Irradiation kills pathogens not taste, according to study

By George Reynolds

- Last updated on GMT

Related tags Irradiation Food irradiation

Irradiation technology effectively kills foodborne pathogens such
as Listeria without conclusively worsening taste or smell,
according to a new study.

Gamma radiation is a proven method of destroying pathogens in uncooked and ready-to-eat foods.

But while the industy sees irradiation as a practical means of meeting food safety standards, consumer pressure over the safety of the technique has limited adoption of the technology. The groups have also claimed that irradiation worsens the quality of the food products.

A new report, released last week by the International Association for Food Protection (IAFP), is part of a series of studies aimed at alleviating public fears, while providing reliable research to the industry.

"Our results suggest that gamma radiation could be useful to control L. monocytogenes in ground pork and improve the safety of ground pork products," the scientists doing the study stated in a synopsis of their work.

The tests involved contaminating samples of ground pork sausages with Listeria. The sausages were divided into three test samples. The first was refrigerated overnight at 4C, the second chilled at 0C, and the third frozen at -18C. The samples were then exposed to gamma radiation. The first was stored at 4C for seven days. The other two were kept at 0C and -18C for 60 days.

The results for the control sample of non-irradiated sausages indicated that Listeria remained fairly constant at refrigeration, chilling, and freezing temperatures.

However, irradiation total inactivated the three test samples at all the temperatures used in this study.

The scientists then asked a group of panelists to perform a sensory analysis of irradiated and non-irradiated sausages. They used the triangle test, a common method of performing sensory comparisons on foods.

The IAFP said sensory panelists could distinguish between irradiated and nonirradiated sausage but were divided on whether irradiation adversely affected the sausage quality.

Irradiation has long been held out as the answer to improving food safety worldwide. However conflicting and inconsistent regulatory approaches to the use of the technology worldwide has posed a problem for processors.

The process exposes foods to ionizing radiation that kills insects, moulds and bacterium. The technology can kill up to 99 per cent of pathogens, according to previous studies.

Irradiation has been been endorsed as safe for foods and health by the World Health Organisation, the Food and Agricultural Organisation and the Codex Alimentarius, an international standards-setting body.

A World Health Organisation scientific report in 1992 found that irradiation posed no risk to human health.

However, due to consumer concerns many countries require irradiated products to be labelled so that consumers have the choice to purchase or not.

To date, about 50 countries have approved about 60 products to be irradiated. The US, South Africa, the Netherlands, Thailand and France are among the leaders in adopting the technology.

While food irradiation is slowly gaining consumer acceptance in the US and several other countries, the technology has been slow to get support within many parts of Europe, including the UK.

The EU has placed a hold on further irradiation approvals in the bloc until member states come to a concensus on the safety of some chemicals formed when food is exposed to radiation.

Currently regulations on food irradiation in the European Union are not fully harmonised. Directive 1999/2/EC establishes a framework for controlling irradiated foods, their labelling and importation, while Directive 1999/3 establishes an initial positive list of foods which may be irradiated and traded freely between member states.

So far the positive list has only one food category - dried aromatic herbs, spices and vegetable seasonings.

Some countries, such as Belgium, France, the Netherlands and the UK allow other foods to be irradiated, whereas other countries, such as Denmark, Germany and Luxembourg remain opposed. Within the UK seven categories of foods can be irradiated to specified doses.

European anti-irradiation consumer organisations have launched a campaign working to maintain the freeze on further irradiation approvals and to challenge existing approvals to reduce the amount of irradiated food in Europe.

Due to the public concerns, the EU's national regulators are monitoring the situation and turning up undeclared irradiation in foods, serving to make the public even more suspicious about the technology.

For example both the UK and Ireland's governments have reported finding illegally irradiated food products in 2006.

The UK reported that half of all food supplements tested were either wholly irradiated or contained an irradiated ingredient. None of the irradiated products were labeled.

In Ireland, 14 samples of noodles tested positive for irradiated ingredients. None of them were labeled. All irradiated products were removed from sale.

The US requires all single-ingredient irradiated foods sold in stores to be labeled as "Treated with Irradiation" and to carry the "radura" symbol. However, irradiated food served in restaurants, hospitals, schools, nursing homes, day-care centers and other institutional settings do not require a label.

In August 2005, the Food and Drug Administration (FDA) legalised the irradiation of molluscan shellfish, including oysters, clams and mussels.

Still pending before the FDA are industry requests to irradiated crustacean shellfish -- including shrimp, crabs and lobsters -- and ready-to-eat foods, such as deli meats, prebagged salads, frozen meals and baby food.

In the fall of 2006, food irradiation received renewed media attention in the US following the E. coli outbreak in spinach from California. As a publicity stunt, Sadex chief executive David Corbin ate spinach intentionally contaminated with E. coli and then irradiated.

Sadex is among several companies that have claimed future outbreaks could be controlled by using irradiation. The FDA has only approved irradiation for fruits and vegetables for plant pests, and not for killing pathogen contamination.

The Joint Food and Agriculture Organization/International Atomic Energy Agency Division of Nuclear Techniques in Agriculture is currently working to harmonise irradiation regulations worldwide. The ultimate goal is for member nations to comply with new labelling and treatment standards enforceable through the World Trade Organisation.

The International Irradiation Association (iiA) is an industry-funded organisation that is also working to harmonize regulations worldwide and develop new uses for radiation technologies.

Meanwhile the International Council on Food Irradiation (ICFI) is a new international, non-governmental organisation that promotes irradiation to government regulators, the food and nuclear industries, and health professionals around the world.

It replaced the International Consultative Group on Food Irradiation, which for many years was the leading industry and government organisation that advised the World Health Organization, IAEA and FAO on irradiation research, policy and advocacy.

The US National Centre for Policy Analysis estimates that if half the food at greatest risk consumed in the country were to be irradiated, food-borne illnesses would decline by 900,000 cases annually and deaths by 352. The centre estimates irradiation would cost about five cents per pound for meat and poultry products.

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