Food poisoning bacteria on rice
Posted on August 7th, 2011

Dr Hector Perera   England

Home or away

 The staple diet of Asians is rice and the Westerner’s, bread, pasta and spaghetti but how many of us are aware that there are bacteria living on these food substances.

Food poisoning can happen to anyone, by eating at hotels or even at home. I must say the tourists’ hotels in Sri Lanka are really attractive, well presented, all are welcomed. Since I haven’t being to one of them quite recently, a few of us visited one in Colombo Fort. They had plenty of choices and we decided to visit Sri Lankan cuisine section. After visiting the bar for a quick drink, others ordered different things but two of us ordered   what is called CHICKEN BURIYANI.

We had a good evening, eating, drinking then listening to live music at the bar.

It’s possible due to one reason or the other, within less than two hours I felt quite unusual. Ignored it and went to bed but I couldn’t sleep, because I was shaking, shivering, feeling temperature, rumbling, cramp in the tummy and all the rest. Waited for a while to settle down but failing that, took a taxi to visit a doctor’s surgery at 1.00am in the morning. The doctor diagnosed it as nothing but food poisoning and recommended antibiotics. I was wondering how many others must have suffered silently? I am sure this is an isolated case.

Common food poisoning bacteria

There are five most common bacteria; Salmonella, Listeria, E.coli O157, Campylobacter and Clostridium perfringens. When someone swallows bacteria that cause food poisoning, there is a delay (incubation period) before symptoms begin. This is because most bacteria that cause food poisoning need time to multiply in the intestine. The length of the incubation period depends on the type of bacteria and how many are swallowed. It could be hours or days. Fortunately most of them get destroyed inside the body due to our body defence mechanism, if that fails then trouble begins but the defence action keeps on going.

The bacteria stick to the lining of the intestine and destroy those cells, either by sheer weight of numbers or by the toxins (poisons) they produce.

Conditions to grow

Bacteria need warmth and moisture to grow. They reproduce by dividing themselves, so one bacterium becomes two and then two become four and so on. In the right conditions, one bacterium could become several million in 8 hours and thousands of millions in 12 hours.

This means, that if a food is contaminated with a small number of bacteria and if you leave it out of the fridge overnight, it could be seriously contaminated by the next day. I wonder whether the foods are kept under hygienic conditions in large hotels and in takeaway places. Then just one mouthful could make someone ill. If you put food in the fridge it will stop bacteria from multiplying. Since you can’t see, taste or smell bacteria, the only way that you can be sure that food is safe is to follow good food hygiene at all times.

When it comes to food poisoning most of us know the dangers of undercooked chicken or seafood left out of the fridge for too long, but rice can also leave you with more than a full belly. You can get food poisoning from rice, if you don’t store it in the fridge after cooking. I wonder, these hotels and takeaway places always follow good food hygiene rules or over rule the food hygiene inspectors? Sometimes nocturnal creatures such as cockroaches and mice come for quick inspection and leave the water seal approval plus droppings.

“Fried rice diarrhoea”

A food microbiologist from CSIRO, Cathy Moir says, a food poisoning bacteria called Bacillus cereus, is found in uncooked rice. Richard E Barrans PhD, Assistant Director PG Research Foundation, Darren, Illinois says, rice often contains hardy bacterial spores that can withstand the cooking process.  Cooking the rice, however, awakens the spores and they become living, metabolizing bacteria once again.  If the conditions are right for the bacteria to grow (say, if the rice is allowed to stand without refrigeration), the bacteria produce a toxin that causes diarrhoea.  This is sometimes called "fried rice diarrhoea" because fried rice is often made with yesterday's steamed rice. I am sure we ate previous night's rice when we didn't have fridges.
 How to avoid poisoning
When the rice is cooked, the spores can survive. Then, if the rice is left standing at room temperature, the spores will germinate into bacteria. These bacteria will multiply and may produce toxins (poisons) that cause vomiting or diarrhoea. Reheating the rice won't get rid of these toxins.

If we keep the cooked rice for a long time, there is more chance this bacterium come into action and produces this toxin. It's best to serve rice when it has just been cooked. If that isn't possible, cool the rice as quickly as possible (ideally within one hour) and keep it in the fridge for no more than one day until reheating. Remember that when you reheat any food, you should always check that it's steaming hot all the way through, and avoid reheating more than once. 
Sure you can eat plain rice, fried rice, buriyani and many more versions but need to be careful if you happened to eat other than from your home cooking. You can eat safely from dinner parties but I would be cautious after that incident.  It's better to think before you eat than suffering later on. 

We never knew

Many years ago, we hardly knew any of these diseases originated from micro-organisms. One must understand these micro-organisms then the conditions needed for it’s survival then must be knowledgeable how to avoid them as much as possible. Who knows, even now we must be consuming some bacteria but the body defence mechanism destroys them.

Cooking shown in British TV

If the TV celebrity cooks want to teach cooking to other people then they must know some chemistry, biology and other related science in relation to food, otherwise they are totally misleading the viewers.

One of the important conditions for these micro-organisms survival is the temperature then they feed on food or even on left over or even on food smear. If you look at a kitchen shown in some TV programes, one would notice the places are exceptionally hot, cooks sweating, perspiring, smoke, partially combusted gases and other volatile gases in the kitchen. The cooks touch utensils, vegetables, fridge door handles and anything after cutting fish, chicken or meat with unwashed hands that help the germs to spread and grow.

The vegetables might be contaminated with traces of pesticides, fertilizers, dirt and may be some micro organism or larvae clinging on to them. These cooks hardly wash the fish, meat, chicken or even the vegetables as they are in a hurry for the camera and the viewers follow them. In my view they are not setting good examples of good food hygiene. The chefs get heavy pay cheques but some viewers get bad food habits. Is this due to utter carelessness or ignorance of the cooks?  Email:

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