Watermelon is one of the most popular and beloved melon crops. Especially on hot summer days, it's hard to find a tastier and healthier option for a light snack. Watermelon is rich in minerals and vitamins essential to the human body. It consists of 92% water, which not only quenches thirst but also benefits overall health. However, caution must be taken when consuming watermelon. If the fruit is unripe or grown with excessive chemical fertilizers, it can pose a serious health risk. When a watermelon contains a high amount of nitrates, symptoms of poisoning may appear within 4–6 hours. These include nausea, vomiting, diarrhea, abdominal and headache pain, fever up to 38–39°C, low blood pressure, slow heartbeat, chills in limbs, and bluish discoloration of the skin.
How to choose the right watermelon?
First, ask the seller for documents confirming the product’s origin, quality, and safety.
Make sure the fruit is undamaged. When shopping at the market or supermarket, pay attention to its outer appearance. The rind should be intact. If there are punctures or bruises, the fruit may begin to rot.
A naturally ripe watermelon produces a resonant sound when tapped and can be easily scratched with a fingernail. A dried stem also indicates full ripeness.
Main signs of a good watermelon:
Large but not overly heavy
Cracks when squeezed
Makes a resonant sound when tapped
No cuts or cracks
Dried stem
Medium-sized yellow spot on the side
Matte, yellowish-green skin
Clear, defined stripes
The rind protects the fruit from external contaminants. However, watermelons grown with nitrates can be harmful to health. Nitrates convert to nitrites in the body, which interfere with hemoglobin's ability to carry oxygen. This negatively affects the cardiovascular and immune systems and disrupts cellular respiration.
How to choose a nitrate-free watermelon?
Buy watermelons during their natural season.
Look at the color of the veins inside the flesh. If they are yellow or purple, the fruit might be unripe or affected by nitrates.
The skin should have clear, well-defined stripes. Blurry lines may indicate nitrate saturation.
To test the watermelon, place a small piece in water. If the water is slightly cloudy after 1.5 hours — it's safe. If the water turns bright pink, red, or deep orange — avoid eating it.
A large number of white seeds may also indicate nitrate use — the flesh matures faster than the seeds.
If there are too many white or yellowish veins in the flesh, the watermelon may have been over-fertilized with nitrogen.
Note: The presence of nitrates can only be accurately determined in laboratory conditions!
Associate Professor G. S. Mirkhaydarova
Department of Agrochemistry and Soil Science
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