The European Food Safety Authority (EFSA) has published a report on the public health risk posed by Listeria monocytogenes in frozen fruit and vegetables that have been blanched during processing. Blanching before freezing is often carried out by food business operators to prevent enzyme actions which can cause loss of flavour, colour and texture.

The EFSA identifies relevant control activities that food business operators can implement to lower the risks of contamination in frozen vegetables. These range from the cleaning and disinfection of the food producing environment, to water, time and temperature control at different processing steps, and accurate labelling. The report concludes that the risks associated with the consumption of these products is lower than for ready-to-eat foods such as smoked fish, cooked meat, sausages, pâté and soft cheese, which are more often associated with Listeria contamination.

The EFSA also makes recommendations on how to reduce risks at home, including maintaining good hygiene practices such as storing frozen or thawed vegetables in a clean freezer or refrigerator at the appropriate temperature and following the instructions on labelling for safe preparation. In general, risks are much lower if vegetables are cooked properly after defrosting.

This work was triggered by a multi-country outbreak that affected 53 people and caused 10 deaths between 2015 and 2018.