•Chapter Number 2
•Understanding the
Microworld
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2.0
Learning Objectives
After this presentation, you should be able to complete the following
Learning Outcomes
2.1
Factors that affect the growth of foodborne
pathogens (FAT TOM)
2.2
Characteristics of TCS food
2.3
Major foodborne pathogens and their sources
2.4
2.5
Ways of preventing viral, bacteria, parasitic, and fungal
contamination
Naturally occurring toxins and how to
prevent their illnesses
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2.0 KEY TERMS
• Microorganisms:
Small, living organisms
that can be seen only with the aid of a
microscope. There are four types of
microorganisms that can contaminate food
and cause foodborne illness: bacteria,
viruses, parasites, and fungi.
• Pathogens: Illness-causing
microorganisms.
• Toxins: Poisons produced by pathogens,
plants, or animals. Some occur in animals as
a result of their diet.
2.0 KEY TERMS
• Bacteria: Single-celled, living microorganisms
that can spoil food and cause foodborne illness.
Bacteria present in food can quickly multiply to
dangerous levels when food is incorrectly
cooked, held, or reheated. Some form spores
that can survive freezing and very high
temperatures.
• FAT TOM: Acronym for the conditions needed
by most foodborne microorganisms to grow:
food, acidity, temperature, time, oxygen,
moisture.
2.0 KEY TERMS
• Temperature danger zone:
The
temperature range between 41° and 135°F
(5° to 57°C), within which most foodborne
microorganisms rapidly grow.
• Water activity (a): Amount of moisture
available in food for microorganisms to grow.
It is measured in a scale from 0.0 to 1.0, with
water having a water activity (aw) of 1.0. TCS
food typically has a water-activity value of
0.85 or higher.
2.0 KEY TERMS
• Spore: Form that some
bacteria can take to protect
themselves when nutrients
are not available. Spores
are commonly found in dirt
and can contaminate food
grown there. A spore can
resist heat, allowing it to
survive cooking
temperatures. Spores can
also revert back to a form
capable of growth. This can
occur when food is not held
at the correct temperature
or cooled or reheated
correctly.
• Virus: Smallest of the
microbial food
contaminants. Viruses rely
on a living host to
reproduce. They
usually contaminate food
through a food handler’s
incorrect personal
hygiene. Some survive
freezing and cooking
temperatures.
2.0 KEY TERMS
• Spore: Form that some
bacteria can take to protect
themselves when nutrients
are not available. Spores
are commonly found in dirt
and can contaminate food
grown there. A spore can
resist heat, allowing it to
survive cooking
temperatures. Spores can
also revert back to a form
capable of growth. This can
occur when food is not held
at the correct temperature
or cooled or reheated
correctly.
• Virus: Smallest of the
microbial food
contaminants. Viruses rely
on a living host to
reproduce. They
usually contaminate food
through
a food handler’s incorrect
personal
hygiene. Some survive
freezing and
cooking temperatures.
2.0 KEY TERMS
• Parasite: Organism that
needs to live in a host
organism to survive. Parasites
can be found in water and
inside many animals, such as
cows, chickens, pigs, and fish.
Correct cooking and freezing
will kill parasites. Avoiding
cross-contamination and
practicing correct
handwashing can also prevent
illness.
• Fungi: Ranging in size from
microscopic, single-celled
organisms to very large,
multicellular organisms, fungi
most often cause food to spoil.
Molds, yeasts, and
mushrooms are examples.
• Mold: Type of fungi that
causes food spoilage. Some
molds produce toxins that can
cause foodborne illness.
• Yeast: Type of fungi that
causes food spoilage.
2.1
Factors That Affect the Growth of Foodborne
Pathogens
OOD
CIDITY
IME
F A T T OM
EMPERATURE
XYGEN
OISTURE
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2.1
Factors That Affect the Growth of Foodborne
Pathogens
FOOD
Most bacteria need
nutrients such as
carbohydrates or
proteins to survive. This
includes meat, poultry,
dairy products, and
eggs.
