Irradiation should be approved to eliminate food pathogens – Canadian researcher

Dr Rick Holley, a food microbiologist at the University of Manitoba, and his team are nearing completion of a study reducing strains of E.coli and Salmonella on fresh beef through low dose levels of gamma and electron beams.

Currently, Health Canada does not approve irradiation in ground beef or chicken but as far back as 2002 it published draft regulations and held consultations on its potential use.

Food irradiation can be used for spices, wheat flour, potatoes and onions in Canada.

The research, funded by the Beef Cattle Research Council (BCRC), runs until September and has tested 32 different strains of E.coli and six strains of Salmonella since 2010.

Dr Holley told FoodProductionDaily.com while ground beef irradiation was not permitted in Canada “meat, poultry, mangoes and shrimp can be irradiated in the US.”

“I think what will happen here will be, depending on the results of sensory tests yet to be done, that the industry sponsor will present the results to Health Canada, as further evidence supporting their petition to have irradiation approved for use on ground beef in Canada​.

“I expect until a major problem arises, very little will be done about it and we won’t have a plan in place for the methods of detection​.

“Prevention is the solution, treatment of these organisms is our way of addressing the issues but there is public resistance​,” he said.

Public resistance​

Dr. Holley acknowledged irradiation has not received full public acceptance but it may have to be seriously considered in the future.

“Concern is well-founded with the use of all new technology in food processing, we all accept that, but what you find when people find out about irradiation is that their attitude changes 180 degrees and they come on board as they recognise there is significant potential here to address foodborne illness​.

“Depending on the dose level the costs go up-higher dose levels of radiation equal higher cost, but it may become cost effective​,” said Holley.

“One concern is the change to the nutritional make-up of the food, even with the reduced levels changes are reported but there is nothing to say it is any different than cooking in a conventional oven​.”

The team exposed different cuts of beef meat pieces to gamma and electron beams.    

“We tested 32 strains of VTEC E.coli including O157:H7 and the US “big six” O26, O45, O103, O111, O121 and O145, and six of the most commonly encountered serovars of Salmonella (Enteritidis, Typhimurium and Montevideo).​

“We tested two low levels (300Gray in bacterial culture media and 1 kilogray (kGy) in fresh beef meat pieces). The Salmonella were generally resistant to 300Gray​.

“We inoculated the meat at either log 7 or log 3/g. We found that at both inoculation levels E.coli were reduced 3 log and Salmonella were reduced 2 log​.”

Lactic acid use​

Researchers want to extend the project until December this year, to see if lactic acid and a low dose of radiation can be combined to make the treatment of meat more effective.

“We may try a combined treatment with lactic acid in the near future, otherwise we will move to sensory evaluation of irradiated ground beef (colour, odour) at different fat levels and in mixtures with different proportions of irradiated lean meat​.”