WESLACO — If grapefruit could talk, it would tell you exactly where and when in its post-harvest life it got bruised. Steps could then be taken to soften the blows since bruises allow pathogens to enter the grapefruit, causing it and others around it to spoil.
Short of teaching grapefruit to speak, there is a more precise and scientific way to determine the many forces that impact grapefruit once it’s picked from a tree. It’s called an instrument sphere, a ball-shaped device that rolls alongside other grapefruit through a packing shed. As it moves along, a computer chip in the sphere records thousands of bits of information about velocity changes and accelerations. The sphere then is plugged into a computer and the information downloaded.
The device is being used in Lower Rio Grande Valley packing sheds by Dr. Bhimu Patil, a post-harvest physiologist at the Texas A&M-Kingsville Citrus Center in Weslaco.
“This information can pinpoint exactly when and where in the picking or packing process the fruit is being bruised,” said Patil. “It measures the g-forces acting on the sphere. Growers and packers can then know exactly where to pad those areas to reduce the amount of fruit loss. For grapefruit, any impacts under 40 g’s are OK. Oranges are lower since their skin is thinner than grapefruit. But the forces are much greater at various points such as when it hits the bottom of an empty bin, or if it slams into a piece of steel at high speed.”
Patil says bruising on citrus is not immediately noticeable. It’s not until days or weeks later when the grapefruit reaches its destination, be it Chicago, Denmark, or Japan, that bruising is detected by the green or blue mold that has developed in the fruit via the weakened spot on the peel.
“This mold spreads from one grapefruit to another during its shipment in cold storage. This not only causes fruit loss and profit loss, it could eventually damage the good reputation that our Texas citrus has developed worldwide,” said Patil.
The sphere is on loan to Patil from Michigan State University where different sized versions of it have been used to pinpoint problem packing areas of potatoes, onions and apples.
“We’re still in the trial and error process, running it through one of the four or five packing sheds here in the Valley,” Patil said.
One packing shed already has begun using protective padding on steel parts of its machinery to help absorb some of the impacts. But Patil said it’s not an inexpensive procedure since the PVC material is specially designed and approved by the U.S. Food and Drug Administration for use among fruits and vegetables.
For now, Patil will be measuring impacts only on grapefruit within the packing shed. In the course of a two or three year study, however, he eventually will extend the project to include damage done to oranges and grapefruit by pickers as they pour the fruit out of harvest bags and into both wooden bins and the newer plastic bins now being used by some packers.
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