Sulfur Aroma in Hops – A Brewer Question

We often receive questions from brewers. We do our best to help them right away if we can. Sometimes, brewers can ask challenging questions and we need to reach out to knowledgeable friends who might know the answer. For this question, I consulted a very wise friend who has been in the industry a long time. He knows all kinds of useful random stuff and doesn’t seem to mind helping from time to time. I’ve paraphrased what he had to say about the sulfur aroma question:

 

Question:

Hi! We use your Azacca® in our NEIPA and they smell amazing. But we have gotten a lot of sulfuric aroma in our beers after switching. Then I read somewhere that some hops can indeed impart a sulfuric bite if they are treated with some pesticide [sic]? The problem is increased if you have late additions where that aroma can’t boil off. Any suggestions?

 

Answer:

We have not seen sulfur as a varietal attribute of any specific hop used in dry hopping. Thiols in hops can be perceived as sulfur like as they are very close to the hop terpenes associated with Black Current and/or Tropical aromas. We should also consider the aromas created when dry hopping in the presence of active yeast and that sulfur causing compounds can be malt related.

Another thing to consider is that some folks use C02 to pressurize and or circulate when dry hopping. Too much C02 can have a “scrubbing” effect that makes any underling sulfur notes (contributed by the water/beer soluble fractions) appear to be amplified when actually it is removing (i.e., scrubbing) the non-sulfur components. I would also point out that it may be Dimethyl Sulfide (DMS).

Since it’s a NEIPA, we might also assume that you might be using 5%-20% oats in the mash…. if so, are you allowing for the appropriate beta-glucanase rest?

Regarding the application of elemental sulfur on hop plants. There is a sulfur-based spray for powdery mildew. Hop merchants in the United States require that it not be applied after June 1, well before bloom in the Pacific Northwest. The long time between application and harvest requirement is not because of potential “sulfur” notes in brewing. Rather, it is due to the fact that sulfur is a catalyst killer in the production of some down steam products and the merchants don’t like that.