Citrus Packers Hear Benefits of Ultraviolet Light

Though the bulbs are expensive, their light can kill harmful organisms on produce.

By Kevin Bouffard
Published: Friday, August 22, 2014 at 3:30 a.m.

FORT PIERCE | University of Florida researcher Kevin Folta has shown the light on improving food safety for fresh Florida citrus.

Folta’s research shows ultraviolet light can effectively kill harmful microorganisms on the peel during processing in the packinghouse.

“It would be tremendously beneficial to treat produce with germicidal light,” Folta told more than 100 citrus growers and packinghouse executives at the 53rd annual Citrus Packinghouse Day at the Indian River Research and Education Center in Fort Pierce. “It’s known to kill harmful organisms by damaging their DNA.”

The drawback is the cost of LED lights in the UV range, he added.

Although LED lights for the household have become increasingly common as their costs drop, ultraviolet LEDs are still uncommon and expensive, costing about $500 per bulb.

COST: UP TO $160,000

A back-of-the-envelope calculation shows a UV treatment system in a citrus packinghouse could cost from $4,000 to $160,000, depending upon technical factors such as the speed of the packinghouse line and exposure times, said Folta, a professor of horticulture at the UF Gainesville campus.

“This is an economic question. We know it works,” Folta told The Ledger after his presentation. “I think (UV bulb costs) are going to come down fast.

Competition is fierce for bulbs in the visible range, so a company that diversifies will have a stronger presence in the market.”

There also would be a significant market for UV lighting as a disinfectant for other food products and in hospitals, he added.

Traditional glass UV lights using mercury would not be a viable alternative because their UV output degrades within weeks, hampering the ability to obtain the proper wavelengths needed for

disinfection, Folta said.

LEDs also have lowering operating costs because they require far less electricity and last longer, about 50,000 hours, than traditional UVs.

Folta began his research on UV treatments for citrus in January after he was approached by an industry official who had read about his past research on using visible light to improve fruit quality, he said.

So far, his research has shown UV works in the lab, Folta said, and the next step would involve building a prototype to run on an actual packinghouse line.

UV treatments show promise as an additional food safety step at packinghouses, said Mark Ritenour, associate professor of postharvest physiology and handling at the UF Indian River Center, who organized Packinghouse Day. But it won’t likely replace current disinfection methods using detergents and fungicides.


In other presentations, Jean-Pierre Emond of the Illuminate Group, a science and technology consultant in Tampa, discussed how packaging affects fruit quality in the journey from the packinghouse supplier to the supermarket.

Packinghouses face the same choices, Emond said, as shoppers — paper or plastic. In this case, the choice is between the standard corrugated cardboard boxes, still used by about 90 percent of produce shippers, and hard plastic containers.

“You really support the U.S. produce industry,” he told the citrus representatives, but not in a good way.

Emond was referring to the common practice at supermarket warehouses of stacking citrus cartons on the bottom of a multilayer pallet containing various other produce items.

The common belief is that citrus cartons are stronger and can bear the weight of other boxes placed on top, such as more fragile strawberries or tomatoes, he said.

This causes cosmetic damages that result in unsold fruit, Emond said.

“The consumer will not buy a flat orange,” he said. “It (using cardboard boxes) doesn’t pay at the end of the day. If the consumer doesn’t buy, they (supermarkets) stop ordering.”

Plastic cartons actually cost less, Emond said, but they present logistical problems because the supermarkets must take the responsibility to clean and return them to the packinghouse.

Suppliers also prefer cardboard because the boxes can be printed with the company’s logo.

“The retailer pretty much calls the game,” he said.

Packinghouse Day focuses on Florida’s fresh citrus industry, which accounts for 40 percent of the annual grapefruit crop and more than 70 percent of tangerines and tangelos.