How can you test watermelon for nitrates at home?

It's hard to imagine summer without watermelons. These berries with juicy and sugary pulp appear on store shelves in August and become an integral part of the menu in many families for several weeks. They contain a lot of fiber, a complex of vitamins and acids that have a beneficial effect on the body, and the pulp is low in calories.

But you need to approach the choice of this delicacy wisely. All benefits of watermelons can be negated by careless farmers who stuff plants with fertilizers. This leads to the accumulation of dangerous substances in the berries - nitrates. To avoid unpleasant consequences, you need to know about the characteristics of these substances and how to test watermelon for nitrates at home.

Where do nitrates come from in plants?

Nitrates are derivatives of reactions of nitric acid (HNO3). These substances are found in small doses in any living organism, be it plants or animals. When nitric acid enters the body, it interacts with metals, salts, oxides and hydroxides, resulting in the formation of substances that are called nitrates.

Nitrates play a key role in the life of plants. First of all, they are an essential element for the synthesis of protein molecules. As a result of biochemical processes, nitrates are converted into ammonia, which participates in the formation of chlorophyll - a substance without which photosynthesis, and therefore plant nutrition, is impossible.Thus, without nitrates, the plant will simply die.

Their number depends on various factors: plant varieties, humidity levels, temperature and lighting. But the biggest influence on nitrate levels is the amount and type of fertilizer a farmer uses to grow fruit.

The permissible level of nitrate content in products is determined by the Federal Law on the Sanitary and Epidemiological Welfare of the Population. In accordance with it, the dose is set to no more than 200 mg/kg.

And here is how the WHO determines the maximum permissible daily dose of nitrates:

• for an adult, the maximum permissible norm of nitrates is 500 mg;
• for a child, the permissible limit is no more than 50 mg.

A person can relatively easily tolerate a dose of 150-200 mg of nitrates per day, but a dose of 600 mg is toxic for adults.

Important! It is necessary to carefully monitor the quality of vegetables and fruits when feeding young children. Just 10 mg of nitrates can poison an infant.

Nitrates in watermelons

Due to the popularity of watermelons, farmers are trying to grow a bountiful harvest as early as possible. Some of them exceed safe doses of fertilizers for profit. Thanks to this, they grow huge fruits or harvest striped berries 1-2 months ahead of schedule. But it will be unsafe to eat the result of their labors.

The maximum nitrate content in watermelons is 40–600 mg/kg of fruit weight.

How to Measure Nitrate Content in Watermelon

An accurate and detailed analysis of the composition of watermelon is done in the laboratory. Experts use the ionometric method - the concentration of nitrates is determined using potassium alum.

Such verification requires appropriate conditions and the participation of professionals. It is impossible to carry it out at home, even if you know this method.Accurate measurements without inaccuracy and errors are only possible in the laboratory.

Checking at home

But laboratory testing is not the only way to determine nitrate levels. To check what is pumped into a watermelon during the growth process and whether it is safe, you do not need to have a laboratory. Even at home, you can check striped berries for the presence of nitrates.

Ecotester

This device is better known as a nitrate meter - that’s what people called it. It is compact, easy to use and can measure the nitrate content in a watermelon in a few seconds and compare it with the permissible limit.

To measure, you need to select the desired vegetable, fruit or berry from the menu list and insert a special probe into the pulp.

The device takes a measurement and displays the nitrate concentration on the display. Along with it, the permissible norm is also shown.

Important! Do not forget about the measurement error, which is quite large for these devices. To ensure they are most accurate, the probe must be thoroughly cleaned before each new measurement.

Indicator strips

This is an effective alternative to the nitrate meter, operating on the same principle as the litmus tests known to everyone from school. When interacting with nitrates, they change color depending on the concentration of harmful substances.

To check, you need to immerse the strip in watermelon juice or apply it to the pulp. You need to make sure that the paper is completely wet and wait 2-3 minutes. After this, the changed color of the indicator is compared with the reference scale that comes with the set.

Traditional methods

The methods listed earlier imply the availability of additional instruments and materials for measurement, but they are not always at hand.

If there are no instruments and materials, folk methods come to the rescue. Although their accuracy is not so high, they are simple and do not require anything other than ordinary water:

1. Place the watermelon in a container filled with water. A fruit pumped with nitrates will sink to the bottom, while an edible fruit will float on the surface.
2. Cut off a little pulp (about 20 g), place it in a glass of water and knead it thoroughly there. The water should become cloudy and slightly pink. If it has acquired a rich red color, this is a sign of excess nitrates in the pulp.

Signs of nitrate watermelon and selection rules

Many people believe that harmful “chemistry” can only be detected with the help of special devices, and it is impossible to distinguish a good watermelon from a bad one by eye. But that's not true. Even the appearance of the berry may indicate excess nitrates. So how can you determine the quality of a watermelon?

