story to find out more.
Agricultural engineer Renfu Lu (front) and
visiting Michigan State assistant professor Yankun Peng test a laser-based
multispectral imaging prototype for real-time detection of apple firmness and
sugar content. Click the image for more information about it.
Laser Shows if Fruit's Beauty is Only Skin Deep
By Don Comis
May 6, 2005
The produce industry is working with the
Agricultural Research Service (ARS) to
make sure that fruits and vegetables taste as good as they look. They're
counting on "machine vision" tools that can predict the quality of
fruit or vegetable flavor--right after picking and in the packing
plant--without ever touching the product. Machine vision uses optical sensors
to inspect objects.
Today, batches of fruits and vegetables are judged by sample tastings, but
there is no guarantee that all of the produce in the batch will taste the same.
Samples are also tested for firmness by mechanically stabbing them with a
thick, steel probe. With both methods, the tested produce has to be thrown
While there are machine vision tools that can check skin-deep traits like
size, color and bruising, it is difficult to judge deep, internal qualities
like taste and texture of apples and many other fruits. Now
Lu, an agricultural engineer with the ARS
Beet and Bean Research Unit in East Lansing, Mich., has developed machine
vision prototypes that "taste" every single piece of produce from
right after harvest to when it passes by on the packing line.
Lu and ARS colleagues on the campus of Michigan State University have tested their
laser prototype on apples and peaches. It should work with any produce that is
at least as large as an apple or peach. The detector focuses four laser beams,
each a different light wavelength, into one sharp beam that shines into
Laser light photons momentarily scatter all the way to the fruit's core and
back. The amount of light bounced back after interacting with tissue reflects
firmness. Peaches and apples are separated by whether they are soft, firm or
Since scattered light also indicates the amount of light absorbed by the
fruit, and that absorption is affected by sugar levels in the fruit, this
technology can be used to predict flavors, such as sweetness in apples.
more about the research in the May 2005 issue of Agricultural
ARS is the U.S. Department of
Agriculture's chief scientific research agency.