How Gin Works

By: Dave Roos  | 

Gin, mint, juniper berries
A bottle of gin, mint leaves and juniper berries are pictured on a table of a schnapps distillery in Schallstadt, Germany. Gin is traditionally made with juniper berries. Patrick Seeger/picture alliance via Getty Images

A gin and tonic is one of the world's classic cocktails, but did you know that it was originally created for its anti-malarial properties? And that's not the only gin cocktail with a "health-related" origin story. But before that, gin was once considered so addictive and morally repugnant that some historians compare England's 18th-century "gin craze" to the crack epidemic.

If we have your attention, it's time to learn everything about this ancient juniper-infused spirit that's recently undergone a popular transformation from your grandfather's booze to a trendy, artisinal craft alcohol.

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What Is Gin?

Unlike some other spirits, the definition of gin is pretty loose. Traditionally, gin is defined as any distilled spirit that has juniper as the "predominant" flavor. Juniper is an evergreen shrub found around the world and its berries or "cones" are what give gin its distinctly piney, peppery, citrusy, herbaceous kick.

But even that basic definition of gin is now being challenged. Hundreds of artisanal gin distilleries are producing excellent gins that play down the classic (and somewhat divisive) juniper flavor and play up new flavors like rose, cucumber, peach, lavender and dozens of other locally sourced "botanicals."

To make gin, you start with a distilled base spirit (ethyl alcohol that's 96 percent alcohol by volume [ABV]) and then re-distill the base spirit in the presence of botanicals. More on botanicals in a second.

Gin is somewhat unique in that its base spirit can be distilled from any source material. This is different from Scotch, for example, which must be distilled from malted barley, or rum, which is always distilled from sugar cane. While gin is traditionally made with grain-based spirits (barley, wheat, rye, corn, etc.) it can also be made with base spirits distilled from grapes, potatoes, apples, molasses, honey, even milk!

No matter the source material, once a spirit has been distilled to 96 percent ABV, it's lost almost all color and flavor and is considered a "neutral" spirit. What makes a gin a gin is the second step, re-distilling the base spirit in the presence of botanicals, most notably juniper.

Botanicals are any herb, fruit, seed, spice, leaf, peel or root that is used to impart flavor to the gin. Bombay Sapphire gin, for example, is made with 10 different botanicals.

These botanicals can be incorporated into the distilling process in two ways. The first method is to simply add the botanicals directly to the base spirit in the still. This is called steeping and is similar to making a pot of tea. As the base spirit heats up and simmers, oils are released from the botanicals that transmit their flavors into the final product.

The second way is to suspend the botanicals is called vapor infusion. In this method, used by producers like Bombay Sapphire, the botanicals are placed in a basket above the boiling base spirit in the still. As vapor rises, it passes through the collection of botanicals, picking up subtle notes of citrus and spice.

Some distilleries even mix the two methods to produce a distinctive balance of flavors, seeping some botanicals directly in the base spirit and suspending others above.

A third and less-common method is to use a vacuum still. By distilling the base spirit in a vacuum, it lowers the boiling point of the liquid, which allows the botanicals to steep at a lower temperature. Some distillers argue that this gives the final product a fresher flavor.

Types of Gin

If you visit your local liquor store, you'll find lots of different bottles labeled as gin. But because gin isn't tightly regulated, you may have to read the fine print to know what you're getting.

In both the European Union and the United States, a bottle of liquor can be called "gin" if it's made from distilled neutral spirits that are flavored with either natural botanicals, extracts or artificial flavors, and bottled at no less than 80 proof. So, to qualify simply as "gin," the product doesn't technically need to be distilled in the presence of botanicals. Lower-grade gin of this sort is sometimes dismissed by gin purists as "flavored vodka."

The next grade of gin is labeled "distilled gin" because the gin gets its flavors from actually distilling the base spirit in the presence of botanicals (by steeping or vapor infusion), not just by mixing in flavors.

Under the broad category of distilled gin are several distinct types and styles of gin. The best-known is "London dry gin" or simply "London gin." This is the classic British-style gin popularized by brands like Beefeater, Gordon's and Tanqueray. The flavor profile of a London gin is dry (no sugar) and juniper-centric.

Next is Old Tom gin. This is a distilled gin that's much sweeter and more botanically intense than London gin. As we'll see in the history of gin, Old Tom predates London gin and comes from a time when distillers were using sugar and strong botanicals to cover up the flavor of low-quality base spirits.

