I never order rice when I’m out. When I make rice, it’s into the refrigerator reasonably fast. But lots of people leave it out overnight and that’s the problem.
According to a national Newspoll survey, commissioned for Australian Food Safety Week, 22% of Australians think it is ok to leave cooked rice out of the refrigerator for up to 6 hours or overnight – or even that it doesn’t need refrigerating at all.
Dr Michael Eyles, Food Safety Information Council Chair, said that many consumers consider that cooked rice is a low risk for food poisoning and can safely be left on the benchtop if the fridge is too full.
‘This just isn’t true. Spores from the bacteria Bacillus cereus can survive the cooking process and once the rice begins to cool, they can grow and form a heat resistant toxin. This toxin is not destroyed by further reheating, with only very small amounts needed to make you sick.’ Dr Eyles said.
‘In contrast it was pleasing to see people surveyed were much more aware that raw egg mayonnaise and chicken dishes were a high risk for food poisoning as only 4% thought it ok to leave those products unrefrigerated for up to 6 hours or overnight. But even 4% of consumers taking this risky behavior adds to the estimated 4.1 million cases of food poisoning in Australia each year.
The 2014 Newpoll survey was conducted nationally, over the phone, among 1252 respondents aged 18 years and over.
Effect of temperatures on the growth, toxin production, and heat resistance of Bacillus cereus in cooked rice
Bacillus cereus is capable of producing enterotoxin and emetic toxin, and Bacillus foodborne illnesses occur due to the consumption of food contaminated with endospores. The objectives of this study were to investigate the growth and toxin production of B. cereus in cooked rice and to determine the effect of temperature on toxin destruction. Cooked rice inoculated with B. cereus was stored at 15, 25, 35, and 45°C or treated at 80, 90, and 100°C. The results indicated that emetic toxin was produced faster than enterotoxin (which was not detected below 15°C) at all the storage temperatures (15–45°C) during the first 72 h. Emetic toxin persisted at 100°C for 2 h, although enterotoxin was easily to be destroyed by this treatment within 15 min. In addition, B. cereus in cooked rice stored at a warm temperature for a period was not inactivated due to survival of the thermostable endospores. These data indicate that the contaminated cooked rice with B. cereus might present a potential risk to consumers. Results from this study may help enhance the safety of such food, and provide valuable and reliable information for risk assessment and management, associated with the problem of B. cereus in cooked rice.