Citric acid
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Citric acid is probably way under your radar, but you almost certainly eat many foods that it's used in, like preserves, candy, and crunchy snacks.
So what is this ubiquitous ingredient? Citric acid is a natural, weak organic acid that is found in many fruits and vegetables, especially citrus fruits, hence their name. Because citric acid is also a byproduct of the citric acid cycle, it is also produced by many living organisms, including mold.
Citric acid is prized for its sour flavor, preservative quality, and ability to act as a pH buffer. For these reasons, citric acid is found in the ingredient list of many of the foods in your kitchen pantry.
Production of Citric Acid
Although citric acid is found in high concentrations in many citrus fruits, it is not economical to extract the acid from fruit for industrial use. Plus, the demand for citric acid far outweighs the supply of citrus fruit available.
The ability of the mold Aspergillus niger to produce citric acid as a byproduct of metabolism was discovered by American food chemist James Currie in 1917. The process of cultivating Aspergillus niger and allowing it to metabolize sucrose or glucose to yield citric acid proved efficient and inexpensive.
Once it was possible to produce a seemingly endless supply of citric acid, companies like Pfizer and Citrique Belge began producing it on an industrial scale. Dr. Currie's technique still is used to produce citric acid today
Availability of Citric Acid
Citric acid can be bought in powder form and is usually available in stores with other home canning supplies. Citric acid can also be found in natural food stores or health food stores with other vitamins and dietary supplements. In some grocery stores, citric acid is sold in small shakers and labeled as "sour salt."
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.
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