Starch, iron and tannic acid solution, all found in other foods, removed more chemicals than water and protected the fruit while maintaining quality.
Researchers at the University of British Columbia (UBC) in Canada have developed an inexpensive, biodegradable solution that can keep fresh grapes up to two weeks at room temperature. And there’s more: the solution removes up to 94% of pesticide residues present on the surface of fruits.
According to scientists, simple washing with water, although it helps to remove dirt and some contaminants, is not enough to prolong the freshness of products or to effectively eliminate pesticides. As many of us have noticed, fruit—especially grapes—rot quickly after being washed in water.
The research, in the scientific journal ACS Nano, describes a solution based on natural and available ingredients. The formula mainly uses starch extracted from sources such as potatoes and cereals, combined with iron and tannic acid — compound present in wine and tea.
When mixed, these elements form adhesive structures capable of binding to pesticide molecules, facilitating their removal, explains .
In laboratory tests, apples treated with common pesticides were subjected to the new solution and compared with fruits washed with water alone. The results showed that biodegradable washing removed between 86% and 94% of chemical waste, while water eliminated less than half.
In addition to more effective cleaning, the team discovered that the solution can work as a protective coating. Cut apples and whole grapes were dipped into the mixture, forming a thin layer similar to a breathable “second skin”. In the case of grapes, the effects were particularly notable: the bunches remained firmer, lost less water and remained fresh for up to 15 days, even when not refrigerated. In apples, significantly slower oxidation was observed.
The researchers also indicate that the coating has antimicrobial and helps preserve quality characteristics such as acidity and sugar content. According to lead author Tianxi Yang, the presence of iron in the formulation may even bring additional health benefits.
The cost of the solution appears to be reduced, with initial estimates pointing to an increase of only about three cents per apple, a figure comparable to other coatings already used in the food industry.
The team therefore believes that the technology can be easily adapted to an industrial scale and even to domestic use, through sprays or soluble tablets for washing fruits and vegetables.
