Distillation, which has connections to alchemy, has been around for centuries. The first stills, known as the alembic and the precursor to today’s pot still, were likely invented around 200-300 AD.
Modern distilleries come in a variety of sizes, from small craft producers with makeshift pot-bellied stills made from spare parts, to large and impressive facilities with towering silver column stills. However, the process of making spirits remains essentially the same.
The following is a simplified overview of how spirits are made. Keep in mind that traditions and regulations vary greatly depending on the type of spirit and where it is produced. It is encouraged to explore further to learn about the specific nuances of rum, whiskey, and other spirit categories.
That being said, most spirits go through the following steps.
ACE Copper Spirits Distillation Equipment
Raw materials are grown, harvested, and processed.
Whether it’s grapes, grains, agave, or something else entirely, most distillates start as agricultural products. The raw ingredients are grown and harvested, some by hand and others mechanically, and then delivered to the distillery.
From there, certain ingredients are shredded or milled (agave, sugar cane), pressed (grapes, apples), malted (barley, where it is allowed to germinate), or smoked with peat (primarily barley and other grains).
Yeast is added to jump-start fermentation.
While some raw materials already contain sugar (such as fruit, sugar cane, and agave), others, like grains, need to convert starch into fermentable sugars. This is achieved by cooking the grains in hot water with enzymes. In the production of whiskey and beer, this process is called mashing, and the resulting liquid is known as wort.
Next, the juice, wort, etc. is transferred to fermentation tanks, and yeast is introduced. Some producers use commercial yeast varieties, while others have their own proprietary yeast strains, and some rely on naturally occurring wild yeast. Fermentation typically lasts anywhere from three to five days, although some distillers may extend it to seven to nine days.
Fermentation is a crucial process for developing aromas and flavors. For example, rum-makers believe that fermentation can contribute to at least 50% of a rum’s flavor.
Distillation transforms the liquid into a spirit.
During distillation, the fermented liquid is heated to its boiling point, capturing the vapors that are released. These vapors then condense back into liquid form as they cool.
This process concentrates the alcohol levels but also requires separating desirable and undesirable elements. The first compounds to evaporate are the most volatile ones, known as “heads.” These undesirable compounds are often compared to nail polish remover. Following the heads are the desirable flavor compounds, known as the “heart.” Lastly, the “tails” are collected, which can have odors similar to rubber or vegetal notes like overcooked broccoli. The tails are separated and either discarded or redistilled. It is considered part of the distiller’s skill to determine when to make the first “cut” in order to capture as much of the heart as possible while cutting off the tails.
In many cases, spirits undergo multiple distillations. For instance, Scotch and Irish whiskeys are commonly distilled two or three times to create a lighter and smoother character. Vodka, on the other hand, is famous for undergoing numerous distillations in pursuit of creating the most neutral spirit possible.
Typically, there are two types of stills used in spirit production. Pot stills have a rounded body resembling a kettle and are usually made of copper. They tend to produce more robust and flavorful spirits. On the other hand, column stills have tall, thin chambers resembling columns and can be made of copper or stainless steel. They are known for producing a lighter style of distillate.
The distillate is matured in wooden barrels or other vessels.
After distillation, spirits like whiskey, brandy, and other “brown spirits” are transferred to oak barrels for maturation. This step imparts the familiar amber color to many spirits and adds notes of vanilla, dried fruit, or spice to the aroma and taste.
Bourbon producers are required to use new, charred American oak barrels. Other producers have more flexibility in their choice of cooperage. Some use oak sourced from different countries, while Cognac producers prefer France’s Limousin oak. Japanese whisky-makers may opt for Japan’s Mizunara oak when available. The maturation period can range from days to months or even years.
After the initial aging, some producers transfer the distillate to another barrel for additional “finishing.” These casks may have previously held other liquids such as ex-Bourbon or ex-Sherry casks, adding hints of fruit or spice to the spirits.
It is worth noting that bourbon producers believe that the barrel can contribute 60-70% of a bourbon’s flavor and 100% of its color.
Some spirits are rested in glass or clay vessels instead of wood to mellow the spirit without imparting color, flavor, or aroma. Clear spirits like vodka and gin often skip the maturation process altogether.
Blending and proofing refine the spirit.
With the exception of single-cask products, most producers blend different distillates together to achieve consistency and add flavor and complexity. Whiskey producers, for example, may blend liquid from different barrels to create a spicier or sweeter whiskey. Rum and Cognac producers also commonly blend distillates of varying ages.
While some spirits are bottled at cask strength, most are diluted to a palatable alcohol level using water in a process called proofing. Some producers are experimenting with using liquids other than plain water for proofing.
Filtration adds polish.
Before bottling, spirits are filtered to remove large and small particles and to refine the liquid. This can involve the use of simple metal screens to remove char flakes in the case of bourbon, or carbon (charcoal) filtration, which can remove color, flavor, and impurities. Vodka, in particular, is known for employing elaborate and often exotic materials for multiple filtrations, such as quartz, lava rocks, diamond dust, or coconut husks.
Additionally, many producers employ chill filtration, especially for pot-distilled whiskeys. This involves lowering the temperature of the spirit to below freezing and passing it through a series of filters. The purpose of this step is to remove chemical compounds that may cause cloudiness or haze when the spirit is chilled below 45 degrees Fahrenheit. While usually done for aesthetic reasons, an increasing number of distillers are opting out of chill filtration to preserve desired flavors and texture, labeling their spirits as “non-chill filtered.”
A few finishing touches.
At this stage, some spirits are ready to be bottled and shipped. However, for others, the base spirit is just the starting point. For example, gin is made by steeping or redistilling botanicals like juniper with a neutral spirit. Similarly, spiced rums, flavored whiskey, liqueurs, and other sweetened spirits start with a spirit that is then infused or combined with other ingredients. Regardless of the technique, the ultimate goal is to create an enjoyable drink.