A man with a Tyra Banks-approved smize dispenses a few drops from a pipette into the bottom of a martini glass so frosted that it’s almost opaque. With an enviable level of hand-eye coordination, he slowly swirls this dewy liquid around its glacial depths with one hand while stirring a healthy pour of gin and vermouth around ice cubes in a cut-crystal mixing glass with the other. Then, in a move of peak showmanship (and perhaps enhanced for the many iPhones shoved his way), he pours the alcoholic liquid into the glass from a great height, finishing it off with a slender strip of lemon peel.

The result is a martini of almost dizzying levels of perfection; crisp, soft, ice-cold and, courtesy of the mysterious drops, bright with hints of citrus and a delicate earthiness. That pipette contained Dr Ago’s bitters, a creation of bergamot and ginseng designed by the bar’s director of mixology, Agostino Perrone. It is one of five on offer – the others are tonka, lavender, coriander and cardamom – designed with the sole purpose of elevating the flavour offered in any given cocktail in subtle gradations. Think of it like adding salt to a dish – it doesn’t so much bring any new notes as elevate those that are already there.

“You know when James Bond goes to M to ask for the secret weapon in the pen or in the watch? That’s sort of the case with bitters,” Giorgio Bargiani, assistant director of mixology at The Connaught Bar tells me. “They strike the balance, they elevate the final result of the cocktail. It’s the diamond on top of your ring, it’s the tiny element that makes a difference.”

The word ‘cocktail’ was first coined in print in 1806 in The Balance and Columbian Repository when, in response to a reader enquiring about the word, the editor defined a cocktail as “a stimulating liquor, composed of spirits of any kind, sugar, water and bitters.”

“For a while, if you ordered a cocktail, that combination of ingredients, and only that, is what you would get,” Amanda Schuster, author of Signature Cocktails, tells me of that early definition. “It wasn’t until some time later that the word ‘cocktail’ came to define any sort of mixed drink,
with or without bitters.”

In her book, recently published by Phaidon, Schuster has taken on the herculean task of curating a selection of the 200 most iconic cocktails from around the world. The drinks span over five centuries, with the earliest entry – the Atholl Brose, created in 1475 – significantly predating the first definition of a cocktail in print. It is a fairly exhaustive reference point for both the way cocktails have changed across hundreds of years, but also the ingredients that have remained true throughout the mixology process, even as it has been modernised and adapted. Perhaps unsurprisingly, no ingredient features more prominently than bitters.

“I would say a good ¾ of the book has recipes with bitters of some sort, either with one of the bitter spirits (liqueur, amaro, etc), or with drops of flavoured bitters,” Schuster tells me. “It should be considered that ‘bitter’ doesn’t necessarily mean a drink is going to be harsh or astringent. Bitters are meant to enhance the overall flavour profile of a drink. They are added for balance.” She references the experience guests have at The Connaught when selecting their preferred bitters for their martini, and explains, “we don’t think of the martini as a bitter drink, but this signature is exactly what a good martini should be – relaxing and elegant.”

While bitters are finally getting their place in the sun – and recognition for the enormous impact they have had on cocktail history – the origin of this simple, flavour-packed ingredient wasn’t actually as part of the mixology process at all. “Originally bitters were medicinal,” cocktail historian Ted Haigh tells the team at The Bitter Truth in a series of videos around the brand. “They were used to fix what ails ‘ya,” he adds. It was these origins that led to the development of two of the most popular bitters, the fundamentals if you will: Angostura and Peychaud’s. While the former might be more of a recognisable household name, both of these brands have been going from strength to strength since the 1820s and 1830s respectively.

