Food Irradiation - a better way to kill microbes associated with food borne illness

Food irradiation could play a critical role in ensuring safe, wholesome and high quality foods for consumers, especially in dealing with virulent microbial strains that have withstood other more conventional treatments. This latest E. coli outbreak, centred in Northern Germany, has caused at least 26 deaths and over 2,000 infections in Germany, Sweden and other countries. During the outbreak, purportedly linked to contaminated salad vegetables, food safety experts and press articles have discussed the use of food irradiation in "the battle to destroy illness causing bacteria".

Photo Credit: FAO/Alessio Romenzi Commercial food production involves strict standards and safeguards designed to keep food free of pathogenic organisms. However, production methods alone cannot completely ensure that fresh produce is completely safe at all times. Post-harvest washing treatments can help reduce levels of contaminating organisms but there is lots of evidence to suggest that no amount of washing will rid all organisms from produce such as salad leaves and seed sprouts.

Food irradiation kills bacteria without damaging the food or its health benefits. It is a safe and effective food processing technology. Research has shown1 it to be effective at controlling organisms, for example, E. coli on seed sprouts. A recent study2 assessed the microbiological quality of commercial seed sprouts and the inactivation of these illness-causing organisms using electron beam or gamma irradiation found that irradiation alone is an effective control measure and concluded that combination treatments may minimize the amount of radiation processing required to totally eliminate pathogenic organisms in seed sprouts.

Used on certain foods in Asia, the Americas and parts of Europe, food irradiation involves electron beams, gamma rays or X-rays and is the same technique (and often at the same facility) used to sterilize many medical products and devices. It is one of the few technologies which address both food quality and safety by virtue of its ability to control microorganisms without significantly affecting any sensory or other organoleptic attributes of food.

Food requires proper handling and cooking, but irradiation destroys populations of disease-carrying bacteria, and when used in combination with conventional practices, such as washing and packaging, it can help ensure greater levels of food safety and quality. In addition, food irradiation has several advantages over heat or chemical treatments, refrigeration and freezing:

→ It does not significantly raise food temperature and the food does not "cook"
→ Compared with freezing it does not produce ice-crystals that can affect texture and cause "mushiness"
→ Compared with chemical treatments, irradiation does not leave potentially harmful residues
→ It can be used to treat packaged food, which will remain safe and protected from microbial contamination after treatment.

(1 Reduction of Salmonella spp. and Strains of Escherichia coli O157:H7 by Gamma Radiation of Inoculated Sprouts, Rajkowski, Kathleen T.; Thayer, Donald W., Journal of Food Protection, Volume 63, Number 7, July 2000 , pp. 871-875(5).)

(2 Microbial quality assessment and pathogen inactivation by electron beam and gamma irradiation of commercial seed sprouts, Wajea C.K., Junb S.Y., Leeb Y.K., Kimc B.N., Hanc D.H., Jod C. and Kwon J.H., Food Control, Volume 20, Issue 3, March 2009, Pages 200-204.)