How long can a cut watermelon be kept, 1 day, 2 days?

Let me give you the answer first:

It is recommended to seal the cut watermelon with aluminum foil or plastic wrap and store it in the refrigerator.

Best to eat within 2 days.

After the Grain Full, the temperature gradually rises and heat waves frequently hit. If you want to spend the summer safely, in addition to air conditioning, watermelon is an irreplaceable summer artifact!

In many people’s minds, watermelon’s status in summer even surpasses ice cream. The natural sweetness brought by the fruit and the taste of the juice when squeezed into the mouth are simply something that people never get tired of eating.

Plus, who didn’t have a big watermelon frozen in cold water by their grandma in their childhood? This kind of emotional filter makes the watermelon even more attractive.

However, there is a hidden concern about eating watermelon: if you cannot finish the big watermelon you buy at home in one go, you worry that it will go bad if you leave it alone.

After all, the news often pushes news like "A young man was admitted to the ICU after eating overnight watermelon" and "The whole family suffered kidney failure just because they ate overnight watermelon on the table", which makes people feel scared. How long can a cut watermelon be kept? Today, let's talk about this topic thoroughly.

01

Why does watermelon go bad so easily?

Compared with other fruits, watermelon is one of the fruits that is easier to go bad.

First of all, ordinary watermelons are large and difficult to eat in one go, so they are more likely to be left over than other fruits.

Secondly, the process of cutting watermelon is easy to be contaminated with bacteria. If the melon rind is not cleaned well before cutting, or the knife or cutting board is not clean, bacteria may be brought to the surface of the watermelon.

The moisture and sugar in watermelon can be said to be a good bacterial culture medium. In addition, the temperature and humidity are very high in summer, which provides excellent objective conditions for bacterial reproduction .

Improper storage is also an important reason for watermelon to go bad. If the cut surface of the watermelon is not sealed in time after cutting, it is easy to be contaminated by bacteria. If it is left at room temperature, the bacteria will multiply very quickly and the watermelon will easily go bad.

02

How long can you keep a cut watermelon?

There are many different opinions on the answer to this question. Some people say "a mouthful of overnight watermelon contains 8,400 bacteria", while others say "I've eaten watermelon that was left for 2 days and it was fine"...

How long can a cut watermelon be kept? There is indeed an experiment done by foreign researchers. Although the experiment was conducted a long time ago, the conclusions drawn are still reliable today because the experimental conditions were not complicated.

In short, the experimenters compared the storage time of cut watermelons under different temperatures and different sealing conditions, and found that:

Whether it is from the total number of bacteria or the color, taste and smell of watermelon, watermelons that are sealed and stored at low temperatures are much better than those that are not sealed and not stored at low temperatures .

Specifically, the total number of bacteria in the watermelon wrapped in aluminum foil was still within an acceptable range after being stored in the refrigerator for 7 days. However, on the 4th day, the smell and taste of the watermelon changed significantly.

Considering that there are various other foods in the refrigerator compartment of a general household, it is difficult to avoid the presence of other bacteria. It is recommended that even if the watermelon is sealed and refrigerated with aluminum foil or plastic wrap, it is best to eat it within 2 days .

Of course, it would be best if you can cut and eat it immediately, or eat it on the same day.

03

Will storing watermelon in plastic wrap make it go bad faster?

Let me give you the answer first: what determines the speed at which watermelon spoils is the number of bacteria, storage time and temperature, etc. It has nothing to do with plastic wrap .

If the plastic wrap itself is clean and sterile, and is not contaminated by bacteria on the operator's hands, cutting board, rind or pulp when wrapping the watermelon, then wrapping the watermelon with plastic wrap can isolate it from bacterial contamination and extend the shelf life of the watermelon.

On the contrary, if the watermelon is not cleaned properly before cutting, and the knife, cutting board and the operator's hands are not clean enough, then when the watermelon is cut, there may be bacteria on the surface of the flesh. At this time, wrapping it with plastic wrap will not prevent the reproduction of bacteria.

Of course, using plastic wrap that has been contaminated with bacteria to seal the watermelon may indeed accelerate the deterioration of the watermelon, but the possibility is very small.

04

If you eat a bite of leftover melon, you will ingest 8,400 bacteria?

Some news reports mentioned that "one bite of leftover melon can ingest 8,400 bacteria." Is this true?

Let me tell you the answer first: whether it is true or not, don’t worry.

On the one hand, the presence of bacteria does not necessarily mean that there are pathogenic bacteria. Even if there are 8,400 bacteria in the overnight watermelon, it does not necessarily mean that there will be problems if you eat it.

On the other hand, even if there are 8,400 bacteria, it's actually not that scary.

Refer to the national standard GB 2759-2015 for the total colony count of frozen drinks and ingredients: "Take 5 different parallel samples, and at most two samples can have a total colony count between 25,000 and 100,000/ml, while the other samples must be less than 25,000/ml."

By comparison, a mouthful of overnight watermelon contains 8,400 bacteria. Doesn’t that seem like a lot?

To sum up, if you want to eat melon safely and healthily, you should pay attention to these 4 points:

1. Before cutting watermelon, clean the rind, knife, cutting board, operator's hands, etc. Do not mix fruit cutting knives and cutting boards with those for cutting meat and vegetables to avoid contaminating the watermelon pulp with bacteria during the cutting process.

2. Cut less at a time and make the cut as small as possible (for large watermelons, horizontal cuts are better than vertical cuts). If you are sure that you cannot finish the part, immediately seal it with clean plastic wrap to prevent bacteria in the environment from landing on the watermelon flesh.

3. After wrapping the watermelon, put it in the refrigerator immediately . Keep it separate from raw and cooked food and put it together with cooked food! Keep it away from raw meat, raw eggs and other foods that may carry pathogens to prevent the watermelon from being contaminated in the refrigerator.

4. Eat as soon as possible and do not store for more than 2 days . If you find that the flavor and color of the watermelon have changed, you should avoid eating it.

Finally, I would like to remind everyone: When eating melons in summer, be sure to limit the amount!

Watermelon has a very high water content, which can easily cause a feeling of fullness and affect the intake of regular meals. In addition, the nutrient content of watermelon is unbalanced, with high sugar content and low protein. Eating watermelon as a meal will affect the intake of other nutrients.

Author: Wang Lu, Chinese registered dietitian, Master of Public Health, Peking University

Reviewer: Chen Ran, Associate Research Librarian (Science Communication) / Senior Engineer, COFCO Nutrition and Health Research Institute