Biodegradable Fruit Wash Removes Pesticides, Forms Freshness-Preserving Coating

Researchers at the University of British Columbia have developed a biodegradable wash that removes pesticide residue from fruit and can subsequently form an edible coating to extend freshness. Laboratory tests on apples showed the wash removed between 86% and 96% of three common pesticides. The findings were published in the peer-reviewed journal ACS Nano.

For comparison, rinsing with tap water, baking soda, or plain starch typically removes less than half of such residues.

How It Works: Composition and Method

The wash is composed of starch-based particles capped with iron and tannic acid. According to the research, when combined, these components form clusters that adhere to pesticide residues on fruit surfaces.

Laboratory Testing Results

Testing was conducted on apples treated with three commonly used pesticides at concentrations described as typical for real-world application.

• The wash removed between 86% and 96% of the pesticide residue in these tests.
• The researchers state that, for comparison, rinsing with tap water, baking soda, or plain starch typically removes less than half of such residues.

Secondary Function as a Coating

After the initial wash, a second dip in the solution forms a thin, edible, and biodegradable coating on the fruit.

• Fresh-Cut Apples: Coated apples browned more slowly and lost less water over a two-day refrigeration period compared to untreated apples.
• Whole Grapes: Treated grapes stayed plump for 15 days at room temperature, while untreated grapes showed noticeable shriveling.
• Antimicrobial Effect: The coating demonstrated effects that can inhibit harmful bacteria.

Senior author Dr. Tianxi Yang described the coating as acting like a "breathable second skin" and noted that measures of food quality, such as acidity and soluble sugars, remained higher in coated fruit.

Safety and Cost Considerations

• The study estimated that washing a medium apple with the solution would introduce an amount of iron well below the daily upper limit for adults set by North American food authorities.
• Dr. Yang stated the formulation uses micronutrients like iron and phenolic compounds that may offer additional health benefits.
• Early cost estimates suggest the treatment would add approximately three cents per apple, which the researchers state is comparable to current commercial fruit coatings.

Development Context and Future Plans

Dr. Yang stated the research goal was to create a simple, safe, and affordable wash to improve food safety and quality. The work was prompted by concerns about trace pesticide residues on produce, particularly for individuals who consume large quantities of the same fruit or vegetable.

• The wash ingredients are described as inexpensive and are mixed using water.
• The research team is working on refining, scaling, and testing the formula for potential use in commercial fruit processing facilities.
• The researchers also see potential for a home-use version, such as a spray or tablet to be added to water, but note that more testing, regulatory review, and real-world studies with different fruits are needed before such a product could be available.

Research Support

This research received support from:

• The UBC Faculty of Land and Food Systems Start Up Fund
• The Natural Sciences and Engineering Research Council of Canada (NSERC)
• The Canada Foundation for Innovation (CFI)
• The British Columbia Knowledge Development Fund (BCKDF)