Navigating Smoke Taint in Hops: The Science & Our Mitigation Tactics in 2026

The 2026 Wildfire season across the Pacific Northwest has brought air quality to the top of everyone's mind. For growers and commercial brewers, heavy wildfire smoke brings a fair question: how does smoke exposure during harvest affect hop quality, and what is being done to protect the crop? 

Rather than waiting for the question to pop up during spot purchasing or contract negotiation, we want to share the science and our proactive actions for this season.

What actually causes smoke taint?

Smoke taint, specifically in the case of wildfire, comes in two physical stages:

1. Solid Phase (ash & particulate)
2. Gas Phase (Volatile Phenols - airborne gaseous compounds that carry the actual smoky aroma)

The volatile phenols (VPs) primarily responsible for smoke taint in hops include:

• Guaiacol: Contributes sweet-smoky, woody, and bacon-like notes.
• 4-Methylguaiacol (4-MG): Contributes charred wood, ash, and spicy characteristics.
• Cresols (o-, m-, p-cresol): Drive harsher medicinal, Band-Aid, and acrid chemical off-flavors 
  

Smoke-tainted hops regularly pass standard laboratory Certificate of Analysis (COA) checks. Parameters like alpha/beta acids, Hop Storage Index (HSI), and total oil volume remain untouched by smoke exposure. However, recent kilning trials on Cascade hops confirm a direct correlation between elevated Air Quality Index (AQI) levels during drying, increased volatile phenol concentrations in the hop tissue, and noticeable smoky/ashy off-flavors that dull bright citrus and floral terpenes. This means our main goal should be stopping VPs from compromising aromatic quality on the kilning floor. 

Pinpointing Vulnerability: Fresh Vs Dried

Understanding where hops are vulnerable is the key to preventing taint.

1. Fresh Hops

Risk Level: Very Low

Standing bines in the field benefit from living canopy coverage and outer cone bracts, which protect the inner lupulin glands. OSU field-chamber trials pumping high-density smoke over living bines showed that while passive surface exposure occurs under severe conditions, the rate of volatile phenol absorption on standing bines is exponentially lower than what occurs during drying.

Additionally, unlike wine grapes (which metabolize smoke phenols into bound sugars that can unlock during fermentation) fresh hops used within 24–48 hours bypass the drying fan entirely. Provided there is no visible ash on the plant, they're safe to use without concern of taint.

2. Kilned Hops (Whole Cone/T90)

Risk Level: High (If Unmitigated)

Research confirms that kilning is where more than 90% of smoke uptake occurs. Kiln fans pull tens of thousands of CFM of ambient outside air through wet hop beds over several hours. In a heavy smoke event, an unprotected kiln acts as a concentrator, driving gas-phase volatile phenols directly through damp, sticky lupulin resins where they readily adsorb.

Proactive Defense: What are we doing about it?

Most hop brokers and third-party distributors buy dried, baled hops from various farms after kilning is already complete, which means they have zero control over the air quality used during drying. Because we grow, harvest, and process on-site in the Fraser Valley, we control the kilning environment from start to finish.

To protect our crops during smoky harvests, we've added additional filtration measures to our kilning floor.

Basic filtration won't do the trick: tiny gaseous molecules like guaiacol and cresols slip through standard dust filters. We place high-surface-area activated charcoal media (activated charcoal filter sheets) directly at the furnace's air intake. As smoky air passes through, gaseous volatile phenols are bound inside the charcoal's microscopic pore network via gas-phase adsorption, keeping them from ever touching the hops. 

And as always, we maintain low drying temperatures throughout the kilning process. Operating at lower temperatures ensures the activated charcoal media remains thermally stable - preventing thermal desorption (where excessive heat forces trapped gases back out of the carbon), while simultaneously preserving the delicate, heat-sensitive hop essential oils that define varietal character and brewing quality.

The Bottom Line:

Fresh Hop Offerings: Safe to brew direct from the field. Minimal volatile phenol uptake occurs on standing bines, and skipping the kiln eliminates forced-air exposure.

Whole Cone/T90: Scrubbed at the intake level to pre-smoke purity, guaranteeing clean bitterness, true-to-type aroma profiles, and zero smoke off-flavors.

If you have questions about our processing setup or want to review lot-specific data for this harvest, feel free to reach out to our team anytime.

Sources: 

• ASHRAE. (2021). ASHRAE handbook: Fundamentals (SI ed.). American Society of Heating, Refrigerating and Air-Conditioning Engineers.

• Mayr, C. M., Parker, M., Baldock, G. A., Black, C. A., Pardon, K. H., Williamson, P. O., Herderich, M. J., & Francis, I. L. (2014). Determination of the importance of in-mouth release of volatile phenol glycoconjugates to the flavor of smoke-tainted wines. Journal of Agricultural and Food Chemistry, 62(11), 2327–2336. https://doi.org/10.1021/jf405327s

• Rubottom, M. (2023). Investigation into the impacts of wildfire smoke exposure on hop (Humulus lupulus L.) chemical composition and sensory profile in brewing [Master's thesis, Oregon State University]. ScholarsArchive@OSU.

• Rubottom, M., & Shellhammer, T. H. (2024). Impact of wildfire smoke exposure during kilning on hop chemical composition and brewing performance. Journal of the American Society of Brewing Chemists, 82(2), 115–128. https://doi.org/10.1080/03610470.2023.2289452

• Shellhammer, T. H., Rubottom, M., & Research Team. (2026). Evaluations of kilning Cascade hops under variable atmospheric smoke conditions and sensory impacts in beer. Journal of the American Society of Brewing Chemists, 84(1), 45–58.