UBC-developed seaweed coating keeps strawberries fresh longer without refrigeration

University of British Columbia (UBC) researchers have developed an edible seaweed-derived coating that kept strawberries fresh for at least four days at room temperature, outperforming untreated fruit stored in a refrigerator.

The agar-based coating could give the fresh produce sector another tool to extend shelf life and reduce losses during storage and transport, particularly for highly perishable products.

Our hope is to help keep produce fresh for longer throughout the food system. If we can reduce spoilage during storage and transportation, we can reduce food waste while using less energy to preserve food.”

Dr Tianxi Yang, Assistant Professor in UBC’s Faculty of Land and Food Systems

In a study published in the Journal of Agricultural and Food Chemistry, researchers found that coated strawberries stored without refrigeration remained mould-free for at least four days, while refrigerated coated berries stayed fresh for at least six days.

Untreated strawberries stored at room temperature began developing mould within two days, while most refrigerated untreated berries began deteriorating by day four.

The findings target a significant supply-chain challenge. According to the latest UN Food and Agriculture Organization assessment, fruit and vegetables have the highest global food loss rate of any commodity group, at 25.4 percent, while 13.3 percent of total food production is lost between harvest and retail.

“We wanted to find a simple alternative to cold storage,” said senior author Dr Tianxi Yang, Assistant Professor in UBC’s Faculty of Land and Food Systems. “Once we added the coating, the fruit became far less sensitive to changes in temperature and moisture and stayed fresh longer.”

Turning agar into a protective coating

The researchers created the coating from agar, a red seaweed-derived material widely used as a thickener and vegan alternative to gelatin.

They combined agar with zinc and tannic acid, a plant compound found in foods including grapes and tea. The ingredients self-assembled into microparticles that formed a thin, clear and edible protective layer when the team dipped produce into the solution.

“It was exciting to watch the particles self-assemble in real time, from a cloudy, milky liquid into this incredibly uniform, protective layer,” said lead author and doctoral student Ivy Chiu. “To our knowledge, no one had made an agar-based microparticle coating like this before.”

Over four days at room temperature, coated strawberries lost less than half as much water as untreated fruit and remained firmer, while retaining more vitamin C and antioxidants. Researchers also recorded benefits in grapes for up to 14 days and apple slices for 24 hours.

Tests showed antibacterial properties, while assessments using human intestinal cells found no signs of toxicity. Consumers can remove most of the coating under tap water within two minutes.

From shelf-life gains to commercial use

The research joins a wider industry push to slow post-harvest deterioration. In June, University of Copenhagen researchers unveiled an ethylene-capturing clay designed to slow produce ripening and reduce spoilage.

Last year, Swedish start-up Saveggy began piloting an edible plant-based coating for cucumbers with retailers, designed to extend shelf life while reducing plastic packaging.

The UBC approach combines moisture protection and antibacterial properties with the ability to preserve strawberries at room temperature. A life-cycle assessment also estimated a 14 percent lower carbon footprint than conventional refrigeration and around 85 percent lower freshwater ecotoxicity.

For industry, the use of commercially available food-grade agar provides an important early indication of the technology’s commercial potential. The team achieved similar reductions in moisture loss and spoilage after replacing laboratory-grade agar with the food-grade alternative.

However, commercial adoption will require further validation. A recent review of edible coatings for fresh produce identified regulatory requirements, economic feasibility, sensory compatibility and consumer acceptance among the barriers that can restrict industrial adoption.

“Our hope is to help keep produce fresh for longer throughout the food system,” said Dr Yang. “If we can reduce spoilage during storage and transportation, we can reduce food waste while using less energy to preserve food.”

The team is now testing the coating on additional fruits and vegetables and exploring how it could be scaled and integrated into commercial food systems.