1. Onions, Garlic and other fun Sulfury Flavors from New World Hops
Scott Bickham, Ph.D.
BJCP Exam Director
BJCP Northeast/International Representative
Grand Master IV Beer Judge
Copyright © 2018 Scott Bickham. All rights reserved.

2. 20 Years ago, Sulfur-Struck appeared in Brewing Techniques …Plus ça change, plus c'est la même chose
Original article:
Spanish translation:

3. Sulfur aromas in nature are often warning signs
Stagnant water
Sewage
Poisonous gases
Skunks
Ethanol versus ethyl mercaptan: substituting Oxygen with Sulfur makes a compound that is added to natural gas to make it easier to detect

4. Sources of Sulfur in Brewing
Fermentation (yeast)
Brewing Process:
Mash
Boil
Chilling
water
Thiol compounds in hops:
amino acids

5. Sulfur characteristics are grouped into 4 categories in Class 7 of the Beer Flavor Wheel

6. Second tier descriptors are more familiar terminology when evaluating aroma and flavor

7. DMS is only one element of a larger family of cooked vegetable flavors

8. DMTS can produce onion-like flavors in beer

9. Many popular US and “new world” hops have sulfury aroma and flavor components
S-methyl methanethiosulfonate has been identified as a potent aroma compound in Centennial and Citra hops
Sauerkraut-like flavor with a detection threshold of 5 ppm

10. The way the hops are processed can impact the level of sulfury and grassy flavors in beer
Green: Cat urine, green grass, tomato leaves, green peppers
Vegetal: Celeriac, leek, onion, artichoke, garlic, wild garlic
Stan Hieronymus, “Cascade – a study in hop terroir,” Hops (28-Feb, 2015)

11. Onion and Garlic Character from New World Hops
Mercaptans are sulfur compounds with very low thresholds
They are usually formed by yeast through the metabolism of sulfur-containing amino acids
They are also found in hop oils, particularly in some varieties of New World hops
Citra and Mosaic:
Used in low amounts: pear, tropical fruit or sauvignon blanc
High levels: ribes, cat urine, armpit sweat, or dank (“pungent, funky and odoriferous, refers to both good weed and very hoppy IPAs”)
Simcoe and Summit:
The oils found in these hops varieties include mercaptan which has an aroma like freshly cut onions (dry-hopped IPAs)

13. Isovaleric Acid
Sweaty, leathery or barnyard character from Brettanomyces
Valeric esters have distinctive and pleasant fruit-like odors
Perfumes and cosmetics
Methyl valerate: flowery
Ethyl isovalerate: apple
Amyl valerate: pineapple

14. Troubleshooting Guide for Sulfur Flavors and Aromas (English)

15. Summary
Sulfur compounds in beer originate from all major ingredients: malt, hops, yeast and water
Many are volatile compounds with very low thresholds, but the traditional brewing processes tend to naturally reduce their concentrations to acceptable levels
Sulfur compounds can be difficult to troubleshoot because they readily convert into other compounds in response to changes in pH, temperature, and staling (oxidation) reactions
High levels usually indicate issues with yeast health (autolysis) or contamination by Gram-negative bacteria