You search for the best apples, handle them with kid gloves
and still throw out
half when the hidden bruises show up a few days later. You’d
need X-ray vision to pick
only the perfect apples.

That’s exactly what University of Georgia researchers
concluded. So they developed a new grading system to make
sure the bad apples never reach
supermarket shelves.

How Scientists See Inside
Fruit

Using medical X-ray machines, Bill Tollner
can detect imperfections in fruits and vegetables before
anyone can see them.

“With apples, bruises are a big problem,” Tollner
said. “We can detect
old bruises before they can be seen by the human eye.”

An engineer with the UGA College of Agricultural and
Environmental Sciences, Tollner was using X-rays to
study soil layers when a colleague
suggested he try it with food products.

Why use X-rays?

“One of our food scientists had been working on water
core problems in
apples,” he said. “He asked me to use the X-ray equipment
on them.”

Water core is a condition that causes apples’ internal
moisture to increase.

S. Omahen, UGA CAES

CHECKING THE DATA on fruit in an X-ray machine allows Bill Tollner, above, to look inside the fruit without cutting into it. This equipment is the same as used for medical x- rays.

“It occurs in Red Delicious apples. If you eat the
apple right away, it has a
delicious taste,” he said. “You just can’t store them,
which creates a big
problem for apple processors.”

Water-core apples develop dots near the veins. Over
time, the dots turn brown.

Tollner found the X-ray equipment can easily detect
water core in apples. It can
“see” many other defects in carrots, onions and celery,
too.

“For example, some onion diseases cause air gaps
between the rings,” he said.
“The X-rays clearly show these gaps well before the onion
shows visible signs of
disease.”

This method helps the fruit
industry.

This new grading method could be especially useful for
apple and onion processors who
commonly store their products.

“The whole goal is to keep the product on the shelf
longer,” Tollner said.
“Using this equipment, processors can pull out bad fruit
before storing it side by
side with good fruit.”

The new X-ray grading system has received good reviews
from apple processors in New
York and West Virginia. “I plan to present the new process
to Georgia’s Vidalia onion
growers this month at an upcoming conference,” he said.

Tollner is also working with U.S. Department of
Agriculture researchers at the USDA
Fruit Research Station in West Virginia.

The fruit industry wants the
systems

“They’ve developed an optical grader. We’d like to
combine the two machines,”
he said. “Eventually, we’d like to see apples and other
food items come through the
sorter where the X-rays will find the internal defects and
the optical viewer the surface
defects.”

Mechanical grading systems like these could help food
processors deal with labor
shortages.

“We’re coming to a point in our country where labor to
inspect food products just
isn’t there,” Tollner said. “People feel they have more
stimulating things to do
than inspect food for minimum wage.”

Research proves its
safety

When radiation and food products come in contact, many
shoppers voice safety concerns
at first. Tollner said the radiation levels used in this
process are lower than the levels
used in dental X-rays.

“The canning industry uses X-rays to detect metal
fragments to insure
safety,” he said. “With this process, I’m using them to
improve the quality and
safety of food before consumers buy it.”