You might see some gins labeled as Navy strength. This isn't an official designation as much as a colorful nod to gin's history. Back in the 19th century, sailors wanted to test if their gin rations had been watered down, so they would drizzle some gin over a pinch of gunpowder and take a match to it. If the gunpowder lit, then the gin was said to be "Navy strength." Today, Navy strength means a gin that's at least 57.1 percent ABV. Under the EU rules, the alcohol content of gin can be as low as 37.5 percent ABV.

There are also aged gins. These are distilled gins that are aged anywhere from a few weeks to five or 10 years. Aged gin is a relatively new category and distillers are experimenting with the flavor profiles of aging gin in casks that previously held other spirits like vermouth.

You might also see bottles labeled as "Genever Gin," "Geneva" or "Hollands Gin." This style of gin isn't really gin at all, but a precursor of gin that's distilled from a whiskey-like "malt wine" instead of a neutral spirit. Genever is often darker in color and more malty in flavor than gin, but they both share a top note of juniper berries.

To understand the juniper connection and the roots of both genever and gin, let's dive into the fascinating history of gin.

Gin's Beginnings: From Juniper to Genever

gin distiller
Frank Kuechlin distills gin in Schallstadt, Germany. Patrick Seeger/picture alliance via Getty Images

The history of gin starts with the traditional use of juniper as a medicinal herb. Juniper bushes are stubby evergreens related to the cypress. They grow almost anywhere and can be found across North America, Europe, Northern Asia and Japan. The fruit of the juniper bush is the juniper berry or juniper "cone." When ripe, they look like small blueberries, purplish blue in color and nearly spherical.

In antiquity, juniper berries were a popular herbal remedy. The Ancient Egyptians wrote about juniper as a treatment for headaches and tapeworms. The Roman philosopher and naturalist Pliny the Elder published what might be the very first recipe for a gin-like cure-all in 77 C.E. that was used to treat stomach pains, convulsions, uterine cramps and more. The recipe was simple — boil some white wine with a handful of juniper berries, and enjoy!

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The first stills arrived in Italy in the 11th century brought by Muslim traders. (The distillation process was pioneered during the Islamic Golden Age and used by alchemists to isolate the pure "spirits" of various substances. The word "alcohol" has its roots in Arabic.)

Italian monks began experimenting with distillation to create various "aqua vitae" or "waters of life." They made these elixirs by distilling wine with local medical herbs and plants like rosemary, heather, laurel and of course juniper.

Sahti, one of the oldest styles of beer in the world, is the traditional alcoholic beverage of Finland and is flavored with both hops and juniper berries and branches. It dates from the 14th century.

But if you're looking for an old-school beverage that really set the stage for modern gin, that would be genever (pronounced like "believer").

Genever is a traditional distilled spirit from Holland (it's the Dutch word for "juniper"). In the 13th and 14th centuries, Dutch apothecaries were experimenting with medicinal tonics made from distilled spirits flavored with curative herbs, juniper among them. But what distinguishes genever from other proto-gins is that the Dutch didn't drink genever to cure stomach aches; they drank genever to get drunk.

Genever was one of the first popular recreational spirits made with juniper, which is why it's seen as the most direct precursor of gin.

Traditional genever is brewed like whiskey. The base spirit is made by taking local grains like malted barley, wheat and rye, grinding it in one of those famous Dutch windmills, mixing it with water and letting it ferment into a kind of beer. That beer is then distilled into a higher-alcohol "malt wine" that retains some of the mailty grainy flavor and color of the source material.

The final step to making genever is to re-distill the malt wine with the addition of juniper and sometimes other "botanicals" in the still. The result is a lot like an unaged whiskey with a juniper kick. Since genever was often brewed from low-quality, cast-off grains, the base spirit sometimes had a funky taste, which distillers tried to cover up with more botanicals and lots of sugar.

Genever is the original "Dutch courage." In 1585, Queen Elizabeth I sent British troops to help the Dutch fight for Independence, where they knocked back shots of genever in preparation for battle. English mercenaries also enjoyed a dram of "Dutch courage" when they fought alongside the Dutch in the 30 Years War.

Coming home to England in the late 17th century, British soldiers brought back a thirst for Dutch genever, which they called genever, geneva, Hollands and for the first time, gin. In 1674, the end of the Anglo-Dutch War opened made it legal to import genever by the barrel full. The first "strong water shops" opened in London and the very first British gin distillery opened for business in Plymouth in a former monastery and debtor's prison.

