Yeast as the living agent of fermentation

What was discovered

Three researchers observed under the microscope, almost at the same time, that brewer's yeast is an organism that multiplies by budding and causes alcoholic fermentation. It made the fermentation of bread, beer and wine a biological matter.

The chemists Liebig and Wohler ridiculed the idea and defended a purely chemical fermentation; it prevailed with Pasteur.

What it led to

• the microbial theory of fermentation (Pasteur, 1857)
• pure yeast cultivation (Hansen, 1883)
• yeast industry for baking and brewing

Built on

• Barley beerc. 3500 BCE
• Leavened bread and large-scale bakery

Made possible

• Germ theory (Pasteur)1857-1865
• Pure yeast culture for lager brewing1883
• Cell-free alcoholic fermentation (Buchner's zymase)1897

Links

Sources✓ verified 2026-11-04

• https://en.wikisource.org/wiki/1911_Encyclop%C3%A6dia_Britannica/Fermentation
• https://en.wikipedia.org/wiki/Charles_Cagniard_de_la_Tour