Author Archives: catherine wong

In Australia, there was a recall on September 3, 2015 due to pre-packaged fried rice from the company JL King & Co due to Listeria monocytogenes. Both packagings of 1kg and 450g were on the recall. As of now, there is still no information about the source of contamination, how many or if there were any consumers who got sick. The best before date for this product was September 15, 2015, which was only 12 days from the date the recall was announced. (Australian Competition Consumer Commission, 2015)

Similar to most other ready to eat foods that Listeria monocytogenes like to grow in, the shelf life is quite short and some consumers consume the ready to eat products right after purchasing. Other products such as canned foods that Clostridium botulinum can grow in, the shelf life can be up to 2 years which gives plenty of time for recalls as those consumers may not consume them immediately after purchase. The recalls for ready to eat foods such as the pre-packaged fried rice can serve the purpose of taking the food off store shelves to prevent future consumers from getting sick. However for the consumers who have consumed contaminated products before any recall notification, some of them may not even get sick due to the natural microflora present on their intestinal surfaces.

The ones who are most susceptible to falling ill from Listeria monocytogenes are pregnant women and their unborn or newborn children, seniors and the immunocompromised. For pregnant women in the first three months of pregnancy, being sick with Listeria monocytogenes can cause a miscarriage. If the bacteria is contracted later on in the pregnancy, premature birth, stillbirth or the birth of a severely ill child may happen. The immunocompromised are much more likely to get sick but according to the Public Health Agency of Canada, people suffering from AIDS are 300 times more susceptible to being infected by Listeria monocytogenes compared to healthy individuals. (Public Health Agency of Canada, 2012)

Listeria Monocytogenes luckily cannot grow in all ready to eat food products as long as the food product falls under one of the following three criteria according to Australia’s Food Standards (Food Standards, 2014):
1. pH less than 4.4, no matter the water activity value
2. Water activity less than 0.92, no matter the pH value
3. pH less than 5.0 and water activity less than 0.94

However, if Listeria monocytogenes is present it can survive in acid conditions and in products with low water activity for a long period of time, especially for refrigerated products. Even if the product has gone through a drying process, Listeria monocytogenes may survive. (Lawley, 2013)

If the ready to eat food product is frozen and is consumed frozen, thawed but still eaten cold or heated before consumption then it is most likely safe from Listeria Monocytogenes. (Food Standards, 2014) If the ready to eat food product does not fit with the above criteria, then heating to an internal temperature of 74°C before eating can help in minimizing the chance of Listeria monocytogenes surviving in the food. (Public Health Agency of Canada, 2012)

With all the conditions Listeria monocytogenes can grow or survive in ready to eat products, I feel that one of the better ways to minimize the risks of getting ill from Listeria monocytogenes is to heat ready to eat products except for frozen products before consuming. Although this might be difficult for ready to eat foods that are generally eaten at room temperature such as sandwiches.

Are there any other methods that you think are sufficient in eliminating Listeria monocytogenes?

References:

Andersen, L. (2015) Listeria and Bacteriocin-Producing Starter Culture. Retrieved from http://www.foodsafetynews.com/2015/08/listeria-and-bacteriocin-producing-starter-cultures/#.Vi3XUmSrToB

Australian Competition Consumer Commission. (2015). Product Safety Recalls Australia. Retrieved from http://www.recalls.gov.au/content/index.phtml/itemId/1076441

Food Standards. (2014). Supporting document 1 – Guidance On the Application of Microbiological Criteria for Listeria Monocytogenes. Retrieved from
http://www.foodstandards.gov.au/code/proposals/Documents/P1017-MicroAppR-SD1.pdf

Lawley, R. (2013). Food Safety Watch. Retrieved from http://www.foodsafetywatch.org/factsheets/listeria/

Public Health Agency of Canada. (2012). Listeria. Retrieved from
http://www.phac-aspc.gc.ca/fs-sa/fs-fi/listerios-eng.php