Food Safety

2) Chemical hazards
Inorganic
Mercury, lead, selenium, arsenic, cadmium, sulphites(used in shrimp processing)

Organic
Polychlorinated biphenyls, dioxins, insecticides

Chemical contaminations are caused by industrial procesing, waste from sewage treatment plants, untreatment raw sewage from populations. Based on study from researchers, "organochlorine levels in fish intended for human consumption are low and probably below levels likely to adversely affect human health." The more concern population are those whom seafood is major part of the diet, infants and young children that consume substantial quantities of oily fish.

Critical limits of chemical substances in seafood.



Processing related compounds
Nitrosamines, antibiotics, hormones

Antibiotics are often used to treat the infections in seafood to treat the pathogenic infections.
There is a concern on the effects on antibiotics residues, having effect on human health, as antibiotics are being used on all food of animal origins other than fish. Possible hazards of the presence of antibiotics drugs residues are allergies, toxic effects, acquisition of drug resistance in pathogens in the human body.


for more information on Chemical hazards in seafood.
http://www.fao.org/DOCREP/006/Y4743E/y4743e0e.htm#TopOfPage

shanlyn is SAFE @ 5:11 PM 0 Comments

Seafood

1) Biological hazards

Pathogenic bacteria

- Clostridium botulinum
Possible fish products of proliferating this microbe: fresh & frozen, fermented, salted, canned.
Types of fish that are prone to get contamined from Clostridium botulinum
___________________________________________

- Vibrio cholera
Limits for growth of Vibrio cholera
Temperature (°C)
Optimum: 37°C
Range: 10-43°C

pH
Optimum: 7.6
Range: 5-9.6

water activity (aW)
Optimum: 0.984
Range: 0.970-0.998

Atmosphere
Optimum: Aerobic
Range: Anaerobic- aerobic

Salt tolerance; NaCl (%)
Optimum: 0.5
Range: 0.1-4.0
__________________________________________

- Vibrio parahaemolyticus
Food related to organism are shrimps, crabs, molluscan shellfish, salt-preserved vegetables etc.
Outbreak of organism in food is usually due to uncooked or contaminated food. Seafood has to be chilled to <5°C, holding them under refrigeration. Internal temperature of the food has to reach more than/equal 65°C. At this temperature, the organism will be destroy effectively. Cooked food that should also be eaten within 2 hours.

Limits for growth of Vibrio parahaemolyticus
Temperature (°C)
Optimum: 37°C
Range: 5 to 43°C

pH
Optimum: 7.8 - 8.6
Range: 4.8 - 11

water activity (aW)
Optimum: 0.981
Range: 0.940 - 0.996

Atmosphere
Optimum: Aerobic
Range: Aerobic- Anaerobic

Salt tolerance; NaCl (%)
Optimum: 3
Range: 0.5-10
__________________________________________

- Vibrio vulnificus
It is a harmful bacteria that can be found in oysters. It can be transmitted to humans if the oysters are raw or partially cooked. Vibrio vulnificus infection is hazardous and can be life-threatening.

Limits for growth of Vibrio vulnificus
Temperature (°C)
Optimum: 37°C
Range: 8 to 43°C

pH
Optimum: 7.8
Range: 5-10

water activity (aW)
Optimum: 0.98
Range: 0.96-0.997

Atmosphere
Optimum: Aerobic
Range: Facultative

Salt tolerance; NaCl (%)
Optimum: 2.5
Range: 0.5-5
___________________________________________

- Aeromonas hydrophila
Food asssociated to the organism are fish, shellfish, raw meat like beef, pork etc.

