2. Food Microbiology
Microbiology is the study of organisms
too small to be seen with the unaided
eye
Food microbiology is a subdivision of
microbiology
3. Food Microbiology Studies
Microbes that cause diseases in food
Microbes that cause spoilage in food
Microbes that produce food
How food environments influence
microbes
This science has changed
dramatically over the last 20 years
4. Microorganisms
Were the first organisms to colonize
Earth
Colonize just about every inch of the
Earth’s surface
Most species are either harmless or
beneficial
Pathogenic species can cause
disease
5. Microorganisms
Decompose organic waste
Are producers in the ecosystem by
photosynthesis
Produce industrial chemicals such as ethyl
alcohol and acetone
Produce fermented foods such as vinegar,
alcoholic beverages, cheeses and breads
Produce antibiotics and vaccines
6. Groups of Microbes
Bacteria
Fungi
Protozoa
Algae
Viruses
Helminthes (parasitic worms)
Prions (infectious altered proteins)
Spores and toxins produced by each group
are important
7. Bacteria
Prokaryotes
Reproduce by binary fission at
phenomenal rates
For energy they use organic
chemicals, inorganic chemicals, or
photosynthesis
10. Fungi
Eukaryotes
Use organic chemicals for energy
Molds are multicellular
Yeasts are unicellular
Many produce foods and some
species can cause food spoilage
15. Protozoa
Eukaryotes
Are usually unicellular
Inhabit the water and soil
Absorb or ingest organic chemicals
Can contaminate food and water
supplies
17. Algae
Eukaryotes
Cellulose cell walls
Use photosynthesis for energy (like
terrestrial plants)
Produce molecular oxygen and organic
compounds
Many can produce toxins that
contaminate food and water
20. Viruses
Acellular (non-living)
Consist of DNA or RNA core
Core is surrounded by a protein coat called
a capsid
Viruses are replicated only when they are in
a living host cell
Many are transmitted via contaminated food
or water, and many pass directly from
human to human contact
22. Helminthes
Eukaryotes
Multicellular animals – most are not
parasitic
Some parasitic species are tapeworms,
flukes, and roundworms
Microscopic stages exist in their complex
life cycles
The eggs or larvae of many species can
contaminate meat products and seafood
25. History of Food Microbiology
Humans were originally hunter-
gatherers
Food preservation and storage
procedures were not adequately
developed
Early preservation methods were
most likely accidental
26. History of Food Microbiology
Sun-dried, salted, or frozen foods did
not spoil
Early humans learned to enjoy
“spoiled” milk products
Fermentation became an organized
activity around 4000 B.C.
Knowledge of the presence of
microbes did not occur until the mid-
1600s
27. History of Food Microbiology
In 1665, Robert Hooke published
Micrographia that included the
structure of Mucor, a genus of fungus
In 1676, Antony van Leeuwenhoek
used a crude microscope to study
pond water
28.
29. Biogenesis
The hypothesis that living organisms arise
from nonliving matter is called spontaneous
generation.
The alternative hypothesis, that the living
organisms arise from preexisting life, is
called biogenesis.
In the mid-1700s, Lazzaro Spallanzini tried
to disprove spontaneous generation by
placing boiled meat into sealed containers
to prevent spoiling
30. 1861: Louis Pasteur demonstrated that
microorganisms are present in the air with his
S-shaped flask – disproving spontaneous
generation
31. Louis Pasteur
Commonly called the “Father of
Microbiology”
Showed that microbes are responsible
for fermentation.
Fermentation is the conversion of
sugar to alcohol to make beer and
wine.
32. Louis Pasteur
Microbial growth is also responsible for
spoilage of food.
Bacteria that use alcohol and produce
acetic acid spoil wine by turning it to vinegar
(acetic acid).
Pasteur demonstrated that these spoilage
bacteria could be killed by heat that was not
hot enough to evaporate the alcohol in wine
This application of a high heat for a short
time is called pasteurization
33. History of Food Microbiology
Napolean offered a prize to anyone
who could preserve food
Nicolas Appert won this prize by
heating foods and then canning them
It was not until the 1900s that the
process of canning was fully
understood
34. Robert Koch
1876: provided proof that a
bacterium, Bacillus anthracis,
causes anthrax
Developed Koch’s postulates,
which are used to prove that a
specific microbe causes a specific
disease.
37. Other contributions from
Koch’s lab
Julius Petri invented the petri dish
Walter Hesse began to use agar
instead of gelatin to solidify
microbial media (he got the idea
from his wife)
38. Modern Contributions
Many foodborne pathogens were
discovered in the early to mid 20th
century
Bacteria: Salmonella species,
Clostridium botulinum,
Staphylococcus aureus, Bacillus
cereus
Viruses were first crystallized and
associated with disease in the 1930s
39. Modern Contributions
James Watson and Francis Crick
discovered the structure of DNA in the
middle of the 20th century
This led to a better understanding of
microbes and how they cause illness,
how we can detect them, how we can
use them in industry
Molecular biology is vital to food
microbiology
40. Modern Contributions
GMPs (good manufacturing practices)
provide manufacturers with procedures
that yield safe products
HACCP (hazard analysis critical control
point) plans help to assure safety at
each key step of the manufacturing
process
Food irradiation is approved as “kill” step
in the processing of raw poultry and
meat
41. Recent Concerns
About 1/3 of the world’s food supply is
lost to spoilage
The world is demanding safer food
“Globalization” of the food supply can
cause problems with sanitation
standards
The causes of ½ of foodborne illness
cases are unknown (over 90% of
bacteria remain undiscovered)