Although both evaporated milk and condensed milk both begin with fresh milk that then has much of the water removed, the final product is usually quite different. The most obvious difference is that, in most cases, the evaporated variety is not sweetened, while the condensed usually is. While it may be possible to buy unsweetened condensed milk in some locations, it is uncommon. Without the added sugar to deter bacterial growth, evaporated milk also requires more processing than condensed.
Evaporated milk is unsweetened fresh milk from which more than half of the water has been removed via evaporation. Available canned in fat-free, reduced fat, and whole-milk versions, it is versatile and can be used in a number of culinary applications. Even fat-free varieties can be used successfully to replace whole milk or even light cream in many recipes because of its viscosity. This makes it especially useful for reducing calories and fat in dishes such as casseroles, gravies, and quiches.
Reconstituted with an equal part water, evaporated milk assumes the consistency of fresh milk and may be used as such. The heating process it undergoes caramelizes the sugars naturally present in the milk, giving it a ivory-yellow color. Although this form of milk is homogenized and perfectly suitable for diluting and drinking, it does have a taste that many describe as "canned," and therefore it is not generally preferred as a beverage on its own. It can, however, be mixed with flavorings and used in milkshakes or added to coffee as an alternative to cream.
Sweetened condensed milk is a blend of whole milk and 40 to 45% sugar, which is heated until nearly two-thirds of the water contained in it evaporates. The result is a thick, sticky, exceedingly sweet product that is used to make a variety of candies and baked goods. When it is cooked down to the point of dark caramelization, it becomes dulce de leche, which is popular as a spread and dessert filling in many South American countries and is gaining in popularity in the United States. Vietnamese coffee, or ca phe sua da, is a mixture of sweetened condensed milk and strong black coffee poured over ice.
Both types of milk are shelf stable and may be stored at room temperature until opening. After opening, they should be transferred from the original can to a nonreactive (e.g., plastic or glass) container with a tight-fitting lid and refrigerated. These products should be used within five to seven days of opening.
Although the two products are often confused, they are not interchangeable in recipes that call for one or the other. Evaporated milk, which has no added sugar, may be used in either sweet or savory applications as a substitute for whole milk or light cream. Condensed milk, on the other hand, is suitable only for sweet applications.
If sweetened condensed milk is required for a recipe but only evaporated milk is available, a reasonable facsimile can be made. It can be made by combining 1.25 cups (250 g) white granulated sugar and 1 cup (240 ml) evaporated milk in a small saucepan and heating them over medium heat, stirring, until the sugar has dissolved.