Coconut Milk 101

• Coconut milk is made like other nut milks, by processing the shredded flesh of the coconut to a paste with water. Then, more water is added, and the resulting liquid is strained to remove the fibrous pulp. The result is a white liquid that is infused with the coconut's flavor and much of its nutrition. It also contains much of the natural oil from the coconut, suspended throughout the liquid in the form of microscopic droplets. If left to stand, especially at cool temperatures, the fattier portion of the milk rises to the top. Some recipes call for the milk to shaken before use, to re-combine the milk and cream, while others use the coconut milk or cream separately.

Effect of Temperature

• The heat of even the hottest summer day isn't enough to make coconut milk curdle. It is a tropical product, after all, and, if that were the case, coconut milk would seldom be usable. Milks and milk-like products are emulsions of fat, water, proteins, sugars and other solids, and they curdle when heat or chemical reactions cause the proteins to bind together and settle out of the liquid. The heat of cooking can do that to coconut milk, just as it does with yogurt or sour cream.

Cooking and Curdling

• Proteins begin to bond, or coagulate, at varying temperatures. For example, egg whites begin to grow firm at 180 degrees Fahrenheit. The proteins in coconut milk can take more heat, but will curdle if they come to a boil. The rich coconut cream contains a much higher level of fat and correspondingly less protein, so you can heat it to higher temperatures. As it heats, much of the coconut oil will separate from the cream, but traditional recipes expect this and incorporate that oil into the cooking process.

Cooking Without Curdling

• When you're using coconut milk in sauces or stews, turn down the heat and make sure it cooks at a low simmer rather than at a boil. Frequent stirring also slows curd formation, and keeps the curds small. If you are adding coconut cream as the finishing ingredient in a soup, bring it up to temperature by whisking the soup broth into your coconut milk. It is the same "tempering" technique used that pastry chefs use when incorporating eggs into a custard -- and for the same reason. You can also stabilize the coconut milk by whisking cornstarch into a slurry with a few tablespoons of cold water, and incorporating that into the coconut milk. The mixture will thicken the sauce slightly, and prevent the milk from curdling.