No need to ask the "melon photographer" for help, just look here to know whether the watermelon is sweet or not!

Midsummer has quietly arrived. The most pleasant thing to do on a hot summer day is to eat watermelon in the air-conditioned room. If you come across the "dream melon" with sandy flesh and few seeds, you must take a picture of it and post it on your Moments to show off.

However, for many friends, such good melons are really "unprecedented", why? They don't know how to choose...

Although we all know that we can judge the ripeness of watermelons by patting them with our hands and listening to the sound, when it is our turn, we often pat all the watermelons in the stall one by one, but we still don’t know which one is good, and finally we have to ask: Boss, are your watermelons ripe?

So is it reliable to "identify melons by sound"? What are the tips for choosing melons? Let's talk about it today.

01

Listening to the sound can really identify the melon

First of all, the idea of ​​“identifying melons by sound” is reliable.

For example, in order to avoid selling unripe or rotten melons to customers and receiving bad reviews, some online e-commerce businesses need to have a basic judgment on the ripeness of melons, thus giving rise to a new profession - the melon photographer.

A melon photographer can usually tell the difference between raw melons, ripe melons, overripe melons, melons with many tendons (melons with many white or yellow tendons in the flesh that affect the taste), and bad melons in just 2 to 3 seconds. He has to photograph eight to nine thousand melons a day, and his income is quite considerable.

Image source: Weibo screenshot

So how do you judge whether a melon is ripe by listening to the sound?

According to the watermelon picker, unripe watermelons often make a crisp sound, while ripe watermelons often make a "dong dong dong" sound, which is a bit shaky, and overripe watermelons make a "pu pu pu" sound, which is often deeper. So if you want to pick out good watermelons yourself, you need to practice more on the perception of sound and the feel of your hands, and buy more. Maybe you can become the next watermelon picker.

Of course, as the saying goes, every profession has its own expertise, and the skill of picking melons is not so easy to master. But it doesn’t matter, we will introduce to you a set of particularly easy-to-learn tips for picking melons later.

02

Why can you tell whether a melon is ripe or not by patting it?

So why do different watermelons make different sounds when tapped?

Currently, a more mainstream explanation is that the hardness and cellulose content of the flesh of watermelons of different maturity are often different. Unripe watermelons have a high cellulose content and high hardness, and the vibration frequency is higher when tapped, so the sound will be crisper.

As the watermelon matures further, the cellulose in the watermelon is continuously hydrolyzed, the flesh becomes looser, the vibration frequency is not so high, and the sound becomes lower. Just like the strings in a string instrument, the tighter the string is, the higher the frequency of the string vibration is, and the higher the pitch is. Conversely, the lower the pitch is, the duller it will sound.

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Normally, if we hear the melon wrong, we can just grit our teeth and eat it with tears in our eyes, but in some situations, the consequences of making a mistake can be quite serious.

When I was an undergraduate, a professor once told me that he had taken a course on horticultural product quality analysis. At the end of the semester, there was a practical exam. The exam content was very simple and direct. The teacher brought several watermelons of different maturity, and everyone judged the maturity of several watermelons by tapping the watermelons and listening to the sound. The exam scoring was also very fair and intuitive - cut them open and look.

If your test paper says "this melon is ripe", but you cut it open and find it's raw, I'm sorry, you have to prepare for a make-up exam...

03

This method of selecting melons can be learned by everyone

As mentioned before, although “identifying the quality of a watermelon by its sound” is reliable, it is not easy to learn. So, besides tapping the watermelon to determine its quality, are there any other ways to tell the quality of a watermelon from its appearance?

For this reason, the author specifically asked a student from Huazhong Agricultural University who is engaged in the research of muskmelon (the abbreviation of watermelon and melon). She introduced several major factors for consumers to choose watermelon:

1. The melons should be well-proportioned and round. Do not choose crooked melons.

2. The texture is clear, and the dark green stripes and light green background contrast sharply;

Choose a watermelon with clear lines and a regular shape like the one on the left. Image source: Photo by the author

3. The vines are fresh and green. If there are no vines, it may be that the vines have been stored for a long time and withered, so the stall owner cut them off himself;

Choose a fresh watermelon on the vine on the left. Image source: Photo by the author

4. The vines are bent. Watermelon vines usually bend during the ripening process. The watermelons with straight vines may not be fully ripe.

