanly, which is really nice and might also contribute to the slightly restrained esters.
You don't get all that for free: Jasper's take on Fullers is fractionally slower to hit TG compared to '68 or Pub--but that's still blazing fast. Both my pitches hit TG in four days. It's also more reluctant to flocc, but that makes sense given its higher attenuation rate. More bothersome, it seems to hang around much more persistently in the serving keg than '68 or Pub. Nah, it's not chill haze: you can taste the yeast in the ale. On the plus side, it's a very pleasant yeast taste, nothing bitter or bite-y. It plays nicely with the hops, malt, and water salts. I'm a stickler for clear beer, but my tongue does not object to its presence.
Going forward, I'm really eager to put this strain to work on some UK IPAs. The Thames Valley strains have never impressed me, but I think the Jasper strain might get the job done in spades. Its propensity to clear the way for your water salts makes that a no-brainer. I also think this will excel in stouts and porters where it's drier finish will highlight the dark grains and clear a lane for them to play a bigger role in the ale's finish.
I'm very excited about this strain and, like all Jasper strains, it's a bargain. Their pitches are packaged for 10gal batches and they cost the same as Imperial or Omega. RIP White Labs and Wyeast.
Here are the fermentation curves for the first two pitches:
Ordinary Bitter that is kegged an pleasant.
Dark Mild, crashed today no flavor impressions yet.
Last edited:
