Older recipes often call for milk to be heated, or "scalded," before it is used in recipes. In the days before pasteurization, this killed potentially dangerous bacteria in milk and made it safer for consumption. Heating changes how milk proteins behave, making it better for use in bread or yogurt. Scalding also intensifies milk's flavor, making it taste richer and creamier.
Stove Top Method
Rinse the bottom of a saucepan with cold water then fill it with the required quantity of milk. Move the pot to your stove and place it on a burner at low to moderate heat.
Heat the milk gently, stirring it frequently with a wooden spoon or silicone spatula. The proteins in the milk have a tendency to cook to the bottom of the pot, where the heat source is, unless they are stirred diligently.
Test the temperature of the milk with an instant-read thermometer once the milk has begun to steam and show small bubbles. Milk is considered to be scalded once it exceeds a temperature of 180 degrees F.
Microwave Method
Select a heat-proof measuring cup that is capable of holding at least twice as much milk as you wish to heat. Fill it to the appropriate level with the milk needed for your recipe.
Microwave the milk at high power for one minute. Stir, and allow the milk to rest for 15 seconds as the temperature equalizes.
Repeat the process, watching the milk carefully through the microwave's window. Depending on the quantity of milk, it will begin to foam up vigorously at some time during or after the second minute.
Remove the milk from the microwave and stir. Test the temperature with an instant-read thermometer. It should read 180 degrees F.