The strawberries sitting on your kitchen counter today could stay fresh for four whole days — no refrigerator required. Scientists at the University of British Columbia in Vancouver have created an edible coating made from seaweed that keeps strawberries fresh twice as long as untreated fruit sitting at room temperature. For anyone who has watched berries turn fuzzy and mushy just days after buying them, this small innovation could make a big difference.
The coating comes from agar, a substance extracted from red seaweed that is already widely used in foods like puddings and jellies. Researchers mixed agar with zinc — an essential nutrient your body needs — and tannic acid, a natural compound found in grapes and tea. When combined, these ingredients self-assemble into tiny particles that form a thin, invisible shield around each piece of fruit.
"We wanted to find a simple alternative to cold storage," said Dr. Tianxi Yang, an assistant professor at UBC's Faculty of Land and Food Systems who co-led the research. "Once we added the coating, the fruit became far less sensitive to changes in temperature and moisture and stayed fresh longer."
In lab tests, strawberries dipped in the solution and left at room temperature stayed firm and mold-free for at least four days. Uncoated berries began growing mold within two days. Even strawberries stored in the refrigerator without the coating started going bad by day four. But the real surprise was that refrigeration only slightly helped uncoated fruit, while the coated berries stayed fresh for six days in the fridge.
The benefits extended beyond strawberries. Grapes with the coating stayed fresh for 14 days, and apple slices remained in good condition for 24 hours longer than untreated pieces.
Beyond keeping fruit fresh longer, the coating appears to be better for the planet. A life cycle assessment showed the seaweed coating produces 14% less carbon emissions than traditional refrigeration. It also reduced freshwater ecotoxicity by about 85%, largely by cutting the energy and refrigerants needed to keep food cold during transport and storage.
The research, published in the journal Agricultural and Food Chemistry, also found the coating has antibacterial properties and showed no signs of toxicity in tests using human intestinal cells. If you prefer to eat your fruit uncoated, most of the material washes off with plain tap water in about two minutes.
The team is now testing the coating on other fruits and vegetables and exploring how to bring it from the lab into grocery stores and food supply chains. The goal is not just to keep produce fresh longer on your counter, but to reduce the enormous amount of food that spoils before it ever reaches your home. Nearly half of all food produced in Canada is lost or wasted, costing the economy an estimated $58 billion each year. Fresh fruits and vegetables are especially fragile, losing water and becoming vulnerable to mold as they travel from farm to warehouse to truck to store.
"Our hope is to help keep produce fresh for longer throughout the food system," Dr. Yang said. "If we can reduce spoilage during storage and transportation, we can reduce food waste while using less energy to preserve food."