The Manhattan was invented in the late 1800s and specifically called for Angostura Bitters

Before the days of modern medicine, herbs that were used to treat various illnesses were preserved in alcohol in order to both prevent them from rotting, but also because often these plants were too bitter to ingest directly, so they would infuse their healing properties into the liquor in order to make it palatable to consume. Perhaps the most popular of these is Angostura, first created in 1824 by Dr Johann Siegert who was living in the Venezuelan town of Angostura and formulated the bitters in his role as Surgeon General of the armies of Simón Bolívar. His timing was impeccable; by 1850 Angostura bitters were being exported across the world, a business move that conveniently coincided with the first cocktail recipe that included bitters in its ingredients list being formally printed for the public. Angostura quickly took off around the world, becoming the bitters of choice for bartenders who were innovating within the cocktail industry and creating drinks that would go down in history as classics, such as the Manhattan, which was invented in the late 1800s and specifically called for ‘three or four drops of Angostura bitters’ in the recipe.

Multiple law changes over the years, including the 1906 Pure Food & Drug Act in the US and the beginning of Prohibition in the 1920s, meant that the bitters industry took a rapid hit. The knock-on effects of these were huge and, in addition to a distinct lack of innovation on the cocktail scene until the boom in the late 90s, for many years bitters were overlooked with the exception being those early classic cocktails to which they were essential. “Alexander and I used to be bartenders with a lot of interest in classic cocktail making, and being based in Germany we had little, sometimes no access to the ingredients we would have liked to have behind the bar,” Stephen Berg, co-founder of The Bitter Truth tells me. “We noticed that classic cocktails up to the 1940s always had cocktail bitters in their recipe, but surprisingly there were hardly any available. This forced us to simply start making our own, and The Bitter Truth was born in 2006.”

It’s evident they weren’t alone in this desire for a richer, more diverse range of bitters on the market. They quickly began sweeping awards, including 2008’s Spirit of the Year for their celery bitters at Mixology Bar Awards in Berlin, to best new product for the same bitters at New Orlean’s Tales of The Cocktail awards in 2010. It started something of a movement. When I ask Berg how the bitters industry has changed since they started The Bitter Truth he says “it has changed dramatically. It has gone from almost zero bitters to a flood of bitters. While most bars hardly had any bitters, now you’ll find hardly any cocktail bar worth its name without at least a small range of bitters. They are everywhere now.”

Schuster partially attributes this boom in craft bitters producers to a growth in the understanding of “how essential they are to the sipping experience,” and the realisation for many that “they don’t have to taste bitter to be a bitter.” She also references “Bars like Amor y Amargo, which was the first dedicated to serving only stirred drinks made with bitters, really broke the mould. Once consumers got hip to the idea that practically anything could be a ‘bitter,’ this whole world opened up. A great bitter, and again, this doesn’t necessarily mean it’s a challenging flavour – it could be fruity, or spicy, botanical, aromatic, smoky, umami, floral, really anything as long as it’s safe to ingest – can make or break a cocktail. I would never make a Sazerac without Peychaud’s bitters specifically, for example. To me, that bitter is essential to the sipping experience in that drink. One of the recipes in my book is the Summer Manhattan from Travel Bar in Brooklyn. Orange bitters make it taste refreshing and are ideal for summertime drinking.”

These days, you’re just as likely to find a chocolate or a citrus bitters in a bartender’s repertoire as you are a classic aromatic bitters like Angostura and Peychauds. It is indicative of the new wave of mixologists looking to the past for inspiration as they innovate the industry. The intrigue of cocktails has peaked and troughed over the years, but never has it been more interesting to visit a cocktail bar; and not since those early days of the Manhattans and the Old Fashioneds have bartenders been so creative. That bitters were central to both periods of revolution in mixology feels like more than just coincidence.

As my martini at The Connaught taught me, sometimes even the most perfectly simple drinks can benefit from a little finishing touch – and that’s saying something, coming from a girl who tends to like her cocktails as clean as possible. “Bitters are very much the plot twist,” Bargiani says. “When we develop a drink, Ago will taste it and he will say ‘this drink is very good, but there’s something missing to make it exciting.’ And very often that something is a bitter.”