Surprise! The rosy strawberries don’t taste sweet at all? The reason is…

Many people like to eat strawberries, and I like them too. But do you feel that no matter whether it is a red strawberry or a cream strawberry, it tastes like water without any "strawberry flavor". If so, it may be that too much pesticide has been applied to the strawberries.

The flavor and nutritional value of strawberries are linked. Here is a brief explanation. For example, sweetness usually comes from the amount of dissolved glucose or fructose ; while the aroma comes from volatile compounds such as esters and terpenes . If these components are reduced, the natural flavor will deteriorate.

Comparison of the composition of white strawberries and red strawberries. Image source: Reference [1]

One of the working principles of pesticides applied to fruits is to destroy the cell structure of harmful fungi .

But this is a double-edged sword; in the process of destroying harmful fungi, pesticides interfere with the production of these essential flavor and nutritional compounds .

In order to find out the truth, a team whose main research direction is pesticide analysis and environmental toxicology studied the pesticides sprayed on strawberries: boscalid (BOS) and difenoconazole (DIF), to see if they really make the strawberries lose their strawberry flavor.

Boscalid is a new nicotinamide fungicide, and fenpropimorph is a triazole fungicide. Both are mainly targeted at fungal diseases of fruits and vegetables, and can prevent and control strawberry powdery mildew, ring rot, leaf spot and black spot.

Effects of alfalfa volatile organic compounds (VOCs) on Botrytis cinerea and strawberry fruit. Image source: Reference [1]

However, the two have different mechanisms of action. Boscalid works by inhibiting succinate coenzyme Q reductase (also known as complex II) in the mitochondrial electron transport chain. Difenoconazole works by interfering with the C14 demethylation of pathogenic bacteria cells, inhibiting the biosynthesis of ergosterol, thereby retaining sterol in the cell membrane, damaging the physiological function of the membrane, and causing the fungus to die.

The scientists grew three groups of strawberries under identical conditions.

When the strawberries were still green, they used boscalid and difenoconazole on two groups, while the third group was not treated with any pesticides. When the strawberries were ripe, the scientists took the experimental strawberries back to the laboratory. If you only look at the appearance, no one can tell the difference between the three groups of strawberries, all of which are rosy, plump and shiny. But if you look at the inside, that is, the composition of the strawberries, they have undergone some changes.

Treatment of three groups of strawberries. Image source: Reference [1]

Scientists have found that the sucrose and vitamin C content in strawberries sprayed with pesticides is much lower than that in strawberries not sprayed with pesticides .

In addition, some of the sugar in strawberries that have been sprayed with pesticides is converted into acid , so they do not taste sweet.

Scientists have also discovered that some oxidation reactions in pesticides also inhibit the production of strawberry flavor and aroma components.

Subjective evaluation of three groups of strawberries. Image source: Reference [1]

If we compare two groups of strawberries sprayed with pesticides, scientists found that the group treated with boscalid lost more strawberry flavor.

After further observations, the scientists found that boscalid had a direct effect on gene regulation in cellular pathways responsible for producing sugars, volatile compounds, nutrients and amino acids.

This assessment was also verified by a blind taste test, in which people who tasted all three groups of strawberries consistently preferred the ones without pesticides.

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If the pesticides left on the strawberries are washed off, the strawberries may just taste bland. But if the pesticides are not washed off, it is not just unpalatable, it may also be harmful to your body.

In Europe, a study by the Pesticide Action Network found that a third of apples and half of blackberries on the market had pesticide residues, some of which have been linked to health conditions such as cancer, heart disease and birth defects.

Of course, the results of the study will not stop strawberry growers from using pesticides, after all, not using pesticides is likely to cause strawberry diseases, which will reduce production. If you can't even eat strawberries, there's no point in discussing whether they taste like strawberries.

Strawberry powdery mildew. Image source: 51agritech

This study is more about telling us the mechanism behind it. Maybe someone can come up with a suitable countermeasure based on this in the future, which may allow for a good strawberry harvest while retaining more strawberry flavor. Who knows?

References:

[1] Yuping Liu et al. (2023) Insights into the Mechanism of Flavor Loss in Strawberries Induced by Two Fungicides Integrating Transcriptome and Metabolome Analysis

Author: Su Chengyu, popular science creator

Source: Bringing Science Home

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