The Gin Craze

Gin Lane
"Gin Lane," by the artist William Hogarth, depicts the evils of the Gin Craze and was done in support of the passage of the Gin Act. Wikimedia Commons

In 1688, William of Orange, a Protestant king from the Netherlands, assumed the throne of Great Britain in the Glorious Revolution. William and the rest of the British aristocracy at the time were drinking imported genever. But the masses couldn't afford fancy imported spirits, so they started making their own cheaper version of genever, what could only be called rotgut gin.

In 1716, London was the largest city in Europe with 500,000 people and 8,000 more arriving every year. Poverty and squalor ran rampant, and the street drug of choice was cheap moonshine adulterated with industrial chemicals and sold as gin. By 1743, at the peak of the Gin Craze, the English were consuming 8 million gallons of spirits every year, almost exclusively gin. That was a gallon for every man, woman and child in the country.

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Even though juniper can be grown and harvested all over Europe, it's still labor-intensive to pick and dry and distill into proper genever or gin. So, London's moonshiners got creative. They started with a low-quality grain alcohol and spiked it with oil of turpentine for that piney kick, oil of almonds to replace cardamom, and "oil of vitriol" — sulphuric acid! — for some nice heat.

Sugar from the West Indies was also cheap, so they'd cover the foul taste of the rotgut gin with lots of sweet sugar.

How bad was the 18th-century gin craze? If you read contemporary accounts, gin was worse than the crack and opioid epidemics combined. The slums of London were piled with comatose gin addicts who robbed and murdered to get their next fix. Drunken mothers were passing out and dropping their infants into the fireplace. Parents would sell children into slavery for enough money to buy another bottle.

Social commentators blamed gin for corrupting the working class, lowering the moral character of the nation's artisans, sailors and soldiers, and crippling the economy. But modern historians question the accuracy of these published tirades, often written by a British upper-class that was obsessed with the degradation of the English character. The truth was that London and other British port cities were experiencing unprecedented levels of urbanization, and the gin craze was a product of urban poverty, not the cause of it.

Parliament passed 8 different "Gin Acts" between 1729 and 1751 to try to rein in the production and sale of rotgut gin. Chemical additives were eventually outlawed and distilleries were required to register with the government.

The Continuous Still and London Dry Gin

The next big evolution in gin came in 1830 with the invention of the continuous sill. Before this innovation, all distillation was done in traditional pot stills. Pot stills are simply large copper pots in which the mash is boiled, and then the alcohol, which boils off first, is condensed and collected as a distilled spirit.

The disadvantage of a pot still is that you can only get one distillation from each pot of mash, which results in a relatively low-ABV spirit (around 50 percent ABV) that could still contain a lot of impurities and "off" flavors. And to make more booze, you have to empty and replenish the still.

A continuous still overcomes both of those problems. As the name implies, the still operates continuously, replenishing the mash as needed. The continuous process allows the still to distill purer and purer alcohol over time, resulting in clear, flavorless grain alcohol with ABVs around 96 percent.

With the continuous still, gin could now be distilled from a much cleaner and purer spirit. That meant that it didn't require as many additives to cover up the nasty flavor, although sugar was still a popular addition. The sweeter gins of the early 19th century are the origins of what's known as Old Tom gin, varieties of which are still sold today.

But at the same time, a lot of upper-class Victorians went on a health kick and decided to shun sugar. Over time, this evolved into a distinctively dry version of gin that became known as London dry gin characterized by its clean, juniper-forward flavor.

In the early 19th century, new laws in England regulated the minimum still size of gin distilleries, which put a lot of the smaller distillers out of business. This paved the way for the rise of the first big national gin brands like Gordon's, Beefeater and Tanqueray, all specializing in London dry gin.

Gin & Tonics, Prohibition and All That Jazz

police, gin labels, confiscated
Police display gin labels and presses they confiscated in 1921 during Prohibition. Bettmann/Getty Images

The characteristic flavor of London dry gin is the product of 19th century imperial expansion. Juniper strikes the strongest note, but the taste of a classic London dry gin is created by a blend of a dozen or more botanicals sourced from exotic ports as far away as Africa, China and South America.

In 1868, a typical London dry gin recipe might include: juniper, sweet fennel, orange peel, orange flower water, coriander seed, angelica root, calamus root, cassia buds, lemon peel, cardamom, oil of cedar, sweet almonds, nutmeg, mace, caraway seed, wintergreen and honey.

