food contamination
DESCRIPTION
Food Contamination & SpoilageDefinition of TermsFood contamination ± presence of harmful substances in food; tasteless & odorless1Definition of TermsFood spoilage ± damage to the edible quality of food; unacceptable taste & appearanceSpoilage affects the aroma, texture and/or appearance of food. Examples: sour milk, moldy cheese, slimy, rancid meat, or mushy, discolored vegetables2When food spoils, the following may change: appearance taste texture odour Food may becomTRANSCRIPT
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Definition of Terms
Food contamination – presence of harmful substances in food; tasteless & odorless
Food Contamination & Spoilage
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Food spoilage – damage to the edible quality of food; unacceptable taste & appearance
Spoilage affects the aroma, texture and/or appearance of food.
Examples: sour milk, moldy cheese, slimy, rancid meat, or mushy,discolored vegetables
Definition of Terms
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When food spoils, the following may change:
• appearance
• taste
• texture
• odour Food may become unsafe to eat.
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Color can often indicate the type of microbe involved in the spoilage: Black spots on meat are the result of Cladosporium
species. White spots are from Sporotrichum carnis. Yellow or green spots form as a result of the Penicillium
species. A rainbow effect, often seen on bacon and fish, is
caused by a spoilage bacteria known as Photobacteria that can break down ATP to produce visible light. After a couple of days, this bacterium can grow sufficiently to enable raw fish to glow in the dark!
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Food infection – caused by harmful live microorganisms that are present in food when consumed
Definition of Terms
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Definition of Terms
Food intoxication – caused by food containing toxins produced by harmful microorganisms
Food toxicoinfections – foodborne illness caused by a combination of food intoxication and food infection
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Definition of Terms
Foodborne illness – disease occurring as a result of consumption of contaminated food
Foodborne outbreak – development of foodborne illness in two or more people who have eaten a common food that is shown by laboratory analysis to be the source of the illness
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Potentially Hazardous Foods
Any natural or synthetic food or food ingredient that supports the rapid growth of infectious or toxigenic microorganisms or the slower growth of C.botulinum
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Potentially Hazardous Foods
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Potentially Hazardous Foods
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Not Potentially Hazardous Foods Hard-boiled eggs with shells intact, which
have been air dried Foods with Aw ≤0.85 Foods with pH ≤4.6 Foods that have been adequately
commercially processed & remain in hermetically sealed containers
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Not Potentially Hazardous Foods Foods for which laboratory evidence
(acceptable to the regulatory authority) demonstrates that rapid & progressive growth of infectious & toxigenic microorganisms or the slower growth of C. botulinum cannot occur.
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Sources of Food Contamination
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Types of Sources of Food Contamination Primary contamination
Infected animalsFecal pollution
Secondary contamination Infected humansOther animalsFomites (water, soil, plants, air)Food additives
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Types of Contamination
BiologicalChemicalPhysical
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Biological Contamination
Cause of most foodborne illness Caused by bacteria, viruses, parasites, &
fungi Can be spread by the air, through direct
contact, & through food itself Most are destroyed by adequate cooking, &
proper cooling during distribution & storage
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Foodborne infection
Salmonella sp.(chicken) Shigella sp. (fecal contamination) Campylobacter jejuni (chicken) Listeria monocytogenes (soil, chicken)
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Foodborne Intoxication
Bacillus cereus (rice) Staphylococcus aureus (infected food
handler) Clostridium botulinum (product, soil)
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Viral Infection
Hepadnavirus (water) Norwalk virus (fecal contamination)
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Biological Toxins
Seafood ToxinsCiguateraScombroidShellfish (histamine)Systemic fish toxins (e.g. pufferfish)
Plant Toxins Fungal Toxins
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Parasites Associated with Foodborne Diseases Taenia spp. Trichinella spiralis Toxoplasma gondii
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Chemical Contamination
Toxic substances that may occur naturally or may be added during the processing of food
Substances such as food additives & preservatives, pesticides, toxic metals, & toxic cleaning products
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Man-made Chemical Contaminants Cleaning solutions Food additives – nitrites, sulfites & MSG Pesticides – plant sprays Heavy metals – Cu, Cd, Pb, Zn, & brass Drugs – growth hormones, antibiotics
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Physical Contamination
Results from the accidental introduction of foreign objects into foods
Includes metal shavings, staples, glass, blades, fingernails, hair, bandages, pieces of wood, etc.
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Common Causes of Food Spoilage
Improper storage temperatures Incorrect storage times Improper ventilation Failure to separate foods Excessive delays between receiving and
storing Inadequate food safety standards
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Factors contributing to food poisoning outbreaks 1980 - 1995
Other 6%Poor personal
hygiene 9%
Inadequate cooking 27%
Temperature control 20%
Contaminated equipment 19%
Unsafe food source 19%
Source: Crerar, S.K. et al 19967.
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The food poisoning time bomb
8.
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Low-Temperature Food Preservation
Chilled storage: 50˚F (10˚C) to 59˚F (15˚C)
Refrigerated storage: 32˚F (0˚C) to 45˚F (7˚C)
Freezer storage: 0˚F (–18˚C) or below
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Pasteurization
High-temperature food preservation
Food product heated to 145˚F (63˚C) for 30 minutes or to 161˚F (72˚C) for 15 seconds then immediately cooled to 50˚F (10˚C) or less.
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Sterilization
High-temperature food preservationVirtually kills all microorganisms and their spores.
Heating usually takes place in a large container which is pressurized according to the food product, its ability to withstand heat, and packaging.