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Beam Me Up

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the February 2014 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission.

No one wants to throw up in zero gravity, so space programs take great care to avoid food poisoning among astronauts. Irradiation has been used to pasteurize astronauts’ food since 1966. In fact, irradiation has been the most studied of all food-processing technologies over the past 60 years. Irradiation improves food safety by fatally damaging bacterial DNA. This stops the growth and reproduction of the bacteria that can cause food to spoil or people to become sick.

Irradiation is also approved as a food safety treatment in over 50 countries back here on earth. For example, France, Belgium and the Netherlands use irradiation to combat food-borne pathogens in frogs’ legs, seafood, and poultry. The U.S. has approved irradiation of meat. Canada has approved irradiation for spices, seasonings, flour, onions and seed potatoes, but not meat or poultry. Irradiation is safe for human food use at doses more than eight times higher than those approved for meat in the U.S. Irradiation does not cause the meat to become radioactive, and has less of an effect on food nutrients than cooking does, but irradiation can have undesirable effects on flavour or colour under some conditions.

Dr. Rick Holley at the University of Manitoba recently published two papers from research funded under Canada’s Beef Science Cluster.

One paper (Meat Science 96:413-418) examined whether a low dose (one kGy) of non-radioactive, ionizing electron-beam irradiation can eliminate verotoxigenic E. coli (VTEC) and salmonella from beef trim.

VTEC, also known as Shiga toxin-producing E. coli or STEC, are E. coli that can cause illness in humans. E. coli O157:H7 is one of about 200 serotypes of VTEC. More than a third of VTEC-related illnesses in humans are also caused by non-O157 serotypes such as the “top 6” E. coli O26, O45, O103, O113, O111, O121 and O145. Salmonella is relatively uncommon in beef, but is more irradiation resistant than E. coli because salmonella is better at repairing DNA damaged by irradiation.

The second paper (Journal of Food Science 78:920-925) examined whether e-beam irradiation of beef trim affects the colour, aroma, texture, juiciness or flavour of beef patties.

What They Did:

Over 30 different VTEC (including E. coli O157:H7 and the “top 6” non-O157 VTECs), and six different salmonella serovars were screened for resistance to the one-kGy e-beam. Twelve of these bacteria were then pooled in four groups to test for survivors on beef. Fresh muscle pieces (outside flat, inside round, brisket, and sirloin) were separately inoculated with either 1,000 bacteria/gram or 10 million/g of each of the four bacterial mixtures. These numbers are up to a million times higher than would normally be found in beef. The inoculated beef was exposed to a one-kGy e-beam. Surviving bacteria were recovered and counted during storage at 4oC for up to five days. Inoculated muscle pieces were also pre-treated with five per cent lactic acid before being frozen and exposed to the e-beam.

For sensory tests, the same types of fresh muscle pieces (but not inoculated with bacteria) were treated with the one-kGy e-beam. Fresh ground beef patties (10, 20 or 30 per cent fat) were separately formulated with zero, 10, 20, 50 or 100 per cent lean beef treated with the one-kGy e-beam, cooked and evaluated by a similar panel for colour, aroma, texture, juiciness and flavour.

What They Learned:

In spite of the artificially high level of experimental contamination, treating fresh beef with the one-kGy e-beam eliminated more than 99.99 per cent of the VTEC E. coli and 99 per cent of the salmonella. The e-beam had less effect on salmonella when used on frozen beef, but this could be overcome if the beef was dipped in five per cent lactic acid before freezing.

The trained panel observed no effects of irradiation on the colour, aroma, texture, juiciness or flavour of beef patties, even when they were made entirely with beef that had been e-beam treated.

What It Means:

Irradiation was highly effective even in beef that was experimentally contaminated with up to a million times more bacteria than would be found in retail beef. Under normal processing conditions, a one-kGy e-beam would be expected to eliminate the hazard represented by all types of VTEC E. coli. Low-dose (one-kGy) e-beam treatment can effectively control E. coli O157:H7, non-O157 VTEC E. coli and salmonella in fresh beef trim. The e-beam did not significantly affect any sensory attributes of the beef patties, regardless of how much irradiated beef they contained. Low-dose e-beam treatment of beef trim to formulate ground beef appears to be a viable pathogen mitigation process that does not affect product quality.

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James BradburyFebruary 18, 2014

Still hard to believe there is a consumer "Ick" factor with this technology. This needs to be put in place so that cooking doneness by the consumer is not the only stop-gap measure to illness.


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adminApril 9, 2014

The following was published in the April 2014 issue of Canadian Cattlemen magazine:

Don't Beam Me Up

Regarding the column by Reynold Bergen “Beam Me Up” in the February 2014 issue of Canadian Cattlemen.

