Butter

Before refrigeration, butter was typically made from soured cream.  After the advent of refrigerated storage, uncultured butter from fresh, pasteurized cream or Sweet Cream Butter became popular in North America.  Pasteurization reduces the amount of bacteria responsible for spoilage and fermentation. Butter contains at least 80% fat or butterfat, no more than 16% water and 2-4% milk solids.  Sweet cream butter is characterized by a smooth, and neutral flavor.  Sweet butter is unsalted and is preferred for cooking and baking.

Salt had been added to butter in the days before refrigeration as preservative.  Salted butter still uses salt to extend its shelf-life as well for its flavor.  Preferring to control salt directly, most cooks prefer to use unsalted butter for cooking and baking.

European or Cultured butter is made from cream in which fermentation—the conversion of milk sugars into lactic acid—has begun to take place.  Fermentation creates a sharp, “cultured” taste. Cultured butter is the preferred style in most of continental Europe.

When butter heated and allowed to settle, it separates into layers of milk solids, water and pure butterfat.  Removing  its water and milk solids the pure fat is referred to as clarified butter.  Clarified butter has a higher smoke point than regular butter and can be used in higher heat cooking.  Traditional Indian cooking uses ghee, which is made by heating unsalted butter until the milk solids sink to the bottom and brown. The foam is skimmed, and then the pure butterfat is poured off, leaving the solids behind. Ghee has a nutty flavor,  can be stored at room temperature.  

Pungent-tasting preserved butters such as smen, a Moroccan delicacy, belong to a variety known as fermented butter; they have been allowed to age for anywhere from two weeks to two years and are sometimes seasoned with herbs and spices.

Whipped butter was invented around the mid-20th century, and made by whipping nitrogen gas into churned butter.  (Air would have introduced oxygen to the butter and promoted spoilage.)  Whipped butter is  designed to be soft enough to spread when you take it out of refrigeration.  Whipped butter is not suitable for cooking.

Margarine is an imitation butter spread used for spreading, baking, and cooking. It was originally created as a substitute for butter in 1869 in France by Hippolyte Mège-Mouriès. Margarine is made mainly of refined plant oils and fats and water.  It can replace butter in cooking but lacks butter’s flavor.  Read Crimes Against Butter.