A new study conducted by researchers at the University of Arkansas and WBA Analytical Laboratories in the USA has revealed that bacterial pathogens may persist on the surfaces of the reusable plastic containers (RPC) often used to transport fresh produce and other foods even after standard cleaning and sanitising.
The researchers, led by Dr Steven Ricke of the Center of Food Safety at the University, placed coupons made from RPC material in liquid cultures of Salmonella, Listeria monocytogenes and E. coli O157:H7 and incubated them to allow the bacteria to grow on the surfaces. After careful rinsing, the coupons were examined using scanning electron microscopy to look for attached bacteria. In all cases, the bacteria had produced attached biofilms on the plastic surfaces.
Further experiments were then carried out to determine the effect of typical cleaning and sanitising procedures used to clean RPC in the food industry. This was done by applying cleaning and sanitising agents directly and by swabbing the plastic coupons to mimic the effect of physical cleaning. The results showed that bacteria remained attached to the plastic surface after cleaning.
The findings suggest that biofilms could build up on RPC over time as they are reused and could act as a source of pathogen contamination for transported foods. However, the researchers conclude that more research is necessary to determine whether there is a real risk to consumers from RPC as opposed to single use containers. There are no documented cases of RPC acting as the source of contamination in food poisoning outbreaks.
A draft report of the study findings can be found here.