We came across SH-45 in a Bintani product announcement earlier this year. A new thiol-unlocking yeast from Fermentis. With cooler weather rolling in and a gap in the limited release calendar, a red and black IPA co-release felt like the right way to put it through its paces. We've been "watching this space" on thiolized yeasts and are excited to be sharing two IPAs into this space at last.
Two beers, one yeast. Welcome to Unseen Spectrum.
Thiols are sulphur-containing aroma compounds behind some of the most prized tropical notes in beer — passionfruit, guava, grapefruit, blackcurrant. The catch is that most of the thiols in raw ingredients aren't free aromatics. They're bound up in non-aromatic precursor molecules, sitting quietly in the grain and the hops, doing nothing for the nose.
A thiol-unlocking yeast does what the name suggests. During fermentation it produces enzymes that cleave those precursors and release the free thiols into the beer. Aromatics that were chemically invisible become the loudest thing in the glass.
SH-45 is a new dry lager yeast from Fermentis built specifically for this job. It's the lens. The raw ingredients — malt, hops, even the water — are the spectrum we're trying to reveal.
One beer is a data point. Two beers tell the story.
We wanted to put SH-45 against two different malt canvases and two different hop bills, brewed within a week of each other for repitching and fermented identically. Same pitch rate, same starting temp, same fermentation schedule. One dark and roasty, one red and resinous, both pointed at tropical fruit through the yeast.
The grist sits on Voyager Atlas Latrobe with Munich Schooner for body, plus Briess Midnight Wheat and Weyermann Carafa Special II for colour without the harshness those late-addition dark malts can drag in. Dextrose at the end of the boil keeps the finish dry.
OG 1.063 | FG 1.012 | >80% apparent attenuation.
In addition to experimenting with the new yeast, Ultraviolet trialled mash-hopping with Columbus. Mash hopping isn't standard for brewing, with most of your aromatics get boiled off later, but is used for planting planting bound thiol precursors early in the process. This gives SH-45 more raw material to act on during fermentation. We backed it up with whirlpool Cascade, Vista and Columbus, then dry-hopped with Cascade and Vista plus a dose of Clayton Hops Cascade Amplifier hop oil for an aromatic boost.
Papaya, ripe melon and citrus over a properly black malt base. The thiol contribution from SH-45 is clearest in this beer — the tropical character is brighter and louder than the hop bill alone would suggest.
One of two beers in our Unseen Spectrum dual release, brewed with SH-45 — a new thiol-unlocking yeast. Dark Belgian candi syrup keeps Infrared dry where reds usually run sweet, clearing space for a blazing canopy of Amarillo, Audacia, Citra and Chinook. Orange marmalade, sweet pine and red berry, burning bright and finishing crisp.
This time the base malt is a 60/40 blend of Voyager Atlas Latrobe and Veloria Schooner building up the malt body with SM40 and Redback bringing the red colour and a touch of depth. To minimise the toasty characteristic of typical red IPAs, we we add Belgian dark candi syrup late in the boil to bring colour and a hint of dark fruit character. This helps the beer to ferment out dry, so you get the red appearance without the malt weight.
OG 1.068, FG 1.013, >80% attenuation.
The hop bill is where Infrared gets loud. Chinook in the boil for bittering, Amarillo and Audacia in the whirlpool, then Citra, Amarillo and Audacia in the dry hop. Audacia is the wildcard — a 2023 Indie Hops release out of Oregon, child of Hersbrucker, known for huckleberry, red currant and floral notes that play well with thiol-driven yeasts. We wanted to see what it would do with SH-45 working underneath it.
Orange marmalade, sweet pine and red berry. Resinous and crisp rather than rich and sweet. We've seen some releases being dubbed a West Coast Red and we reckon Infrared this fits that billing.
A few takeaways:
We'll keep brewing! There's a few more ideas in the Unseen Spectrum series already on the whiteboard, and we'll share notes again when it lands.
Cans of Ultraviolet and Infrared are available now from the cellar door, online store and through our wholesale network from later this week. See the write-up on crafty pint, too!
What a good idea!
Two beers. Two playlists to drink to.
Ultraviolet Playlist
Dark, dubby, nocturnal. Tropical fruit lifting out of pitch-black. Massive Attack, Broadcast, Surprise Chef and more.
Infrared Playlist
Warm, dusty, resinous. Desert rock and analogue heat. Mildlife, Khruangbin, King Gizzard and more.
