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Balancing the Scales

Distillers need to understand the potential for variability when taking batches from small scale to large scale, and vice-versa.

Reade Huddleston Jan 28, 2025 - 10 min read

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From one liter to 1,000 gallons, distillers work on stills of all shapes and sizes, and they often need to be able to work at different scales in the same facility. It’s common practice for a distiller to perfect a product in the lab before bringing it up to full-fledged production.

However, scaling recipes for consistent flavor can be a tricky task, and there are many factors that can create variability when trying to scale distillations up or down.

Here are some key considerations to help ensure success.

Quantity and Speed

The first factor to consider is the changes in still interactions, such as reflux.

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Unless a distiller is performing a very small change, scaling a distillation will either increase or decrease the liquid level of the still considerably, and that may even necessitate using a different still. While that may seem like a minor alteration, changing the amount of liquid in a still affects how distillate vapors interact within the still, potentially creating serious changes in the flavor and final proof of the distillate.

Reflux, in terms of distillation, is the distilled vapor that condenses and returns to the pot for re-boiling. As the liquid in a still boils, some of the rising vapor collects on the sides of the still, condenses, and falls back into the boiling liquid. The amount of liquid that does this depends on the still’s unique reflux ratio, which is based on factors such as height, volume, and heat source. Stills that have high reflux ratios (more liquid condenses and returns to the pot) tend to produce very clean spirits, while stills with low reflux ratios (less liquid condenses and returns to the pot) tend to produce heavier, more flavorful spirits.

There are many ways to alter the reflux ratio of a still, but liquid level is one of the more obvious ones. When a still’s liquid level changes, the amount of surface area on which vapor can condense and fall back also changes, thus altering the reflux ratio.

For example: Consider a distiller who has a 1,500-liter still that they normally charge with 1,000 liters of wash. One day, because of a production mishap, they can fill the still with only 700 liters. That leaves an extra 300 liters’ worth of space that would not normally be exposed, providing more surface on which condensation can occur. It also increases the distance the vapor must travel upward before it can make it out of the still. That change increases the reflux of the still, causing it to produce a lighter spirit. Likewise, if the still were filled with 1,300 liters of wash, it would have 300 liters less space, less surface area, and the vapor would have less distance to travel before exiting the still. That decreases the reflux in the still, producing a heavier, more flavorful spirit.

Distillation speed is another factor that can influence how spirits scale. Knowing when to make cuts in a distillation is one of the most important skills for a distiller. Cutting too early from the heads to the hearts can cause dangerous compounds such as methanol to build in finished distillate; cutting too late between hearts and tails can cause heavy and unpleasant flavors to enter the finished product. This is why monitoring cut points is of vital importance for any distillation.

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Unfortunately, when distillers scale their distillations up or down, the speed at which the cuts can transition changes exponentially. That can make it very difficult for distillers to accurately catch a cut point because the resolution between what is hearts and what is not becomes very low.

For instance, many distillers will say they know they are out of heads once the distillate loses its aroma of nail-polish remover (acetone) and begins to taste sweet. When distilling at the nano scale, however, the amount of heads that actually smells like acetone can be very minute—as little as a few drops. That can make it very difficult for a distiller to make accurate cuts if they are relying only on smell and taste.

Conversely, if a distiller is scaling up from a lab still, they may misjudge the amount of heads that they should expect and cut prematurely. That’s why it’s important for distillers to always have a way to ensure their cuts are accurate—through volume collections, analytical testing, or some other method. That should ensure that the right amount of distillate is collected, regardless of distillation size.

Sensory Thresholds

Another factor to consider, especially when scaling up a distillation, is that the taste of cuts may also change greatly. That’s because many flavor-active compounds must reach a minimum concentration—known as a sensory threshold—before they can be detected.

When you’re distilling a very small volume, the concentration of these flavor-active compounds may be below the sensory threshold. However, as the volume of distillate increases, the amount of said compound also increases, making it detectable. That often means that the size and flavor of small-scale distillations can be radically different from larger-scale ones.

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Another example: A distiller decides that before conducting an at-scale whiskey distillation they’ll first do a nano-scale distillation, to determine the expected efficiency and flavor profile. During the nano distillation, they take 500 milliliters of wash and distill it, cutting as soon as they begin to taste the heavy notes that come toward the tails. This produces 10 milliliters of heads, 30 milliliters of tails, and 50 milliliters of a light, flowery distillate. From this, the distiller might assume that if they distilled 500 liters of wash in exactly the same way, they’d receive 50 liters of acceptable distillate and 40 liters of heads and tails. However, when the distiller attempts to perform this scaled-up distillation, they collect 45 liters of medium-bodied spirit before the distillate becomes heavy and unpalatable.

That happens because the distiller didn’t realize that there were flavor-active compounds in the distillate that, on the small-scale distillation, had not yet reached their sensory threshold. When the distiller scaled up, the concentrations of heavy and unappealing flavor-active compounds were able to reach their sensory thresholds.

That phenomenon can often be frustrating to distillers who expect to scale up their distillations in a linear fashion, but it’s unavoidable. Many distillers find they must adjust their cuts when scaling distillations; experienced distillers develop a sense for what changes happen at different scales. Nonetheless, it’s sometimes impossible to exactly mimic the flavors experienced from one size distillation to another.

Botanical Spirits

When scaling botanical spirits, such as gin or aquavit, you need to pay special attention to the botanicals you’re using. Many common botanicals, such as juniper and coriander, do not scale in a linear way; scaling up the amount for a 10-gallon batch may not give you the correct amount for a 100-gallon one.

Predicting how a botanical will scale can be difficult, and there’s no exact rhyme or reason to it. Many distillers have found, when scaling up gins, that they can achieve the same flavors with far less juniper than they did at a small scale. That’s significant because juniper oils can cause spirits to louche, or go cloudy, when proofed down; that’s considered a defect. Being able to use less juniper in large-scale batches helps to maintain the clarity and therefore salability of gin.

There are many other botanicals that don’t scale in a linear way. Highly aromatic botanicals such as cardamom and cassia can increase in flavor impact when scaled up, while roots such as orris and licorice sometimes can have less impact in large batches. Much of this is hearsay, and there hasn’t been much scientific research on this matter.

To compound the potential for confusion and frustration, simple variances between batches of botanicals can also sometimes radically affect the final flavor of a distillate, making it even harder to determine exact scaling requirements. That’s why distillers may need to make multiple batches of a scaled botanical spirit before they can copy the original flavor adequately. Distillers also should keep stocks of individually distilled botanicals, so they can adjust the final flavor of a batch to more closely match the original.

Be Ready to Adjust

Correctly scaling a distillation either up or down is no easy feat. Aside from those mentioned here, many other factors can prevent a recipe from scaling one-to-one.

Over time, distillers get to know their recipes and how they’ll scale; nevertheless, there’s always a chance that something unexpected might happen. When scaling a distillation, therefore, distillers should always be ready for a little trial and error.

Reade Huddleston is director of distillation and spirits for Monster Brewing. Huddleston received his masters in brewing and distilling science from Heriot-Watt University in Scotland and has been working professionally in brewing and distilling for the past 11 years in Britain, Canada, and the United States.

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