Food safety
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Food safety is a scientific discipline describing the handling, preparation, and storage of food in ways that prevent Foodborne illness.
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[edit] Domestic foodborne illness prevention
At home, prevention of Foodborne illness mainly consists of:
- separating foods while preparing and storing to prevent cross contamination. (i.e. clean cutting boards, utensils, and hands after handling meat and before cutting vegetables, etc.)
- washing hands and/or gloves before handling ready-to-eat foods.
- respecting food storage methods (hot foods hot and cold foods cold) and food preservation methods (especially refrigeration), and checking the expiration date;
- avoiding over-long storage of left-overs;
- washing the hands before preparing the meal and before eating;
- washing the fresh fruits and vegetables with clear water, especially when not cooked (e.g. fruits, salads), scrubbing firm fruits and vegetables with a brush to clean;
- washing the dishes after use, rinsing them well in hot water and storing them clean and dry;
- keeping work surfaces and chopping boards clean and dry;
- keeping the kitchen and cooking utensils clean and dry;
- not relying on disinfectants or disinfectant-impregnated cloths and surfaces as a substitute for good hygiene methodology (as above);
- preventing pets walking on food-preparation surfaces.
[edit] Bacterial growth
Bacteria need warmth, moisture, food and time to grow. The presence, or absence, of oxygen, salt, sugar and acidity are also important factors for growth. In the right conditions, one bacterium can multiply using binary fission to become four million in eight hours. Since bacteria can be neither smelled nor seen, the best way to ensure that food is safe is to follow principles of good food hygiene. This includes not allowing raw or partially cooked food to touch dishes, utensils, hands or work surfaces previously used to handle even properly cooked or ready to eat food.
High salt, high sugar or high acid levels keep bacteria from growing, which is why salted meats, jam, and pickled vegetables are traditional preserved foods.
The most frequent causes of bacterial foodborne illnesses are cross-contamination and inadequate temperature control. Therefore control of these two matters is especially important.
[edit] Food temperature
Thoroughly cooking food until it is piping hot, i.e. above 70 °C (158 °F) will quickly kill most bacteria, parasites and viruses. Clostridium botulinum, Clostridium perfringens and Bacillus cereus, produce a heat-resistant spores that survive temperatures up to 100 °C (212 °F). Norovirus and Hepatitis A can sometimes survive temperatures up to 190°F. Once cooked, hot foods should be kept at temperatures out of the danger zone. Temperatures above 63 °C (135 °F) stop microbial growth.
Cold foods should also be kept colder than the danger zone, below 5 °C (41 °F). However, Listeria monocytogenes and Yersinia enterocolitica can both grow at refrigerator temperatures.
Hot foods should be held at 57°C (135 °F) or hotter until ready to cool. Hot foods need to be cooled quickly to limit the amount of time the food is in the danger zone (temperature range at which bacteria can grow.) The food should be cooled from 57 °C (135 °F) to 20 °C (70 °F) within two hours. Then further chilled to less than 5 °C (41 °F) in 4 hours. Foods take much longer to cool than most people realize. Food should then be held chilled at 5 °C (41 °F) or less.
[edit] UK HACCP guidelines and other official information
The UK Food Standards Agency http://www.food.gov.uk/ publishes recommendations as part of its Hazard Analysis and Critical Control Points (HACCP) programme. The relevant guidelines are at: http://www.food.gov.uk/multimedia/pdfs/csctcooking.pdf. They state that:
"Cooking food until the CORE TEMPERATURE is 75°C or above will ensure that harmful bacteria are destroyed.
However, lower cooking temperatures are acceptable provided that the CORE TEMPERATURE is maintained for a specified period of time as follows :
- 60°C for a minimum of 45 minutes
- 65°C for a minimum of 10 minutes
- 70°C for a minimum of 2 minutes"
Previous guidance from a leaflet produced by the UK Department Of Health “Handling Cooked Meats Safely A Ten Point Plan” also allowed for:
- "75°C for a minimum of 30 seconds
- 80°C for a minimum of 6 seconds"
as well as the above. Secondary references for the above may be found at:
- http://www.rushcliffe.gov.uk/doc.asp?cat=8455
- http://www.wiganmbc.gov.uk/pub/ehcp/eh/commlflt/cookmeat.pdf This document states that: "This publication may be freely reproduced, except for advertising, endorsement or likely that, in the interests of good customer relations they will be commercial purposes. Please acknowledge the source as Wigan Council Community Protection Department."
- http://www.nottinghamcity.gov.uk/fs1694b.pdf
- http://www.wollongong.nsw.gov.au/Downloads/Documents/Safer_Cooked_Meat_Production.pdf
- http://www.west-norfolk.gov.uk/pdf/Food%20Safety%20-%20Ten%20Point%20Plan%20for%20Safer%20Cooked%20Meat.pdf
Note that recommended cooking conditions are only appropriate if initial bacterial numbers in the uncooked food are small. Cooking does not replace poor hygiene.
[edit] Critique
Note that the above advice is open to critique[citation needed]:
- For example, some spore forming bacteria can survive cooking until the CORE TEMPERATURE is 75°C or above - and may in fact be stimulated to grow. If food is cooked to a core temperature of 75°C, it must be kept out of the "danger zone" (5 to 60°C) thereafter to prevent spore formers from multiplying. Spore formers like Clostridium perfringens can cause serious gastroenteritis.
- Another problem is that although a core temperature of 75°C will kill most dangerous vegetative bacteria it does not inactivate some toxins (eg staphylococcal enterotoxin). So it is possible to become ill after eating well cooked food, as the food may already be contaminated with toxins before cooking.
For more information, see Foodborne illness.
[edit] See also
- Foodborne illness
- Potentially Hazardous Food
- Food Safety Inspection Service
- European Food Safety Authority
- Under Secretary for Food Safety
- National Food Safety and Quality Service
- Advisory committee on the microbiological safety of food
- Committee on the Environment, Public Health and Food Safety
- ISO 22000
- International Association for Food Protection
- ServSafe
- National Food and Research Institute (NFRI)
- International Life Sciences Institute
- Conference for Food Protection
- Food microbiology
- Food Safety Network
[edit] Notes
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