Butter is a product made from the solid components in milk (fat and protein). Although most often made from cow’s milk, butter can be made out of milk from sheep, goats, buffalo, or other mammals.
Butter usually consists of approximately 80 percent fat, 15 percent water, and five percent protein. The small amount of protein in butter acts as an emulsifier allowing the water and fat to stay suspended in single-phase solution. The unique mixture of fats on butter allows it to stay solid at room temperature and melt at approximately 90 degrees Fahrenheit.
The natural color of butter ranges from white to pale yellow depending on the diet of the animal that produced the milk. Commercial butters are usually colored yellow with annatto or carotene to fulfill consumers expectations of yellow butter.
Sweet Cream Butter – Sweet cream butter is made from cream that has been pasteurized to kill any bacteria that would normally ferment the natural sugars in the cream. Sweet cream butter has a light, fresh flavor and is the most common commercial butter sold in the United States.
Raw Cream Butter – Raw cream butter has not been pasteurized nor has it been allowed to ferment. Raw cream butter has a very short shelf life (approximately 10 days) and is prized for its fresh, clean flavor.
Cultured Butter – Cultured butter is produced by allowing bacteria to ferment the sugars in cream prior to churning it into butter. This provides a tart, tangy, and complex flavor. Cultured butter was the predominant type of butter prior to refrigeration and pasteurization. Today, commercial cultured butter is made from cream that has been pasteurized and then re-inoculated with a specific bacteria strain to produce fermentation.
Ghee – Ghee, or clarified butter, is produced by heating butter until the water evaporates off and the proteins separate from the fat. The resulting product is almost 100 percent butterfat. Ghee, which has a unique flavor, is a popular ingredient in Middle Eastern cuisine.
Spreadable Butter – Butter can be quite stiff at refrigerated temperatures and manufacturers have produced varieties of spreadable butter to help combat this problem. Spreadable butter is usually made soft by combining traditional butter with oils, such as vegetable oil, that remain liquid at cooler temperatures. Whipping air or water into butter is another technique used to create a spread that remains soft at cold temperatures.
Fruit, Vegetable, and Nut Butters – Butter is often used to describe other spreadable purees that do not contain any dairy products. Nut butter, such as peanut butter or almond butter, have a high-fat content and a consistency similar to dairy butter but contain no milk products. Fruit and vegetable butter, such as apple butter, are simply pureed fruit or vegetables that have been cooked down to reduce the moisture content and create a spreadable consistency closer to that of dairy butter.
How to Store Butter
Butter should be kept refrigerated below 40 F to protect against rancidity. Reducing exposure to oxygen and light by storing butter tightly wrapped and in a dark place (such as a refrigerator) will also delay rancidity. Keeping butter tightly wrapped is also important to protect it from absorbing rogue flavors.
At refrigerated temperatures, butter will stay fresh for up to four months. Butter can also be frozen and kept fresh for up to a year. At room temperature, the length of freshness will depend on the butter’s exposure to light and oxygen, but butter will generally stay fresh for several days unrefrigerated. Covering butter in a ceramic dish or butter bell will help preserve freshness at room temperature by reducing oxygen exposure and heat.
Butter that has a strong smell or a bitter or sharp flavor has most likely gone rancid and should be discarded.