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Food safety
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Why is Food Safety Important?
Food-borne illness: symptoms or illness from
food or water that contains an infectious agent,
poisonous substance, or protein causing an
immune reaction.
• 76 million people report food-borne illness
•
each year.
Many more cases go unreported.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Why is Food Safety Important?
• Food spoilage can be from enzymes naturally
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found in the food or from microbes that
colonize the food.
Processed foods can spoil just as fresh meats,
fruits, and vegetables do.
Three factors most often responsible are:
(1) oxygen
(2) light
(3) heat
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Why is Food Safety Important?
• Food producers may use chemicals, drugs, or
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•
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other substances to manipulate food products.
Food additives: chemicals added to enhance
foods.
Food preservatives: chemicals added to food to
maintain freshness and appearance.
Pesticides: family of chemicals used in both
the field and storage areas to decrease plant,
fungal and animal pests.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Government Regulators
Multiple government agencies are involved in
ensuring the safety and quality of the food
supply:
• States Department of Agriculture (USDA)
• U.S. Food and Drug Administration (FDA)
• Centers for Disease Control and Prevention
•
(CDC)
Environmental Protection Agency (EPA)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Causes of Food-Borne Illness
Food infections: illness resulting from eating
food contaminated with living organisms.
Food intoxications: illness resulting from eating
food in which microbes have secreted toxins
(poisons).
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Causes of Food-Borne Illness
Bacteria are the most common microbes causing
food-borne illnesses.
Of the bacteria, the most common food contaminants
are:
• Campylobacter jejuni
• Salmonella
Also, Listeria monocytogenes, Shigella, Vibrio
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Causes of Food-Borne Illness
Campylobacter jejuni
Campylobacteriosis:
•Diarrhea
•Cramping
•Abdominal pain
•Fever withing 2-5 days
post-exposure
Commonly found in
chickens, also cow’s udders
More than ½ of raw chicken
in the US market has
Campylobacter on it
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Salmonella
Salmonellosis
•Diarrhea
•Abdominal cramps
•Fever 12-72 hours postinfection
•Infection may last 4-7 days
Salmonella live in the intestinal
tracts of humans and other
animals
Credit Rocky Mountain Laboratories, NIAID, NIH
Salmonella invading cultured human cells
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Foods of animal origin may be
contaminated: raw eggs,
unpasteurized milk and raw
meat, also unwashed produce
Causes of Food-Borne Illness
Other microbes causing illness include
• Viruses such as hepatitis A, hepatitis E,
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Norwalk virus
Helminths or worms, such as tapeworms,
flukes, and roundworms.
Giardia, causing a diarrheal illness called
giardiasis
Fungi causing food spoilage
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Hepatitis E
Drs. E.M. Kraan a, dr. M. Koopmans b, dr. P.M. Schneeberger c,
Fataal verlopen infectie met in Nederland verworven hepatitis E
virus bij een patiënte met een vermoedelijk hepatocellulair carcinoom
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Parasitic worms
Credit: Red Book Online, American Academy of Pediatrics
Brain scan of pork tapeworm Taenia tolium
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Toxoplasma gondii
• Parasite
• Modes of transmission:
(1)consumption of raw foods
(2)Fecal-oral route
(3)Mother to fetus
(4)Blood transfusion (rare)
Credit: Image provided by Ke Hu and John Murray
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Giardia
SEM image:
Content Providers(s): CDC/ Janice Carr
Credit: Public Health Image Library
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Causes of Food-Borne Illness
Some microbes cause illness by secreting poisons
called toxins.
• Clostridium botulinum produces botulism toxin
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•
which blocks nerve transmissions to muscle
cells.
Mycotoxins are secreted by fungi.
Toxins can be neurotoxins or enterotoxins.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Food Allergies
• Allergic reactions to food may include
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symptoms such as rashes, headaches, or bowel
disturbances.
The foods that most often cause allergic
reactions include cow’s milk, eggs, nuts, citrus
fruit, seafood, wheat, corn, soy.
Most food allergies are reactions to proteins
contained in the food.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Food Allergies
• Some food allergies are fixed – the reaction
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occurs every time the food is eaten.
Some food allergies are cyclic – after 3 to 6
months without the food, it may be slowly
reintroduced to the diet with no effect.
Many children outgrow early food allergies.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food-Borne Illness
When preparing foods at home, be sure to
• Wash hands and kitchen surfaces often
• Separate foods to prevent cross contamination
• Cook foods the their proper temperature
• Chill foods to prevent microbes from growing
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food-Borne Illness
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food-Borne Illness
• Foods should be cooked thoroughly to kill
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microbes.
Leftovers should be stored in the refrigerator
for a limited period of time.
Food should be thawed slowly in the
refrigerator.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food-Borne Illness
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food-Borne Illness
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food-Borne Illness
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food-Borne Illness
Thoroughly cooking
food destroys
microbes but toxins
may remain in the
food.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food-Borne Illness
When eating out:
• Eat at restaurants that look clean
• Insist that food be cooked thoroughly
When traveling:
• Avoid raw foods, salads, uncooked fruits and
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vegetables, unpastuerized milk
Only drink bottled water or soda, boiled water
such as tea, beer, wine
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food Spoilage
Spoilage can be prevented by many natural
techniques:
• Salting or sugaring
• Drying the food
• Smoking
• Cooling
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food Spoilage
More modern techniques include:
• Industrial canning
• Pasteurization
• Chemical preservatives
• Irradiation
• Genetic modification
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Preventing Food Spoilage
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Food Additives
• Natural food additives include beet juice, salt,
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and citric acid.
Many other additives are synthetic chemicals
added to food.
Additives can be used for adding flavor, color,
or nutrients to foods.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Food Additives
Flavorings:
• Flavoring agents such as essential oils or spices
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are used to replace flavor lost during
processing.
Flavor enhancers do not have flavor of their
own.
• Examples include maltol and MSG
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Food Additives
Colorings:
• Beet juice (red), beta carotene (yellow), and
caramel (brown) are natural coloring agents
Vitamins and minerals:
• Vitamin E, ascorbic acid (vitamin C), vitamin
D, iodine
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Food Additives
Other food additives include:
• Texturizers, stabilizers, thickening agents, or
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emulsifiers that change the consistency of
processed foods
Humectants or desiccants that maintain the
proper moisture levels
Bleaching agents to change the color of food
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Residues on Foods
Various chemicals can persist and even
accumulate in foods.
These residues can include:
• Persistent organic pollutants (POPs)
• Pesticides
• Growth hormones
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Persistent Organic Pollutants
Persistent organic pollutants: chemicals released
into the atmosphere from industry, agriculture,
automobiles, and waste disposal.
• Found on virtually all categories of food.
• Includes:
• Mercury and lead
• PCBs
• dioxins
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Pesticides
Pesticides are used to help protect against crop
losses, reduce the incidence of disease, and
increase crop yields.
• Most common are insecticides, herbicides,
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fungicides
Can be natural or synthetic
Can remain as a toxin on foods
Regulated by the EPA
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Growth Hormones
Recombinant bovine growth hormone (rBGH) is
a genetically engineered growth hormone given
to cows
• Increases muscle mass; decreases fat
• Increases milk production
• Causes mastitis in cows, resulting in increased
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antibiotic use in the cows
Risks to humans are still being studied
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Organic Foods
Organic foods are grown without the use of
synthetic pesticides
• Standards for organic production are regulated
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by the USDA
Benefits of organic foods:
• 2.5 times more nutritious
• Higher vitamin and mineral content
• Lower in toxic metals
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings