Leaf extract can extend shelf life of blueberries, says US researcher

An Oregon State University researcher isolated a substance in blueberry leaves that can be used to coat the berries, extending their shelf life and boosting their antioxidant levels.

Image:Marijn de Vries Hoogerwerff
Image:Marijn de Vries Hoogerwerff

Working with a team of scientists in China, food scientist Yanyun Zhao found that the extract helped delay decay and retain water.

Such a coating could allow fresh blueberries to be sold pre-washed and ready-to-eat. Currently, most blueberries are sold unwashed as rinsing removes their waxy coating, a natural preservative.

Sold as a herbal remedy, blueberry leaves contain high levels of antioxidant phenolics – chemical compounds with antimicrobial properties that protect against fungi and bacteria.

To create the coatings, researchers mixed these phenolic extracts with chitosan, a natural preservative that comes from crustacean shells. Berries were dipped in the coating and allowed to dry. then dried at room temperature to form dried coatings.

Zhao suggested that the coating could be sprayed automatically onto berries as they pass on a conveyor belt, but conceded this would add to their cost.

The results are published in the journal Postharvest Biology and Technology.

Zhao earlier developed chitosan-based coatings for strawberries and raspberries. 


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