As far as It ingredients go, citric acid is an unlikely one – it's the stuff found at the bottom of the bag of sour gummy candies. But the grainy, white powder's ability to heighten flavours and bring balance to a dish – the supreme goal of good cooking – is turning it into an essential tool for the contemporary chef.
When Toronto chef Rebekah Pearse was a contestant on Top Chef Canada in its first season, she chose to include citric acid as one of just 10 items she was allowed to bring from home. She used it to make fresh ricotta and last-minute buttermilk by adding one teaspoon of citric acid to a litre of milk. Appealing to Pearse's inner-science nerd, she says it has become one of her favourite ingredients: "People say, wow, how did you do that?"
Citric acid occurs naturally in such fruits as limes, pineapples and gooseberries. The dry, powdered citric acid used as an industrial food additive since the early 19th century, however has a less appetizing source; it is manufactured using a mould that feeds on corn syrup glucose.
Found in supermarket staples from sodas and teas, to juices and jams, it's widely revered for its anti-bacterial, preservative and stabilizing qualities. Chefs have long held a stash of it, for instance to keep fruits and vegetables from oxidizing and turning brown while travelling from cutting board to table. But more and more chefs are wielding citric acid's sour strength – the fairy dust of flavour amplification – in creative new ways.
Chef Kevin Mathieson, owner of Ottawa's industrial-chic gastronomic café and patisserie Art is in Bakery, first experimented with citric acid back in 2000 during his apprenticeship at Peltier, a prestigious pastry shop in Paris.
He sprinkles a mixture of citric acid, icing sugar and salt over orange peel or wild blueberries before drying out the fruit for a week.
Using a coffee grinder, he blends it all into a powder that gets added to jellies inside chocolate truffles, infused into marmalade that gets slathered on brioche for a duck confit BLT sandwich, or dusted over crème fraîche as a garnish for a bowl of soup.
"It gives everything a bright, zesty taste," he says. "It also preserves the fruit's natural colour."When it comes to popular taste, sour is no longer a four-letter word, so to speak. An increased appetite for pucker-inducing and tangy flavours seems to run alongside several other major food trends including the rise of artisan sourdough breads, the new-to-North America sour beer sensation, ongoing interest in fermented and pickled foods that happen to be the perfect foil to the rich and fatty flavours of charcuterie, as well as the growing popularity of sour flavours associated with Asian and Mexican cuisines. "Look at the tamarind in pad Thai," says Mathieson of the ubiquitous Thai noodle dish, "It's got those same sour qualities as citric acid."
At Bar Buca in Toronto, Chef Rob Gentile uses citric acid to brighten the taste of a low-acid berry sorbet. "It opens up the flavour," he says. He also mixes it with water to make a solution that prevents finicky artichokes from oxidizing while they are being prepped and cleaned for artichoke crudo. Citric acid adds tartness where you don't want to add liquid, he says, "We add lemon juice at the end so we can control the flavour."
The popularity of citric acid among chefs doesn't surprise Colin Leach, owner of the Silk Road, an online spice merchant with a shop in Calgary. He says he sells a "surprising amount" of citric acid and also uses it himself to create the shop's spice blends. He sees the pursuit of perfect balance – a quest for capturing all five tastes in everything we eat – as the new orthodoxy in cooking. "If you making a barbecue rub for instance," he says, "and you taste it and it feels like something's missing, it's usually something sour that's needed. That's where we'd use citric acid."
Chef Robert Belcham, owner of Campognolo in Vancouver remembers using citric acid more than a decade ago to create a less-sweet "neutral" caramel and melting it into a lacy cage that lay over top of tuna tartare. These days he tends to use it directly on a dish as a flavoured salt to give food a dose of agrodolce, sweet and sour flavour. At Belcham's bar, Campognolo Upstairs, nuts are cooked in simple syrup and tossed with butter, salt, two kinds of chili and citric acid.
"It's a chef's tool," he says, explaining how citric acid allowed him to reinvent a popular bar snack. "First you taste sweet and nutty, then a bit of sour as you chew and it finishes with salt and heat. It transforms the way the dish plays out in your mouth."
"When I tasted this salad dressing for the first time, I didn't know what citric acid was," says Carlotte Langley, chef de cuisine of catering at the Storys Building in Toronto.
"I thought it was one miraculous vinaigrette.
"It's super zingy and coats everything without being too wet. I was taught to make it by a Lebanese Parisian woman, the mother of the owner of a tiny café on Murray St. in Ottawa where I had my first kitchen job."
500 ml of the loveliest olive oil in your cupboard
2 tbsp dry oregano
1 tbsp fresh oregano
1 tsp citric acid
250 ml of feta liquid
Whisper of pepper
Blend on high speed until smooth.
No salt is required thanks to the feta juice.