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Plate 4. Germ Theory. Miasma. During the 1800s, the miasma theory of disease dominated medical thought It was believed that disease could be caused by the foul smells created by decomposing bodies, food, human waste, marsh gases and general filth.
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Plate 4 • Germ Theory
Miasma • During the 1800s, the miasma theory of disease dominated medical thought • It was believed that disease could be caused by the foul smells created by decomposing bodies, food, human waste, marsh gases and general filth. • Road sweeping was one way to help clean up the streets and hopefully prevent the spread of disease. http://www.sciencemuseum.org.uk/hommedia.ashx?id=7673&size=Small
The Problem • Wine did not have consistent flavors from one year to the next • Microscopic examination showed that yeast and bacteria were in spoiled wine and yeast alone in good wine http://wpcontent.answers.com/wikipedia/commons/f/f6/Kombuchacultsm.jpg
Vinegar • The word "vinegar" comes from the Old French vin aigre, meaning "sour wine". http://www.touchofeurope.net/linens/Vinegars.html
Pasteur’s Experiment • Pasteur boiled grape juice (w/ yeast) plugged and let cool – no growth • When added just yeast then grape juice turned into good wine so he determined that yeast was necessary for wine http://www.icbm.de/~palmikro/mikrobiologischer-garten/pics/hefe_ph.jpg
Pasteur’s Experiment • Bacteria are agents of change – they alone sour wine • Acetobacter aceti bacteria turn alcohol and sugars into acetic acid http://www.vinegarman.com/zoo_vinegar_bacteria1.shtml
Pasteur’s Conclusion • Microorganisms might be agents that cause disease • Pasteurization (rapid heating and cooling) retards spoilage by killing all living cells, does not kill spores of bacteria (milk, OJ, many food products)