History of food microbiology

Microbiology is the study of living organisms that are so small that they can only be observed with the aid of a powerful microscope. In food microbiology, the organisms of concern are usually classified as bacteria, fungi (yeasts and molds), viruses, and parasitic protozoa

1. HISTORY OF FOOD MICROBIOLOGY Dr. Sujeet Kumar Mrityunjay, PhD Assistant Professor Department of Life Science School of Sciences ITM University, Gwalior (Turari Campus) Madhya Pradesh-474001 (India) 1

2. 2 HISTORY OF FOOD MICROBIOLOGY

3. 3 Microorganisms have always been closely related to food and food systems. Authorities believe that approximately 8,000 to 10,000 years ago, humans began to have problems associated with food poisoning and food spoilage. The importance of one’s ability to produce and preserve food was recognized early. Both livestock and salt had monetary value and could be compared to today’s currency. Wealth and social status in many cases was based upon the amount of success one had at producing in times of plenty and preserving what could not be consumed immediately for times of hardship.

4. 4 Many early religious laws prohibiting the consumption of “impure” or “unclean” foods were based on hygiene, and were similarly seen in countries not conforming to the same religious beliefs. The first individual to describe microorganisms was Kircher in 1658 who reported “worms” that were undetectable to the naked eye on several decomposing items. Shortly thereafter the theory of spontaneous generation, later known as abiogenisis , became widely accepted.

5. 5 In 1683, Leeuwenhoek’s superior knowledge of lens design allowed him to be the first to observe and record yeast cells using a primitive microscope. Spallanzani sought to disprove spontaneous generation in 1765 when his beef broth did not spoil after being boiled in a sealed container for an hour. Critics, however, disagreed, believing his process was void of oxygen, a vital ingredient to spontaneous generation.

6. 6 In 1785, the French government offered a prize to anyone who could develop a practical method to preserve food. In 1809, Nicholas Appert was successful by preserving meats that had been boiled in water in corked glass bottles. At the time, he was unaware of the microbiological logic behind this process.

7. 7 Louis Pasteur, however, was the first to understand the role of microorganisms in food. He was most noted for his heat pasteurization process to destroy deleterious organisms in beer and wine. Pasteur’s process was later commercialized in 1867. He also proved that microorganisms caused souring milk.

8. 8 Some other examples of important dates in food microbiology history include:- 1825 - U.S. patent issued for food preservation in tin cans. 1840 - Fresh fruit and fish were first canned. 1857 - Milk identified as a vector for typhoid fever. 1874 - Use of ice for transport of meat at sea was widespread. 1880 - Milk pasteurization began in Germany.

9. 9 1888 - Salmonella enteriditis isolated from meat in a food poisoning outbreak. 1895 - First bacteriological study of canning. 1906 - U.S. Congress passed the Federal Food and Drug Act. 1928 - Controlled atmosphere was commercially used for storage of apples. 1929 - Frozen foods introduced into retail markets.

10. 10 1967 - United States was the first to design a commercial irradiation facility. 1976 - In California infant botulism was identified. 1981 - First outbreak of foodborne listeriosis occurred in the U.S. 1986 - The first diagnosis of Bovine Spongiform Encephalopathy (BSE).

11. 11 Some Very old Extant 7000 BC – Evidence that the Babylonians manufactured beer (fermentation). Wine appeared in about 3500 BC. In early civilizations (and even today in underdeveloped countries where modern sanitation is lacking), alcoholic beverages like beer and wine were much safer to consume than the local water supply, because the water was often contaminated with intestinal microorganisms that caused cholera, dysentery and other serious diseases

12. 12 6000 BC – The first apparent reference to food spoilage in recorded history. 3000 BC – Egyptians manufactured cheese (fermentation) and butter (fermentation, low aw). Again, fermented foods such as cheese and sour milk (yogurt) were safer to eat and resisted spoilage better than their raw agricultural counterparts. Several cultures also learned to use salt (low aw) to preserve meat and other foods around this time. 1000 BC – Romans used snow to preserve shrimp (low temp), records of smoked and fermented meats also appear.

