Cookbook:Crème Fraiche

Crème fraîche is a cultured cream product similar but not identical to sour cream.

Characteristics
Crème fraîche is made either by allowing raw cream to culture naturally or by introducing lactic acid cultures to pasteurized cream. This process results in a slight acidification, which thickens the cream and gives it a tangy flavor. In general, the cream used has at least 30% fat, which makes the product smooth and rich. The exact texture varies slightly, and it can be thin to thick, depending on the culture time and amount of moisture left in the final product.

Selection and storage
Crème fraîche is perishable and must be kept in the fridge to prevent it from over souring and eventually spoiling. Discard if you see any mold or pink patches growing on it.

Use
Crème fraîche is particularly useful in finishing sauces in French cooking because its high fat content reduces its risk curdling when heated. However, "light" crème fraîche with a low fat content will curdle when heated. Crème fraîche is also used as a topping for fruits and desserts, and it can be incorporated into ganache and other confections.

Substitution
If you can't get your hands on crème fraîche, you can make it yourself by mixing cultured buttermilk into heavy cream (about 5–20% buttermilk by volume) and letting it sit at room temperature (~70°F/22°C) for 12–36 hours until soured and thickened to your preference. Sour cream also makes a reasonable substitute, though you should note that the fat and moisture contents can differ between sour cream and crème fraîche.