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Understanding the Microworld

Chapter Number 2

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Learning ObjectivesAfter this presentation, you should be able to complete the following Learning Outcomes

2.0

2

2.1

2.2

2.3

2.4

2.5

Factors that affect the growth of foodborne pathogens (FAT TOM)

Characteristics of TCS food

Major foodborne pathogens and their sources

Ways of preventing viral, bacteria, parasitic, and fungal contamination

Naturally occurring toxins and how to prevent their illnesses

• 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.

KEY TERMS2.0

• 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.

KEY TERMS2.0

• 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.

KEY TERMS2.0

• 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. Theyusually contaminate food through a food handler’s incorrect personalhygiene. Some survive freezing and cooking temperatures.

KEY TERMS2.0

• 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. Theyusually contaminate food througha food handler’s incorrect personalhygiene. Some survive freezing andcooking temperatures.

KEY TERMS2.0

• 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 freezingwill kill parasites. Avoidingcross-contamination and practicing correct handwashing can also prevent illness.

• Fungi: Ranging in size frommicroscopic, single-celledorganisms to very large,multicellular organisms, fungimost 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.

KEY TERMS2.0

2.1

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Factors That Affect the Growth of Foodborne Pathogens

FAT T OM

OOD

CIDITY

IME

EMPERATURE

XYGEN

OISTURE

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Factors That Affect the Growth of Foodborne Pathogens

2.1

Most bacteria need nutrients such as carbohydrates or proteins to survive. This includes meat, poultry, dairy products, and eggs.

FOOD

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Factors That Affect the Growth of Foodborne Pathogens

2.1

Bacteria growbest in food that is neutral to slightly acidic, a pH of 7.5 to 4.6. The following common types of food have a pH that is ideal for bacterial growth:

ACIDITY

Bread – pH 5.0 – 6.0

Raw Chicken – pH 5.5 – 6.0

Milk – pH 6.4 – 6.8

Canteloupe – pH 6.1 – 6.5

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Factors That Affect the Growth of Foodborne Pathogens

2.1

Bacteria grow rapidly between 41° and 135°F (5° and 57°C) This is called the Temperature Danger Zone.

TEMPERATURE

Bacteria grow even more rapidly from 70° to 125°F (21° to 52°C).

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Factors That Affect the Growth of Foodborne Pathogens

2.1

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.

TIME

Foodborne Illness

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Factors That Affect the Growth of Foodborne Pathogens

2.1

OXYGENSome bacteria need oxygen to grow. Others grow when oxygen is not there. Bacteria that grow without oxygen can occur in:

Baked PotatoesCooked Rice

Garlic/Oil Mixes

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Factors That Affect the Growth of Foodborne Pathogens

2.1

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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Characteristics of TCS Food2.2TCS (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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Characteristics of TCS Food2.2TCS (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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Major Foodborne Pathogens2.3• 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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Major Foodborne Pathogens2.3

Person to person

Sneezing or vomiting

onto food or food-contact

surfaces

Touching dirtyfood-contact surfaces and

then touching food

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Major Foodborne Pathogens2.3• 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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Major Foodborne Pathogens2.3• The Big Five– Shigella spp– Salmonella Typhi– Enterohemorrhagic and shiga toxin-producing E. coli– Hepatitis A– Norovirus

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Ways of preventing viral, bacterial, parasitic, and fungal contamination

2.4

Prevent Contaminatio

n

Prohibit food handlers who are

vomiting or who have diarrhea or jaundice from working

Avoid bare-hand contact

with ready-to-eat

food

Make surefood handlers

wash their handsregularly

and correctly

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Naturally occurring toxins and ways of preventing illnesses from them

2.5

• 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.

Seafood Toxins

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Naturally occurring toxins and ways of preventing illnesses from them

2.5

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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Naturally occurring toxins and ways of preventing illnesses from them

2.5

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