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But one of the most fascinating byproducts of 19th century British imperialism is how the rigors of international sea travel and the health challenges of tropical colonial living led to the invention of classic gin cocktails like the gin and tonic, the pink gin and the gimlet.

First, the gin and tonic. Malaria was a plague on sailors and British colonists living in tropical climates. For centuries, natives of South America chewed on the bark of the chinchona tree to combat the symptoms of malaria. The bark contains a natural chemical called quinine that not only calms the muscle aches and spasms caused by malaria, but disrupts the malaria parasite's metabolism, eventually killing it.

When European doctors got wind of this, they began prescribing prophylactic chinchona bark to British soldiers and colonists in India. In the 1840s, British soldiers and settlers were consuming 700 tons (635 metric tons) of chinchona bark a year.

A water-soluble form of quinine was invented in the 1850s, which lead to the bottling of the first "Indian quinine tonics," the earliest tonic waters. Schweppes was one of the first big bottlers of carbonated tonic water.

Meanwhile, the British Navy was sailing to every port in the world and bringing bottles of London dry gin with them. It was only a matter of time before officers and colonists began combining their favorite tipple with a shot of tonic water for their health. And the gin and tonic was born!

The same with bitters. Bitters were first prescribed up as a curative tonic for gout in the 18th century. But by the 19th century, bitters were being sold as a cure-all for a host of travel-related ailments related to long sea journeys and life in tropical climates. The basic recipe for bitters is bitter orange peel, oil of carraway, cardamom, oil of wormwood and plenty of sugar.

A German named Johann Siegert moved to Venezuela in the 1820s to serve as the surgeon general in a revolutionary army. He settled in the town of Angostura and began producing his own brand of bitters for treating his soldiers for seasickness and digestive ailments. In the 1830s, he started bottling and selling his now-famous angostura bitters.

Soon British sailors worldwide were downing "medicinal" cocktails of London dry gin and a shot of Angostura Bitters, or what's known as a pink gin.

And then there's scurvy, the deadliest scourge for long-haul sailors. Over the 18th century, it's estimated that scurvy killed more British soldiers than the French. Scurvy is caused by a vitamin C deficiency that brings on a host of nasty symptoms: lethargy, bleeding gums, teeth fall out, old wounds reopen, loss of sensation in the limbs. It killed sailors in droves.

Scurvy can be easily cured with citrus fruit, but fresh citrus doesn't last long aboard a ship. Sailors tried to boil and condense lime juice, but the process cooked out the vitamin C. Eventually, a Scottish scientists named Lachlan Rose figured out a way to preserve lime juice by mixing it with a small quantity of sulphur dioxide. Rose's Lime Juice became a shipboard staple, and it wasn't long before it was being mixed with gin to make a classic gimlet.

(There are competing stories about the naming of the gimlet. Other sources say it might be named after Sir Thomas Gimlette, surgeon general to the British Navy, or the screwdriver-like hand tool used to open barrels of lime juice.)

Prohibition and "Bathtub Gin"

While the British colonists were enjoying their first mixed drinks, Americans were brewing up a cocktail culture of their own. By the Civil War (1860s), American-style cocktails were characterized by various combinations of liquor, bitters and sugar water and went by names like "gin-sling, sangaree, mint julep, sherry-cobbler and timber doodle."

The classic gin martini showed up in the 1870s and 1880s. From Richard Barnett, author of "The Book of Gin: A Spirited World History from Alchemists' Stills and Colonial Outposts to Gin Palaces, Bathtub Gin, and Artisanal Cocktails": The martini is "an embodiment of American history at its most diverse: Dutch and English gin, mixed with French vermouth, and served with Mediterranean olives, German-Jewish pickled onions or Caribbean lemons." The distinctive conical martini glass was popularized in the first decade of the 20th century.

But the real American cocktail boom was spurred by the passing of Prohibition in 1920. With a ban on the production and sale of alcohol, the booze industry went underground, and gin is one of the easiest spirits to make on the cheap.

The 1920s were like the Gin Craze all over again. Bootleggers would do anything to get their hands on grain alcohol. That included backdoor deals with industrial alcohol manufacturers and buying up moonshine from backwoods stills. Once you have the grain alcohol, it's a quick step to making gin. You could simply add water and juniper oil, but some folks were going back to the Gin Craze days of spiking grain alcohol with turpentine oil and sulphuric acid.