13. 13 Even though early human cultures discovered effective ways to preserve food (fermentation, salt, ice, drying and smoking), they did not understood how these practices inhibited food spoilage or food borne disease. Their ignorance was compounded by a belief that living things formed spontaneously from nonliving matter (Theory of Spontaneous Generation).

14. 14 1665 – An Italian physician by the name of Francesco Redi demonstrated that maggots on putrefying meat did not arise spontaneously but were instead the larval stages of flies (put meat in container capped with fine gauze so that flies couldn’t get access to deposit eggs). This was the first step away from the doctrine of spontaneous generation. 1683 – Anton van Leeuwenhoek from the Netherlands examined and described bacteria through a microscope. At about the same time, the Royal Society was established in England to communicate and publish scientific work, and they invited Leeuwenhoek to communicate his observations. He did so for nearly 50 years until his death in 1723. As a result, Leeuwenhoek’s reports were widely disseminated and he is justifiably regarded as the person who discovered the microbial world.

15. 15 1765 – Italian named Spallanzani tried to disprove the theory of spontaneous generation of life by demonstrating that beef broth which was boiled and then sealed remained sterile. Supporters of the theory discounted his work because they believed his treatment excluded O2, which they thought was vital to spontaneous generation. 1795 – The French government offered 12,000 francs to anyone who could develop a practical way to preserve food. A French confectioner named Nicholas Appert was issued the patent after showing that meat could be preserved when it was placed in glass bottles and boiled. This was the beginning of food preservation by canning.

16. 16 1837 – Schwann demonstrates that healed infusions remain sterile in the presence of air (which he passed in through heated coils), again to disprove spontaneous generation. It is interesting to note that although Spallanzani and Schwann each used heat to preserve food, neither man apparently realized the value of turning these observations into a commercial method for food preservation. (Critics suggest heating somehow changed the effect of air as it was needed for spontaneous generation.)

17. 17 The first person to really appreciate and understand the causal relationship between microorganisms in infusions and the chemical changes that took place in those infusions was Louis Pasteur. Through his experiments, Pasteur convinced the scientific world that all fermentative processes were caused by microorganisms and that specific types of fermentations (e.g. alcoholic, lactic or butyric) were the result of specific types of microorganisms.

18. 18 In 1857 he showed that souring milk was caused by microbes and in 1860 he demonstrated that heat destroyed undesirable microbes in wine and beer. The latter process is now used for a variety of foods and is called pasteurization. Because of the importance of his work, Pasteur is known as the founder of food microbiology and microbiological science. He demonstrated that air doesn’t have to be heated to remain sterile using his famous swan-necked flasks that finally disproved spontaneous generation.

19. 19 Some of Pasteur’s most notable achievements include: Demonstrated that fermentation was a product of microbial activity and that different types of fermentation (i.e. lactic, butyric, etc.) were caused by different types of microorganisms. The knowledge that microbes were responsible for fermentation and putrefaction led Pasteur to argue that microbes were also causative agents in disease. These arguments eventually reached an English surgeon named Joseph Lister who used them to develop the first aseptic surgical procedures. he developed the pasteurization process used to preserve wine

20. 20 He developed a vaccine to protect sheep from anthrax by isolating an attenuated ( avirulent ) strain of the causative bacterium, Bacillus anthracis . Pasteur isolated the attenuated organisms by growing them at elevated temperature (42˚C). Sheep exposed to the attenuated bacterium became immune to virulent strains. Although Pasteur did not understand the basis for attenuation, we now know that virulence in this bacterium depends on the presence of a plasmid that cannot replicate at 42oC. Pasteur also developed a method to make chickens immune to cholera caused by Pasteurella septica , again using an attenuated bacterium that he had isolated in his laboratory. He developed the method for treating rabies still in use today.