February 16, 2022 knowledge, new releases Richard Preiss

Thiol Libre: How to Liberate Thiols In Your Beer

Thiol Libre is a new yeast bred to enhance thiol and tropical fruit aromas in your beers. Read on below for tips on how to use Thiol Libre to its full potential!

For the most up-to-date guidance on using Thiol Libre, see its Tech Sheet.

Why Enhance Thiols?

Thiol compounds can smell like Sauvignon Blanc wine, gooseberry, guava, grapefruit, and passionfruit! It’s no surprise that the hops with the highest amounts of free aromatic thiols are also the most expensive: Citra, Sabro, Mosaic, Nelson Sauvin, to count a few.

Thiols and their release is all the rage these days, with new yeasts coming onto the market that have been modified or bred to enhance thiol release.

This includes our brand-new Thiol Libre! Thiol liberating yeast strains open up a new world of opportunities for flavour development, and give us entirely new ways to make aromatic beers.

These yeasts have all been developed to have enhanced activity from the IRC7 enzyme, which is a beta lyase that helps the yeast release aromatic thiols from flavourless precursors.

So you can throw tons of $$$ Citra at your beer and it will taste good because it already has a ton of free thiols. But there’s huge opportunity to release bound thiols from lower-cost ingredients, in unexpected places. Some common and lower-cost hops such as Cascade, Saaz, and Calypso contain large amounts of bound thiols that can be released by yeasts with strong thiol release capabilities.

Mash hopping? Grape pomace powder? What the heck is going on?

The availability of thiol liberating yeasts has brought with it a number of innovative techniques to maximize thiol aromas in beer.

While it had a little blip of popularity a few years ago, mash hopping is back in a big way. We see brewers experimenting with mash hopping to enhance thiols. This sounds like a crazy idea, but there’s some solid science behind it. The bound thiols in hops take the form of either cysteine-bound or glutathione-bound precursors. In the mash, barley enzymes can facilitate the conversion of glutathione-bound thiols into cysteine-bound thiols. Since yeast releases cysteine-bound thiols, this can result in stronger thiol release. It’s also important to mention that malt also contains thiol precursors, so with Thiol Libre, you can get some tropical, grapefruit aromatics with malt alone!

New ingredients have also emerged that pair extremely well with thiol liberating yeasts. This includes Phantasm, a New Zealand Sauvignon Blanc grape pomace product that contains high amounts of bound thiols. When Phantasm is added to the hot side of the wort process, it can add a large amount of bound thiols that can be released by certain yeasts. This releases the tropical, passionfruit aroma that NZ Sauv Blanc is famous for.

Yeast IRC7 activity is the key to thiol release

The best yeast strains for thiol biotransformation are strains that are both capable of beer fermentation and have high IRC7 enzyme activity. Unfortunately, this combination is quite rare among the yeast world. Most traditional beer yeasts don't have an active form of the IRC7 enzyme.

We thought that there was room for improvement among traditional yeasts, which is why we developed Thiol Libre.

Methods used to develop new yeasts for enhanced thiol biotransformation includes genetically engineering existing strains to have higher IRC7 activity, or breeding strains with naturally high IRC7 activity to achieve “hybrid vigor”.

How did we make Thiol Libre?

We used the breeding route, made easier with modern science. Here at Escaprment we have a history of breeding strains that are greater than the sum of their parts. This is how we made Thiol Libre! It is a classic example of hybrid vigor, since it shows strong thiol biotransformation and better beer fermentation performance than its parents.

Our tips for liberating thiols in your beer:

Select a yeast such as Thiol Libre that has strong IRC7 activity.
Select hops with high amounts of bound thiols, such as Cascade, Saaz, Calypso, and Perle. This opens up the possibility of using and enhancing locally-grown hops! Use these in the mash (mash hopping) and whirlpool. You can dry hop with the big-money hops like Citra and Mosaic later on if you like!
Try adjuncts like Phantasm that contain a high amount of bound thiol precursors.
Experiment with base malts, including locally-produced options. Different malts have different bound thiol concentrations.

Thiol Libre can unlock aromas in local ingredients, too!

Lastly, please consider using local ingredients! New yeasts can help you create totally new flavour combinations and can help unlock flavour and aroma in local hops and malt. We have seen promising results using local Ontario-grown Cascade and Centennial hops when paired with the right yeast and brewing process.

Future experiments with Thiol Libre

We’re not going to leave you hanging post-launch. In the next few months, expect to hear from us about:

How to get the best results from Thiol Libre and Phantasm (these experiments are already fermenting away)
Pairing a new Motueka variant from New Zealand with Thiol Libre
Dialling in mash hopping with Thiol Libre
Comparing base malt thiol potential with Thiol Libre