Craft Beer & Brewing Magazine Podcast 467: Adjusting the Thiol Dial with ISM, Ology, and Berkeley Yeast
Mar 31, 2026
Gene Wagoner, head brewer at ISM Brewing known for New Zealand-style IPAs; Tim Sciascia, Berkeley Yeast brand ambassador and former Cellarmaker co-founder; and Nick Harris, Berkeley Yeast co-founder and fermentation product lead. They explore thiol chemistry, how concentration changes perception, yeast and precursor strategies, practical brewing tweaks like co-pitching and mash/hop choices, and using thiols to shape balance and shelf life.
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Why Thiols Define Tropical Beer Aroma
- Thiols are powerful, low‑threshold sulfur molecules that drive tropical fruit aromas like grapefruit, guava, and passion fruit.
- Nick Harris explains they act at nanogram–microgram per liter levels and different thiols (3MH vs 4MMP/3MBT) give very different, sometimes polarizing, notes.
Barley Supplies 3MH Precursors While Hops Add Free Thiols
- Thiol precursors live in both barley and hops, but precursors themselves are odorless until enzymatically released.
- Nick Harris notes barley supplies many 3MH precursors while hops contain both free thiols and precursor forms extracted on the hot side.
Cellarmaker Customers Preferred Tropics For Juiciness
- Tim Sciascia recounts Cellarmaker using both Chico and Tropics strains side-by-side to compare hop expression and customer preference.
- He found customers preferred London Tropics beers for their passion fruit 3MHA aroma and overall juiciness.