Within gin production we spend a huge amount of time trying to control the variables. This ensures a balanced and consistent product for both the distiller and customer. What follows are some thoughts on achieving consistent results with juniper from a guy who went and started a PhD in the subject.

Sourcing Juniper and Botanicals

I come from a commercial production background and have a fairly hard-nosed perspective. That’s why, while the notion of foraging is undeniably romantic, I have a tendency to be a bit of a heartbreaker when someone presents me with a strange bag of dried herbal matter foraged from the wild. Unless I am able to source a reasonably sized sack of those botanicals from a reputable source, with traceability and batch paperwork, I am highly reluctant to rely on them as a gin ingredient. And, quite apart from traceability concerns, the fact that those botanicals may form part of a more complex ecosystem means you may be robbing something of its dinner!

The other issue that leads me to decline wild-foraged ingredients (carefully and sensitively, I hope) is one of consistency. Consistency is so important that it is in fact the subject of a paper submitted as part of my PhD (release date tbd). It was while preliminarily studying small-scale trial batches of juniper from various regions and different suppliers of whole juniper berry that the consistency issue within supply came into sharp focus for me.

While running a small-scale distillation trial on glass lab kits — less than 10 g of juniper per distillation — I got some unusual results that had me scratching my head. My quantitative analyses were hugely variable. So I returned to the drawing board and went back to base principles of what was going in versus what was coming out and measured out three doses of the worst offending sample.

To my astonishment there was a huge variability not just between samples but within certain samples. There were different-sized berries and different shapes and conditions of berry. Some were wrinkled and shriveled-up specimens, and some were slightly small, bordering on underdeveloped. One could adjust for this accordingly within the recipe, but for direct comparison, this is a major issue.

Juniper Quality Control

Within the U.K. distilling industry, around November comes the “Big Sniff.” This is when the new juniper harvest is in, and distillers need to make decisions around which region’s harvest they will be committing to for the next year of production. (In some larger concerns, it is two years’ of production, much to the accountants’ dismay.)

This sounds like no big deal if said quickly, but don’t forget: If you are making a London dry gin, juniper should be your star botanical to which all other botanicals play a supporting role. If you suddenly change the source, it can have dire consequences for the mechanics of your recipe, not to mention your marketers and customers in the form of product creep.

The brewing and distilling process relies a huge amount on sensory analysis, both informal and formal. Here are the key methods for effective sensory evaluation of juniper:

  1. Visual Inspection
    The first stage of inspection should always be to look over the berries and evaluate the initial quality and consistency of the berries by eye. They should be a uniform size and shape, with no sign of shriveling.
  2. Give Them a Squeeze
    If there is no give in the berry and they are hard and brittle with no resinous qualities, they are too dry and will not have enough aroma left to give to your gin.
  3. Conduct a Small-Scale Distillation Trial
    Next, distillers should replicate their recipes at small scale, no smaller than 800 ml distillation charge volume, with standardized cut points scaled accordingly. You may be tempted to distill just the juniper and smell the sample in isolation, but remember: Your goal is to evaluate the impact of the juniper within the matrix and framework of other flavors in the gin. You can then carry out what is known as a triangle test.
  4. Conduct a Triangle Test
    To conduct a triangle test, take your benchmark spirit and your testing spirit and pour three samples: two the same and one different. Participants should evaluate each sample and try to identify which one is different. Ideally, you should change the order in which the glasses are presented and even the sample that is the odd one out.

If your panel identifies the difference more times than what could be explained by chance (the null hypothesis, in this case 1 in 3), then you have a problem. This is important, as spotting this at the small-scale sample selection stage is much preferred to halfway through the year’s production via consumer review or the dreaded negative social media post.

Botanical Storage

Storage can be another botanical quality issue. Botanicals should be stored within an inert, rodent-proof container with a snug-fitting lid that is replaced after use. If you can smell the botanicals as you walk in the door, the lid does not fit tightly enough. Proper storage will help you to retain the volatile molecules that you have paid dearly for and need to keep for your signature gin expression. Ideally, all botanicals need to be kept cool, dark, and odor-free to avoid pickup of other flavors.

If using dried botanicals, it should be okay to keep them wrapped tight in the original packing with the bag closed in a temperature-stable environment. That’s easier said in a lab in bonny Scotland than within a working distillery, I understand, but there are always lessons to be learned from laboratory best practices that can be used within production.

Fresh botanicals can be tricky due to moisture-content issues affecting consistency, especially if frozen, which itself can add variability to quality. That said, if you must have fresh botanicals, frozen is the best storage option if they cannot be used immediately. Berries should be frozen vacuum-packed as soon as possible in a dedicated freezer for botanicals to avoid flavor transfer.

Treat Your Juniper Well

Juniper is the leading lady of your gin — and it deserves to be treated that way. There are several pitfalls to sourcing, quality control, and storage that can cost you money and damage your brand if you don’t take them seriously. But thoughtful, careful management and analysis will help your gin please consumers time and time again.

Variables Within Sensory Analysis

An effective triangle test — or any other sensory analysis — should include the following components:
  • Dilution proof of 20% ABV is ideal for samples.
  • All samples should be at room temperature.
  • The samples should all be stood for the same amount of time, not left out over a long period.
  • Cover your sample glasses with watch glasses to retain those all-important volatile compounds.
  • Minimize or eliminate external smells from people, the space, or the location.
  • Coach your panelists to keep their thoughts and reactions to themselves during the test. You don’t want comments and vocalizations to influence others.
  • Make it clear there are no wrong answers, because the point of the test is to provide useful information, not to stroke someone’s ego or please the boss.
  • The more sensory panelists, the better, as a larger sample set adds power and strength to the results due to the diversity of panelists and their own sensitivities and blind spots.