1857–1866 · France
Pasteur establishes what fermentation is
Fermentation was shown to be the work of living organisms, and winemaking stopped being a mystery and became a process.
What happened
Before Pasteur, fermentation was widely held to be a purely chemical decomposition. He demonstrated that it is carried out by living yeast, and that spoilage is caused by other micro-organisms.
Études sur le vin, published in 1866, applied this directly to wine. It identified the organisms responsible for common faults and proposed gentle heating to stabilise wine — the technique that took his name.
He also worked out the role of oxygen, distinguishing the controlled exposure that helps a wine mature from the excess that ruins it. That distinction is still the framework used today.
The practical consequences were immediate and enormous. Understanding that specific organisms caused specific problems made hygiene, temperature and sulfur use into rational interventions rather than superstitions.
Everything in modern oenology — cultured yeast, malolactic management, controlled fermentation, fault diagnosis — descends from this work.
How firmly this is dated
Documented. Recorded contemporaneously. The date is not in question.
Pasteur’s published papers and Études sur le vin (1866), commissioned in part at the request of Napoleon III.
People: Louis Pasteur
What this follows from, and leads to
A timeline is a list; these are the links between its entries.
Sources
Sources consulted
- INRAE — French National Research Institute for Agriculture, Food and Environment — INRAE
- The Oxford Companion to Wine — Oxford University Press
- UC Davis Department of Viticulture and Enology — University of California, Davis