By Harold McGee
The word doughnut was coined in the United States in the 19th century to name what the Dutch called olykoeks, portions of fried sweetened dough. Their great popularity flowered in the 1920s, when machinery simplified the handling of the soft, sticky doughs, which are rich in sugar, fat, and sometimes eggs. There are two main styles: yeasted doughnuts are light and fluffy, while cake doughnuts, leavened with baking powder, are denser. Light, yeasted doughnuts ride on the oil surface and must be turned, which leaves a white band around their circumference where the oil surface cooks the dough less thoroughly. Doughnuts are fried at a moderate temperature, originally in lard and now usually in a hydrogenated vegetable shortening, which solidifies when the doughnut cools to provide a dry rather than oily surface.