lesson 6

lesson 6 - 3 Categories of Microorganisms in Food: Spoilage...

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3 Categories of Microorganisms in Food: Spoilage organisms which caus food to become inedible, ex. Molding bread Pathogens which cause disease est. 76 million get sick each year Beneficial microorganisms serve useful functions (fermentation, probiotics) All microorganisms are too small to be seen by the naked eye Antoni van Leeuwenhoek and ‘wee animalcules’ was a dutch cloth merchant. He was the first to observe living bacteria; he referred to these microorganisms as ‘wee animalcules’. Conducted expierement with two ladies (wife and daughter) and two elderly men who had never brushed their teeth before, he described the motions of the bacteria , observed using a microscope and looking at teeth plaque. Louis Pasteur (chemist, contributed to vaccines rabies and anthrax)& spontaneous generation -Louis Pasteur was a French chemist who debunked the myth of spontaneous generation . Pasteur showed that microorganisms caused food to spoil -Proved through heating meat broth that there is no such thing as spontaneous generation, put it in S shaped glass and it stayed clean, then bent it into bottom and it got dirty, Pasteurization is named after him. Robert Koch’s Postulates (1890) - Won nobel peace prize, working with cattle infected with Bacillus anthrasis (anthrax) Koch was able to inject the blood of diseased cattle into mice, causing the mice to come down with the anthrax. The blood was then cultured, re-injected into the healthy mice and the disease again formed, this led to the Germ theory of disease- that a particular agent was responsible for causing disease Two Types of Cell Structure Work by early microbiologists, set the groundwork that led to advances in medicine and food preservation techniques. Eukaryotic- membrane bound DNA, contained by cell membrane (cell wall) examples: humans, plants, insects, animals. Prokaryotic- DNA is free, no membrane structure surrounding the DNA, DNA molecules are loosely contained within an area called the nucleoid. Bacter are Prokaryotes, the fact that they have a different cell structure form humans is an advantage in fighting bacterial diseases. Types of Microorganisms:
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Bacteria- single cell prokaryotes- found in nearly all natural environments, very small, approx. 10 times more bacteria cells then human cells within the body, can contribute to food spoilage, cause disease, or ferment milk into cheese or yogurt. Typically a few micrometers, must be magnified tens of thousands of times for humans to see. Yeast- are single cell cukaryotes, important in fermentation of bread and wine. Can be beneficial- species
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lesson 6 - 3 Categories of Microorganisms in Food: Spoilage...

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