For Prohibition partiers, gone was the clean, piny finish of a London dry gin. Instead, they got "bathtub gin," a colorful nickname that alluded to its homemade origins and dirty aftertaste. But no worries, because even the foulest tasting bathtub gin could be covered up by a combination of strong bitters, citrus and simple syrup.

The martini, the Manhattan, the gin fizz, the gimlet: Jazz-Age Americans were crazy over cocktails, and after Prohibition ended in the 1930s, cocktail parties became the fashionable way to entertain.

Gin Fizzles Out But Makes a Comeback

La Gintoneria di Davide
La Gintoneria di Davide bar in Milan, Italy, specializes in gin and cocktails, as evidenced by their large display of gin varieties. Eddy Buttarelli/REDA&CO/Universal Images Group via Getty Images

Starting in the 1960s, gin lost some of its glamour. The counterculture movement dismissed classic gin cocktails as their grandfather's booze. And upwardly mobile "Mad Men" types embraced the James Bond cool of the vodka martini.

Chances are if you grew up in the 1970s and 1980s and had your first legal drink in the 1990s, it probably wasn't a gin and tonic. The traditional juniper-forward London dry gins from Beefeater and Gordon's were pretty much the only game in town for decades, and not everybody like the piney flavor of juniper. Some people disparagingly describe it as "drinking a Christmas tree."

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But gin has made a comeback. If you could put a start date on it, it was probably 1998 when Bombay Sapphire first came out in the U.S. Although sold as a London dry gin, Bombay Sapphire is not as juniper-centric, and the eye-catching sapphire-blue bottle lists 10 other botanicals (and their lands of origin) that gave it its trademark complexity: licorice (China), juniper berries (Italy), cubeb berries (Java), angelica root (Saxony), almonds (Spain), coriander (Morocco), cassia bark (Indo-China), Iris root/orris root (Italy), lemon peel (Spain), grains of paradise (West Africa).

Bombay Sapphire made a big splash in the cocktail world and opened up the market for new twists on gin. The next big release was Hendrick's Gin in 2003. For the first time, a gin-maker dared to dethrone juniper from its top position in the flavor mix. Yes, there's juniper among Hendricks' 11 botanicals, but the first things you taste in a Hendrick's gin are rose and cucumber. That was an absolute shock to the drinking establishment and flung the doors wide open for gin innovation.

Since 2010, there's been a bona fide gin renaissance. Hundreds of new gin labels have sprung up to serve a growing thirst for all things hand-crafted and artisanal. Distillers around the world are sourcing wild local herbs, fruits and spices to create their own unique botanical blends with their own "terroir," to borrow a term from winemaking.

South African gin-makers include flavors like wild geranium. Australian distillers get citrus notes with lemon myrtle. New Zealand gins include indigenous manuka berries and kawakawa leaves.

The base spirit used to make gin is even up for grabs. No longer is gin made purely from grain alcohol. There are artisanal gins made from sugar cane, grape, potato, honey, molasses, apple, pure juniper and even sheep's milk! Producers argue that subtle flavor notes from the base spirit carry through to the final product. It's also an excellent marketing ploy.

Interestingly, while the gin renaissance has absolutely been fueled by a strong consumer preference (especially among millennials) for local, small-batch food and drink with a cool backstory, smaller distillers were originally attracted to gin for more practical reasons.

Aaron Knoll, founder of the website The Gin is In and author of "Gin: The Art and Craft of the Artisan Revival," explains that if you want to open a whiskey distillery, it will take years to start earning revenue, because whiskey has to age. Vodka doesn't have to age, but the vodka market is hard to break into and is dominated by big brands. That's not the case with gin, though.

Distillers figured that they could quickly get their name out there by bottling a distinctive gin with a unique botanical profile. Gin could help "keep the lights on" while the distiller produced aged spirits like whiskey that take more time to earn a profit. Knoll says that distillers mostly drove the gin renaissance in its early days from 2010 to 2014.

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Originally Published: Jun 19, 2020

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  • Barnett, Richard. "The Book of Gin: A Spirited World History from Alchemists' Stills and Colonial Outposts to Gin Palaces, Bathtub Gin, and Artisanal Cocktails." Grove Press. 2012
  • Knoll, Aaron, author of "Gin: The Art and Craft of the Artisan Revival" and founder of the website The Gin is In, where he has reviewed more than 750 bottles of gin. Personal interview