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Introduction to Food Microbiology - Food Microbiology - Lecture Slides - Document's extract

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Introduction to Food Microbiology, History of Food Microbiology, Sanitation, Foodborne Pathogens, Techniques in Microbiology, Molecular Genetics and Biotechnology, Topics in Food Microbiology are points of this lecture slides about food microbiology subject.

Introduction to food microbiology A brief history Topics in food microbiology Survey of microbes Docsity.com People have “practiced” food microbiology for thousands of years Docsity.com History of food microbiology • 8-10,000 years ago – Food preservation • Ca. 4,000 years ago – Fermented foods • 1600s – Early observations with microscopes • 1700s – Spontaneous generation was challenged (in experiments involving food) Docsity.com 1800s –The Golden Age of Microbiology -Cell theory -Spontaneous generation disproved -Proof that fermentation is a biological process -Germ theory of disease -Canning invented -Discovery of organisms that cause foodborne illness -Techniques for studying microbes Docsity.com Sanitation • 1849 John Snow: cholera spread through water contaminated with feces • Several waterborne pathogens isolated More pathogens isolated from food, diseased animals, feces Docsity.com Foodborne pathogens • Salmonella enteriditis- isolated from meat as well as person who ate it • Staphylococcus • Clostridium botulinum • Isolated in late 19th century • Koch’s postulates in action! Docsity.com Techniques in microbiology • • • • • • • • Pure culture technique Microscopy Staining, esp. Gram stain Sterile microbiological media (liquid and solid) Aseptic technique Methods to control microbial growth Biochemical tests to distinguish microbes Studying beneficial microbes as well as pathogens Docsity.com Molecular genetics and biotechnology • Rapid identification • Genetic engineering • Understanding mechanisms of resistance, biochemical processes, etc. Docsity.com Limitations of microbiological techniques • Most microbes cannot be grown in the laboratory • Microbes do not grow in isolation • Most microbes have not even been discovered! Docsity.com Topics in food microbiology • Fermentation/probiotics – Fermented foods and important metabolites • Making fermenting strains mo

re stable – Resistant to viruses – Enhance fermentation capacity • Understanding probiotics and their effect on the body (the microbiome) Docsity.com Food spoilage • • • • Which microbes, and under what conditions? What are the metabolites (products)? How do they work in the cold? How can they be controlled? Docsity.com Foodborne pathogens • • • • • Detection Identification Control How do we monitor and share information? Are we making the problem worse? – Antibiotic resistance – Are we introducing pathogens through our processes? Docsity.com What kinds of microbes are found in food? • Bacteria • Fungi (yeasts and molds) • Viruses • Protozoans, algae, helminths to a lesser extent • (Helminths=worms) • Protozoans and helminths are considered “accidental” Docsity.com Classification of organisms Where are viruses and prions? Docsity.com Prokaryotes vs eukaryotes prokaryotes • Smaller cells • No nucleus or organelles • Single-celled • Bacteria and archaea eukaryotes • Larger cells • Cells have nucleus and organelles • Can be single-celled or multicellular • Plantae, Animalia, Fungi, Protista • Viruses and prions are not cells so are not considered alive Docsity.com Nomenclature • Binomial name: genus and species – Ex. Salmonella typhimurium; S. typhimurium • Subspecies: – Lactococcus lactis ssp. lactis, (soft cheese) – L. lactis ssp. cremoris (hard cheese) • Serovar, pathovar, biovar Docsity.com Yeasts and molds • Yeasts: single-celled eukaryotes • Molds: multicellular structure (filaments, spores) required for reproductions • Can be used to make foods but also involved in spoilage • Saccharomyces cerevisiae: • Carbon dioxide and ethanol Docsity.com Docsity.com Molds can grow almost anywhere • • • • • Food spoilage Toxins Allergens Food processing Different genera grow on different foods – Rhizopus- fruits, vegetables, bread – Geotrichum- dairy

mold – Penicillium-spoils almost everything, but also used to make cheese Docsity.com Viruses infect cells Can cause disease Interfere with food processing Hepatitis A- infects humans Docsity.com Protozoans, algae, helminths • Protozoans can cause parasitic disease (Giardia, Cryptosporidium, Toxoplasma) • Algae- photosynthetic protists – Contaminants, food products, toxins • Helminths- parasites – Roundworms, tapeworms- contaminated food Docsity.com Life cycle of a tapeworm (helminth) Docsity.com Bacteria (“eubacteria”) • We will spend much lecture time, and most lab time, working with them • Classification is complicated and changing all the time • Most bacterial species have not been described, but many have been very well studied Docsity.com Major classification criteria • Gram-positive or Gram-negative Docsity.com Morphology Docsity.com Bacterial classification, continued • Aerobes, anaerobes, fermenters • Spore formers, non spore formers • What metabolic products do they produce? – Acids, alcohols, gases- and which ones? • What do they use for food? – Carbohydrates, lipids, proteins • Under what conditions do they grow? – Temperature range, pH range, availability of water Do they cause disease? What kind? Docsity.com What should a food microbiologist know? • Characteristics of the different types of microbes • How to identify and enumerate them • Factors that affect their growth (innate and introduced) • Fermentation vs spoilage • How microbes cause disease • That the field of food microbiology is a work in progress! Docsity.com

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