Pick the watermelon with twisted vines on the left. Image credit: Photo by the author

5. Smooth surface. The fuzz on the surface of a ripe watermelon will fall off, and the surface of the peel will be smoother (of course, it is possible that the fruit has been touched too many times and has become shiny and glossy...).

Once you have learned these, and then try taking pictures, it will be easy to pick good melons.

04

Professionals, choose melons like this

However, for professionals, the safest way to choose melons is not to look or listen, but to rely on the calendar.

In the watermelon production and harvesting process, the maturity of watermelons is generally not judged by tapping the watermelons. Instead, a basic understanding of the maturity of the watermelons is obtained by calculating the number of days from pollination to maturity. Then, through sampling surveys, individual watermelons are cut open to check their maturity. This is more convenient and more accurate. After all, if you go to the watermelon fields every day to tap and look for watermelons to harvest one by one, just thinking about the workload makes you weak.

Generally, early-maturing watermelons mature about 27 days after pollination of female flowers; mid-maturing watermelons mature about 30 days after pollination; and late-maturing watermelons mature more than 35 days after pollination. This method of judging maturity is often more direct and less prone to error.

You know, in the watermelon breeding base, even experienced staff will occasionally make mistakes when tapping the watermelons to test their maturity (you see, I said tapping the watermelons is not that easy to learn).

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05

The sweetness of watermelon comes from hard work

As an article that teaches people how to choose and eat watermelons, it could actually end here, but since we are in the science popularization section of China, we would still like to tell you some scientific research stories behind watermelons.

When it comes to the "watermelon-eating crowd", we are undoubtedly the number one. After all, Chinese consumers eat about 70% of the world's watermelons every year.

While enjoying the happiness brought by watermelon, we should also feel extremely proud of our country's watermelon industry.

Unlike apples, grapes, strawberries, tomatoes and other fruit varieties that have long relied on imports, the common varieties on the market such as 'Zaojia 8424', 'Meidu', 'Texiaofeng', 'Jingxin', 'Zaochun Hongyu', 'Zhongwei Selenium Sand Melon', etc. are all domestic varieties. The selection and breeding of these excellent varieties is inseparable from the lifelong efforts of outstanding scientists and breeders in my country's muskmelon industry.

For example, Xu Yong, the "Watermelon King", led a scientific research team to complete the construction of the world's first genetic map of the whole genome sequence of watermelon, revealing the genetic code of watermelon and making outstanding contributions to the genetic research and variety breeding of watermelon. The varieties he bred, such as 'Jingxin', 'Huaxin', and 'Jingmei', are all over the Huanghuaihai region.

Academician Wu Mingzhu is the founder of my country's cantaloupe industry. She not only bred excellent watermelon varieties such as 'Zaojia 8424', but also made outstanding contributions to the breeding of melon varieties. She wrote in her diary on her 21st birthday: "The best thing in life is that everything you create can serve the people." She is now in her 90s and is still fighting Alzheimer's disease. Even so, she still mutters from time to time, "It's time to pollinate the melons."

8424 Watermelon. Copyrighted images from the photo library. Reproduction and use may cause copyright disputes.

In addition, the deliciousness of watermelon is inseparable from factors such as the soil, temperature difference, and climate of the place of production, which has also created several major watermelon producing areas in my country.

For example, Dongming watermelon in Shandong; Dongtai watermelon produced in Yancheng, Jiangsu; Zhongmu watermelon, Xiayi watermelon, Kaifeng watermelon in Henan; Selenium sand melon (stone melon) produced in Ningxia; Guangxi, Hainan and other regions are the main production areas of winter watermelon, mainly planting Qilin melon, Te Xiaofeng, Black Beauty, etc. These production areas have their own main types of watermelon, and also have different listing times, which has created the year-round production of watermelon in my country, and there are watermelons to eat in all seasons!

The big watermelon is not only a magic weapon for cooling off in the summer, it carries the beautiful memories of summer for generations of us, and is also a microcosm of our country's national prosperity and the booming seed industry.

Today's facility planting technology has made great progress. Even in the cold winter, we can still eat fresh and refreshing watermelons. But this still cannot shake the status of watermelons in summer. Because summer is inseparable from watermelons, watermelons will always belong to summer!

Author: Zhang Cong, a graduate student in agronomy and seed industry, majoring in vegetables

Reviewer: Cheng Xuzhen, Researcher, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences

Planning editor: Ding Zong

Editor-in-charge: Ding Zong

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