Hops have one of the most seductive aromas known to mankind with a spectrum that is staggeringly broad so it is amazing that hops have never been widely explored in distillates. Unfortunately, a notorious louching problem is presented by hops which this exercise will explore. The recipe is less explicit than some of the previous exercises because hops vary so significantly. It is recommended to try the many proposed options and enjoy both your successes and cloudy failures in cocktails.
The inspiration for the hopped gin exercise came from the brilliant but seldom imported Japanese product Kiuchi No Shizuku which is produced by the Hitachino brewery. The famous Hitachino white ale is reportedly distilled once to a low proof, briefly mellowed in barrels, and then re-distilled with more hops, coriander, and orange peel. Other similar distillates might be the seldom imported beer schnapps of Bavaria.
Hopped spirits may not be common to the market because of how hops behave when distilled. A clear distillate is very challenging to achieve when working with hops and clarity is something consumers expect out of un-aged distillates. Unlike hopped distillates, most typical distillates become cloudy when certain compounds are included that are volatile only at high temperatures. These compounds can be avoided by making tales cuts below a certain temperature (which corresponds to a certain alcohol level). Whatever clouds hopped distillates, curiously, comes through at low temperatures and is therefore very difficult to avoid because these compounds overlap with (or even are) much of the hop defining aroma. The poorly soluble compound is likely a terpene and could possibly be separated through terpene separation instead of a heads cut where removal could separate other aroma compounds with it.
Hitachino mellows their distillate in barrels at a low proof before re-distilling which presents a clue. Wonderful research on limoncello, to which terpenes are important in defining flavor, state that if the alcohol content goes below 30%, terpenes are at risk of separating as either a louche or possibly an insoluble oil floating on the top. In the Hitachino production process, terpenes could be separated through mellowing at low proof before re-distillation. Stability tests could then be conducted to determine what percentage of terpenes could be reintroduced to the distillate while maintaining clarity at a range of proofs. A practical test for consumers would be making a chilled shot while maintaining crystal clarity.
Terpenes, which have a piney character, are often separated during the production of citrus essences and the process is described well by Joseph Merory in his text, Food Flavorings. The essential oils spend time in a conical separator where the terpenes accumulate on the surface as an insoluble oil that is easy to separate. Terpenes are also reportedly separated from commercial orange liqueurs due to concerns with either their solubility or possible concerns with their stability as an aroma. Conversely, as previously mentioned, terpenes are critically important to limoncellos where they contribute unique timbre and terroir, but also from the limoncello literature, terpenes reportedly can change detrimentally due to hydrolysis.
A concern about hopped distillates which can be explored (with self control not to drink it all!) is whether they change markedly over time which might be a reason they have never been common to the market. Hops are so magical an aroma that you would think every major gin distiller has explored them but perhaps taken a pass due to consumer notions of the stability of distillates. Certain hop distillates explored during development of this exercise have sat around longer than a year and some varietals seem to have lost aroma though age-ability trials were never set up systematically so no conclusions can be drawn for sure. There is also unexplored concerns whether the compound responsible for skunking beer is volatile and could effect a hop distillate stored in clear bottles. Supply chain management is much different than it used to be and with a more educated consumer base, there might now be room for a hopped distillate with a best by date.
The recipe tries to present an elegant starting point for hop aroma that works for nearly every varietal, but if the goal is to learn more about terpene management it may make sense to distill a concentrate, lower the proof, patiently separate the terpenes, re-distill, blend down with plain gin, then re-introduce the terpenes while doing stability tests.
500 mL dry gin (Seagram’s)
8 g hops (Cascade is a good place to start, but experiment with numerous types)
Mix and re-distill together on high reflux until the thermometer on the still reads 93.33°C. Going past 93.33°C may result in a cloudy distillate for other reasons.
Using your hydrometer re-cut the distillate to your desired proof (recommended 80-90).
Hops vary in the potency of their aroma. If the hop distillate is too aromatic it can always be diluted with more plain gin.
It may also be rewarding to collect the product one ounce at a time in small canning jars then dilute them one at a time from the beginning into the first half of the hearts to reduce the proof by 50%. This will illustrate how the first fractions louche. The distillate can slowly be married from the back to the front exploring the sensory contribution of each re-introduced fraction.
I.P.A. → I.P.C. (Imperial Pegu Club)
1.5 oz. Cascade hopped gin
.75 oz. triple-sec
.75 oz. lime juice
dash Angostura bitters
1 oz. Pacific Jade hopped gin
1 oz. sweet vermouth
1 oz. Campari
expressed oil of grapefruit peel
hopped Gin Fizz
1.5 oz. Chinook hopped gin
.75 oz. lemon juice
.75 oz. simple syrup (1:1)
top with soda water