A seaweed-derived coating that is capable of keeping strawberries fresh at room temperature for four days has been developed by a team of researchers at the University of British Columbia.

In the lab tests, the seaweed-coated strawberries stayed fresher for longer than refrigerated uncoated berries, thus suggesting the coating could one day reduce produce spoilage and food waste during storage and transport.

Source: Clare Kiernan/UBC

Designed as a possible alternative to cold storage so that produce can be safely transported over long distances — from farm to supermarket — the coating made the fruit less sensitive to fluctuations in temperature and moisture, staying fresh longer.

According to the team, the coating is composed of agar, which is a substance found in red seaweed. Currently, it is used as a vegan alternative to gelatin as well as a thickener in foods like puddings and jellies. Alone, agar creates a thick gel. However, when the agar is mixed with zinc and tannic acid, the material self-assembled into tiny microparticles that formed a thin protective layer around the fruit.

In addition to testing the coating on strawberries, the team also dipped grapes and apple slices into the material, which created a thin, edible coating that dried completely clear and that kept the produce mold-free for up to four days without refrigeration and six days when refrigerated.

The team also discovered that the coating reduced moisture loss, preserved nutrients, demonstrated antibacterial and non-toxic properties, washed off easily, and had a lower environmental impact than conventional refrigeration.

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

The coating’s developers are currently testing it on fruits and vegetables and exploring how it could eventually be integrated into commercial food systems.

An article detailing the coating, “Self-Assembled Metal–Phenolic–Agar Microparticle-Derived Coatings Enable Scalable and Sustainable Fresh Produce Preservation,” appears in the Journal of Agricultural and Food Chemistry.