 In the 19th century, for the first time, bread was made only from beer yeast and new dough rather than a sourdough starter.The first known example of this was the sweet-fermented Imperial "Kaiser-Semmel" roll of the Vienna bakery at the Paris International Exposition of 1867.These sweet-fermented rolls lacked the acid sourness typical of lactobacillus, and were said to be popular and in high demand.