Evidence of a fermented alcoholic beverage made from fruit, honey, and rice found in Neolithic China dates back to BCE. There is also strong evidence that people were fermenting beverages in Babylon around BCE. Even before fermented alcoholic beverages were developed, humans were fermenting a type of food with notoriously poor holding qualities — dairy. Particularly, the milk of camels, goats, sheep, and cattle was naturally fermented as far back as 10, BCE.
The subtropical climate where this dairy fermentation took place likely played a large role in its occurrence, as thermophilic lactic acid fermentation favors the heat of this climate. In , a French chemist by the name of Louis Pasteur connected yeast to the process of fermentation, making him the first zymologist — or someone who studies the applied science of fermentation.
At this time, fermentation was still being used solely to increase the holding and storing properties of food. A Russian bacteriologist, Elie Metchnikoff, noted that Bulgarians had an average lifespan of 87 years, which was exceptional for the early s. In inspecting aspects of the Bulgarian lifestyle that may have set them apart and contributed to the long lifespan, Metchnikoff identified a greater consumption of fermented milks than in other cultures.
He named a bacteria found in these fermented milks Bulgarian bacillus, and he inspired a surge in the consumption of fermented milks by attributing many benefits of good health and longevity to this strain of bacteria. Bulgarian bacillus, later named Lactobacillus bulgaricus , was shown to be unable to survive in the human digestive system by Leo F. Rettger of Yale in This discovery caused a fall-off of the fermented food phenomena. Rettger continued to investigate different strains of Lactobacillus , however, concluding in that certain strains of Lactobacillus acidophillus not only could survive the environment of the human gut — they were very active!
In the last 40 years or so, extensive research has been conducted examining the health benefits of consuming friendly bacteria. There appear to be linkages between consuming these friendly bacteria and improved digestion and detoxification, among other areas. P2G35 Pasteur's and Tyndall's study of spontaneous generation. Call Number: QP P44 Studies on fermentation. The diseases of beer, their causes, and the means of preventing them by Louis Pasteur; Frank Faulkner; D.
P3 Early Fermentation Fermentation is one of the oldest forms of food processing known today. Alcoholic fermentation is possibly the most well known of the three types, its byproducts having been enjoyed by human civilization for millennia. Acetic acid fermentation is the process that begins where alcoholic fermentation ends.
The most common result of this fermentation process is vinegar. This relatively simple tool soon revolutionized man's knowledge of the heretofore invisible microbial world. In the Dutch merchant Anton van Leeuwenhoek, the greatest of the early microscopists, saw and reported one-celled organisms, which he called "animacules. Then in , using a microscope that magnified the diameter of each object fold, he looked at yeast and found them to consist of tiny spheroids.
While the protozoa were clearly alive, the yeast did not appear to be. No connection was drawn between the existence of these tiny organisms and the well known phenomenon of fermentation. So for years after van Leeuwenhoek's pioneering observations, it was hardly thought that these minute organisms could be important enough to deserve serious study. The early s saw a great increase of interest in microbiology in Europe.
The scientific period began with great advances in botany, increased interest in microscopy, and willingness to investigate individual organisms. The two major problems that would challenge the greatest researchers in the new field of microbiology concerned the basic nature of the fermentation process and the basic nature of enzymes.
The scientific breakthroughs that would lead to the unraveling of the mysteries of fermentation starting in the s were made primarily by French and German chemists. In the late s Lavoisier showed that in the process of transforming sugar to alcohol and carbon dioxide as in wine , the weight of the former that was consumed in the process equaled the weight of the latter produced.
In J. The entire process was considered to be simply a chemical reaction and yeast which was not yet even classified as a definite substance, much less a living organism instrumental to fermentation was thought to play a physical rather than a chemical role, an idea dating back to the time of Georg Stahl in It was held that either the catalytic action at the yeast cell or the molecular vibrations from the decomposing organic matter arising from the death of the cells, sparked the chemical changes resulting in fermentation.
Putrefaction, spoilage, and fermentation were all considered to be processes of death, not life. The first solid evidence of the living nature of yeast appeared between and when three publications appeared by C.
Cagniard de la Tour, T. Swann, and F. Kuetzing, each of whom independently concluded as a result of microscopic investigations that yeast was a living organism that reproduced by budding. The word "yeast," it should be noted, traces its origins back to the Sanskrit word meaning "boiling.
Soon bacteria were also discovered; the term was first used in English in the late s, but it did not come into general use until the s, and then largely in connection with the new germ theory of disease.
The view that fermentation was a process initiated by living organisms soon aroused fierce criticism from the finest chemists of the day, especially Justus von Liebig, J. Berzelius, and Friedrich Woehler. This view seemed to give new life to the waning mystical philosophy of vitalism, which they had worked so hard to defeat. Proponents of vitalism held that the functions of living organisms were due to a vital principal life force, chi, ki, prana , etc. As we shall soon see, the vitalists played a key role in debate on the nature of fermentation.
A long battle ensued, and while it was gradually recognized that yeast was a living organism, its exact function in fermentations remained a matter of controversy. The chemists still maintained that fermentation was due to catalytic action or molecular vibrations.
The debate was finally brought to an end by the great French chemist Louis Pasteur who, during the s and s, in a series of classic investigations, proved conclusively that fermentation was initiated by living organisms. In Pasteur showed that lactic acid fermentation is caused by living organisms.
