Most people think vermouth is a spirit that can be kept on the shelf for years.

MARTINI Brand Ambassador Roberta Mariani told Business Insider it's actually a wine — and should be consumed fresh and kept in the fridge.

She explained what to look out for on a label when buying a vermouth — and how to drink it.

Whether you're a martini lover or you've recently discovered the joys of the negroni, chances are you've come across vermouth at some point in your life — but do you have any idea what it is?

"What is vermouth" and "Is vermouth a spirit" are often-Googled questions — so we spoke to MARTINI Brand Ambassador Roberta Mariani to get some answers.

Italian-born and London-based Mariani started working behind the bar around 10 years ago while studying languages, and said she "fell in love with [the] mix of science and art while creating cocktails."

"You need to know the math behind them," she told Business Insider. She decided to move to London, which she calls "the best city in the world to make a bartending career" thanks to its incredible bars, people, and community willing to share their knowledge of the business.

She worked at the Sanderson Hotel for a few months before joining Farringdon's Zetter Townhouse, a collaboration with renowned mixologist Tony Conigliaro.

She then spent some time working at Conigliaro's 69 Colebrooke Row before opening Bar Termini with him in 2014 — and it was named the best bar in London in 2017. She had been there for two years when an opportunity came up to be a MARTINI ambassador in 2016 — and it was a perfect fit.

An aperitivo state of mind

Now, she spends her time teaching masterclasses and educating the world on "aperitivo" — an hour or two spent enjoying a pre-dinner cocktail, or apéritif, with friends.

"Apertivo for an Italian is state of mind, it's the start of evening," she said. "It's not after work drinks, it's just enjoying a drink and some food with friends to just enjoy the moment."

These cocktails typically involve vermouth, gin, or an apéritif spirit like Campari.

"I found out how little European countries know about this topic and category," she said.

The myths of vermouth

According to Mariani, there are a number of myths about apertivo — and vermouth in particular.

Firstly, she said most people think vermouth is a liqueur — but it's actually a wine.

"When you talk about cocktail, you usually think about spirits," she said. "But [vermouth is] actually a wine. There's a massive difference."

She added that people "always think about vermouth as red and sweet" — however, vermouths are mostly made with white wine, and the colour in a rosso (or red) vermouth comes from caramel.

How to buy it, store it, and drink it

For starters, Mariani recommends looking for a brand you know and trust when buying a vermouth, and checking on the back whether there are artificial or natural ingredients listed.

"If the word 'vermouth' is on the label, you want to be sure [it also says] 'vermouth di Torino,'" she added.

This is a control measure introduced in March 2017 which, like with a parmesan cheese or parma ham, indicates that all of the ingredients are coming from the right place in Italy — in the case of vermouth, Turin.

She added: "Always look at expiry date. It's a product you want to drink fresh, [and the] shelf life of a product is two to three years — if it's already dated three years or more, you shouldn't buy it."

Because people assume it's a spirit, she added that they often leave an opened bottle on a shelf for months or years, then experience a bad taste when they drink it.

Instead, she said it should be kept in the fridge for a maximum of a few months to prevent it from oxidising or "going bad" — something more and more people are starting to realise.

MARTINI Brand Ambassador Roberta Mariani. MARTINI

'It works with almost everything'

One classic use for vermouth is, of course, the martini.

"Vermouth in a dry martini can really make the difference. It can give you aromatised notes, depth, texture — ask your bartender for a recommendation for the vermouth [next time you order one]," she said.

However, she said that the gin trend has helped peoples' palettes get used to the bitterness — which has, in turn, made the negroni ever more popular, even ranking as the second best-selling cocktail for 2018.

While the classic recipe calls for ice, vermouth, Campari, gin, and a slice of orange, The MARTINI Negroni Cocktail calls for MARTINI Riserva Speciale Bitter, MARTINI Riserva Speciale Rubino vermouth di Torino, and Bombay Sapphire Gin, and is a more complex and gentle version.

Other popular ways to drink it include a long vermouth and tonic, or on the rocks with a slice or lemon or orange — even adding a few dashes of bitters and gin to add more depth, like in a preparado, which is popular in Spain.

It can even be mixed with vodka, bourbon, whiskey, scotch, and tequila in more classic cocktails.

"It's really versatile," she said. "It's really well balanced and works with almost everything."

However, the most important thing?

"Use a lot of ice, always a lot of ice," she said. "Less ice just means dilution — you want your drink kept quite cold."