Salted butter is cooled pasteurized cream that has been churned to form large globules of butter. After the remaining liquid from the cream (buttermilk) is drained off, a maximum of 3 percent salt is added. Unsalted butter is produced in the same manner, but without the salt added. In some countries, unsalted butter is also known as sweet butter.
Cultured butter is also unsalted. Before churning, a selected culture is added to the cream, which is held at a controlled temperature overnight to allow the development of an acidic flavor.
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