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Melons can transfer pathogenic germs

22/2013, 09.08.2013

The BfR recommends to keep melons refrigerated or to consume them soon after preparation

Melons are popular due to their sweet, juicy and soft flesh. In summer especially, consumers are fond of eating large amounts of the fresh and healthy fruit. However, melons can be contaminated with pathogens during production, transport or storage. When prepared for consumption, these pathogens can then be transferred to the flesh of the fruit. "Salmonella, listeria and EHEC can multiply relatively quickly on the flesh of the fruit which is low in acidity", says Professor Dr. Dr. Hensel, President of the Federal Institute for Risk Assessment (BfR). "To protect themselves against infections, consumers should therefore eat pre-cut melons quickly or refrigerate them." Melon pieces which have been left unrefrigerated for several hours should be disposed of for safety reasons. In general, the BfR recommends that the rules of kitchen hygiene be strictly applied when preparing and storing melons. Pregnant women, small children as well as old and sick people should, to be on the safe side, refrain from eating cut melons which have been stored at room temperature for several hours.

Shops sell melons either whole or in parts (half and quarter melons). Pre-cut melons too are popular; they are sold ready to eat, often mixed with other types of fruit. Microorganisms can easily adhere especially to the rough surface of netted melons such as cantaloupes, for example. If pathogenic bacteria come into contact with the flesh of the fruit which is low in acidity and the fruit is not refrigerated, they can multiply within a few hours and thus potentially pose a serious health hazard. In connection with the consumption of melons, outbreaks of illness have been triggered predominantly by salmonella, listeria and EHEC (enterohaemorrhagic Escherichia coli).

In the USA in 2011, for example, at least 147 people contracted an infection caused by Listeria monocytogenes following the consumption of contaminated Cantaloupe melons. 33 people died as a result of the infection and one pregnant woman suffered a miscarriage. The germs had been transferred from the skin to the flesh while the fruit was cut. In Germany, the United Kingdom and Ireland, the consumption of imported water melons led to a salmonella outbreak at the end of 2011. The risk of becoming ill following the consumption of melons cannot be assessed for Germany, however, due to a lack of data.

Melons can come into contact with pathogens at various stages of their production, for example through inadequate hygienic precautions during production or while they are washed. In addition, infected persons can spread pathogens directly on to the melons in case of insufficient hygiene.

When melons are cut up, bacteria can be transferred from the skin to the flesh. Additionally, the flesh can be contaminated with pathogenic germs through hands or unclean kitchen implements (knives or chopping boards).

In order to minimise the risk of a food-borne infection, the general rules of kitchen hygiene should therefore be followed under all circumstances when cutting up melons. This notably involves washing hands and using clean knives and chopping boards in order to avoid cross-contamination. These rules equally apply to the preparation of melons in food retail stores, private households as well as community institutions and other catering establishments such as restaurants.

The BfR recommends to food retail stores, restaurants and eateries, and community institutions to cut melons only in small quantities which can be sold to customers within about two hours.

Consumers should always cover leftover parts of melons and store them in the refrigerator, if they cannot be eaten immediately. Pregnant women and persons with an underdeveloped or weakened immune system (infants, old and sick people) should, as a precaution, refrain from eating cut melon which has been stored at room temperature for several hours. Such persons should think carefully before eating melons, if they do not know whether the fruit has been left unrefrigerated for a long period of time.

About the BfR

The Federal Institute for Risk Assessment (BfR) is a scientific institution within the portfolio of the Federal Ministry of Food, Agriculture and Consumer Protection (BMELV). It advises the Federal Government and Federal Laender on questions of food, chemical and product safety. The BfR conducts its own research on topics that are closely linked to its assessment tasks.

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