CFS announces results related to risk assessment study on potential risk of Listeria in refrigerated food with long shelf life

The Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department today (September 17) announced the results of a recently completed risk assessment study on the microbiological quality, in particular the level of Listeria monocytogenes, of prepackaged long shelf life refrigerated ready-to-eat food products at the end of shelf life. Results showed that none of the samples contained excessive Listeria monocytogenes and the microbiological quality of about 90 per cent of the samples was either satisfactory or borderline in terms of the aerobic colony count (ACC) or Escherichia coli (E. coli) count, both being hygienic indicators.

A total of 100 prepackaged long shelf life refrigerated ready-to-eat food samples, including cheeses, smoked seafood, processed meats and salads, were taken from different retail stores. The samples were refrigerated until laboratory analysis for their microbiological quality, including Listeria monocytogenes count, ACC and E. coli count, was conducted within the week in which the samples were to become expired.

A spokesman for the CFS said, "Results showed that all samples contained less than 20 colony-forming units per gram of Listeria monocytogenes."

He added, "Although results of this study showed that none of the samples contained excessive Listeria monocytogenes, people should not drop their guard. In view of the recent rising trend of listeriosis and the fact that Listeria monocytogenes may continue to grow slowly at refrigerated temperatures as low as 0 degrees Celsius, making refrigerated ready-to-eat food with a long shelf life a potential high-risk item for contracting listeriosis as prolonged storage in a refrigerator may allow Listeria monocytogenes to have sufficient time to grow, the CFS advised those belonging to the high-risk groups, i.e. pregnant women, the elderly and those with a weaker immune system, to avoid high-risk food, for instance refrigerated food with long shelf life, to ensure food safety."

Listeriosis is usually caused by eating food contaminated with Listeria monocytogenes. Most healthy individuals do not develop symptoms or only have flu-like symptoms. However, severe complications such as septicaemia, meningitis or even death may occur in newborns, the elderly and those with a weaker immune system. Although infected pregnant women may just experience mild symptoms generally, the infection of Listeria monocytogenes may cause miscarriage, infant death, preterm birth, or severe infection in newborns.

Concerning ACC and E. coli count, the spokesman said that both of these criteria are indicators of hygienic quality, not safety, of food.

"The results showed that one smoked seafood sample and seven processed meat samples were found to contain ACC at levels exceeding the 'Microbiological Guidelines for Food' which might be caused by post-processing contamination or inadequate temperature control. Furthermore, three cheese samples were found to contain high E. coli count which might be due to the use of raw milk contaminated with E. coli in these products. Consuming the above samples does not represent a health risk, but the test results indicated that the food processing conditions needed to be improved," he said.

The spokesman advised consumers to read food labels carefully to make informed food choices. Those belonging to the high-risk groups should avoid high-risk food.

He also appealed to the food trade to provide sufficient information on food labels for consumers to make informed food choices. They should also maintain good food and personal hygiene at all food processing stages, as well as an adequately refrigerated environment (at or below 4 degrees C) throughout the supply chain for refrigerated products.

The risk assessment study is now available on the CFS website (www.cfs.gov.hk).

Ends/Wednesday, September 17, 2014