Updated: Apr 30, 2019
Jeff here again, this time to nerd out about a fascinating concept sure to get more traction in years to come, the use of terpenoids and by extension, terpenes in beer. Terpenes are aromatic organic compounds found in many plants including hops that directly influence beer aroma and flavor. Terpenes are undergoing a cultural and academic renaissance dating back to the first time terpenes were characterized in plant essential oils due to their large role in cannabis research and legal product development, however terpenes have had influence in the production of beer and essential oils from the moment the first human decided to play around with herbs and wort together.
Commercially terpenes are a constituent of essential oils, perfumes, and legal cannabis products. Terpenoids are derived from terpenes, but contain additional chemical functional groups. Terpenoids are water soluble, so they blend into solution readily and as such are commercially viable for direct dosing applications.
While cannabis remains illegal in Wisconsin outside of industrial hemp and hemp derived CBD, many uses the word “terpenes” so as to have become synonymous with its use in cannabis. We are focusing on the broad use of terpenes across multiple brewing applications that is not limited by this narrow perception. Terpenes are building blocks of flavor for many plants and herbs including conifers, citrus family and of course hops.0 Their application in brewing extends beyond the cannabis context.
Terpenes and terpenoids are produced both biochemically by plants and synthetically in labs. There are many varieties of hop cultivars which can differ in both genotype (genetic code compliment) and phenotype (outward perceived physical appearance) yielding distinct alpha and beta acid concentrations that affect the bittering capacity, and distinct flavor/aroma profiles characterizing a specific hop strain. Hop breeders use these terpene profiles and concentrations in their ad copy,
and when talking about novel experimental varieties as a way to better parse the overall flavor/aroma profile of a hop providing more detail than just alpha and beta acid concentrations.
These only scratch the surface as Mainiacle Yeast Labs (highly recommend Mainiacle Yeast Labs) explained when they revealed their terpenoid product line for homebrewers and commercial brewers (link). While hop breeders list a handful of tentpole terpenes, most brewers are familiar with, Mainiacle Yeast characterized over 40+ terpenoids across multiple hop varieties using GC-MS (Gas Chromatography- Mass Spectrometry) further elucidating the true scope of hop terpene profiles and how they all work
together to achieve an overall flavor profile we perceive as hop.
Terpenes is characterized by the number of Isoprene units (see above). We are mostly concerned with monoterpenes, and sesquiterpenes, which contain two and three isoprene units respectively.
I first started playing around with terpenes around 2017 after reading the 2010 paper titled Biotransformation of Hop-Derived Monoterpene Alcohols by Lager Yeast, and Their Contribution to the Flavor of Hopped Beer put out by Sapporo in conjunction with the Frontier Laboratories Value Creation division. Their findings were substantial (more on that later) however it was not their findings I found fascinating, but rather their methodology. They studied the effect lager yeast have on hop derived monoterpenealcohols to see if their concentrations changed during fermentation (spoiler alert: they did!) and to achieve a base concentration for their experiment they dosed wort with terpenes extracted from hop pellets which they added to a pilot wort solution verified by a sensory panel. You can literally squirt stable hop flavor into your beer. That's amazing.
Indirect Application -Dry Hopping the Haze Craze + Biotransformation
We talked about terpenes a bit when explain yeast biotransformation in our Yeast Post. The idea that during fermentation yeast transform one terpene to another, perhaps more favored terpene. This phenomenon is observed by recording the concentration of particular terpenes before, during, and after fermentation is complete. Researchers observe a decline in some terpenes' concentration and a rise in others throughout beer fermentation.
We see this expressed in the previous paper observing concentrations of geraniol and β-citronellol. As concentrations of geraniol began to decrease around day 2 of active fermentation, a previously nearly non existent β-citronellol increased in concentration entirely dependent on the original geraniol concentration suggesting that geraniol was biotransformed in β-citronellol.
Geraniol expresses a distinct floral rose aroma and flavor, while β-citronellol imparts a pleasant lemony, lime aroma.
A simplified view of this phenomenon suggests that if geraniol rich hops are added during day 2 (high krausen) yeast mediated biotransformation will change the rose forward profile to a more citrus forward aroma profile which is typically selected for in early dry hopped beers such as NEIPA.
However, like most things in biology rarely are things THAT simple. That very same year Takoi and colleagues elaborated this specific pathway yielding results suggesting there are more terpenes at play. Utilizing the citra hop, and using a similar methodology, researchers tested for concentrations of geraniol, β-citronellol, and linalool in their test batches of beer yielding some fascinating results. Not only do these terpenes seem to have a direct inverse relationship based on their concentration
through the fermentation timeline, the coexistence of these terpenes even if they don't necessarily have a direct relationship, appear to attenuate sensory properties. Hopping test wort with citra hops yielded a citrus/tropical fruit aroma and flavor profile that was not expressed previously with only geraniol and β-citronellol.
