The Art (and Science) of Producing Liqueurs

In this first of a two-part series, Devon Trevathan lays out the basics of what it takes to make a successful liqueur—from choosing a spirit base to flavoring and filtration. The most important ingredient, however, may be trial and error.

Devon Trevathan Nov 15, 2023 - 11 min read

The Art (and Science) of Producing Liqueurs Primary Image

Photo: Matt Graves/

As long as there have been spirits to drink, there have been people adding more flavor to those spirits and dosing the concoction with sugar to make it more palatable.

Traditional liqueurs exist all over the world—bitter red Italian liqueurs, Scotch whisky liqueurs, German licorice-infused liqueurs, limoncello, sambuca, triple sec, sloe gin, and more. Many of these styles have their own unique histories that span centuries. Going back even to ancient times, there is some evidence of crude distillation for purposes that likely included perfumes and medicinal tinctures based on various botanicals. Over time and through study, people found that alcohol was a better solvent than water—alcohol could extract more flavor and was a better preservative.

To understand the wide world of liqueurs, it helps to first understand how they’re made. As flavored spirit-based drinks, most liqueurs fall between 15 and 30 percent ABV and have a sugar content of at least 10 percent. While almost all commercial examples are within those specs, many stylistic, economic, and regional choices lead to a wide landscape of distinct products.

The first step, in any case, is to choose the spirit base.

The Base

Modern liqueurs typically work from a neutral base—a spirit that has been distilled to such a degree that it no longer retains character from the source of sugar or starch from which it was distilled.

This has several benefits, the most obvious being that producers have a blank canvas on which to build their liqueur’s flavor—there is no need to contend with any pre-existing flavor in the spirit. Because producers typically buy their base from a facility that specializes in neutral spirits, they know that one element of their production will always remain consistent. The caveat, however, is that it’s then up to the producer to build a cohesive, structured profile from scratch, paying mind not only to the flavors themselves but also to the scaffolding to support them.

An added benefit is that producers don’t have to buy a still or start distilling to start a line of liqueurs. With relatively little space and limited equipment, and without any knowledge of distillation, a producer can make a line of liqueurs, creating unique products simply through the ingredients they add to a finished spirit. Many distilleries that actively produce their own spirits such as whiskey or rum in house still purchase neutral grain spirit (NGS) to use as the base for their liqueurs.

Flavor Additions

To that base, a liqueur producer adds flavor, often by steeping fruits, botanicals, spices, herbs, barks, bitters, or some combination of those—basically, anything with flavor that they would want to imbue. These flavors may be regional, historical, cultural, medicinal, or unconstrained. They may be local and seasonal or exotic, hailing from anywhere in the world. The methods used to get the flavor from the ingredients varies among producers, and they may deploy more than one method on the same product. Common methods include extraction, infusion, distillation, and less commonly, smoking.

In the pharmaceutical use of the term, extraction refers to using solvents to separate out the medicinally useful substances from plant tissue. We can apply the same logic to extracting plant material for aromatic and gustatory use. The goal is to capture the desired aromatic and flavor portions of a plant or botanical and discard the unwanted material. Following preparation, you’re left with a concentrated extract that contains the various terpenoids, flavonoids, lignans, and anything else that provides the distinct flavor of the botanical from which it was extracted.

General techniques of extraction include infusion, maceration, percolation, decoction, hot continuous extraction, counter-current extraction, sonication, hydrodistillation (or steam distillation), and hydrolytic maceration followed by distillation, expression, and enfleurage. Most of these techniques are not known or used by producers making liqueurs; some are just more formal names for processes that are familiar—sonication, for example, is the use of sound energy to agitate particles in a liquid. Famously, Copper & Kings distillery in Louisville, Kentucky, uses five subwoofers to blast bass music in their barrel warehouse, a process they refer to as sonic aging.

While extraction and infusion are sometimes used interchangeably, they do not denote strictly the same process. Infusion can be used as part of extraction, with the result being a concentrated extract, and infusion can also be its own process. There is further confusion within the industry between the terms “maceration” and “infusion” because both techniques involve submerging ingredients in a solvent, such as alcohol. According to Difford’s Guide, the difference is that, in the act of infusion, herbs, spices, nuts, fruits, or other ingredients are immersed in alcohol whole and left to soak. Maceration also involves immersing ingredients, but they have first been broken down by slicing, crushing, or dicing to achieve a greater exposed surface area and thus more extractable elements.

