Liebig: fermentation is transmitted decomposition, not the work of a living thing

1839 Fire and matter theory theory refuted

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A theory in which fermentation is a purely chemical transmission of decomposition, not a consequence of the life of yeast. Yeast in this picture is itself in a state of continuous decomposition and communicates that motion to the sugar molecules, which fall apart into alcohol and carbon dioxide.

The German chemist Justus Liebig put the theory forward in 1839 in reply to the conclusion of 1837. Life is not needed in the explanation; fermentation, putrefaction and decay are one class of phenomena. Liebig and Wöhler also printed in their own journal an anonymous skit in which yeast under the microscope looked like a little animal shaped like a still, swallowing sugar.

The mechanism of transmitted decomposition does not exist, and Pasteur showed as much. But the demand that fermentation be explained chemically rather than by a vital force was borne out by Buchner in 1897, so Liebig's theory is marked as a dead end that has offspring.

Why this date

High for the year. J. Liebig, "Ueber die Erscheinungen der Gährung, Fäulniß und Verwesung und ihre Ursachen", Annalen der Pharmacie, vol. 30, no. 3 (1839), DOI 10.1002/jlac.18390300303. The anonymous skit "Das enträthselte Geheimniss der geistigen Gährung" appeared in the same journal, vol. 29 (1839), 100-104. The page range of the main paper could not be verified against the title page (an antiquarian description of the issue gives its length as 38 pages), so no pages are cited.

What it grew from

• Brewer's yeast turns out to be a living organism: Cagniard-Latour, Schwann, Kützing

  influenced · Confidence: high

  Liebig's theory of 1839 is a direct answer to the conclusion of 1837: first an anonymous skit mocking the microscopical findings, then a purely chemical explanation of his own. According to Payen, Liebig's attacks pushed the view of yeast as a living thing into the background for twenty years.

  Link sources

  • Jacques Payen, «Cagniard de la Tour, Charles», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026

    Schwann came to the same conclusion at the same time, but Liebig's violent attacks forced this point of view into the background for twenty years.

  • James A. Barnett, «Beginnings of microbiology and biochemistry: the contribution of yeast research», Microbiology 149 (3), 557-567 (2003) Verified 20 Sep 2026

    Von Liebig and Wöhler went so far as to publish jointly in their journal, Annalen der Pharmacie, an anonymous skit mocking the microscopical findings they rejected.

  • James A. Barnett, «Beginnings of microbiology and biochemistry: the contribution of yeast research», Microbiology 149 (3), 557-567 (2003) Verified 20 Sep 2026

    This was a remarkable event in the history of science and probably held up the development of microbiology for about twenty years.

  "Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.

What grew out of it

• Buchner: alcoholic fermentation by cell-free yeast juice, and zymase

  influenced · Confidence: medium

  The mechanist line, of which Schriefers names Liebig the exponent, survived down to Buchner and was vindicated in substance precisely by his result: fermentation turned out to be a chemical, enzymatically catalysed process not bound for good to the life of the cell. Liebig's own mechanism was not revived.

  Dispute: The words "Buchner vindicated Liebig" are not stated outright by any of the historians read. Schriefers places the discovery in the frame of the mechanist-vitalist dispute and names Liebig the exponent of the mechanists, but does not assert that the theory of 1839 gave rise to the work of 1897. Hence medium confidence, and the link is drawn as influence rather than as a direct improvement: Buchner did not improve Liebig's mechanism, he confirmed the side of the question opposite to Pasteur's.

  Link sources

  • Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026

    Between 1830 and 1860, prior to Buchner's discovery, two theories of fermentation had divided the scientific world into vitalists and mechanists.

  • Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026

    Liebig was the exponent of the mechanists.

  • Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026

    life and fermentation are not unalterably bound to each other. Instead, fermentation is a chemical, enzymatically catalyzed process.

  • James A. Barnett, Frieder W. Lichtenthaler, «A history of research on yeasts 3: Emil Fischer, Eduard Buchner and their contemporaries, 1880-1900», Yeast 18 (4), 363-388 (2001)

    the von Liebig-Stahl idea of transmitting motion and Pasteur's belief that fermentation is necessarily produced by living organisms

  "Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.

Other links

• Pasteur: fermentation is the physiological work of living cells, from the Bigo factory to the Études sur la bière

  refuted by · Confidence: high

  Pasteur grew yeast in a purely mineral medium with sugar, containing none of the decomposing organic matter that Liebig's theory required; the mechanism of transmitted decomposition was left without a subject. The mechanical explanation clashed head-on with Pasteur's physiological interpretation.

  Dispute: The dispute was not closed in the lifetime of either man. What was refuted is Liebig's particular mechanism (transmitted decomposition), not his commitment to a chemical explanation: Schriefers writes that Pasteur's view of the inseparability of life and fermentation "nevertheless found acceptance among the majority of scientists", that is, a side won rather than a proof, and that between 1830 and 1860 science was divided into vitalists and mechanists. Thirty-seven years later Buchner showed that "life and fermentation are not unalterably bound to each other", and the chemical side of the argument turned out to be right in substance, though not in mechanism. Liebig's theory is therefore marked a dead end with a caveat: what is a dead end is the particular hypothesis of transmitted decomposition, not the commitment to explaining fermentation chemically.

  Link sources

  • Geison G. L. «Pasteur, Louis», Complete Dictionary of Scientific Biography (via Encyclopedia.com) (2008) Verified 20 Sep 2026

    Above all, there is in this medium none of the ‘unstable [organic matter]’ required by Liebig's theory.

  • Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026

    The mechanical theory of fermentation, regardless of whether it interpreted yeast as an expression of a ‘catalytic force’ or of a body in the process of decomposing, clashed with Pasteur's vitalistic interpretation of the fermentation process.

  "Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.

Node sources

• Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026

  According to his theory, formulated in 1839, yeast causes fermentation because, as a body in a state of continuous decomposition, it stimulates the sugar molecules to decompose into alcohol and carbon dioxide.

• Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026

  Liebig was the exponent of the mechanists.

• James A. Barnett, «Beginnings of microbiology and biochemistry: the contribution of yeast research», Microbiology 149 (3), 557-567 (2003) Verified 20 Sep 2026

  Von Liebig and Wöhler went so far as to publish jointly in their journal, Annalen der Pharmacie, an anonymous skit mocking the microscopical findings they rejected.

"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.

Further reading

Not evidence: these carry no quotation and support nothing we wrote. They are books and scans to read next.

• Justus Liebig, «Ueber die Erscheinungen der Gährung, Fäulniß und Verwesung und ihre Ursachen», Annalen der Pharmacie 30 (1839), 3 (1839)
• Elio Schaechter, «It's Funnier When You're Right» (2014)

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