In summer, how should we eat ice watermelon?

In the hot summer, watermelon has become a favorite of every household with its unique coolness and sweetness. Imagine taking a piece of iced watermelon out of the refrigerator on a hot afternoon. The refreshing coolness and sweetness seem to instantly sweep away the summer heat.

However, regarding the consumption of watermelon, there are always some voices ringing in our ears, reminding us that iced watermelon may be bad for health, and there are even various concerns about overnight watermelon. But what is the truth?

Will chilled watermelon hurt your stomach?

It’s true that cold food can be upsetting to some people’s stomachs.

Cold, as a stimulus, may cause the stomach to contract, leading to short-term stomach pain or diarrhea. But this does not mean that iced watermelon will cause substantial damage to the stomach. Everyone has different tolerance levels, and the temperature of iced food we come into contact with on a daily basis is unlikely to reach a level high enough to cause frostbite. In fact, if we really feel uncomfortable because the food is too cold, our body will instinctively produce a protective response to remind us to stop eating.

In addition, studies[1] have shown that drinking ice water (4°C) can reduce a person’s heart rate compared to drinking water at room temperature (25°C). This may also cause discomfort, but it is not enough to cause damage. If you find yourself uncomfortable with iced food, it is recommended to reduce the ice time, so that you can enjoy the delicious taste of watermelon while reducing the stimulation to your body. At the same time, another benefit of iced watermelon is that low temperature can inhibit the growth of bacteria and extend the shelf life of watermelon.

However, the suggestion to eat chilled watermelon after leaving it for a while is not a good habit. Low temperature can inhibit the reproduction of bacteria. Once the watermelon returns to room temperature, it will become a paradise for bacteria. This may increase the risk of gastrointestinal infection and lead to gastroenteritis. Therefore, the correct approach is to eat it as soon as possible after chilling to keep the watermelon fresh and safe.

Is it true that overnight watermelon cannot be eaten?

It is reported that a mouthful of overnight watermelon may contain up to 8,400 bacteria. It sounds scary, but in fact, this number is nothing.

We inhale far more microorganisms with every breath of air we take. Research from Nanyang Technological University[2] shows that we inhale up to 1 million microorganisms, including bacteria and fungi, every day.

Therefore, it is not very meaningful to simply focus on the number of bacteria. What we should pay more attention to is whether there are pathogenic bacteria among these bacteria and the number of pathogenic bacteria.

Whether the watermelon is left overnight or not does not completely determine the number of pathogens. In fact, factors such as the initial bacterial condition of the watermelon, storage conditions and methods, etc., will affect the number of pathogens. If it is a whole intact watermelon, it can be stored at room temperature for 1-2 weeks; if it is immediately placed in the refrigerator after being cut, and the refrigerator itself is not contaminated, and it is sealed with sterile plastic wrap, the storage time can reach 2 days. Even the National Watermelon Commission of the United States has found that if stored properly, cut watermelons can be eaten after 7 days.

Image source: watermelon.org

Although overnight watermelon can be eaten if stored properly, I still don't recommend that you keep watermelon for too long. After all, it is difficult to ensure that it is stored properly every time. In addition, I also don't recommend that you eat too much watermelon, as this will consume a lot of sugar. For modern people's lifestyle, it is better to reduce sugar intake to be more beneficial to health.

Finally, let's talk about how to enjoy watermelon safely. First, choose ripe watermelon to avoid the discomfort that unripe watermelon may cause. Second, before cutting the watermelon, make sure the knife and hands are clean to reduce bacterial contamination. Third, try to eat it as soon as possible after cutting. If you need to store it, use plastic wrap to cover it and store it in a clean refrigerator. Finally, eat it in moderation and enjoy the delicious taste of watermelon, but be careful not to overeat to maintain healthy eating habits.

Through these methods, we can safely enjoy the coolness and deliciousness brought by watermelon while maintaining a healthy lifestyle. Watermelon is not only a summertime holy grail, but also a delicious gift given to us by nature. While enjoying it, we must also know how to cherish and use it reasonably.

References:

[1]Chiang CT, Chiu TW, Jong YS, et al. The effect of ice water ingestion on autonomic modulation in healthy subjects. Clin Auton Res. 2010;20(6):375-380.

[2]Gusareva ES, Acerbi E, Lau KJX, et al. Microbial communities in the tropical air ecosystem follow a precise diel cycle. Proc Natl Acad Sci US A. 2019;116(46):23299-23308.

Author: Jiang Yongyuan, Master of Internal Medicine, Third Military Medical University

Reviewer: Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center

The article is produced by Science Popularization China-Creation Cultivation Program. Please indicate the source when reprinting.