Here's a piece of retail technology that's more chemical than digital: For about a penny each, retailers will--within two to three years--have the option of placing stickers on a piece of fruit or vegetable to reveal if it's ripe yet, thanks to a University of Arizona assistant professor of agricultural and biosystems engineering named Mark Riley.
The story, coming to us from the Arizona Daily Star, says that a marker on Riley's RediRipe stickers detects ethylene gas, which is released by fruit or vegetables as they ripen. As that happens, the sticker turns from white to blue. The more ethylene the fruit produces, the darker the blue. The color shift needs about 24-48 hours, depending on how fast the fruit is ripening. A few bugs that still need to be peeled away: The stickers do not change color to reflect an over-ripe or rotten piece of fruit and not all fruit produces enough ethylene to be detected by the the sticker. But given the tons of product discarded every year and the burden on the supply chain to quickly move the produce from where it goes to where it's eaten, this looks like one academic effort that may truly bear fruit.