What even is a Thiolised IPA?

We’re thrilled to have collaborated with Brook House Hops on an English-hopped, thiolised IPA that we will be releasing mid-August.

It’s one of the first commercial beers in the UK to use brand new yeast ‘Hop Unlock’ – a thiolised yeast strain from WHC Labs which enables access to previously unattainable thiols.

But what is a thiol, anyway?

Thiols are flavour/aroma compounds that are found naturally in differing types of hops and malts, in varying quantities. Think white grape, lychee, melon, mango, passionfruit…

They’ve always been there, but as a lot of these compounds are ‘bound’ we haven’t experienced much of the effect of them in the flavour of the finished product. This new ‘Hop Unlock’ yeast contains an over-expressed enzyme which can ‘free’ thiols, thus unlocking a more powerful aroma including notes of mango, guava, passion-fruit and white wine.

How did we end up with this yeast?

Our Head brewer, Tom, bloomin’ loves yeast, fermentation and all things related (as you’d expect), so he’d heard about thiolised beers popping up in the US through a podcast and asked WHC Labs if they were working on something similar. It just so happened they were, and they sent us some ahead of its commercial release. (NOTE: Hop Unlock is now available commercially) We have a long-standing relationship with WHC Labs as they’re our main lab and they store our house lactobacillus culture that we use to give all of our sour beers that distinct ‘Brick’ taste.

Why is it exciting?

This is one of the first brews to use the yeast in the UK. (and our first time using it, obviously)
Forefront of the future of yeast and brewing methods.
Environmental reasons
- The theory is that we will be able to use UK hops in the same way we currently use American hops, as we can now access these bonus, previously-hidden flavour compounds. If so, we wouldn’t need to import as many hops, and we could achieve brilliant results with local, sustainable, UK hops.
Flavours! Aromas! White grape, lychee, mango, passion fruit flavours. Thiols are often desirable in Sauvignon Blanc production.

How have they made it?

In the US, you’re allowed to genetically modify yeast, whereas over here you can’t, so Hop Unlock was made by ‘forced selective breeding’ favourable components from previous yeast strains, and then cultivating them over time.

What changes did we make during the brew to optimise the yeast’s effects?

Use of hops with high amounts of bound thiols, including some UK varieties:
- UK Challenger, UK Chinook, Cascade Leaf, Idaho 7 Cryo, Riwaka T90, Eclipse T90

4 step hopping process to optimise the benefits of the yeast strain and access as much flavour as possible.
- Mash hopping – thiol precursors are found in malt, adding hops in the mash allows extraction of bound thiols.
- Whirlpool hopping with hops that have high levels of bound thiols.
- Declaration hopping – hopped as the beer is transferred and cooled from the kettle to the fermenter. Its purpose is to preserve heat-sensitive aromas that would otherwise be boiled off.
- Dry Hopping with even more thiol-forward varieties.

Brook House Hops

This beer is a collaboration with Brook House Hops, a well-respected UK hop-grower based in Herefordshire. They also import hops, but they put a big focus on their own UK hops. They kindly provided some of our hops for the brew, including the UK varieties of Chinook & Challenger.