Chicken, eggs and shellfish are classical high-risk foods when it comes to food poisoning, but then so is rice, pasta, couscous and other cereal-based starchy foods that have high moisture content. The risk of diners being subject to food poisoning from cooked rice and other grain’s comes from Bacillus cereus bacterium, which unless serving, storing and reheating guidelines are followed, takeaway owners that serve these items may be in hot water with Environmental Health and the Food Standards Agency.
Many myths exist surrounding the cooking and re-heating of rice. It is well known and well documented that cooking and serving rice can carry certain risks if not carried out correctly. However it is possible to safely cook and serve rice, even reheated rice, as long as strict attention to all levels of food safety and good practice are observed which will in turn minimise risks.
The risks involved in serving cooked rice and other grain’s, comes from Bacillus cereus, a ‘spore forming’ bacterium which is naturally found in cereals such as rice as well as other cooked cereals such as cous cous and bulgur wheat, in addition to pasta. Washing will not help avoid the potential problem as the Bacillus cereus bacteria are literally embedded into the food and cannot be removed.
When rice is cooked, it can be consumed quite safely if it is eaten immediately when hot. However the Bacillus cereus bacteria survives by forming protective spores and when the temperature conditions are again favourable and the rice is left in the ‘danger zone’ of between 5-63°C for a prolonged period of time, when the spores germinate. This causes the Bacillus cereus bacteria to be released into the rice, which in turn then grow and multiply excreting a waste product called exotoxin which is poisonous to humans.
This toxin is heat stable, and therefore even if the rice is thoroughly reheated before consumption, it will still be present in the food. The poison affects the upper gastrointestinal tract and the consequences of eating food containing the toxin will be abdominal cramps and vomiting within 1 to 5 hours after eating, with the symptoms lasting for 6 to 24 hours. If the rice is not piping hot before consumption, the bacteria is broken down in the intestine where they release another type of poison called ‘endo toxin’ which within 8-12 hours will result in stomach pain and diarrhoea which may last for 1-2 days.
With rice to be served cold (for a salad bar) which has been subject to temperature abuse, or rice which has not been reheated thoroughly and left in the danger zone, one can be affected by the full effects of Bacillus cereus – vomiting then diarrhoea.
For takeaway owners, many challenges exist that require strict controls to ensure the risk of multiplication of the Bacillus cereus bacterium is minimised.
What are the rules when cooking, serving, storing and re-heating rice?
Cooking and even re-heating rice safely to prevent the risk of food poisoning is actually quite simple and straight forward, as long good strict food hygiene and safety processes are observed. Food poisoning is quite easily prevented by following simple time/temperature controls:
Ensure that dry rice is stored in dry conditions – as dried rice contains Bacillus cereus spores, as rice becomes damp the moisture can cause the spores to germinate.
Avoid cross contamination of Bacillus Cereus from dried rice to other foods in storage, especially ready to eat foods.
Cook rice thoroughly (to 75°C) and serve immediately.
If rice is not to be served immediately, keep hot at 63°C or above.
When cooling to serve cold or to store in a refrigerator, cool as quickly as possible using cold running water and refrigerate at preferably 5°C or below.
Whilst cooking and serving rice fresh each time is preferable, rather than reheating, however rice can be reheated but ensure it is piping hot (75°C or above) throughout before it is served.
The steps that are required to avoid food poisoning with Bacillus cereus are the same as those needed to prevent many other types of bacterial food poisoning. Stick to these guidelines and we will all be safer.
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