This suggests terpenes not only coexist in an entourage effect with cannabinoids, but also with other terpenes yielding flavor profiles greater than the sum of their parts. Understanding the terpene profiles of our hops, and the various biotransformation pathways allow us to control specific early dry hop applications for an intended flavor profile. While early dry hop additions are the norm to selectively activate these pathways via hop and yeast selection new research also suggests adding hops
during the whirlpool may yield the most terpene extraction relative to other hopping applications. However you do it, knowing you hop terpene profile, and if and when you want to change is just another tool brewers may use to produce quality stable beer.
Direct Applications, So we utilize terpenes indirectly via hop additions in our beer all the time. We can also add terpenes and terpenoids directly to the beer circumventing or in addition to traditional hopping regimens. Terpenes can be oxidized in the presence of oxygen on a long enough timeline through mechanisms we understand. (Almeida et al., 2015) However, terpenoid products (Mainiacle Yeast) exist on the market that are both water soluble, and unable to be oxidized meaning they can be blended readily into beer solution and are shelf stable. As more players come to market and competition ramps up, we will see more and more direct terpene products trying to capture specific hop profiles, or blends of hops.
Cannabis derived terpenes can also be used in beer to express aroma profiles evocative of cannabis which are also typically conserved in hops as well, yielding those dank notes. While I do not see this application taking over traditional dry hopping, as hops provide the basis for enzymatic reactions, antimicrobial properties in boil, and excellent bittering capacity. I see terpenes having a place in supplement with whirlpool/dry hop additions adding to a selected flavor profile, and perhaps allowing
for better product yields if terpene additions allow for less physical hop material and by consequence absorption to occur.
One last point relates to research being done on terpenes/terpenoids and their value for legal cannabis products. Many companies like extract labs who produces cbd concentrates sold legally here in Wisconsin reintroduce terpenes and the reason is twofold, flavor, and a noticeable yet non-psychoactive effect that has been documented via oral administration. New research suggests these terpenes have noticeable perceivable effect independent of thc and thus, cannabis.
More research is needed to determine needed parameters like dosage thresholds, feasibility in beer, coexistence with alcohol during metabolism, and viability after first pass metabolism before we can suggest hop derived terpenes are making you feel “something”. Either way we are just scratching the surface in our understanding of terpenes and their relationship with beer. I am truly excited to see where this wave takes us from here. To many more skunky hazy bois with only the best yields to come!
Few things coming up!
We are collecting data for a long term dry hop creep expirement post across multiple batches of beer. We are hopeful we will have all data collected and ready to publish here by next month.
This weekend I start spring cleaning for my garage lab to begin bioprospecting for the spring! I capture wild yeasts from all over Wisconsin for funky beer projects with O'so and isolate ones with value for future brewing projects. I will be updating our progress throughout the spring into the summer and fall.
Thanks to everyone who has been following along so far! Your support through the opening of the Madhouse and canning line has been amazing. We love and appreciate every one of you!
-Jeffrey the lab guy
Almeida, Natália E. C. de, Aguiar, Inara de, & Cardoso, Daniel R.. (2015). Mechanism of Hop-Derived Terpenes Oxidation in Beer. Journal of the Brazilian Chemical Society, 26(11), 2362-2368. https://dx.doi.org/10.5935/0103-5053.20150231
Daniel C. Sharp, Yanping Qian, Gina Shellhammer & Thomas H. Shellhammer (2017) Contributions of Select Hopping Regimes to the Terpenoid Content and Hop Aroma Profile of Ale and Lager Beers, Journal of the American Society of Brewing Chemists,75:2, 93-100, DOI: 10.1094/ASBCJ-2017-2144-01
Kiyoshi Takoi, Koichiro Koie, Yutaka Itoga, Yuta Katayama, Masayuki Shimase, Yasuyuki Nakayama, and Junji Watari, Biotransformation of Hop-Derived Monoterpene Alcohols by Lager Yeast and Their Contribution to the Flavor of Hopped Beer
Journal of Agricultural and Food Chemistry 2010 58 (8), 5050-5058
Takoi, K. , Itoga, Y. , Koie, K. , Kosugi, T. , Shimase, M. , Katayama, Y. , Nakayama, Y. and Watari, J. (2010), The Contribution of Geraniol Metabolism to the Citrus Flavour of Beer: Synergy of Geraniol and β‐Citronellol Under Coexistence with Excess Linalool. Journal of the Institute of Brewing, 116: 251-260. doi:10.1002/j.2050-0416.2010.tb00428.x