New fruit wash removes pesticides and slows spoilage

Researchers have developed a fruit wash that removes most pesticides from the surface while leaving an edible coating designed to delay spoilage.

This combination transforms a routine rinse into a method that can make fresh produce cleaner and keep it fresh for longer.

Pesticide residue on fruit peel

In tests on apples treated with three widely used pesticides, the wash removed between 86 and 94 percent of residue from the fruit’s skin.

Dr. Tianxi Yang, an assistant professor at the University of British Columbia (UBC), demonstrated the outcome while evaluating a rinse intended to deal with the contamination consumers may bring home.

Water alone, starch and baking soda each cleaned the apples to some extent, although none achieved the same removal rates.

The difference raises an obvious question: what enables this fruit wash to lift so much more residue from the produce?

How the fruit wash removes pesticides

The liquid contains minute starch particles loaded with iron and tannic acid, the plant compound responsible for tea’s dry, astringent flavour.

Together, these components form a sticky metal-phenolic network, creating a web capable of attaching itself to pesticide molecules.

As this network adheres to both the apple surface and the residue, it can lift away much of the contamination.

Starch is also important because material derived from maize and potatoes naturally breaks down rather than creating a persistent plastic layer.

Why a dual-action wash is needed

Fresh produce deteriorates quickly, with worldwide fruit and vegetable losses reaching 25.4 percent in 2023.

A large share of this waste results from fruit continuing to respire after harvest: bruised and drying produce uses up its water and sugars.

Conventional washing may reduce some pesticide residue, but it cannot prevent the subsequent drying and bruising.

That created an opportunity for a wash that removes contaminants first, then protects fruit in the vulnerable period after it is bought.

The edible protective coating

Following the initial rinse, a second dip dries into a thin edible coating that reduces oxygen transfer and moisture loss.

This is significant because sliced fruit browns when enzymes come into contact with oxygen, while dehydration hastens the softening people tend to notice first.

“The coating acts like a breathable second skin,” said Dr. Yang. Since gases can still pass through the layer, it may delay decay without trapping fruit in low-oxygen conditions.

What the apples revealed

The effect of the coating appeared rapidly in freshly cut apples, which browned more slowly and lost less water over two days in refrigeration.

By retaining more moisture, the slices remained firmer, while fewer cut surfaces became the dull brown colour shoppers commonly avoid.

Levels of acidity and natural sugars were also higher, indicating that the fruit may have retained more flavour too.

Although the delay is brief, it is particularly relevant for cut fruit, which can begin spoiling almost as soon as it is sliced.

What the grapes revealed

Whole grapes demonstrated the longer-term benefit, remaining plump for 15 days at room temperature as untreated grapes visibly shrivelled.

The coating achieved this by reducing water loss through the skin, the quickest route to wrinkling.

Treated grapes also displayed antimicrobial activity, meaning they could slow harmful microbes and potentially further delay spoilage.

For growers and retailers, even a relatively small improvement could provide valuable extra time during transport and on shop shelves.

Safety of the rinse

Safety relied as much on dosage as on the chemistry itself, and the additional iron from one washed apple remained extremely low.

The upper daily limit for iron in adults is 45 milligrams, considerably higher than the amount contributed by the coating.

“Our goal was to create a simple, safe and affordable wash that improves both food safety and food quality,” said Yang.

The claim still requires wider testing, as a safe amount for one fruit does not account for every diet or age group.

The potential cost of scaling up

Commercial adoption will hinge on cost, with early estimates placing treatment at around three cents per apple.

That figure was based on inexpensive ingredients combined with water, while tannic acid and iron salts accounted for only part of the cost.

It did not include the equipment, wastewater management, maintenance or regulatory requirements faced by large-scale packing operations.

Nevertheless, the ability to match the cost of existing coatings while also removing pesticides may attract processors’ interest.

From the laboratory to the kitchen sink

A household version is still some way off, although Dr. Tianxi Yang has already suggested that a spray or dissolvable tablet could work.

“Imagine a spray or tablet you could add to water right before washing your fruit,” said Yang.

Domestic use will still require regulatory assessment and real-world testing across different fruits, peel types and washing routines.

For now, official advice remains to wash fruit under plain running water, while this formula represents a promising possible next step.

Why this fruit wash could matter

This food technology stands out because it addresses two everyday problems at once: chemical residue and rapid spoilage.

If larger studies produce similar results across a wider range of produce, the wash could reduce waste without requiring shoppers to peel away freshness.