Limits for growth
Temperature (°C)
Min: >0, <4
Max: >42, <45
Optimum: 28-35

pH
Min: <4.5
Optimum: 7.2

NaCl (%)
Max: >5, <6
Optimum: 1 - 2

Click this web for more information on Aeromonas spp.
___________________________________________

- Plesiomonas shigelloides
It is likely that fish and shellfish is primary reservoir of Plesiomonas shigelloides. It may cause gastroenterities with symptoms varying from illness of short duration to severe diarrhoea.
__________________________________________

- Listeria Monocytogenes
- Salmonella sp.
- Shigella
- E.coli

------------------------------------------------------------------------------
Viruses

- Hepatitis A
Hep. A virus is the most serious and common seafood-associated viral infections. It is usually isolated from infected seafood and faeces from infected human. Hep. A virus is more heat resistant, able to survive @ 60°C for 4 hours.
More information can be found from here http://www.fao.org/DOCREP/006/Y4743E/y4743e0b.htm#TopOfPage

- Norwalk virus
- Snow Mt Agent
- Calicivirus
- Astrovirus
- Non-A and Non-B

------------------------------------------------------------------------------
Biotoxins
Toxins in fish and shellfish are usually produced by marine algae (phytoplankton). Such toxins are known as phycotoxins. Consuming shellfish that are contamined with the toxins, can caused mild diarrhoea, vomitting, memory loss, paralysis and even death.
Seafood poisoning syndromes associated with toxic marine algae are:
Paralytic shellfish poisioning (PSP)
Amnesic shellfish poisoning (ASP)
Diarrhetic shellfish poisoning (DSP)
Neurotoxic shellfish poisoning (NSP)
Azaspiracid shellfish poisoning (AZP)

Other types of food-poisoning associated with finfish includes:
Ciguatera poisoning
Puffer fish poisoning (Tetrodotoxin)

Most of these algal toxin are heat stable and will not be inactivated by cooking.

More information on these biotoxins can be found from here:
http://www.fao.org/DOCREP/006/Y4743E/y4743e0d.htm#TopOfPage

shanlyn is SAFE @ 10:02 PM 0 Comments

Overall informations on the Microbes

Listeria Monocytogenes

A Gram- positive bacterium

Illness: Listeriosis

Sources: raw milk, ice cream, raw vegetables, raw meat, raw and smoked fish. Its abiliity to grow at temperature as low as 3°C permits multiplication in refrigerated foods.

Favourable conditions
- grow under aerobic and anaerobic conditions
- able to grow @ refrigeration temperatures (to 1°C; 34°F)
- low pH (<4.6) prevents growth of organisms
- withstands repeated freezing and thawing
- survives for prolonged periods in dry conditions
- low aW of 0.90 @ 30°C control growth of organisms.



_____________________________________

Clostridium Botulism

an anaerobic, gram-positive, spore-forming rod that produces a potent neurotoxin

spores are heat-resistant and can survive in foods that are incoorectly or minimally processed.

Illness: Botulism

Sources: chicken, green beans, canned food etc; Almost any type of food that is not very acidic (pH above 4.6)

Favourable conditions
- organisms grow best under anaerobic/reduced oxygen conditions. Non-proteolytic types can grow @ low temperature (to 3°C; 37°F). Most proteolytic types can grow to 10°C.
- low pH and low aW control the growth.



_____________________________________

Salmonella spp.

non-sporeforming and graw-negative.

Illness: Salmonellosis

Sources: raw meats, poultry, eggs, milk and dairy pdts, fish etc

Favourable condition
- will be killed by mild heat (above 60°C)
- grows under aerobic and anaerobic conditions. Grow in temperature range of 5.2 to 47°C. Optimum temperature for growth is 35 to 37°C.
- low pH (<4.6) prevents growth. Optimum pH: 6.5 to 7.5



_____________________________________

Staphylococcus aureus

Gram-positive

Illness: Staphylococcal food poisoning

Sources: Poultry and egg products, salads, chicken etc

Favourable condition
- killed by mild heat (above 60°C)
- grows in either aerobic or anaerobic conditions. Temperature growth range is 6.7 to 45.4°C. Optimum growth temperature is 37 to 40°C.
- pH growth range 4.5 to 9.3.
- organisms resistant to high salt (up to 15%)



_____________________________________

Bacillus cereus and other Bacillus spp.

gram-positive, facultatively aerobic sporeformer

Illness: food posioning

Sources: meats, milk, vegetables, rices products, starchy food such as potato, pasta etc

Source of website

shanlyn is SAFE @ 9:57 PM 0 Comments