A national microbiological survey, undertaken by the Food Safety Authority of Ireland (FSAI) and Safefood, has highlighted the potential low-level risk of illness for consumers who eat non-ready-to-eat frozen vegetables, fruits, or herbs without prior cooking.
The survey was undertaken in light of a European outbreak of Listeria monocytogenes, where there were 53 cases and 10 fatalities linked to the consumption of uncooked, non-ready-to-eat frozen sweetcorn and frozen vegetable mixes containing sweetcorn.
It was also conducted against a backdrop of increased consumer interest in eating frozen fruit, vegetables and herbs, the FSAI said.
Non-ready-to-eat foods
These are required to be fully cooked prior to eating by following the cooking instructions labelled on the packaging.
The microbiological study analysed almost 1,000 samples of frozen vegetables, fruits and herbs for the presence of L. monocytogenes, Salmonella, Listeria spp. and Escherichia coli.
L. monocytogenes was found in 27 of the samples tested (3%), the majority of which were non-ready-to-eat frozen vegetables (21 samples).
Symptoms of L. monocytogenes infection can include mild flu-like symptoms, or gastrointestinal symptoms such as nausea, vomiting and diarrhoea.
While figures were low for the presence of L. monocytogenes, it is a potential health risk for people who may eat these non-ready-to-eat frozen foods uncooked frequently; and/or if consumer preparation and handling practices allow L. monocytogenes, if present, to grow to levels high enough to cause listeriosis.
Frozen fruit and veg
The consumer research part of the survey surveyed 815 people across the island of Ireland and found that 80% said they regularly eat frozen vegetables; 40% eat frozen fruits; and 13% eat frozen herbs.
While most (68%) said they would cook the product before eating, others (32%) said they regularly eat one or more types of frozen vegetables, fruits or herbs without cooking them.
Strawberries, blueberries, raspberries, and mixed berries were the frozen fruits most likely to be eaten uncooked in a dessert or in a smoothie.
A smaller number of consumers said they would regularly eat uncooked non-ready-to-eat frozen vegetables such as sweetcorn, carrots, peas, peppers, and spinach in a salad or as a garnish.
The FSAI and Safefood advise that all non-ready-to-eat frozen vegetables, fruits and herbs should be cooked prior to eating and in accordance with the cooking instructions on the label.
If these products are eaten uncooked by people who are immunocompromised, pregnant, the elderly or young children, there is risk of serious illness.
Commenting at the release of the study, chief executive, FSAI, Dr. Pamela Byrne, emphasised the importance of correct labelling and that caterers and foodservice businesses must ensure they are following the manufacturers’ instructions when they are preparing food for their customers.