Let’s talk about thiols. If you crave tropical flavors in your beer or IPA, listen up. This bit of fermentation science is for you.
Thiols are aroma compounds and they come in two forms – free form and precursor. The free form are volatile and pungent thiols found in tropical fruits, grapes, and hops. Those thoils boast flavors of passion fruit and guava and fresh grapefruit. When a beer is more “thiol expressive” it is far bolder and big-time tropical.
Sounds good right? Eventually, but some fermentation science has to happen first.
Chicago-based Omega Yeast Labs introduced “Cosmic Punch,” a thiolized version of their British Ale yeast in 2021. This engineered yeast strain biotransforms the massive amount of thiol precursors in malt and hops to free form (expressive) thiols. Ultimately, the thiol output is far greater using this yeast than found in the traditional brewing process.
How? Omega’s goal was to make freeing these thiols more efficient. It’s about the IRC7, a gene in yeast that creates an enzyme that frees thiols from their precursor form. The challenge was that many brewing strains have mutations in the IRC7 gene that disable the enzyme, resulting in low thoil output.
Extremely simplified – Omega developed a yeast that keeps the gene active, and thus the enzyme. The final beer – which so many are IPAs or hoppy lagers are bright, snappy, and quite expressive.
It’s that bit of science behind New Realm Brewing’s new Psychedelic Rabbit Transcendent IPA. While the brewing team had created a few test batches of an IPA with Cosmic Punch, Kane Wille, brewer at New Realm says it was Omega’s Star Party yeast that really made a difference. “We did a 20-barrel batch in Atlanta and loved it, so it became Psyche Rabbit,” Wille says.
Azacca, Cashmere, Citra, and Mosaic hops headline this beer, and with the help of Star Party, you really find out what thiols are all about. The result is truly a burst of passionfruit, pineapple, and citrus flavors, in a beer that looks so much more of a west coast IPA, with a lighter mouthfeel, without having to be overly dry-hopped. “We wanted to bring something innovative to the market this year, and have been overwhemed by the success of this IPA already,” Jeff Chassner, Chief Sales Officer tells Beer Street Journal. “We are very fortunate to have such a talented brewmaster in Mitch Steele and an amazing team of brewers”
The India pale ale has always dominated craft beer, always going through a plethora of identities as the years pass. By the taste of it, the days of quadruple dry-hopping an IPA might be fading, with the rise of these yeasts.
Hops: Azacca, Cashmere, Citra, Mosaic
Availability: 12oz Cans, Draft. Year-Round.