A Fraîche Start: Cheese-making cultures put authentic crème fraîche within reach

There is something mysterious about authentic crème fraîche. In an age when armchair gastronomists have thoroughly deconstructed the wonders of the home kitchen, crème fraîche is a paradox: within reach, but unpredictable.

Pronounced krem fresh, it’s sometimes used interchangeably with sour cream. It’s most widely known for its role in traditional French cooking, but it’s also heavily used in the cuisines of Belgium, the Netherlands and Scandinavia. Like much about French cooking, crème fraîche rose to American consciousness when Julia Child did. Nearly as fond of it as she was of butter, she also appreciated its aesthetic. “I always have a large glass jar of crème fraîche in my refrigerator,” she wrote, “because I like the comfortable looks of it.”

The first thing you should understand is what you’re getting into. Full-fat sour cream has 18 percent butterfat, but authentic crème fraîche contains a minimum 35 percent. Though at a certain point that may just seem gratuitous, the fat serves a purpose beyond inspiring gratitude for the onset of sweater season: Unlike sour cream and yogurt, crème fraîche is heat stable. It boils without curdling and it retains its structure when added to hot liquids, making it ideal for cream soups and pasta sauces.

Many home cooks have made a quick batch by combining a cup of cream and a tablespoon of buttermilk in a glass jar, placing it in a warm spot and waiting half a day. The buttermilk reintroduces cultures to the heat-pasteurized cream, allowing lactic acid and the fermentation processes to go to work. This method is simple, and the result is satisfying; crème fraîche made this way is thick, mildly acidic and faintly sour.
But it’s just as easy to use bacterial cultures specifically collected for authentic crème fraîche in lieu of the buttermilk, and the resulting flavor and texture makes it well worth the effort of tracking down the culture. There are several online sources for cheese-making supplies; locally, cheese-making instructor Merryl Winstein sells the culture (Cheesemakingclass.com). Yes, we are dealing with a less-complicated rendition of the cheese-making process. Don’t be frightened.

Here’s how it works: The added culture gently acidifies the cream by turning sugar into lactic acid. The cream is left to ferment just long enough that the acids begin to contribute sourness, but not so long that all the sugars are consumed. All the variables in this process (temperature, the proteins in the cream, the bacterial interaction) determine the final result, and there’s always some variation. Whatever the precise balance of flavors, though, the finished product will be a full-bodied, sweet, pleasantly tangy, delicately nutty, slightly acidic and well-structured cream that holds its shape on a spoon.

At this stage you can use it, adding it to sauces, soups and batters. It may be substituted for mayonnaise or sour cream, and of course it’s a flawless accompaniment to chilled salmon and herring. But if you can hold off a few more hours, move it to the fridge to slow the fermentation and then drain it through dampened cheesecloth for six to 12 hours for a fresh, creamy homemade mascarpone.

The fermentation process is preservative, and refrigerated crème fraîche will last for 12 days. When you’re down to your last spoonful, just add another cup of heavy cream, heat it, and wait.

For more recipes using crème frîache, visit the Extra Sauce section of saucemagazine.com throughout the month.