Rice and other starchy foods

Rice and other starchy foods like potato flakes and custard powder can contain harmful bacteria that may cause illness if the food isn't handled safely.

Bacillus cereus infection

Rice and other starchy foods such as potato flakes, custard powder and pasta can be infected with Bacillus cereus – a bacterium that can cause nausea and vomiting. The bacteria grow when these foods have been cooled too slowly, or not correctly stored in a refrigerator.

How to avoid infection

Always follow safe practices when cooking and storing starchy foods. Don't leave cooked or prepared food to cool slowly at room temperature. Make sure the cooked product is either:

  • eaten immediately
  • kept hot at above 60 degrees Celsius
  • cooled and stored under refrigeration until used.

If rice has been cooked for sushi or egg-fried rice, cool it in the refrigerator until it is ready to be used. Sushi rice usually includes the addition of sushi vinegar and a mixture of sugar and salt, which helps prevent the growth of Bacillus cereus bacteria.

Reheating rice or other starchy foods doesn't kill the bacteria. The bacteria can withstand heating for 90 minutes at a temperature of 126 degrees Celsius.

Read more about Bacillus cereus in MPI's Meet the Bugs pamphlet [PDF, 1.3 MB]

Who to contact

If you have questions about food safety, email info@mpi.govt.nz.

Last reviewed: