[NAFEX] new way to tell if fruit is ripe

Lon J. Rombough lonrom at hevanet.com
Wed Jul 26 18:47:51 EDT 2006

  Professor invents 'ripeness' sticker
TUCSON, Ariz. - A University of Arizona professor has invented a 
sticker that can tell consumers if a fruit or vegetable is ripe. The 
stickers will be available to growers next year and should make their 
way to supermarkets within two to three years, said Mark Riley, a UA 
assistant professor of agricultural and biosystems engineering.

He said growers and grocers throw out thousands of bushels of fruit 
each year because it ripened faster than it could get to market or be 

With no simple way to tell whether fruit that looks good on the outside 
will taste good on the inside, consumers often buy peaches, pears and 
melons they can't eat because they're under-ripe or overripe.

"Right now, picking fruit is more of an art than it is a science," 
Riley said.

A marker on Riley's RediRipe stickers detects a chemical called 
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 gas the fruit produces, the darker the blue, Riley 

The color shift is not instantaneous once a sticker is attached. It 
takes about 24 to 48 hours, depending on how fast the fruit is 
ripening, Riley said.

And there are still bugs to be worked out: The stickers do not change 
color to reflect an overripe or rotten piece of fruit. Also, not all 
fruit produces enough ethylene to be detected by the sticker, said Jim 
McFerson, manager of the Washington Tree Fruit Research Commission, a 
growers' research group that helped sponsor the research.

"There is still a lot of research to do," McFerson said.

Each sticker is expected to cost growers and grocers about a penny, 
Riley said.

There is a patent pending for the stickers through the UA. Riley said 
when RediRipe goes to market, the university will keep the patent and 
the company will license the product.

Research on ethylene's use in fruit ripening began in the 1940s, and 
the gas is used to ripen fruits and vegetables in storage.

Riley has done multiple small field tests on his stickers — including 
at an apple orchard in Willcox — and plans a much larger field test 
this fall in Washington.


Information from: Arizona Daily Star, http://www.azstarnet.com

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