Language
Country/Area
No result found
Louis Pasteur's legendary discovery: Why do beer and wine ferment so differently?
In the field of biochemistry, fermentation theory refers to the historical study of natural fermentation processes, especially alcoholic and lactic acid fermentations. Louis Pasteur was an important contributor, formulating a theory of the fermentation process based purely on microorganisms, and his experimental results laid the foundation for fermentation science. Pasteur's discovery not only affected the theory of fermentation, but also promoted the development of the theory of pathogenic microorganisms, making the theory of spontaneous generation a thing of the past. Before Pasteur's research, although humans had been using fermentation technology for thousands of years, the underlying biological and chemical processes were not fully understood.
Overview of fermentation
Fermentation is an anaerobic metabolic process that converts sugars into acids, gases, or alcohols, especially in an oxygen-deprived environment. Yeast and many other microorganisms commonly use fermentation to perform necessary anaerobic respiration. Even the human body undergoes fermentation during prolonged exercise. For example, during marathon running, lactic acid accumulates in the muscles. Although fermentation produces less ATP than aerobic respiration, it does so at a much faster rate.
Fermentation has been used consciously by humans since 5000 BC. Microbial residues similar to the winemaking process were found in jars excavated in the Zagros Mountains of Iran.
Historical background
Prior to Pasteur's research, there were some preliminary competing concepts about fermentation. Justus von Liebig, a scientist who had a major influence on fermentation theory, believed that fermentation was primarily a decomposition process caused by the exposure of yeast to air and water. In contrast, Charles Caniard de la Tour and the cell theorist Théodore Schwann believed that alcoholic fermentation relied on biological processes in the yeast Saccharomyces cerevisiae.
Pasteur noted some extraordinary properties, such as the ability of amyl alcohol, a by-product of lactic acid and alcoholic fermentation, to "rotate the plane of polarized light" and "asymmetric atomic arrangements." These characteristics were characteristic of organic compounds, but they became obstacles to his research.
Pasteur observed the microorganisms responsible for alcoholic fermentation through a microscope in 1856 while he was a professor of science at the University of Lille. Legend has it that Pasteur's chemistry students asked him for help in overcoming his failures in winemaking. While conducting experiments in a winery, he noticed that the yeast foam became longer when lactic acid was produced, while it was rounder and fuller when alcohol was produced. Among different observations, he examined particles on grape vines that revealed the presence of living cells that, when soaked in grape juice, caused an active alcoholic fermentation process. These observations provided a preliminary hypothesis for his future experiments.
Pasteur’s Theory of Spontaneous Generation
In the 1860s and 1870s, Pasteur criticized Pouchet's theory and conducted his own experiments. His first experiment involved boiling sugar-yeast water sealed in an air-tight device. He found that feeding high-temperature, sterilized air kept the mixture unchanged, while introducing atmospheric dust revealed the presence of microorganisms and mold. 's appearance. This led him to conclude that dust in the air carried microorganisms that were responsible for the "spontaneous formation" he observed.
Pasteur's experiments confirmed that the growth of bacteria in nutrient solutions was supported by a biological process, challenging the theory of spontaneous generation.
Current application
Today, the fermentation process plays an important role in a variety of applications in daily life, including medicines and the production of beverages and food. Currently, many companies such as Genencor International are involved in the production of enzymes in the fermentation process, with annual revenue exceeding $400 million. In addition, many drugs, such as antibiotics, are also made through the fermentation process. For example, steroid drugs can be prepared by fermenting diosgenin, a plant steroid, using enzymes provided by Rhizopus nigricans.
Yeast is widely used in the production of various alcoholic beverages. Examples of distilled alcoholic beverages, including classic moonshine, and foods such as yogurt are also products of fermentation, which is a fermentation containing the lactic acid bacteria Lactobacillus bulgaricus and Streptococcus thermophilus. dairy.
With the advancement of science, Pasteur’s research has brought us an understanding of the different microbial mechanisms behind beer and wine fermentation. However, humans still know very little about the potential capabilities of these yeasts and microorganisms. What can you find in these ancient technologies?
