Biotransformation: When Hops Become Something More (And How to Actually Use It to Your Advantage)

Hops aren’t what they seem.

Or rather, they’re not only what they seem when you open a fresh pellet bag and take that first glorious sniff.
That amazing aroma? It’s just part of the story.

What really matters is not just what hops bring as-is, but what they can become—and to unlock that, we need to talk about biotransformation.

This isn’t just a buzzword or a fancy way to say “use good hops.” It’s a real biochemical process that happens in your tank, and if you know how to work with it, it can elevate your beers in ways you might not expect.

So What Is Biotransformation?

In the simplest terms: biotransformation is what happens when yeast modifies hop compounds during fermentation. The yeast doesn’t just make alcohol—it’s also breaking down, reshaping, and sometimes fully transforming certain hop molecules into entirely new aromas and flavors.

This isn’t guesswork. It’s been studied, tested, and observed both in labs and in real-world breweries. A foundational study by Praet et al. (2012) showed, for example, that geraniol (a floral, herbal terpene found in hops) gets transformed by yeast into β-citronellol, which gives off bright citrus and lemon peel notes.

So yeah—same hops, different beer, depending on what your yeast is doing with them.

It’s Not Magic—It’s Chemistry (and Yeast)

Biotransformation involves specific compounds in hops, mainly:

• Monoterpene alcohols, like geraniol and linalool

• Bound glycosides, which are aroma compounds “locked” to sugars
  

• Thiol precursors, especially the sulfur-based ones that can unleash guava, passionfruit, grapefruit, and other tropical notes
  
  

When yeast with the right enzyme activity (think β-lyase, among others) encounters these molecules during active fermentation, it can release or convert them—creating new aromas that didn’t exist in the raw hops.

This is especially important if you’re brewing hop-forward beers. You might think you know what a hop variety will give you, but depending on your yeast strain, timing, and fermentation dynamics, you could end up with something much more layered—or totally different.

What the Science (and Experience) Say

In The New IPA, Scott Janish digs deep into this. He shows data where hops like Centennial and Strata, rich in geraniol, led to much higher levels of citronellol in the final beer—not because the hops had it, but because the yeast made it through biotransformation.

One of my favorite things from his book is this idea:

You're not just dry hopping for what you smell—you’re dry hopping for what you want to create.

It’s not about throwing more hops into the tank. It’s about making smart choices based on what the hops can do when paired with the right yeast and used at the right time.

Timing: The Key You Can’t Skip

If you’re looking to harness biotransformation, when you add your hops is just as important as which hops you use.

• Adding hops pre-fermentation? You’ll lose aroma through CO₂ stripping.
  

• Adding them post-fermentation? Yeast is already done doing its thing—you’ll get raw hop aroma, but no transformation.
  

• The sweet spot? During active fermentation, usually around high krausen (say 1.020–1.030 gravity), when yeast is working at full power.
  
  

That’s when your hops and yeast can really have their moment together.

Picking Hops with Biotransformation in Mind

So, how do you choose the right hop?

You look for hops with transformable compounds—like high levels of geraniol, linalool, or thiol precursors. Not every hop brings that to the table.

Here are a few worth watching:

• Centennial – surprisingly rich in geraniol in some lots
  

• Strata – amazing for biotransformative character
  

• Citra – already big, but with potential for even more citrus through yeast interaction
  

• Nelson Sauvin, Motueka, Sabro – depending on your yeast, you can pull some wild tropicals
  
  

That said, not all yeasts will give you the same results. Some strains (like London Ale III, Conan, or certain Kveik strains) are way more active in biotransformation than clean Chico-style yeasts.

And this is where brewing becomes art: matching hop + yeast + timing for the outcome you want.

You Don’t Need to Use More Hops. You Need to Use Them Better.

Biotransformation isn't just science—it’s a strategy.
It’s how you go from brewing a good IPA to brewing one with layers, with surprises, with that “what is that amazing thing I’m tasting?” moment.

And best of all? It’s already happening in your brewery—you just need to understand it and work with it.

So next time you're planning a recipe, don’t just think “what does this hop smell like?”
Think: What can it become in the hands of my yeast?

Let them do their dance—and you’ll get more aroma, more flavor, and more depth without having to spend a euro more on hops.

References:

• Praet, T., Opstaele, F., & Aerts, G. (2012). Biotransformation of hop-derived compounds by brewing yeast. Journal of the Institute of Brewing, 118(4), 360–368. DOI: 10.1002/j.2050-0416.2012.tb00436.x

• Janish, S. (2019). The New IPA: Scientific Guide to Hop Aroma and Flavor. Scott Janish Publishing.