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Ready for their close-ups

The Aberdeen Times of Aberdeen, Idaho

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ARS scientists use scanners to check fruit for contamination

It's 9 p.m.: Do you know where your bedtime-snack apple has been?

I'm a stickler for thoroughly washing fruits and veggies; that's why it always amazes me to see people "sampling" fruit right out of the produce section in the grocery store (for one thing, that fruit isn't free for the taking, and for another thing, it's not washed!). When it comes to microbes, what you can't see most definitely can hurt you.

Fortunately for all of us who love fruit and other produce, the scientists of the Agricultural Research Service (ARS) are equally interested in what we can't see, but need to know, especially when it comes to defects and contamination on the items we're going to put in our mouths.

That's why they developed a "lights, camera, action" setup that would make Cecil B. DeMille jealousexcept I don't think Mr. DeMille made a habit of shooting inside produce packinghouses.

The scientists' patented optical scanning system uses two different kinds of lighting, a sophisticated camera and other equipment to scrutinize produce-section favorites while they're still at the packinghouse. Their system can provide evidence of certain kinds of defectsanything from bruises to cutsand contaminants such as specks of fertilizer picked up from the field or the orchard.

The researchers use a type of camera known as a highspeed multispectral/hyper-spectral line-scanner. Here's how it works: The scanner is positioned above the packinghouse conveyor belt, where it captures images of each fast-moving item, such as an apple, that passes below. Each apple is exposed simultaneously to ultra-violet light from a UV fluorescent lamp and near-infrared light from a halogen lamp.

The near-infrared light that bounces off the apple can be captured by an instrument known as a spectrograph and analyzed for tell-tale patterns of defects, while the UV light beamed onto the apple can show up the whereabouts of any contaminants.

The system then combines the information from both forms of illumination into a single image with the contaminant and defect results. When linked to a sorting machine, the system can signal a sorter to separate the problem apples from others.

This sounds like a time-consuming process, but in fact the system can inspect three to four apples per second, providing a 180-degree view of each apple's exterior. But of course, apples go all the way around, so the scientists are working to improve the process so it will give a 360-degree, whole-surface view of the produce for a more thorough inspection.

Produce isn't the only commodity that gets an "up close and personal" examination from these ARS scientists. They've also devised a similar high-speed on-line imaging system for inspecting raw chickens.

Because these systems all use optically filtered light and opto-electronics to "see," they're known as "machine vision." Machine vision uses multiple images at selected wavelengths to supplement human inspectors' efforts with instruments that shine light on every single fruit, vegetable, piece of meat or poultry carcass that speeds by on the processing line.

In the case of chickens, the system developed by the ARS scientists spots almost all biological conditions that could cause a human inspector to take a second look, such as signs of disease that could pose food safety risks. Meanwhile, ARS scientists at another location are working on a similar system that combines mathematical equations and optics to detect fruit sweetness and firmness, actually "tasting" the apple without ever touching it.

If you've ever seen the great 1933 movie "Dinner at Eight," I know you'll remember that fabulous closing exchange between Jean Harlow's hotsy-totsy character "Kitty" and the much-older-and-wiser "Carlotta" character played by Marie Dressier.

Kitty is telling Carlotta, as they go in to dinner, that she was "reading a book the other day," a statement that practically stops Carlotta in her tracks. Kitty goes on to describe it as "a nutty kind of a book ... Do you know that the guy says that machinery is going to take the place of every profession?"to which Carlotta gives Kitty the onceover and says, "Oh, my dear, that's something you need never worry about."

But with these all-seeing sensors in the packinghouses, Kitty just might have a point!

The Agricultural Research Service is the chief in-house scientific research agency of the U.S. Department of Agriculture. You can read more about ARS discoveries at http://www.ars.usda.gov/news/.



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Original Publication Date: July 6, 2011



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