November 04, 2023

Science experiments tell us we've been eating watermelons wrong all our lives

There are melons and there are melons

Summer and watermelon are best combination

But not finished watermelon

Can I eat after night

How to store it more securely

Hey, you're asking right person

Recently Xiangshan County, Ningbo, Zhejiang Province

Microbiological Laboratory of Center for Inspection and Testing of Food Products

Especially on question of "how to store watermelon"

A comparative experiment with watermelons was carried out

Watermelon storage experiment

●Purpose of experiment

Simulate two common ways to store watermelons in everyday life:

1. Store at room temperature at 30 °C;

2. Keep refrigerated

Experiment to determine if you want to wrap a watermelon that you can't finish eating?

●Experimental method

According to GB 4789.2-2016 National Food Safety Standard. Determination of total number of bacterial colonies of food products during microbiological control, total number of bacterial colonies is quantified in microbiological laboratory. The total number of colonies reflects purity of food, higher value, more "dirty".

●Experimental process

Don't look at simplicity of "eating melons" if you are scientific and strict about it, there are university questions about it.

In lab, Xiangshan County Food Inspection and Testing Center simulated two storage methods for daily watermelons, one at room temperature at 30°C and other at 4°C in refrigerator. Then, sliced ​​watermelons were divided into two shells wrapped in plastic wrap and not wrapped in plastic wrap, and placed for 4 hours, 8 hours, 16 hours, 24 hours, and 48 hours, respectively, and then total number of bacteria in the watermelon samples was counted.

The experimental data is as follows


Direct experiment on uncut surface of a watermelon

Notes: Currently, our country does not have regulations on total number of colonies of fresh fruits and vegetables, and regulations for fruit products should not exceed 1000 CFU/g.

It turns out

After 4 hours and 8 hours, total bacteria count is basically <20 CFU/g whether refrigerated or not, with or without plastic wrap, starting at 16 hours. , bacteria begin to multiply, and after 24 hours bacteria multiply exponentially. That is, if a watermelon is stored for 8 hours, then it does not matter if it is in plastic wrap or in refrigerator.

However, watermelons stored at room temperature more than 24 hours had a million times more bacteria than watermelons stored in refrigerator (with or without plastic wrap). It is recommended that watermelons stored at room temperature should not be consumed after 24 hours.

If watermelon is too big to be eaten in a day, it's best to store it in refrigerator. There are a lot of things in family refrigerators, so it is safer to cover them with plastic wrap.

Some families cut off surface of a watermelon taken out of refrigerator before eating. Does this method affect reduction of bacteria? Look at results provided to us by lab.

Cut off 0.5cm from surface of watermelon for experiment

Notes: Different conditions and temperatures will have different results, such as whether air conditioner is turned on, whether refrigerator is clean, whether watermelon cutter and table are clean, and end result is different.


The striking difference is that after 16 hours storage at simulated room temperature, a notched watermelon is clearly 100 times smaller than an unnotched watermelon.

When stored in refrigerator, whether it is 24 hours or 48 hours, total number of bacteria in cut surface watermelon within 48 hours is less than 10. On one hand, such an environment can inhibit rate of bacterial reproduction, on other hand, after As surface of watermelon is cut off, bacteria on surface is removed, so eating watermelon is safer and more hygienic. This shows that after long-term storage of watermelon, cutting off flesh of watermelon on surface can reduce number of bacteria.

Come on, come on, class reps online

Summing up for friends

Correct posture "eating melon in summer"

1. Before eating a melon, you must not forget to wash melon, before you cut melon, do not forget to wash knife;

2. If you eat it within 8 hours of cutting it, you can put it in a ventilated place indoors. You don't need to cover it with plastic wrap, you can use a sarong to cover it; if you like icy taste of cooling, you can put it in refrigerator, with or without plastic wrap;

3. If you eat it more than 16 hours after cutting, be sure to cut off a 0.5 cm thick piece from remaining surface of watermelon and store it in refrigerator! But it is better to eat it as soon as possible and not leave it for a long time.

Your family hasn't finished their watermelon today,

Have you figured out how to save it?