Episode 362: Aroma Hop Shelf Life
A recent OSU study challenges the brewing industry's obsession with hop freshness, revealing that for some varieties like Citra and Centennial, hops stored properly for up to six years can perform as well as fresh ones in sensory tests. The research, funded by the Hop Research Council and involving real-world inventory samples from major producers and brewers, found that oxygen levels inside sealed packages—rather than chronological age—were the true predictor of hop quality. Contrary to conventional wisdom, HSI (Hop Stability Index) was shown to be a poor proxy for aroma quality, often failing to correlate with actual sensory differences. Surprisingly, free thiols in Citra hops remained stable over time, and some older hops even showed enhanced terpenoid profiles. The findings suggest brewers could save money and reduce waste by using aged inventory strategically, especially when guided by nose and sensory testing. The study also hints at the possibility of 'beneficial aging' in certain varieties, echoing historical practices with German noble hops. This paradigm shift calls for a move away from 'newest crop first' inventory policies toward data-driven, oxygen-aware storage and usage strategies. The episode underscores a critical disconnect between industry assumptions and empirical data. While many brewers default to the latest harvest, the research shows that for resilient varieties, older hops aren’t necessarily worse—just different.
For Citra and Centennial hops stored properly, four to six years of age makes no significant difference in sensory quality compared to fresh hops.
Oxygen levels inside sealed hop packages are a stronger predictor of quality than chronological age, with some samples showing 10-20% oxygen—indicating packaging flaws.
HSI (Hop Stability Index) is unreliable as a standalone metric for aroma hops, often failing to correlate with actual sensory performance.
Free thiols in Citra hops remain stable over time, challenging the belief that they degrade rapidly with age.
Some older hops may develop more desirable flavor compounds—suggesting 'beneficial aging' is possible, especially in terpenoid-rich varieties.
…and 3 more takeaways available in PodZeus
The Myth of Freshness: Why Brewers Might Be Overpaying for New Crop Hops
“A brewer logs in, searches for the hop variety they need, then sorts the search results not by price but by newest crop year. Then they purchase the new crop even when there's a listing for the previous crop year at a significant discount.”
Designing a Real-World Study: From Industry Samples to Sensory Trials
The researchers explain how they gathered 45 real-world hop samples from major producers and brewers, including some up to six years old. They emphasize the importance of using commercially stored hops under real conditions, not forced aging, to avoid artificial results. The study included chemical analysis, oxygen testing, and crucially, actual brewing trials.
Citra, Cascade, and Centennial: The Three Varieties That Upend Conventional Wisdom
“For Citra and Cascade, the story was easier. Citra was holding well on chemistry point of view, and then the sensory was matching. Cascade was the opposite story. We were already seeing differences with the chemistry, and then it matched up the sensory.”
The HSI Problem: Why a Key Metric May Be Misleading for Aroma Hops
“The HSI is a marker for bitter acid degradation, which may or may not correlate with aroma quality degradation.”
Sensory Reality: When 'Different' Isn't 'Bad' and 'Old' Isn't 'Worse'
“When you see discrimination data and you see that we can find a difference, you've got to hit pause and don't immediately jump to the conclusion that because there is a difference... That it's bad.”
“There was a good 10% of them or more that had packaged oxygen levels that would be higher than what we would expect. When I say higher than what we would expect, I would have expected packaged oxygen levels to be... like close to zero, but certainly below 1%.”
“So the HSI is a marker for bitter acid degradation, which may or may not correlate with aroma quality degradation.”
“It would need more results again back us up but it seems like yes sometimes the variability across vintage or lots could be significant enough that you would want to sit on some of those lots.”
Host
Guests
Citra
other
Tom Schellhammer
person
Cascade
other
Cecile Chenot
person
Centennial
other
Oregon State University
organization
Lupulin Exchange
organization
Hop Research Council
organization
Strata
other
Hopsteiner
brand
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