A US academic has developed a sticker that tells consumers when fresh produce is ready to eat. The RediRipe sticker changes from white to blue when it detects ethylene gas as fresh produce ripens. Mark Riley, associate professor at the University of Arizona has received funding from the Washington Tree Fruit Research Commission and the Small Business Innovation Research programme of the US department of agriculture.

“The device is a small flat sticker, akin to the stickers already placed on fruits as labels,” said Dr Riley. “The sticker begins with an off-white colour. In response to ethylene the reagents in the sticker react and change colour to increasingly dark versions of blue to a degree dependent on the amount of ethylene being released… A consumer would use the sticker to evaluate which fruit would be ready to eat based on how much ethylene is being released. It is easy to discriminate the degree of colour change which we will correlate to different practical measures of fruit ripeness.”

Dr Riley said he and his team were aware of the award-winning Ripesense device developed in New Zealand three years ago. “The Ripesense device may be responding to aromatic volatiles released by pears and not necessarily ethylene,” said Dr Riley. “Since the RediRipe approach responds to ethylene, this is likely more easily applied to a greater variety of types of fruits and vegetables.”

The University of Arizona team says its product is suitable for a huge range of climacteric fruits and vegetables including apples, peaches, pears, tomatoes, and some varieties of melons, however it is not suitable for bananas.

The team is already running field trials this summer and autumn and then hopes to have materials to distribute to the Washington apple industry. “If successful in those larger trials, we would then move into commercial markets,” said Dr Riley. “It is likely to be two years before the product reaches consumers.”

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