Reynold’s column discusses the safety and acceptability of using irradiation to improve the safety of food in general and beef in particular.

There is an interesting parallel in history that is appropriate to review in this context – the pasteurization of milk. Pasteurization was and is seen as a major advance to reducing human illness related to the consumption of dairy products. Just like irradiation, pasteurization had little, if any, impact on the taste of the product but it had an enormous and positive impact on the safety of the product. Nutritionally pasteurization does have a negative impact, but that may not be true with the irradiation of beef.

Today, less so in Canada more so in the US, there exists two dairy systems. A ‘Raw Milk’ dairy system and an ‘industrial’ (pasteurized) dairy system. Both produce an extremely ‘safe’ product. However there are interesting differences. When milk is tested prior to bottling at a raw milk dairy the product is safe - as it must be. However, milk tested just prior to the pasteurization stage in the conventional dairy is not. The difference between these two products is not so much the difference in the way the milk is produced on the farm but rather what happens to the milk when it leaves the farm. Ray milk leaves the farm in a milk bottle. Industrial milk leaves the farm in a bulk tanker where it is mixed with the milk from many farms and transported for many hours with multiple handling stages.

So how does this relate to the irradiation of beef? If the irradiation of beef became common practice, and perhaps even mandated, would it change the way the beef is handled in the packing plant? Would meat backers become less concerned about the sources and frequency of contamination of the product? Since the consequences of contamination would be greatly reduced I suspect the frequency of contamination would increase despite promises to the contrary.

Our beef industry has a sordid history of innovation when it comes to how we produce our product and consumers are showing increasing signs of losing confidence in our ability to produce a safe, healthy, high quality product. More and more we see requests for beef that is free of antibiotics, beta-agonists, hormones, and genetically modified feeds, beef that is grass fed, organic, and ‘natural’. Consumers are no longer trusting that our industry has their best interests at heart. That we are putting safety ahead of profit.

Irradiation may be a perfectly safe and valuable tool in the process of producing a safer product but it couldn’t come at a worse time. I don’t believe our customers have the stomach for yet another ‘science based’ innovation that makes food more ‘industrial’ and less ‘natural’.

David Dockendorff
Silver Rapids Farm
Powassan, ON

Reynold's Response

Thanks for your comments. It’s great to know that people are reading this stuff!

I agree - the parallels between irradiation and pasteurization really are interesting.

Back in the early 1900’s, opponents of pasteurization suggested that it would be used to mask low quality milk, or would fail to destroy bacterial toxins in milk, or may lower the nutritional value of milk or could give consumers a false sense of security, or increase the price of milk, or put small milk dealers out of business….

Pasteurization didn’t do any of those things. Replace “milk” with “meat,” and we’ve got the same concerns being raised about irradiation today. Parallels indeed.

Pasteurization helped eliminate the transmission of bovine tuberculosis to humans through milk. It improves the safety of milk, without reducing the nutritional value in any meaningful way. Irradiation has the same potential for beef.

After approving irradiation for poultry in 1990, the US went on to approve it for beef, lamb and pork in 1997. Beef consumption did not suddenly drop as a result of that decision. The US also allows irradiation of poultry, eggs, sprouting seeds, fruit and vegetable juice, imported fruits and vegetables, shellfish, lettuce and spinach. Over 50 other countries around the world allow irradiation for one food or another. Canada also allows irradiation of some foods. It just doesn’t allow our own Canadian beef to be irradiated.

The recommendation that industry re-submit its irradiation petition to the Government of Canada came out of the 2012 Independent Review of the XL Foods Inc. Beef Recall. The petition does not ask that beef irradiation be made mandatory in Canada, but there are valid questions about why it is not legal to use a tool that can make ground beef safer without affecting quality or nutritional value. The idea is simply to allow packers the option of using irradiation as a final food safety step, for customers who would appreciate that additional level of assurance. Approving irradiation for trim or ground beef only would mean that the other food safety interventions and standards that are already in place for carcasses and cuts would still be necessary in order to ensure that the other cuts (stew beef, steaks, roasts, etc.) are just as safe as they are now.

These columns are a great opportunity for me to explain the science and technologies that Canada’s applied beef and cattle researchers are developing. Consumers are human; most of their fears are really based on a lack of understanding. I believe if people really understood the science and technology that our industry, they would be less fearful. Hopefully these columns provide producers like yourself with some information to share with consumers you interact with from time to time.

Reynold Bergen PhD
Science Director
Beef Cattle Research Council


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