Margarine consists of a water-in-fat emulsion, with tiny droplets of water dispersed uniformly throughout a fat phase in a stable solid form. While butter is made by concentrating the butterfat of milk through agitation, modern margarine is made through a more intensive processing of refined vegetable oil and water.
Per federal regulation, margarine must have a minimum fat content of 80 percent (with a maximum of 16% water) to be labeled as such in the United States, although the term is used informally to describe vegetable-oil-based spreads with lower fat content. In Britain, Australia and New Zealand, it can be referred to colloquially as marge.
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