A U.S.-Chinese research partnership has discovered a substance found in blueberry leaves can extend the fruit's shelf life and raise its antioxidant levels through use in berry coating.

While working with an international team of scientists in China, Oregon State University food scientist Yanyun Zhao found the edible coating with blueberry leaf extracts helped delay decay and retain water, thus slowing down the blueberries' natural deterioration.

Aside from the shelf life benefits, an OSU release added the extra weight could also translate to more money for growers as the fruit was often sold by volume.

It saidmost blueberries in stores were unwashed because rinsing them removed their natural waxy coating that preserved the fruit, but natural coatings could allow fresh blueberries to be washing and sold as ready-to-eat products.

"Normally, blueberry leaves fall to the ground as waste," Zhao said.

"We've discovered a use that can change how the berries are stored, sold, as well as increasing their nutritional value."

To create the coatings, researchers mixed phenolic extracts from the blueberries with chitosan, a natural preservative that comes from crustacean shells. Testing was done for leaves picked at different stages of berry maturity, with extracts formulated into five different treatments based on varying phenol levels.

Blueberries were then dipped in the liquid coating and dried at room temperature to form dried coatings, but Zhao added that nozzles could also spray coatings onto the surface of the berries as they passed by on a conveyor belt.

She said the added cost of the coating was still unclear.

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