Scientists Develop a Seaweed Coating to Extend the Freshness of Fruit

A new seaweed coating can keep strawberries fresher at room temperature than even a refrigerator, offering a lower-carbon way to fight food waste.

A new seaweed coating can keep fresh fruit lasting longer than even a refrigerator can. Researchers at the University of British Columbia (UBC) developed the edible dip. In tests, coated strawberries stayed fresh at room temperature for four days or more.

Uncoated strawberries left at room temperature molded within just two days. Even refrigerated, untreated berries started molding by day four regardless. Coated strawberries kept in the fridge lasted a full six days, the longest result recorded in the study.

The seaweed coating relies on agar, a substance pulled from red algae. Agar is already a common food additive and a popular vegan substitute for gelatin. On its own, though, agar simply forms a thick, unremarkable gel.

Doctoral student Ivy Chiu led the study alongside senior researcher Tianxi Yang at UBC. The two published their findings in the Journal of Agricultural and Food Chemistry in August 2026. Their team says no one had combined these particular ingredients into a coating like this before.

Everything changed once researchers added zinc and tannic acid to the mix. Zinc is an essential nutrient, and tannic acid occurs naturally in grapes and tea. Together with agar, these ingredients self-assembled into tiny, evenly spread microparticles.

That self-assembly surprised even the research team studying it. The particles form a thin, clear film that seals in moisture and blocks gas exchange. The coating also carries antibacterial and antioxidant properties that further slow spoilage.

Researchers describe watching the mixture transform from a cloudy liquid into a uniform layer. The process happens within minutes once all three ingredients combine in solution. Dipped fruit emerges with a coating so thin it dries almost invisible.

Cut apple slices treated with the seaweed coating stayed fresh for about 24 hours. Untreated slices, by comparison, began visibly decaying within 12 hours. Coated grapes lasted almost 14 days, a full week longer than untreated fruit.

Across all three fruits, the coating roughly doubled shelf life compared to no treatment. Weight loss at the four-day mark dropped from 30% down to 13%. Treated fruit also kept more of its vitamin C and antioxidant content.

Safety testing found no signs of toxicity in human intestinal cells. Researchers say the coating is safe to eat and washes off easily. It also preserves the fruit’s normal nutritional value throughout storage.

A lifecycle analysis compared the coating’s environmental footprint to standard refrigeration. Emissions from the seaweed coating came in lower than or equal to those from cold storage. Researchers say these modest savings could add up across an entire supply chain.

Reducing spoilage matters most in a food system that wastes enormous amounts of produce. Nearly half of all food produced in Canada is lost or wasted every year. That waste costs the Canadian economy an estimated $58 billion annually.

Fresh fruits and vegetables are especially prone to this kind of loss. They lose moisture quickly and become vulnerable to mold soon after harvest. Long supply chains that rely heavily on refrigeration add further cost and emissions along the way.

Cutting down on refrigeration could also ease strain on energy grids. Maintaining cold temperatures from farm to store demands significant infrastructure and power. A coating like this could reduce that demand at several points along the supply chain.

They are also testing the seaweed coating across a wider range of fruits and vegetables. The team describes their invention as a practical strategy for building more resilient produce supply chains. Cutting food waste at this scale could ease pressure on refrigeration-heavy supply chains everywhere.

A simple seaweed coating might not replace the fridge completely. But it could give fresh produce a longer, greener path from farm to table.