We can harness probiotic bacteria to make many wonderful things, but crème fraîche is by far the easiest. This nutty, buttery, soured cream can be frustratingly hard to find in prepared form and—if you do happen to find it—can cost you as much as a dollar an ounce. crème fraîche can be sweetened and whipped into whipped cream or whipped unsweetened until it separates into butter—and the bonus by-product liquid is old-fashioned buttermilk (which is different from the cultured buttermilk used in this recipe).
What is Crème Fraîche and How to Make it?
Crème fraîche is sour cream’s thinner French cousin. Used as a topping, in sauces, or in a variety of other sweet and savory applications, it has a delightful tanginess that comes from bacterial cultures.
There are several different methods for making crème fraîche. In France, the heavy cream used to make it is unpasteurized (raw). It therefore contains natural bacteria, and when allowed to “age” at room temperature, it cultures on its own. In the United States, however, the pasteurization process required of most commercial dairy products means that the crème fraîche must be made in a different manner—that is, via fermentation.
Beneficial bacteria, in the form of cultured buttermilk or a starter, are introduced into cream, transforming it into crème fraîche. One of these guys is Lactococcus lactis (lacto for “milk”), a microbe that is informally classified as the lactic acid bacterium, due to its ability to transform lactose into lactic acid via fermentation. The increase in acid decreases the pH of the cream, changing its flavor and making the environment inhospitable to other, less friendly microbes.
It’s very easy to make crème fraîche with pasteurized cream. Simply combine buttermilk with heavy cream, and then leave at room temperature for half a day. Though this may seem like an unsafe practice, the bacteria present actually keep it from spoiling. Once made, the crème fraîche can be used in dressings, dips, and even ice cream! (Keep in mind, however, that heating it to higher than 100°F (38°C) will kill most of the beneficial bacteria.)