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Food Microbiology Lecture 2.pptx
- 3. In 1658- First person-role of microorganisms in spoiling foods- A. Kircher Saw what he referred to as “worms” invisible to the naked eye
- 4. Food Preservation 1782—Canning of vinegar was introduced by a Swedish chemist 1810—Preservation of food by canning was patented by Appert in France 1813—Use of SO2 as a meat preservative 1825—T. Kensett and E. Daggett were granted a U.S. patent for preserving food in tin cans 1835—A patent was granted to Newton in England for making condensed milk 1839—Tin cans came into wide use in the United States
- 5. 1840—Fish and fruit were first canned 1843—Sterilization by steam was first attempted by I. Winslow 1853—R. Chevallier- Appert obtained a patent for sterilization of food by autoclaving 1854—Pasteur began wine investigations Heating to remove undesirable organisms was introduced commercially in 1867–1868 1855—Grimwade in England was the first to produce powdered milk
- 6. 1865—The artificial freezing of fish on a commercial scale was begun in the United States 1874—The first extensive use of ice in transporting meat at sea was begun 1874—Steam pressure cookers or retorts were introduced 1880—The pasteurization of milk was begun in Germany 1886—A mechanical process of drying fruits and vegetables was carried out by an American, A.F. Spawn 1890—The commercial pasteurization of milk was begun in the United States 1907—E. Metchnikoff and co-workers isolated and named one of the yogurt bacteria, Lactobacillus delbrueckii subsp. bulgaricus
- 7. 1916—The quick freezing of foods was achieved in Germany by R. Plank, E. Ehrenbaum, and K. Reuter 1954—The antibiotic nisin was patented in England for use in certain processed cheeses to control clostridial defects 1955—Sorbic acid was approved for use as a food preservative 1967—The first commercial facility designed to irradiate foods was planned and designed in the United States 1988—Nisin was accorded GRAS (generally regarded as safe) status in the United States 1990—Irradiation of poultry was approved in the United States
- 9. Food Fermentation 1822 C.J. Person named the microscopic organism found on the surface of wine during vinegar production as Mycoderma mesentericum Pasteur in 1868 proved that this organism was associated with the conversion of alcohol to acetic acid and named it Mycoderma aceti In 1898, Martinus Beijerinck renamed it Acetobacter aceti 1837 Theodor Schwann named the organism involved in sugar fermentation as Saccharomyces (sugar fungus) 1838 Charles Cogniard-Latour suggested that growth of yeasts was associated with alcohol fermentation 1860 Louis Pasteur showed that fermentation of lactic acid and alcohol from sugar was the result of growth of specific bacteria and yeasts, respectively 1883 Emil Christian Hansen used pure cultures of yeasts to ferment beer
- 10. Food Spoilage 1804 Francois Nicolas Appert developed methods to preserve foods in sealed glass bottles by heat in boiling water. He credited this process to Lazzaro Spallanzani (1765), who first used the method to disprove the spontaneous generation theory 1819 Peter Durand developed canning preservation of foods in steel cans 1870 L. Pasteur recommended heating of wine at 62.7°C for 30 min to destroy souring bacteria. F. Soxhlet advanced boiling of milk for 35 min to kill contaminated bacteria. Later, this method was modified and named pasteurization, and used to kill mainly vegetative pathogens and many spoilage bacteria 1895 Harry Russell showed that gaseous swelling with bad odors in canned peas was due to growth of heat- resistant bacteria (spores) Louis Pasteur
- 12. Foodborne Diseases 1820 Justin Kerner described food poisoning from eating blood sausage (due to botulism). Fatal disease from eating blood sausage was recognized as early as A.D. 900 1849 John Snow suggested the spread of cholera through drinking water contaminated with sewage In 1854, Filippo Facini named the cholera bacilli as Vibrio cholera, which was isolated in pure form by Robert Koch in 1884 1856 William Budd suggested that water contamination with feces from infected person spread typhoid fever and advocated the use of chlorine in water supply to overcome the problem In 1800, G. de Morveau and W. Cruikshank advocated the use of chlorine to sanitize potable water John Snow
- 13. 1885 Theodor Escherich isolated Bacterium coli (later named Escherichia coli) from the feces and suggested that some strains were associated with infant diarrhea 1888 A.A. Gartner isolated Bacterium (later Salmonella) enteritidis from the organs of a diseased man as well as from the meat the man ate In 1896, Marie von Ermengem proved that Salmonella enteritidis caused a fatal disease in humans who consumed contaminated sausage 1894 J. Denys associated pyogenic Staphylococcus with death of a person who ate meat prepared from a diseased cow 1895 Marie von Ermengem isolated Bacillus botulinus (Clostridium botulinum) from contaminated meat and proved that it caused botulism Theodor Escherich
- 14. Microbiology Techniques 1854 Heinrich Schröder and Theodore von Dusch used cotton to close tubes and flasks to prevent microbial contamination in heated culture broths 1876 Car Weigert used methylene blue (a synthetic dye) to stain bacteria in aqueous suspensions 1877 Ferdinand Cohn showed heat resistance of Bacillus subtilis endospores 1878 Joseph Lister isolated Streptococcus (now Lactococcus lactis) in pure culture by serial dilution from sour milk 1880s Robert Koch and his associates introduced many important methods that are used in all branches of microbiology, such as solid media (first gelatin, then agar) to purify and enumerate bacteria, Petri dish, flagellar staining, steam sterilization of media above 100ºC, and photography of cells and spores 1884 Hans Christian Gram developed Gram staining of bacterial cells Robert Koch