X-ray irradiation does not affect food quality, say US scientists

By Jane Byrne

- Last updated on GMT

X-ray irradiation does not affect food quality, say US scientists
X-ray technology is effective in killing bacterial pathogens in leafy greens without causing undesirable changes in product quality, claim US researchers.

Bradley Marks and Sanghyup Jeong, who are both based at Michigan State University (MSU), claim that X-rays can kill bacterial pathogens such as E. coli 0157:H7​ and Salmonella​ on the most delicate vegetables as well as extending the shelf life of the produce.

Irradiation from other sources has been used for years to protect ground meat and other products. The process exposes foods to ionizing radiation that kills insects, moulds and bacterium and the technology can kill up to 99 per cent of pathogens.

The US Food and Drug Administration (FDA) recently published a final rule allowing the use of irradiation for iceberg lettuce and fresh spinach; the technology can already be used with other foods such as spices, poultry and shellfish including oysters, clams and scallops.

Lower dosage

The MSU researchers said that they have been applying a higher dose than that used for medical X-ray imaging, but a lesser dose than that used by competing irradiation methods.

“That means less protective shielding is necessary, so the equipment is more compact and food companies can install it at their processing plants,”​ claim the researchers.

The X-ray technology, continued the MSU scientists, is being tested in the university’s biosafety level-2 pilot processing facility and is being commercialized by US company Rayfresh Foods.

Peter Schoch, CEO of Rayfresh Foods, claims the potential for widespread contamination is compounded by the mingling of greens from different sources in processing plants.

He claims that food irradiation based on the use of gamma rays from radioactive material or machine-generated electron beams tends to cause cellular damage and visually degrade food, whereas irradiation using x-rays promise a gentler, more scalable approach.

Other applications

According to Schoch, the company has recently won its first contract to build an X-ray machine to treat ground beef for Omaha Steaks, which inspected the prototype at MSU: “The university’s validation work was pivotal in winning that first order,”​ he added.

The MSU researchers said that work is also being undertaken on validating the technology to kill salmonella on almonds.

Market focus

According to Global Industry Analysts, the world food irradiation market is predicted to exceed $2.3bn by 2012.

However, the analysts claim that the market has not lived up to expectations as controversies and narrowing consumer acceptance have limited take up of the technology.

"Market growth thrives on factors such as industry and consumer acceptance and application parameters ranging from types of foods to be irradiated to dosage levels.

“Competition from existing proven food sterilization technologies such as steam pasteurization and refrigeration, coupled with the high capital outlay required to set up an irradiation processing plant, and stiff opposition from certain quarters thwarts widespread acceptance of the food irradiation technique,” ​they added.

The analysts said that the US remains the single largest market for food irradiation, accounting for an estimated 32 per cent of global demand in 2008.

According to the report, irradiation technology, though approved for selected products in Europe, has not demonstrated significant penetration in that geography but Asia and Latin America are expected to exhibit potential opportunities in the future.

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