Introduction to Food Microbiology - Food Microbiology - Lecture Slides, Slides for Microbiology. Shoolini University of Biotechnology and Management Sciences

Microbiology

Description: 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.
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Introduction to food microbiology

Introduction to food microbiology

A brief history Topics in food microbiology

Survey of microbes

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People have “practiced” food microbiology for thousands of years

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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)

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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

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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!

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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

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Molecular genetics and biotechnology

• Rapid identification • Genetic engineering • Understanding mechanisms of resistance,

biochemical processes, etc.

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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!

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Topics in food microbiology

• Fermentation/probiotics – Fermented foods and important metabolites

• Making fermenting strains more stable – Resistant to viruses – Enhance fermentation capacity

• Understanding probiotics and their effect on the body (the microbiome)

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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?

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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?

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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”

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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

• Viruses and prions are not cells so are not considered alive

eukaryotes • Larger cells • Cells have nucleus and

organelles • Can be single-celled or

multicellular • Plantae, Animalia, Fungi,

Protista

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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

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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

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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

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Viruses infect cells

Hepatitis A- infects humans

Can cause disease Interfere with food processing

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Protozoans, algae, helminths

• Protozoans can cause parasitic disease (Giardia, Cryptosporidium, Toxoplasma)

• Algae- photosynthetic protists – Contaminants, food products, toxins

• Helminths- parasites – Roundworms, tapeworms- contaminated food

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Life cycle of a tapeworm (helminth)

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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

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Major classification criteria

• Gram-positive or Gram-negative

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Morphology

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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?

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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!

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