Process Adds Safety; Consumer Acceptance Increasing

September 24, 2007

FDA is considering a rule change concerning irradiated products: If the irradiation does not change the taste or texture of the product, then it would not have to be identified as irradiated.

The current guidelines for the labeling of irradiated foods date back to the final rule published by FDA in 1986, which stated that any food product treated by ionizing radiation be labeled with the radura logo and the statement “treated with radiation” or “treated with irradiation.”

The rule change is just part of a “perfect storm” for irradiation, said Richard Wiens, product manager of sterilization for MDS-Nordion. In addition to the concerns over food safety and the proposed rule change, the United States recently signed a bilateral trade agreement with eight nations that would allow the import of irradiated food items if the member nations reciprocate and USDA Animal and Plant Health Inspection Service approves the facility. Cooperation among nations should help create guidelines for trade of irradiated produce.

“I think that will at least draw us to international standards,” Wiens said.

Irradiated mangoes from India were brought to the United States this year following an inspection by APHIS at the Indian plant. The country’s mangoes haven’t been allowed into the United States before because they contain a seed weevil has only effectively been eliminated with irradiation. The Indian mangoes sold well, despite very strong anti-radiation advocates out there, Wiens said.

The process is not well understood by the general public, but some of the products bought in retail stores already have been sanitized using the process. Wegmans is the only grocery store to widely sell irradiated food, including irradiated ground meat, although USDA reported that 8 million pounds of fruits and vegetables sold in the United States have been irradiated to control pests.

Irradiation improves food safety, extends shelf life and inhibits ripening, sprouting and post-harvest growth, said Xuetong Fan, a researcher with USDA’s Agricultural Research Service Eastern Region Research Center. At 1 kiloGray (kGy), there is a 5-log reduction in E. coli O157:H7, and most fruits and vegetables can withstand 1 kGy. Fan said he’s gone up to 3 kGy in lettuce, and at that level the cells began to break down and softening was seen.

Irradiation is the process of using low levels of radiation to energize ions that penetrate skin and biofilms on produce, disrupting the DNA replication of bacteria and viruses. Three types of waves are used: electron-beam, x-ray and gamma ray. Electron beam (e-beam) is the fastest form of irradiation, but also has the least penetration of only a couple of inches. X-ray and gamma ray have higher penetrations – enough that irradiation can be done once the product is processed and packaged. However, gamma radiation is slower and requires a radioactive source.

The research at ARS-ERRC found that the appearance of irradiated food is usually not negatively affected, and in most cases decay was delayed. In one 14-day study, most irradiated produce fared much better than non-irradiated fruits and vegetables. Celery and green onions, in particular, had less browning after 14 days.

Fan said the process had little effect on taste, but more testing will be needed on individual items. The research did show, however, that irradiation can have unexpected positive benefits. He found antioxidant levels increased in romaine lettuce after irradiation. The process could also be more useful in modified atmosphere packaging, because the lack of oxygen that prolongs shelf life would also inhibit the repair and growth of pathogens.

The difficulty in using an irradiating process is different fruits and vegetables require different levels of ionizing radiation. That is mostly the result of the amount of water in the produce, but too much energy and the quality will decline. In a test of fresh-cut apple slices, Fan said the apples lost firmness – although the change might not be noticeable to consumers. Apples have a wide range of taste differences, from variety to season or region, and the differences caused by irradiation was no more noticeable than the natural differences.

Nutritional changes can occur, seen most often in iceberg lettuce. Iceberg is primarily water and already has a low nutritional value, and irradiating it can reduce it even more.

Byproducts formed by irradiating food include 2-alkylcyclobutanones (2-ACB), but Fan said produce has so little fat that few negative byproducts are formed. Another byproduct is furan, but the amount created in irradiated produce is still small compared to that created in thermally processed food.

The costs of an irradiation line at a processing facility add up to more than just the machinery – skilled employees are needed to monitor the plant and its safety protocols. But if a plant has a high volume, amortizing the machinery annually over the amount of produce processes may amount to only pennies on the pound, Wiens said. But with slim profit margins, companies may still be unwilling to increase their operating costs.

“I guess what I would ask is: What is the cost of not having customers buy their product because they have concerns about the safety of the product?” Wiens said.

Consumer Acceptance

Education may be the largest hurdle to overcome, said Christine Bruhn, Extension specialist with the University of California, Davis, Department of Food Science and Technology.

“Acceptance increases when people hear about safety testing, who endorses it and the threat it reduces,” she said.

According to UC Davis research, most consumers’ feelings about irradiated food are positive or neutral, with a minority opposed.

“Probably significantly less than 10 percent (are opposed), but they are very vocal,” Bruhn said.

Bruhn said consumer acceptance of irradiated produce could be high. He cited the case of a Chicago retailer that began selling irradiated strawberries in 1992, in addition to its non-irradiated strawberries. Customers liked the longer shelf life so much they outsold the non-irradiated berries 20 to one. Bruhn said the retailer felt bad about offering the irradiated fruit at the same price, because shrink was reduced so much they were more profitable.

“People weren’t threatened by the irradiation, they were attracted to the quality of the irradiated products,” she said.

Customers will be more likely to accept irradiated foods if they are presented in an environment where shoppers feel comfortable, such as their local grocery store, Bruhn said. Positive media coverage about the benefits of produce also will help prepare shoppers to see the products.

Wegmans, a Northeast chain of grocery stores, has been a leader in irradiation. Stores stock irradiated ground beef, and customers have responded well to the product. But more education is needed to combat the vocal opponents of irradiation, Bruhn said.

“Activists will continue to describe the food as dangerous,” she said, “but there is absolutely no scientific support for their view.”


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