The algorithm is like this:

1. The very first sign is the size. Too large and early fruits (more than 7-10 kg) clearly grew with excess fertilizer, and small ones, most likely, were collected ahead of time and did not ripen. The optimal weight of a watermelon is 5–7 kg.
2. Pay attention to the tail. It should be yellow, dry and not too thin. A green and thick tail means that the watermelon is unripe, and these are often the ones with the highest concentration of nitrates.
3. Stripes should be contrasting in color.
4. earthen spot should be uniformly yellow in color and medium in size. A pale spot is a sign of immaturity.
5. There are no extraneous marks on the rind of a proper watermelon. Brownish-black spots are a sign of high nitrate levels.
6. Glossy and lumpy crust - another “symptom” of nitrate watermelon.
7. Don't buy cut ones (even if the seller cut out a piece in front of you to check ripeness) or damaged watermelons. This berry is stored in a cut state for only a few hours, and it easily absorbs harmful substances from the air.
8. When tapped, a ripe watermelon makes a booming sound and crackles slightly when squeezed.. It is worth mentioning that this method does not provide a 100% guarantee. When choosing you can't rely on him alone.

After purchasing, it is worth checking the watermelon pulp itself. You can also determine whether it is safe for consumption by color, consistency and texture:

1. If the flesh is unevenly colored and has wide white or yellow veins, this means that the watermelon was pumped with fertilizers and harvested before it was ripe.
2. Bright red flesh with a purple tint also indicates an abundance of nitrates and additives that artificially give it a “ripe” color.
3. Completely smooth (“mirror-like”) pulp on the cut - a sure sign of nitrate. Its texture should be granular and without traces of mucus.
4. Cavities and cracks in the pulp indicate that the growth and ripening of watermelon was accelerated by the use of excess fertilizer.
5. Seeds should be large and brown. Small and pale seeds are a sign of a nitrate fruit.
6. The cavities in which the seeds lie should not differ in color. If they have a yellow or orange tint, such You shouldn't eat watermelon.

Other harmful substances in watermelon

Even if the concentration of nitrates does not exceed the permissible dose, there is still a risk of being poisoned by the purchased watermelon.

The reason for this is harmful substances that accumulate in the pulp, in addition to nitric acid salts:

1. In addition to nitrates, phosphorus and chlorine can accumulate in melons, which are also used in fertilizers to accelerate growth.
2. Unscrupulous sellers can disguise the unripeness of a watermelon by introducing the additive E124 into it. It gives the pale flesh a red color.
3. There is a large flow of cars on city roads and suburban highways. All of them emit exhaust gases, which are easily absorbed by watermelons. Because of this, heavy metals accumulate in the pulp, in particular lead.
4. In a watermelon that has been lying in the sun for a long time (especially if its skin has been damaged), fermentation processes begin. Eating this berry can cause severe eating disorders.
5. Violation of the integrity of the crust also leads to the entry of various dangerous microorganisms into the pulp.
6. If the watermelon is damaged while still in the melon patch, there is a risk that mineral fertilizers and pesticides that are used against insects will get inside it. Both can lead to dangerous consequences for the body.

Typically, small farm owners and street vendors resort to fraud.. But large stores should not be completely trusted.

A number of checks have shown that even large chains produce watermelons with dangerous concentrations of harmful substances. Therefore, if you have the slightest doubt, ask for product certificates and inspection results.

Tips and tricks

To prevent nitrates from causing you trouble, you need to know a few rules that will minimize the risk of harming the body:

• You should only purchase watermelons in large stores that check the quality of incoming products;
• buying from street vendors is dangerous - there is no guarantee that the products have passed all tests and have a certificate;
• Under no circumstances should you buy watermelons from open stands near roads - these berries absorb harmful substances from exhaust gases;
• unripe watermelons are especially dangerous - it is at the initial stage of ripening that the concentration of nitrates in the fruit is maximum;
• purchased watermelon must be thoroughly washed before use - nitrates dissolve in water, and the risk of introducing dirt into the pulp when cutting is reduced;
• out-of-season watermelons can contain much higher doses of nitrates than those that are ripe on time. Those who want to please themselves with these berries early need to carefully check them and be sure to clarify where the watermelons were brought from. In warm countries they ripen earlier, but there is a risk of purchasing irrigated watermelons, which are grown with a large amount of fertilizer.

Laboratory studies of watermelons have shown that the highest concentration of nitrates is found just under the skin. Therefore, those who like to eat sweet berries to the very crust should give up this habit. Eat only the pink flesh.

What to do if you are poisoned by watermelon

If the purchased watermelon turns out to be nitrate, and the buyer has eaten a large portion of the dangerous berry, nitrate poisoning may occur. This is a rare occurrence, but it is fraught with serious consequences. Its symptoms appear 3–5 hours after consumption:

• attacks of nausea;
• vomit;
• diarrhea;
• low blood pressure.

Chills, blue lips, rapid pulse, shortness of breath and damage to internal organs are also possible. Even convulsions and loss of consciousness are possible.

If you notice these signs, you must do the following:

• drink plenty of warm salted water;
• two minutes after drinking water, induce vomiting;
• repeat these steps several times;
• take medications that help with poisoning (activated carbon or Enterosgel);

If diarrhea, weakness and shortness of breath do not go away and loss of consciousness occurs, emergency help must be called. Self-medication for such symptoms of nitrate poisoning can only worsen the situation.

Important! Alcohol is strictly contraindicated during treatment. It aggravates the toxic effect of nitrates.

Conclusion

Watermelon is one of the leaders in its ability to accumulate nitrates and harmful substances. Because of this unpleasant property, be careful when choosing it in stores.

Always choose large stores where the goods have the necessary certificates. Pay attention to the appearance of the rind and pulp, check the watermelon for the presence of nitrates using any of the methods listed above. Following these rules will allow you to enjoy the striped berry without any health risks.