Flour milling and baking became industrialized in the United States in the nineteenth century. Increasingly, bread was not baked at home but purchased from shops and bakeries. One sign of the changing nature of food production and distribution was the formation in the United States in 1898 of the National Biscuit Company (later shortened to Nabisco), which was an amalgamation of 114 bakeries, representing 90 percent of American commercial biscuit production. In Britain, the dominance of national bakery chains is a much more recent phenomenon, with no more than 40 percent of all bread consumed produced in large plant bakeries as late as 1953.

The automation of bread-making began with the introduction of roller milling of flour in the 1870s. Roller mills could produce much finer and whiter flour of a more consistent quality than grindstones. This had two major implications for bread-making: the finer flour could absorb more water, producing a lighter and more malleable dough, and the natural oils in the wheat berry were extracted at an early stage, leaving a flour with a longer life. In the 1920s, the factory bread-making process was accelerated when high-speed dough mixers became available.

The phrase “the best thing since sliced bread” appeared in the United States in the 1930s following the introduction of presliced Wonder Bread. In 1928, after sixteen years of development work, Otto Frederick Rohwedder launched the first practical bread-slicing and wrapping machine in Battle Creek, Michigan. In the same year, the Continental Bakery in NewYork introduced Wonder Bread, the first nationally distributed wrapped loaf of bread. Two years later, using Rohwedder’s machines, it introduced presliced Wonder Bread. Wrapped, presliced bread also appeared in the United Kingdom in 1930. By 1933, 80 percent of the bread sold in the United States was presliced and wrapped.

Sliced bread was convenient and of a standard thickness. Its introduction no doubt helped the sales of electric toasters throughout the 1930s. However, healthfood campaigners argued that the convenience of the presliced white loaf came at the expense of its nutritional value. By the 1940s and 1950s, white bread was routinely enriched by the addition of vitamins and minerals. Stoneground whole wheat flour and unwrapped loaves enjoyed a revival from the late 1950s as a result of the growth of the health foods movement. For example, the American health food guru Gayelord Hauser was a strong advocate of the benefits of wheat germ.