Over the centuries, making bread became an art. It took some time, however, for science to catch up. Eventually, a Dutch lens maker named Anton Leewenhoek developed the first microscope. This invention in 1676 led to the identification of microscopic organisms, including yeast.

During this time there were no good sources of wheat. Europeans primarily used flour made from rye, millet, oats and barley. While early Americans used corn for most of their bread, they soon began producing bountiful crops of wheat. By the 1770's, wheat was their largest export. In fact in 1776, 75 tons of wheat were exported from George Washington's Mount Vernon farm.

The 1800's were known as the Golden Age for bread bakers. Milling processes improved and new wheat varieties and leaveners were developed. Commercial and home bakers refined their breads but dough still didn't always rise consistently. All too often, the result was dense, coarse bread. Leaveners from the 18th century included frothy scrapings from brewers' vats, starchy foods added to breads to nourish any yeast that might be present, and perlash (water in which hardwood ashes had been soaked).

In 1859, Louis Pasteur, the father of modern microbiology, discovered how yeast works. By feeding on the starches in flour, yeast produces carbon dioxide. This gas expands the gluten proteins in the flour and causes the dough to expand and rise.