Is it safe to eat pre cut watermelon? (main risk)

In this article, we will discuss whether it is safe to eat pre-cut watermelon, what are the risks of eating pre-cut watermelon, when is pre-cut watermelon not safe to eat, and how to safely consume pre-cut watermelon.

Pre-cut watermelon is a very convenient food Previously cutting the watermelon considerably reduces the time necessary to prepare watermelon, as it is not a practical fruit and requires good cutting skills.

Is it safe to eat pre cut watermelon?

Yes, it is safe to eat pre-cut watermelon, unless there are signs of spoilage in the fruit. Pre-cut fruit is very convenient, however, it may be a risk, due to its very short shelf life and perishability (1, 2).

However, when improved sanitation is used during the preparation and safety recommendations are properly followed, pre-cut watermelon can be safely consumed for many days (1).

Is pre-cut watermelon less safe than whole watermelon?

Yes, pre-cut watermelon is less safe than whole watermelon. Food handling is one of the most critical issues in food safety to increase the risk of contamination (1, 2, 3).

A whole watermelon is free from microorganisms in its centre, which is protected by the rind. When the watermelon is cut, the microorganisms that are outside of the fruit migrate to the inner part of the fruit.

When food is handled it enters into contact with cutting surfaces, cutting utensils, and environmental oxygen. All these factors accelerate microbial spoilage.

To reduce the risks, wash the whole watermelon with water containing sodium hypochlorite or other sanitising agent before cutting. Improved cleaning of surfaces and utensils is required as well as best hygienic practices (2, 3).

What are the risks of eating pre-cut watermelon?

The risks of eating pre-cut watermelon are mainly related to foodborne diseases caused by the consumption of contaminated fruit. Pre-cut fruit is susceptible to microbial spoilage due to its intensive handling during the preparation.

The common microorganisms related to the spoilage of pre-cut fruits are Salmonella, Shigella, faecal coliforms, acid lactic bacteria, Yersinia enterocolitica, Listeria monocytogenes, Escherichia coli, and yeasts (2).

The consumption of pre-cut watermelon with an elevated microbial count may or the ingestion of toxins produced by microorganisms may lead to foodborne illnesses.

Possible symptoms of a foodborne illness caused by pathogens are diarrhoea, fever, stomach cramps and vomiting (3).

Is it safe to eat pre-cut watermelon when pregnant?

No, it is not safe to eat pre-cut watermelon when pregnant. Due to the weakened immune system during pregnancy, there is a higher susceptibility to having a foodborne illness (3).

In the case of infections caused by Listeria monocytogenes in pregnant women, there is a risk of spontaneous abortion and stillbirth. When pregnant, prefer eating pasteurised fruit juices and freshly washed and cut or cooked fruits (4).

When is pre-cut watermelon not safe to eat?

Pre-cut watermelon is not safe to eat when it has signs of spoilage. Possible indications that the pre-cut watermelon is the following (1, 2):

  • The presence of discolouration in the fruit
  • Excessive softening of the flesh
  • Loss of firmness with juice leakage
  • Water-soaking appearance 
  • Presence of off-odours
  • Presence of mould colonies

What is the shelf life of pre-cut watermelon?

The shelf life of pre-cut watermelon varies between 2 days to 2 weeks when stored in the fridge, depending on many factors, such as the packaging, the hygienic practices during the preparation, and the application of a post-cutting process (1, 2).

For instance, while untreated homemade pre-cut watermelon has a shelf life of 2 days,  pre-cut watermelon mild heat-treated with a solution of 1 % calcium chloride has a shelf life of 8 days in the refrigerator (1).

Pre-cut watermelon packed in high carbon dioxide and low oxygen concentration modified atmosphere packaging had a shelf life of over 10 days as related in a study (1).

How can you improve the shelf life of pre-cut watermelon?

Some possible methods to improve the shelf life of pre-cut watermelon are described in the table below (1, 2):

Factor influencing shelf life Description Effects
Sanitising the whole watermelon  Carefully washing and sanitising the whole watermelon before cutting using a hypochlorite solution  Reduces the microbial load of the fruit surface of the watermelon, lowering the risk of contamination
Cutting watermelon into larger cubes The size of the watermelon cubes should be rather larger than smaller Reduces tissue damage during handling and transportation, improving the shelf life
Treating watermelon cubes with 1% calcium chloride at 45 °C Calcium chloride binds to hydroxyl acid, forming calcium pectate  Improvement of the cell tissue firmness and consequent increase in the shelf life
Packing of pre-cut watermelon in a modified atmosphere packaging  Reduces the respiration rate of pre-cut watermelon, reduces microbial growth Improvement of the shelf life 

Conclusion

In this article, we discussed the safety of eating pre-cut watermelon, the risks of eating pre-cut watermelon, when is pre-cut not watermelon safe to eat, and how can you increase the shelf life of pre-cut watermelon.

Watermelon is not a practical fruit to eat, however, due to its short shelf life when pre-cut, I still prefer to cut it right before eating, although if the watermelon is properly handled, pre-cut watermelon can be perfectly safe to eat!

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References

1.-

Lee YZ. Improving quality maintenance of fresh-cut watermelons (Doctoral dissertation, University Of Tasmania).

2.-

Chauhan OP, Raju PS, Bawa AS. Pre-cut fruits and vegetables: Pre-and post harvest considerations. Fresh Prod. 2007;1(2):82-93.

3.-

Harris LJ, Farber JN, Beuchat LR, Parish ME, Suslow TV, Garrett EH, Busta FF. Outbreaks associated with fresh produce: incidence, growth, and survival of pathogens in fresh and fresh‐cut produce. Comprehensive reviews in food science and food safety. 2003 Jan;2:78-141.

4.-

Dean J, Kendall P. Food safety during pregnancy. Food and nutrition series. Food safety; no. 9.372. 2004.