UBC researchers have created an edible coating from agar, zinc and tannic acid that self-assembles into a microscopic, transparent film around fruit. Coated strawberries lost less moisture, stayed firmer, and retained more vitamin C and antioxidants than uncoated berries, remaining mold-free for at least four days at room temperature. Lab tests found antibacterial activity and no toxicity; a life-cycle assessment showed a 14% smaller carbon footprint and about 85% lower freshwater ecotoxicity than conventional refrigeration. The team replicated results with food-grade agar and is now exploring scale-up and commercial use.
Seaweed Coating Keeps Strawberries Fresh for Days — No Fridge Needed
(Photo by Atlantic Ambience via Pexels)
Researchers at the University of British Columbia (UBC) in Vancouver have developed an edible, seaweed-derived coating that helps strawberries and other fruit stay fresh at room temperature for days — in some cases outperforming refrigerated, uncoated fruit.
How the Coating Works
The transparent coating is made from agar (a gel-forming extract from red seaweed) combined with zinc and tannic acid. Instead of forming a thick gel, this mixture self-assembles into microscopic particles that create a thin, protective film around fruit when they are dipped in the solution and allowed to dry.
(Clare Kiernan/UBC via SWNS)
Key Findings
In laboratory tests, coated strawberries lost less than half as much water over four days at room temperature compared with uncoated berries. The coated fruit also stayed noticeably firmer and retained higher levels of vitamin C and antioxidants. Untreated strawberries kept at room temperature began developing mold within two days, while many uncoated refrigerated berries started to deteriorate by day four.
Coated strawberries stored without refrigeration remained mold-free for at least four days; coated berries kept in a refrigerator stayed in good condition for at least six days. The team observed similar benefits for other produce: coated grapes maintained quality improvements for up to 14 days, and apple slices showed improved freshness for about 24 hours.
(Clare Kiernan/UBC via SWNS)
Safety, Sustainability and Practical Use
The coating showed antibacterial properties in lab tests and produced no signs of toxicity in experiments using human intestinal cells. Most of the coating can be washed off under tap water within roughly two minutes for consumers who prefer to remove it.
A life-cycle assessment comparing the agar-based coating with conventional refrigeration found a 14% lower carbon footprint and roughly an 85% reduction in freshwater ecotoxicity, primarily because the coating can reduce reliance on energy-intensive cold chains and refrigerants. The researchers also reproduced their results using commercially available food-grade agar, suggesting the approach may be feasible beyond the lab.
"Once we added the coating, the fruit became far less sensitive to changes in temperature and moisture and stayed fresh longer," said study senior author Tianxi Yang. Ivy Chiu, the study's lead author, added: "It was exciting to watch the particles self-assemble from a cloudy liquid into an incredibly uniform, protective layer."
Next Steps
The UBC team is testing the coating on additional fruits and vegetables and investigating how it could be scaled, validated, and integrated into commercial supply chains. If successful, the technology could help reduce produce spoilage, cut food waste, and lower energy use across storage and transport systems.
Help us improve.
