From Vol. 1, No. 3, August 2017, and updated several times since.
In 2006, when Japanese researcher Toru Kishimoto at Asahi Brewing first identified 4-mercapto-4-methylpentan-2-one (4MMP) and 3-mercaptohexan-1-ol (3MH) as “high impact” contributors to hop aroma he focused on relatively few varieties. He found 4MMP at significantly high levels in Simcoe, Summit, Apollo, and Topaz; at a level well above perception in Cascade; and barely perceivable in Millennium, Willamette, Pacific Gem and Perle. Not long after, Tom Nielsen at Sierra Nevada Brewing added Citra, Chinook, Bullion, and Cluster to the list of cultivars containing 4MMP.
By the mid-teens, brewers understood thiols contribute to “exotic” (whatever that means) aroma and flavors, including a full range of ones that deserve multiple adjectives, but there was no “go to” source that listed which varieties are rich in thiols and which contain none. There still isn’t, but what follows will give you a running head start.
The lists here are for free thiols. Many cultivars contain thiol precusors (also known as bound thiols), which may be more plentiful than free thiols. Malt also contains thiol precursors. Standard issue beer yeast strains are not particularly skilled at freeing those precursors. That’s why two companies offer strains engineered to makes those transformations.
4-mercapto-4-methylpentant-2-one (4MMP, same as 4MSP)
Tomato plant, chives, black currant, cat pee
Perceived at 1.5-6 ng/L
3-mercaptohexan-1-ol (3MH/3SH)
Grapefruit, other citrus, passionfruit, muscat, gooseberry
Perceived at 60 ng/L
3-mercaptohexyl acetate (3MHA/3SHA)
Passionfruit, other citrus, guava, body sweat
Perceived at .08-4 ng/L
3-mercapto-4-methylpentan-1-ol (3M4MP/3S4MP)
Passion fruit, grapefruit, rhubarb
Perceived at 70 ng/L
In 2017, Dr. Martin Steinhaus from the German Research Center for Food Chemistry outlined a procedure for measuring thiols at the International Brewers Symposiums on Hop Flavor and Aroma in Beer. He shared what the center had found while examining 46 cultivars. That is the foundation the 4MMP (also known as 4MSP) list here is based on.
Reality check: The threshold for perception if thiols is quite low (6 parts per trillion, on average), but they also make up a tiny fraction of essential oil. They are highly volatile, and are expensive to measure. I am not aware of a standardized procedure. Still other factors, such as how mature cones are when they are picked, may impact the results from the laboratory of your choice. You’ve been warned.
High levels: Citra, Simcoe, Eureka!, Sorachi Ace, Strata, Summit, Apollo, Topaz, Mosaic, Sabro, Ekuanot, Galaxy, Nelson Sauvin, Ella, Vic Secret, Talus.
Significant levels: Zeus, Cluster, Chinook, Cascade, Centennial, Amarillo, German Northern Brewer, Hallertau Blanc, German Cascade, Mandarina Bavaria, Polaris, Ariana, Callista, Tango.
Measurable but low: Bravo, Calypso (but rich in bound thiols), Sultana, Galena, Lemondrop, Sorachi Ace, Super Galena, Willamette, Halltertau Tradition, Herkules, Perle, Taurus, Tettnanger, Styrian Golding, Pacific Gem, Saaz.
None: Hallertau Mittelfrüh, Hersbrucker, Hüll Melon, Magnum, Saphir, Spalter Select, Bramling Cross, East Kent Golding, First Gold, Fuggle, Pilgrim, Progress, Wye Challenger, Wye Target.
Nelson Sauvin, Amarillo, Mandarina Bavaria, Mosaic, Simcoe, Citra, Cascade, Calypso, Tomahawk, Columbus, Zeus, HBC 682 (previously known as Pahto), Columbus, Centennial, Comet, Idaho 7, Bravo, Sabro, Chinook, Palisade.
Citra, Mosaic, Amarillo, Hallertau Blanc.
Nelson Sauvin, Hallertau Blanc, Strata, Amarillo, Sabro, Mosaic, Simcoe, Citra, Cascade.