Most liqueur producers use both infusion and maceration, meaning they typically soak botanicals, fruits, spices, and the like, both whole and broken down, in an alcohol base. They may use different atmospheric elements to expedite or intensify the rate of extraction, such as the application of sonic energy mentioned above. Some producers macerate materials in their base over heat, similar to using hot water to brew tea. Employing heat comes with risks, though: Too much heat can cause a Maillard reaction, which can darken and change the flavor of the distillate in undesirable ways. Most liqueurs are made by infusing or macerating ingredients into a finished distillate and filtering it afterward instead of running it back through a still; the many colors of liqueurs can only be achieved without a final redistillation.

Certain distillers, however, might use a still to infuse some of their desired flavors into their liqueur, either by macerating them in a liquid base and redistilling it or by vapor infusion. Vapor infusion involves packing a vapor basket that’s connected to the top of the pot still full of fresh and dried ingredients. As the spirit rises out of the pot in a vapor, and before condensing back down to a liquid, it enters the vapor basket, moving through all the ingredients and picking up their flavor, with little to no risk of browning. This process, also used in gin distillation, leaves the distiller with a stable spirit with the flavors that they were hoping to cultivate.


Once producers have created the desired character from the post-distillation ingredients, they can then introduce sugar into the mixture. A variety of sugar sources are typically used: granulated sugar, sugar syrup, turbinado sugar, honey, agave. Different sources have differing levels of sweetness and water content; as with so many other elements of liqueur production, producers need to go through a period of trial and error until they find the right proportion. Most of the best-known bitter red aperitivi have sugar contents greater than 20 percent, with the iconic Campari on the higher end at 24 percent sugar.


The final and crucial step to producing a liqueur is filtration. Because a producer has steeped a variety of organic materials in alcohol, likely at a higher proof than the final bottling strength, there has been a breakdown of those materials. You will inevitably have a haze in the mixture, made up of fruit pectin, bark particulate, or other small flocculants. So, filtration is important, especially because so many of the best-known brands, such as Campari, Aperol, and Chartreuse, are crystal-clear in the bottle. Filtration is an asset to product stability, but also to aesthetics—there is also a demonstrated visual element to sales, and that is particularly apparent for liqueurs.

Filtration can be tricky when it comes to liqueurs because the ingredients used to make them can run a wide gamut, and because there are differences in weight and texture among the three primary elements of the solution: flavor ingredients, alcohol, and sugar. Basically, producers can expect more than a little trial and error before they find the exactly right technique. “It comes down to really what the situation is,” says Justin Juengel, key account manager at Gusmer Enterprises, a company that specializes in liquid filtration products, fermentation technology, and beverage processing aids. “It depends on, one, how much volume you’re doing at one time. You can actually get a little bit better filtration with cartridge filtration if you’re doing small volumes, but if you’re doing a large volume, a plate-and-frame or a lenticular are usually your best options.”

Another variable to consider is whether filtering the final product altogether is the best approach. “With liqueurs, depending on what the flavor of it is, sometimes we’ll actually look at filtering the flavor and the spirit separately and then blending them, and sometimes it makes sense to do them post-blending,” Juengel says. If producers are going to filter post-blending, they must be absolutely sure that all elements have fully integrated, including all the sugar. If not, the filtration matrix may capture larger molecules, throwing off the flavor, texture, and alcohol content of the finished product.

In part of this series, we’ll look at the cultural history and current climate of liqueurs, including the ways they are consumed and the unexpected rise of liqueurs in the United States over the past decade. So, prepare an aperitivo and prime yourself for what’s to come.

Devon Trevathan is a freelance trade writer as well as the cofounder and co-owner of Liba Spirits, a nomadic distilling company. She has held a variety of positions related to beverage alcohol: bartender, server, writer, brand ambassador, marketing consultant, tour guide, wine manager. Follow her on Instagram @devlovesbev for updates on the journey of owning a distilling company but mostly pictures of her dog Gilberto.