The longevity of brewing ingredients, particularly hops, is a common concern among homebrewers aiming for consistency and cost efficiency. The question of how long hops can maintain their integrity when stored in a freezer is explored in the accompanying video, where an illuminating experiment on old vs new hops in an American Pale Ale is thoroughly documented. This investigation meticulously compared the sensory impact of Cascade hops harvested in 2017 and stored for six years, against a fresh 2022 harvest, within two identical batches of an American Pale Ale.
For many homebrewers, bulk purchasing of ingredients is an attractive proposition, yet the risk of degradation over time can temper such enthusiasm. The Brülosophy experiment, highlighted in the video above, addresses this by providing empirical data on whether a significant difference can be reliably detected between beers brewed with aged hops versus fresh hops. This article further elaborates on the scientific principles underpinning hop degradation, the methodology of the experiment, and the broader implications for brewers.
Understanding Hop Degradation and Storage
Hops, critical for bitterness, flavor, and aroma in beer, are organic materials susceptible to degradation over time. The primary culprits in this process are oxidation, heat, and light, which collectively diminish the potency of alpha acids and alter aromatic compounds. Consequently, proper storage techniques are paramount for preserving hop quality.
Freezing, especially in oxygen-barrier packaging, is considered the gold standard for long-term hop storage. This method significantly slows down the chemical reactions responsible for degradation. The low temperatures inhibit oxidation, which is the reaction of hop compounds with oxygen, and also minimize the formation of off-flavors that can develop from the breakdown of hop oils. Nevertheless, questions persist regarding the practical limit of this efficacy, particularly over extended durations such as several years.
The Chemistry of Hop Aging
The principal bittering compounds in hops are alpha acids, primarily humulone, cohumulone, and adhumulone. During the boil, these alpha acids isomerize into iso-alpha acids, which are much more soluble and contribute the characteristic bitterness to beer. Over time, particularly with exposure to oxygen, these alpha acids can oxidize into less desirable compounds, leading to a “cheesy” or “dank” aroma often associated with poorly stored or aged hops.
Moreover, the delicate essential oils responsible for the aromatic qualities of hops (e.g., myrcene, humulene, caryophyllene, linalool, geraniol) are highly volatile. These oils can degrade, evaporate, or undergo chemical transformations, leading to a loss of desired hop character and the development of less pleasant aromas. Therefore, the effect of hop age is not merely about bitterness but also about the complex interplay of flavor and aroma contributions.
Experimental Design for Assessing Hop Age
The Brülosophy experiment demonstrated in the video employed a rigorous methodology to investigate the impact of hop age. Two distinct 5-gallon batches of American Pale Ale were brewed simultaneously, ensuring that all variables, except for the age of the Cascade hops, were meticulously controlled. This careful control allowed for a direct comparison of the sensory outcomes attributed solely to the hop variable.
A consistent malt bill was established for both beers, comprising 90% Pale Ale malt, 7% Caramel 20, and 3% White Wheat Malt. This formulation was designed to produce a beer with an approximate gravity of 4.9% ABV, providing a clean canvas for hop character to shine. Mash conditions were standardized at 152°F (67°C) for 60 minutes, ensuring uniform sugar extraction from the finely crushed grains.
Addressing Alpha Acid Discrepancies
A critical consideration arose due to the significant difference in alpha acid content between the two Cascade hop lots: the 2017 batch registered 7.2% alpha acids, while the 2022 harvest contained 4.7%. Such a variance could profoundly influence bitterness if only Cascade hops were used for all additions. Consequently, a workaround was implemented: Warrior hops were utilized as the universal bittering hop for both batches, with a 60-minute addition of 15 grams. This strategic decision effectively isolated the influence of the Cascade hops to only the flavor and aroma contributions, which are primarily derived from later boil additions and dry hopping.
The chosen yeast strain was Imperial Flagship (A07), a robust Chico strain known for its clean fermentation profile, fermented at a consistent 68°F (20°C) for approximately two weeks. Intriguingly, slight variations in finishing gravities were observed, with the old hops beer finishing at 1.008 and the new hops beer at 1.006. While this minor difference in gravity could subtly impact body, it was not expected to overshadow the primary hop comparison.
Sensory Evaluation of Aged Hops
The core of the experiment resided in the sensory evaluation phase, conducted as a blind triangle test. This method is widely employed in sensory science to determine if a perceptible difference exists between two samples. Participants were presented with three colored cups: two containing the old hop beer and one containing the new hop beer, or vice versa. Their task was simply to identify the odd beer out, without any prior knowledge of the variables.
A panel of 20 participants, largely composed of local professional brewers, engaged in this blind testing session. For statistical significance in a triangle test with 20 participants, 11 correct identifications are typically required to confidently assert a discernible difference. However, in this particular study, only 9 tasters successfully identified the unique sample. This result indicates that, for the blinded participants taking a single test, a statistically significant difference between the American Pale Ale brewed with six-year-old Cascade hops and that brewed with fresh Cascade hops could not be reliably established.
Individual Perception vs. Statistical Significance
Interestingly, the narrator, Martin Keen, undertook the triangle test himself five times, successfully identifying the unique sample in each instance. This personal finding highlights a common dichotomy in sensory research: while a group may not reach statistical significance, individual tasters, particularly those with heightened sensitivity or experience, might consistently perceive a difference. This can be influenced by repeated exposure, allowing for more nuanced detection than a single blind test might permit.
Witt Baker, a brewmaster who hosted the tasting, also expressed a lack of surprise at the results. He suggested that modern hop packaging techniques are highly effective, allowing hops to retain their quality well beyond five years. This perspective aligns with the idea that advancements in vacuum sealing and cold storage have significantly extended the usable life of hops, challenging older assumptions about rapid degradation.
Practical Implications for Homebrewers
The findings of this experiment carry significant weight for the homebrewing community. The inability of a professional panel to statistically differentiate between beers made with six-year-old frozen hops and fresh hops suggests that homebrewers can confidently utilize well-stored older hops, especially for flavor and aroma additions, without drastically compromising beer quality. This can lead to substantial cost savings through bulk purchases and reduce ingredient waste.
However, it is important to consider the potential for subtle differences that may not reach statistical significance in a single blind test but could still be perceived by individual brewers. The narrator’s personal success in repeatedly identifying the old hop beer implies that while the difference may be subtle, it is not entirely absent. This could be attributed to slight variations in perceived bitterness, possibly influenced by the higher initial alpha acid content of the older Cascade hops, even when used as late additions.
Therefore, while the experiment provides reassurance regarding the use of aged, properly stored hops, brewers should remain attuned to their own sensory perceptions. Experimentation with old vs new hops in their own recipes can help individual brewers determine their personal threshold for detectable differences. This commitment to continuous learning and personal evaluation remains a cornerstone of advancing brewing expertise.
The ExBEERiment’s Aftertaste: Your Hops Q&A
What was the main purpose of this experiment?
This experiment aimed to find out if using old hops (specifically 6-year-old hops) instead of fresh hops would make a noticeable difference in the taste of an American Pale Ale.
Why is hop storage important for homebrewers?
Proper storage helps prevent hops from degrading due to exposure to heat, light, and oxygen, which can cause them to lose their bitterness, flavor, and aroma over time.
What is the best way to store hops for a long time?
The best method for long-term hop storage is to keep them frozen in packaging that prevents oxygen from reaching them, such as vacuum-sealed bags.
What did the experiment conclude about using old hops?
The experiment found that most taste testers could not reliably tell the difference between beer brewed with 6-year-old properly stored hops and beer brewed with fresh hops, suggesting older hops can still be used effectively.
