EFSA has assessed the risks to public health from Listeria contamination of vegetables that are blanched – scalded in hot water or steam for a short time – before they are frozen. They conclude 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, soft cheese – which are usually associated with listeria contamination.

Food business operators often blanch vegetables before freezing them because this stops enzyme actions which can cause loss of flavour, colour and texture.