In he demonstrated that bacteria cause souring in milk, a process formerly thought to be merely a chemical change, and his work in identifying the role of microorganisms in food spoilage led to the process of pasteurization. In , working to improve the French brewing industry, Pasteur published his famous paper on fermentation, Etudes sur la Biere , which was translated into English in as Studies on Fermentation.
He defined fermentation incorrectly as "Life without air," but correctly showed specific types of microorganisms cause specific types of fermentations and specific end products. In the era of modern medical bacteriology began when Koch a German physician; and Pasteur showed that the anthrax bacillus caused the infectious disease anthrax. This epic discovery led in to Pasteur's general germ theory of infectious disease, which postulated for the first time that each such disease was caused by a specific microorganism.
Koch also made the very significant discovery of a method for isolating microorganisms in pure culture. Interestingly, until his death in , the eminent German chemist J. He recognized the similarity of these phenomena but refused to believe that living organisms were the main causative agents.
Fermentation, he felt, was primarily a chemical rather than a biological process. History has shown, with the discovery of enzymes, that Pasteur was not entirely right, nor Liebig entirely wrong.
The work of Pasteur and his many colleagues and predecessors opened up vast new vistas in the fields of biochemistry, microbiology, and fermentation. The term "biochemistry" was first used in English in , but this new science of the application of chemistry to biology was generally called "physiological chemistry" until the early s.
The two outstanding pioneers were Liebig and Pasteur. The term "microbiology" was first used in English in , long after Pasteur's major discoveries. But basic knowledge of this new science of the study of minute living organisms closely related to human activity or welfare did not begin to enter the popular consciousness until the early s.
At about this time the scientific breakthroughs of the s and s had begun to produce a change in people's conception of the world around them so sweeping and profound as to be termed revolutionary. Food microbiology was finally set on a scientific foundation, based on the action of specific microorganisms.
A rational theory of infectious diseases which formerly were not differentiated from one another set people's minds free from the age-old fear of vengeance from an unknowable and invisible disease-causing entity.
And the ancient theory of spontaneous generation of lower life forms, which said they could arise de novo and fully formed from decomposing matter, was replaced by the verifiable theory of biogenesis. For the first time people began to accept the fact that they shared their environment with multitudes of minute organisms that exerted an ongoing powerful influence on human life.
This new world view, among other things, provided a tremendous stimulus for new research on fermented foods. Although showing that fermentation was generally the result of the action of living microorganisms was an epic breakthrough, it did not explain the basic nature of the fermentation process, or prove that it was caused by the microorganisms that were apparently always present. As early as the late s it had been recognized that there was another type of chemical change that resembled the yeast fermentation in some respects.
This was the sort of changes that occur, for example, in the digestion of food. In Reamur, in studying the digestive processes of a falcon, showed that its digestive juices were able to dissolve meat.
In William Irvine discovered that aqueous extracts of sprouted barley caused liquefaction of starch. The first clear recognition of what were later called "enzymes" came in when two French chemists, A.
Payen and J. Persoz, made a more detailed investigation of the process of solubilizing starch with a malt extract to form a sugar that they called "maltose. In the German naturalist Swann, mentioned above for his early work with fermentation, isolated a substance from gastric juice which could bring about the dissolution of meat but which was not an acid. He called it "pepsin" from a Greek word meaning "digestion. Under the influence of the vitalists, ferments were grouped into two types: those involved with life process were called "organized ferments" and those which were not like pepsin were merely "unorganized ferments.
Traube put forward the theory that all fermentations were due to ferments, definite chemical substances he regarded as related to the proteins and produced in the cells by the organism. In , to reduce confusion that existed concerning the two types of ferments, the German physiologist Wilhelm Kuehne suggested that an unorganized ferment, acting in the absence of life, be called an "enzym," after the Greek words meaning "in yeast;' in this term was anglicized to "enzyme" by William Roberts, and it had begun to catch on by the s.
Many scientists, including Pasteur, had attempted unsuccessfully to extract the fermentation enzyme from yeast. Success came finally in when the German chemist Eduard Buechner ground up yeast, extracted a juice from them, then found to his amazement that this "dead" liquid would ferment a sugar solution, forming carbon dioxide and alcohol. Clearly the so-called "unorganized ferments" behaved just the organized ones.
From that time on the term "enzyme" came to be applied to all ferments. The term "ferment" dropped out of the scientific vocabulary altogether and the vitalist position collapsed, never to recover. Thereafter it was agreed that only one set of laws applied to all things, both animate and inanimate, and that there was no special vital force which characterized living things and acted under different laws.
And it was finally understood that fermentation is caused by enzymes which are produced by microorganisms. In Buechner won the Nobel Prize in chemistry for his work, which opened a new era in enzyme and fermentation studies. The sciences of microbiology, biochemistry, fermentation technology, mycology, and bacteriology all shared a deep interest in the nature and working of enzymes. Yet still by the early s no one knew exactly what enzymes were or how they acted.
As the agricultural microbiologist Conn asked in , "How can they produce chemical actions without being acted upon or entering into the reactions? Are enzymes fully lifeless or semi-living? We still do not know the fundamental mystery of fermentation. In Harden and Young discovered coenzymes, agents necessary for the action of enzymes. In the American biochemist J.
Sumner first purified and crystallized an enzyme urease and showed that it was a protein, more precisely a protein catalyst. Eventually enzymes came to be seen as the key catalysts in all the life processes, each highly specialized in its catalytic action and generally responsible for only one small step in complex, multi-step biochemical reactions.
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