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2.1
Factors That Affect the Growth of Foodborne
Pathogens
ACIDITY
Bacteria grow
best in food that is
Bread – pH 5.0 – 6.0
neutral to slightly
Raw Chicken – pH 5.5 – 6.0
acidic, a pH of 7.5 to
4.6. The following
common types of food
Canteloupe – pH 6.1 – 6.5
have a pH that is ideal
Milk – pH 6.4 – 6.8
for bacterial growth:
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2.1
Factors That Affect the Growth of Foodborne
Pathogens
TEMPERATURE
Bacteria grow rapidly
between 41° and 135°F
(5° and 57°C) This is
called the Temperature
Danger Zone.
Bacteria grow even
more rapidly from 70°
to 125°F (21° to 52°C).
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2.1
Factors That Affect the Growth of Foodborne
Pathogens
TIME
Bacteria need time
to grow. The more
time bacteria spend
in the temperature
danger zone, the
more opportunity
they have to grow to
unsafe levels.
Foodborne
Illness
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2.1
Factors That Affect the Growth of Foodborne
Pathogens
OXYGEN
Some bacteria need oxygen to grow. Others grow
when oxygen is not there. Bacteria that grow without
oxygen can occur in:
Cooked Rice
Garlic/Oil
Mixes
Baked
Potatoes
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2.1
Factors That Affect the Growth of Foodborne
Pathogens
MOISTURE
– Bacteria grow well in food with high levels of
moisture.
– The amount of moisture available in food for this
growth is called water activity (aw).
– The aw scale ranges from 0.0 to 1.0. The higher the
value, the more available moisture in the food.
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2.2
Characteristics of TCS Food
TCS (Time and Temperature Control for Safety):
TCS food is typically moist and contains protein, as
well as having a neutral or slightly acidic pH.
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2.2
Characteristics of TCS Food
TCS (Time and Temperature Control for Safety):
This food also has a history of involvement in
foodborne illness outbreaks, as well as a natural
potential for contamination due to methods used to
produce/process it.
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2.3
Major Foodborne Pathogens
• Microorganisms are small, living organisms that
can be seen only through a microscope.
• Many microorganisms are harmless, but some
can cause illness. These are called pathogens.
• Some pathogens make you sick when you eat
them.
• Others produce poisons—or toxins—that make
you sick.
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2.3
Major Foodborne Pathogens
Person to person
Touching dirty Sneezing or
food-contact
vomiting
surfaces and onto food or
then touching food-contact
food
surfaces
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2.3
Major Foodborne Pathogens
• The symptoms of a foodborne illness vary,
depending on which illness a person has. But
most victims share some common symptoms:
– Diarrhea
– Vomiting
– Fever
– Nausea
– Abdominal cramps
– Jaundice (a yellowing of the skin and eyes)
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2.3 Major Foodborne Pathogens
• The Big Five
– Shigella spp
– Salmonella Typhi
– Enterohemorrhagic and shiga toxin-producing E. coli
– Hepatitis A
– Norovirus
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2.4
Ways of preventing viral, bacterial, parasitic,
and fungal contamination
Prohibit food
handlers who are
vomiting or who have diarrhea
or jaundice from working
Avoid barehand contact
with
ready-to-eat
food
Prevent
Contamination
Make sure
food handlers
wash their hands
regularly
and correctly
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2.5
Naturally occurring toxins and ways of
preventing illnesses from them
Seafood Toxins
• Fish toxins can be a natural part of the fish. Other
toxins are made by pathogens on the fish. Some
also occur when fish eat smaller fish containing
the toxin.
• Shellfish, such as oysters, can likewise become
contaminated when they eat marine algae that
have a toxin.
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2.5
Naturally occurring toxins and ways of
preventing illnesses from them
MUSHROOM TOXINS
• Foodborne illnesses linked with mushrooms
are almost always caused by eating toxic wild
mushrooms collected by amateur hunters.
• Purchasing products from approved, reputable
suppliers helps prevent these types of
foodborne illnesses.
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2.5
Naturally occurring toxins and ways of
preventing illnesses from them
PLANT TOXINS
• Plant toxins are another form of biological
contamination. Illnesses from plant toxins usually
happen because an operation has purchased plants
from an unapproved source. The following are
examples of items that have made people sick:
– Toxic plants, such as fool’s parsley or wild turnips,
mistaken for the edible version
– Honey from bees allowed to harvest nectar from toxic
plants
– Undercooked kidney beans
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