Biotechnological History A: Fermentation, Beer, Bread & Cheese

Vocabulary flashcards covering key historical milestones, prominent scientists, biochemical pathways, and products from the history of fermentation biotechnology.

Fermentation

A biological transformation process in which microorganisms such as yeasts and bacteria convert nutrients into products including ethanol, organic acids, gases, aromas, and other metabolites.

Neolithic China Fermented Beverage (~7000 BCE)

The earliest known fermented drink, evidenced by archaeological findings in Neolithic China, made from rice, honey, and fruit.

Godin Tepe

An archaeological site in Mesopotamia containing evidence of fermented cereal beverages dating back to the 4th millennium BCE.

Preservation by Fermentation

A food preservation strategy prior to refrigeration where acids, alcohol, salt, and microbial competition create conditions unfavorable to unwanted microorganisms.

Brewing Sequence

The eight-step controlled technological process consisting of: (1) malting, (2) mashing, (3) boiling, (4) cooling, (5) yeast inoculation, (6) fermentation, (7) maturation, and (8) packaging.

Starter Cultures

Microbial inoculants used in cheese-making to acidify milk, working alongside enzymes to influence curd formation, texture, aroma, and ripening.

Louis Pasteur

French scientist (1822–1895) whose research between 1857 and the 1870s showed that specific microorganisms cause specific fermentations, shifting fermentation from craft to an experimentally understood biological process.

Theodor Schwann

German scientist (1810–1882) whose 1837 experiments provided evidence supporting the concept that yeast is a living organism involved in alcoholic fermentation.

Emil Christian Hansen

Carlsberg Laboratory researcher (1842–1909) who developed methods in 1883 for isolating and propagating pure yeast cultures, replacing unpredictable mixed cultures.

Eduard Buchner

Biochemist (1860–1917) who demonstrated cell-free fermentation in 1897 using yeast extract, isolated zymase, and received the Nobel Prize in 1907.

Zymase

The enzymatic activity in cell-free yeast extract identified by Eduard Buchner in 1897 that catalyzes alcoholic fermentation without living yeast cells.

Glycolysis (Alcoholic Fermentation Step 1)

The initial biochemical step of fermentation where glucose is converted into pyruvate, yielding ATP and NADH.

Decarboxylation (Alcoholic Fermentation Step 2)

The biochemical step in alcoholic fermentation where pyruvate loses $\text{CO}_2$ to form acetaldehyde.

Reduction (Alcoholic Fermentation Step 3)

The final biochemical step in alcoholic fermentation where acetaldehyde is reduced to ethanol and $\text{NAD}^+$ is regenerated.

Alcoholic Fermentation Overall Reaction

The biochemical transformation pathway in yeast under oxygen-limited conditions represented by: $\text{glucose} \rightarrow \text{ethanol} + \text{CO}_2$.

Pure Culture Revolution

The 1883 breakthrough initiated by Emil Christian Hansen that enabled industrial brewers to utilize specifically selected single yeast strains for consistent fermentation.