intro Flashcards
Contron measure stages in food chain to avoid food poisoning
1) Raw material (Bird/ animal / plant) –> Salughter/ harvest
2) –> not processed OR processed
3) –> Retail
4) –> consumer
Control measure at food chain stage of raw material
Good husbandry practices
Control measure at food chain stage of Salughter/ harvest
hygiene decontamination
Control measure at food chain stage of processing
Heat treatment/ Drying/ Preservatives/ Gas atmosphere
Control measure at food chain stage of retail
Refridgration
Control measure at food chain stage of customer
Hygiene/ cook properly/ Avoid cross- contamination
Bacteria causing foodborne illness from animal
origin
- campylobacter jejuni/ coli
- Salmonella enterica
- Escherichia coli O157
Bacteria causing foodborne illness from human origin
- Staphylococcus aureus
- Norovirvus
Straphylococcus aureus
Characteristics / mechanism / Syptoms / incubation time
Gram- positive
Producing toxin
Cause vomiting, abdominal cramps
Incubation 6- 8hr
Norovirus
syptoms/ spreading pathway
causing nausea, vomiting,
ususally spread by person- to - person contact
Bacteria causing foodborne illness from environmental sources
Listeria monocytogens
Listeria monocytogenes
symptoms/ incubation time/ found in
causing mild flu, meningitis, abortion
incubation 1-90 days
Found in silage, decaying vegetation, may colonise drains and food processing machinery.
Sheep with listeriosis may contaminate vegetation
Bacteria causing foodborne illness from seafood origin
- Vibrio parahaemolyticus
- Vibrio vulnificus
Anaerobic spore formers
- Clostridium botulinum
- Clostridium perfringens
Clostridium botulinum
Characterisitic/ mechanism/ symptoms/ incubation time
Proteolytic types: mesophilic
Non- proteolytic: psychrophilic
Very powerful toxin was produced
Causes double vision, weakness, dry mouth, respiratory paralysis.
Incubation period 18- 36hr
Clostridium perfringens
characteristics/ mechanisms/ symptoms
Spores on meat survive cooking
may germinate and multiply if food keep warm for long period
causing diarrhoea and abdominal pain
Aerobic spore former
Bacillus cereus
Bacillus cereus
Food associate with Food poisoning
Characteristics/ mechanism [2] & incubation time
Rice and other cooked food
Spore survive cooking and may germinate and multiply if rice is kept warm for long period
Toxins:
emetic toxin - cause vomiting nausea, [incubate 1-5 hr]
diarrhoeal toxin - diarrhoea, [incubate 12- 24hr]
Fungi causing food-borne illness
- Aspergillus flavus
- Penicillium expansum
Aspergillus flavus
Mechanism/ Food associated/ Toxin dose/ characteristic
Safe limit
produced aflatoxin, ochratoxin
associated with wheat, rice, maize, peanuts, pistachios etc
- LD(50) : 0.5 - 9 mg/kg
- very carcinogenic for rats
- UK limits: 2ug/kg ; USA limit: 20 ug/kg
penicillium expansum
Mechanism/ Food associated/
- produced patulin
- Apple
Aspergillus flavus case study
2011
Morrison withdraw all date codes of own brand seasonal Unsalted Pistachio Nuts in shell due to the presence of aflatoxins
Protozoan
Cryptosporidium parvum
Cryptosporidium parvum
symptoms / mechanism / related source
causes diarrhoea and bloating in humans
water contaminated by livestock mammal feces
Cryptosporidium cysts resistant to chlorination
Bacterial food-borne infections
organism is ingested with food
• multiplies in the intestine
• often attach to the lining of the large or small intestine
• some may invade cells of the mucosa
• often produce toxins
• infectious dose varies but may be quite small
Bacterial food-borne intoxications
Organism grows in food
• produces toxins in food
• toxins are ingested when food is eaten
• high numbers of bacteria in food needed to produce illness
• symptoms appear relatively soon aftereating food (6-12 h)
Non-bacterial food poisoning
- Shellfish poisoning:
- Red kidney beans
- Scombroid toxin:
Shellfish poisoning
Source and symptoms
tingling, numbness, loss of muscular coordination
dinoflagellate algae accumulate in filter feeders
Scombroid toxin
Source and symptoms
allergic-like reaction (histamine)
rash nausea, vomiting, diarrhoea (tuna etc.)
Red kidney beans
Source and symptoms
vomiting (lectins)
microbes that have growth in food
- Salmonella
- Escherichia coli O157
- Listeria monocytogenes
- Staphylococcus aureus
- Clostridium perfringens
- Clostridium botulinum
- Bacillus cereus
microbes that have no growth in food
- Campylobacter jejuni
- viruses
- Protozoa
- Shellfish poisoning
- nvCJD (Creutzfeldt– Jakob)
Human Defense barriers to infection
• Nitric oxide in saliva • Stomach acid ~ pH 2.0 • Degradative enzymes: – lysozyme – pepsin • Flow of food through intestine • Mucous barrier impairs bacterial motility • Competition with resident gut flora • Iron limitation
Food poisoning
any disease of an infectious or toxic nature caused or thought to be caused by the consumption of food or water
A case
illness affecting an individual person
An outbreak
an incident involving two or more people thought to have a common exposure or, occurrence of cases of disease in excess of what would normally be expected in a defined community, geographical area or season (WHO).
A general outbreak
an outbreak affecting members of more than one private residence or residents of an institution
Prevention of food poisoning in the home
- Prevent spread of contamination in the kitchen
- Prevent bacteria from growing
- Cook to destroy most bacteria
