The first known method of mechanical refrigeration was demonstrated in 1756 by
Though refrigerated railroad cars using a mixture of salt and ice were introduced in the United States in the 1840s, it was not until the 1860s that mechanical refrigeration came into use on the railroads. In the mid-twentieth century, refrigerated trucks became commonplace on the roads. Mechanical refrigeration meant that meat and perishable foods could be shipped, frozen, to Europe and North America from Australia, New Zealand, or Argentina, and still arrive frozen and in good condition. Professional confectioners were early adopters of this method, especially the Sara Lee Company in the United States, which revolutionized the process in the 1950s. See sara lee. The new equipment enabled bakeries to broaden their offerings with a wider selection of ice creams and cakes iced with buttercream.