The boozy, bitter and strong negroni is getting its day in the sun this week.

The annual Negroni Week returns for its fourth edition from tomorrow until June 10, with a bumper crop of more than 80 participating bars.

The global event celebrates the classic Italian aperitif - a stirred-down drink that is typically made with equal parts of gin, Campari and sweet vermouth, and finished off with a twist of orange peel.

Bars will put their own spin on the cocktail and donate at least $1 from the sale proceeds of their drinks to a charity of their choice.

Last year's Singapore edition, which involved more than 60 bars, raised over $10,000, according to the co-organisers, branded beverage company Campari Group. This year's beneficiaries include Food Bank Singapore, Humanitarian Organization for Migration Economics and The Straits Times Pocket Money Fund.

While bar scene stalwarts like Manhattan and 28 HongKong Street will once again participate, there will be many new faces with fresh takes on the negroni.

Among them is Ms Palmira Bertuca, head bartender at Marcello at InterContinental Robertson Quay. The 26-year-old Italian from Bologna would know a thing or two about the negroni, especially since it was the first cocktail she drank and one that was commonplace where she grew up.

But she is not averse to breaking the rules for the classic drink. Her Limonegroni ($18++) uses housemade limoncello to add a subtle lemon undertone to the drink, making it both bittersweet and sour.

"When I was creating the Limonegroni, I was imagining a summer day lounging on the beaches of the Amalfi Coast. It's zesty and refreshing, so perfect for the hot weather we get here in Singapore," she says.

Ms Bertuca will be donating $2 from each drink sold to Food From The Heart, which redistributes surplus food items from bakeries to the needy.

Over at the Chihuly Lounge in Ritz-Carlton, Millenia Singapore, the Islay Negroni ($22++) uses a gin from the whisky-producing region in Scotland where the drink gets its name. Islay is known for its smoky and peaty whiskies.

Senior bartender David Kim says: "The negroni may look very easy to execute, but I believe that it is a true example of 'simple is best'."

The 27-year-old infuses the sweet vermouth with chrysanthemum and mint to enhance the botanical notes in the gin and sprays the glass with a peated whisky "to give a hint of smokiness". He will be donating $2 from each drink sold to volunteer-run soup kitchen Willing Hearts.

This year, four bars - Ah Sam Cold Drink Stall, Mona Lounge, The Wall and Amrith by BarSmiths - will also come together for a series of guest shifts under the banner of Band Of Brothers For Good.

From Wednesday to Saturday, they will each host a themed night, where they will donate $5 a cocktail ($20++ to $22++) sold during the guest shift to Trybe, a voluntary welfare organisation that helps troubled youth. Campari sodas will also be available at $12.

Ah Sam Cold Drink Stall kicks it off on Wednesday, followed by Mona Lounge, The Wall and Amrith.

The choice of charity has a special meaning for Mr Mark Tay, managing director of the BarSmiths Hospitality group, which he started in 2009.

"Over the years, we have employed many individuals who have needed a guiding hand or simply a big brother as they grew or recovered through rehabilitation," says the 43-year-old, who notes the struggles faced by some youths in the F&B industry.

Trybe, whose work revolves around youth-mentor relationships, conducts programmes for mainstream schools and manages two institutions for juvenile offenders.

Amrith, which opened in January this year and is located outside Song of India in Scotts Road, is the group's latest venture.

The first-time Negroni Week participants have come up with the Cha Yen, or Thai milk tea negroni, ($22), by bartender Edwin Poh. It uses Thai tea leaf-infused vermouth and dark rum instead of gin.

"The Thai tea leaves add flavour and a tannic mouthfeel to the cocktail, along with an additional bitterness," says Mr Poh, 28. "To balance the bitterness and top it off, a layer of cha yen espuma is added."

• For a list of the participating bars, go to https://negroniweek.com/venues/