Kilning with smoke-affected air impacts the chemical and aromatic qualities of Cascade hops

As wildfire events intensify in major hop-growing regions, concerns about the impact of smoke exposure on hop quality are growing. This study evaluated the impact of kilning Cascade hops under variable air quality conditions using a pilot-scale system with smoke introduced via combusted mixed fir pellets. A moderate positive relationship (R² = 0.6815) was observed between air quality, expressed through the Air Quality Index (AQI), and total volatile phenol (VP) concentration in dried hops. Guaiacol and 4-methylguaiacol comprised the majority (55-79%) of total VPs, likely due to lignin pyrolysis of the fir wood. Traditional hop quality metrics (e.g., alpha-acids, HSI, total oil, and oil composition) remained unaffected, though some volatile terpenoids (e.g., geraniol, citral) increased modestly with AQI. Sensory evaluation (check-all-that-apply and line scaling) showed that as VPs increased, citrus and overall hop aroma intensity declined, while smoky, meaty, and artificial BBQ descriptors increased in frequency. These findings indicate that smoke-exposed hops may retain core hop quality metrics while exhibiting perceptual degradation due to phenolic uptake, highlighting the need for integrated chemical-sensory approaches to assess smoke taint in hops and inform postharvest handling in wildfire-prone regions.