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Exhibition: Brewing Mysteries

  • A man stands next to a large cylindrical beer vat and gazes into the vat through a small opening in the conical cover.

    Engraving of a beer vat designed by Louis Pasteur, ca. 1880

    Courtesy National Library of Medicine

    The closed fermentation tank prevented air-borne bacteria from entering and spoiling the brew.

  • Three men working at large uncovered wood beer vats under a high vaulted structure.

    “The Brewer,” engraving by Jost Amman, 16th century

    Courtesy National Museum of American History

  • Black and white drawing of various flasks, laboratory set ups, and microorganisms from Louis Pasteur’s research on fermentation.

    Drawings by Louis Pasteur of microscopic organisms, culturing vessels and equipment from his experiments, 1861

    Courtesy Library of Congress

  • Head and shoulders drawing of Louis Pasteur surrounded by a starburst pattern.

    French chemist Louis Pasteur, 1889

    Courtesy National Library of Medicine

    Pasteur’s work is celebrated as laying the foundation for the science of bacteriology. His investigations on the behalf of French industry established tools and techniques necessary for controlling the productive and destructive power of microorganisms.

  • Bulb-shaped glass flask with two long thin necks sits next to an upright brass microscope on a small metal stand.

    Études sur la Bière (Studies on Beer)  by Louis Pasteur, 1876

    Courtesy National Library of Medicine

    Pasteur published the results of his study of beer-making as Études sur la Bière in 1876. This illustration from his book demonstrates a method for examining the yeast in beer without exposing the sample to contamination from other microorganisms. His publication included plans for a fermentation tank that would prevent air-borne bacteria from entering and spoiling the brew.

  • Bulb-shaped glass flask with two long thin necks sits next to an upright brass microscope on a small metal stand.

    Pasteur flask, early 20th century

    Courtesy National Museum of American History

    Microscope, made in France by Nachet et Fils, ca. 1860

    Courtesy National Museum of American History

    Pasteur used special tools and methods for studying the activity of microorganisms in the brewing process. Flasks with long curved necks allowed oxygen to get in while keeping unwanted microbes out. Improvements in microscope lenses made the identification of different microorganisms possible.

  • Black and white drawing of yeast cells as seen through a microscope.

    Yeast, Études sur la Bière (Studies on Beer)  by Louis Pasteur, 1876

    Courtesy National Library of Medicine

    An illustration in Pasteur’s book shows what healthy and worn-out yeast cells look like when viewed through the microscope.

  • Diagram of cylindrical beer vat and a cross-section of the same beer vat showing various parts.

    Diagram and cross-section of beer vat, Études sur la Bière (Studies on Beer) by Louis Pasteur, 1876

    Courtesy National Library of Medicine

  • Four glass test tubes with paper labels and cotton plugs. Dried culture media is in three tubes and a metal cotton swab is in the fourth.

    Prepared culture tubes and sterile swab, Parke, Davis & Company, 1898

    Courtesy National Museum of American History

    These culture tubes were used to grow microbes for identification. They contain a special preparation of nutrients in a jelly-like base. A sterile instrument like the swab was used to transfer the test substance to the tube.

  • Color plate with ten illustrations of lactic acid bacteria growing in test tubes and on culture plates.

    “Bacterium Acidi lactici,” Atlas of Bacteriology, 1897

    Courtesy National Library of Medicine

    Lactic-acid bacteria, a major cause of spoilage in the brewing process, are shown growing on a variety of culture media. Brewing handbooks described the tools and techniques needed for the study of yeasts and bacteria encountered in the brewing process.

  • Drawing of an incubator with its door open to show flasks and culture tubes inside.

    “Incubator” from The American Handy Book of the Brewing, Malting and Auxiliary Trades, by Robert Wahl, PhD, and Max Henius, PhD, 1901

    Courtesy National Museum of American History

    Brewing handbooks described the tools and techniques needed for the study of yeasts and bacteria encountered in the brewing process.

  • White ceramic filter tube with nipple on one end and metal pipe-like case for the ceramic filter.

    Pasteur Chamberland filter, early 20th century

    Courtesy National Museum of American History

    Bacterial filters were an essential tool for securing a supply of uncontaminated water and for purifying products in industrial applications. This porcelain filter, developed in Pasteur’s laboratory, had tiny pores that allowed fluids to pass through while holding back bacteria and other microorganisms.

  • Three black and white drawings of globules of yeast.  Yeast are represented by groups of spheres arranged in small clusters.

    Drawing of Yeast  by Anton van Leeuwenhoek, 1680

    Courtesy National Library of Medicine

    Dutch lens maker Anton van Leeuwenhoek was probably the first person to see yeast. He made this drawing in 1680, after viewing beer through his primitive homemade microscope.

  • Animation on the process of fermentation

    “How did they ferment beer?”

    Created by Link Studio


fermentation iconBeer making is an old technology that relies on microorganisms. Brewers, however, barely knew of the existence of microbes, much less the critical role they played in their livelihood. Problems encountered in beer production, motivated scientists to study the secrets of this “invisible world.”

In the mid-19th century, chemist Louis Pasteur worked with French beer makers to discover what was causing their product to spoil. Through his investigation into the “diseases” of beer, Pasteur demonstrated the essential role that yeast, a tiny living organism, played in the fermentation process and identified microorganisms that caused beer to go bad.

Breweries, as well as other fermentation based industries, adopted new scientific tools and techniques in order to better control the productive and destructive power of microorganisms.

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