By now, you should be adding pickle brine to your picante

For some, Diwali is all about honouring tradition. For others, it’s about card games and cocktails. Sitting squarely in the middle of this Venn diagram is the latest trend in mixology: the ancient practice of fermenting stuff to make them super tasty.

Across cocktail menus—from Goa’s The Second House to Mumbai’s Bombay Daak— drinks using clarified yogurt or fermented fruits are becoming increasingly common, as are drinks with made-from-scratch syrups and vinegars.  Where a splash of soda adds fizz and tonic adds bitterness, ferments like kombuchas, congees, vinegars, and brines layer in acidity, funk, and umami all at once.

“Fermentation is trendy right now, but it’s been around for thousands of years,” says Bengaluru-based master fermenter Payal Shah, adding that our grandparents and great-grandparents were all fermenting food (and drink) long before kombucha became the new fresh-lime-soda-sweet-salt-mix. Fermented ingredients bring layers and complexity to your drinks that standard mixers simply can’t match.

Shah’s job involves running flavour experiments six days a week at The Flavour Lab, a one-of-a-kind geek zone set up by Diageo in Bengaluru’s Whitefield area, where she is the head fermenter. The lab, which is part of The Good Craft Co., is on the top floor of a medical college building and features a full-fledged laboratory (where brands other than those owned by Diageo run experiments too) through the week, which turns into an experience centre on Saturday evenings, open to tipplers who want to know more about why their booze tastes like it does. 

It’s at one of these sessions that Shah walks us through her work at the laboratory. “It’s a spectrum between science and art,” she says, standing in front of a wall lined with dozens of large jars, each holding fruits, vegetables, and more at varying stages of fermentation. “The science is all the rules of fermentation: what you can put in there, what you can’t, how much salt, how much sugar, and what kind of environment you create inside the jar. The art and the craft are where the fun comes in—playing around with different ingredients and flavour combinations and generally letting the microbes do their magic.”

The laboratory’s goal is simple: getting a better understanding of flavours. This means deducing what works well with what, why one ingredient shines over another, and how ferments can be used to enhance a drink, whether that’s a cocktail, an infusion, or a standalone beverage.

Working closely with Shah is Neil Alexander, the head mixologist at The Good Craft Co, who loves working with ferments because “they’re dynamic and alive”. Unlike regular (non-fermented) ingredients, ferments keep evolving; their flavours change from one day to another. This also makes them exciting and challenging to work with. “You need to taste often and adapt, and also design flexible, modular recipes,” he says. Among many others, he has used Shah’s ferments to create a crisp and herbaceous savoury cocktail using gin, jalapeno brine, dill, lemon puree, and magic salt. He also had fun bringing out the deep richness of Johnnie Walker Black Label by pairing it with a mushroom dashi reduction, miso, sweet corn, and tamarind.

All very different from when Shah first started getting her hands dirty with ferments in her childhood, working alongside her grandmother. “She used to have a lot of fermentation projects going on, without calling it that of course. In Gujarati it’s called athanu, or atho. I used to help her out with small tasks and probably picked up a lot by osmosis.”

At age 18, when she first had a ginger beer, she knew she wanted to go deeper into the world of ferments. Trained as a psychologist, Shah is a self-taught fermenter, who has been officially working with ferments for 25 years and runs a series of workshops for people at different stages of their relationship with flavour-making microbes.

The festive season is as good as any to run some simple but delicious experiments, whether that’s making a syrup of your own (see below), or creating some fun cocktails with easily available ferments. Her thumb rule to get you started is this: “Don’t think of this as traditional flavour pairings—what will go with whiskey or what will go with gin. Think of how you usually like your drink. Fizzy? Instead of soda, use kombucha. If you like lime and sugar, make an oleo saccharum, a fermented syrup made using any citrus fruit and sugar. The possibilities are endless!”

Cocktail upgrades for 2025

DIY Oleo Saccharum 

Perfect for: Any cocktail with a sweet-sour flavour profile, like a Tom Collins or a Mojito

First find a big jar so you can make a big batch. On a weighing scale, add equal weight of sliced lemons (or any citric fruit) and sugar. The sugar will draw out the liquid and in a couple of days you should have a deeply flavourful syrup you can use in your cocktails.

It takes two days to make and lasts at room temperature for over a year. Bonus: You can also just add water to make a delicious nimbu-paani.

Pickled Mangoes FTW

Perfect for: Martini, Picante, Bloody Mary

Raw mangoes are brined in various parts of the country—across Kerala, Maharashtra, as well as parts of Tamil Nadu and Karnataka. Swap the olive brine in your martini for the liquid your mangoes have been sitting in. “This liquid is also a great addition to a picante,” says Shah, adding that she also likes dropping a slice of the pickled mango in her Bloody Mary. “It just adds so many layers to the flavour.”

The Holiday Special

Perfect for: Holiday gifting

Four years ago, Shah created the ‘Slow-fermented Essence of Xmas’, which remains one of her favourites. It brings together oranges, apples, lemons, ginger, sugar, and spices to create something that tastes like a warm hug in a jar. The mixture can be used to make single servings of mulled wine—or non-alcoholic variations—without the mess that mulled-wine-making usually involves. Bonus: it doubles as a thoughtful gift during the holiday season.