Those Bloody Burgers-The same issue at opposite ends of the world
While living in the UK I keep in touch with the news circulating in the country where I have spent most of my life-New Zealand. Given my background in food safety my interest was piqued when I saw the headline “Burger spat gets spicy” on the NZ Stuff website, and so I clicked on the story. There is, shall we say, a divergence of opinions on new information produced by the Ministry for Primary Industries (MPI) as to how burgers should be cooked, and some quite distinct time/temperature combinations have been provided. This has led to the entirely predictable howls of anguish by some chefs who believe this to herald the end of an edible burger, prominent among these being the executive chef of the Duke of Marlborough hotel in the Bay of Islands (a place where I have dined while sheltering from the pouring, actually deluging, rain while awaiting the ferry). There is an obvious clash here; the perceived excellent eating qualities of a medium rare burger are in direct conflict with the perils which might result from eating such a food.
There is a food safety risk
Unlike steaks, where any pathogens will be on the surface and killed by normal cooking even if the centre is still mooing, when burgers are made any pathogens on the outside of the beef will get mixed in. So, any unwanted bugs are not just on the surface, and to make sure that a burger is safe it needs to be cooked all the way through. Or at least that is the easiest way to do it. Another factor is that burgers will be made from the meat of many animals and so one contaminated carcass could lead to the bugs being spread throughout many manufactured burgers.
There have been some very nasty outbreaks of disease resulting from people eating contaminated burgers. In fact, one of the pathogens, Escherichia coli O157:H7, became known as the “hamburger bug” in the USA because of the problems it was causing. The disease which ensues ranges from normal diarrhoea to kidney disease/failure to, occasionally, death. Worse still, there have been outbreaks where the concentration of these bacteria in the incriminated food was very low (see the dose response blog).
Burgers in the UK
The Food Standards Agency has given this whole problem some thought. The recommended cooking regime, 70°C for two minutes, results in a 99.9999% reduction in bacterial numbers. The FSA has listed other means by which satisfactory control and bacterial reductions are achieved (https://www.food.gov.uk/business-industry/guidancenotes/meatregsguid/less-than-thoroughly-cooked-beef-burgers ). This advice includes time and temperature combinations equivalent to 70°C x 2 minutes achieved in the centre of the burger. Overall, the information gives some wriggle room for chefs wishing to prepare safe rare burgers to be imaginative and come up with such a safe method. These cooking parameters do not need to be used “provided that they can demonstrate that they have controlled the risks in other ways as part of their HACCP-based procedures”. In New Zealand, the time prescribed for cooking at 70°C is 3 minutes according to the media.
One possibility that comes to mind would be achievable as long as great care were exercised. Firstly, the meat would need to be obtained from a reputable supplier to reduce the probability that it is contaminated in the first place. But even if it came from the best supplier in the realm, there are no guarantees. Step two would involve searing the meat by, say, frying the outside or using a blow torch. Just a bigger one than you’d use for the crème brûlée! In my past research work we used a Bunsen burner to produce “sterile” pieces of meat. Doing that should mean that all the bacteria on the surface will be killed. Next, mince the meat with a sterile mincer into a sterile receptacle. Well, probably cleaned and sanitised will have to do. There is then the minor issue of the other ingredients which will also all need to be pathogen free to make this work, although there will still need to be a cook step before it is served.
Of course, there may be other ways of achieving the same results. The MPI in NZ have suggested, as an option, sous vide cooking. This is a method whereby the burger would be made, vacuum-packed and cooked in a water bath. To finish it, the burger is then fried to give it the colour and flavour on the outside that people expect. This seems to be a popular cooking method at the moment-just have a look at “Great British Menu”. Again, though, the burger needs to be cooked properly and so the cooking conditions would need to be validated. The MPI have also commented further on the situation and made it clear that a more fluid approach, like that in the UK, could be adopted beyond using their time/temperature combinations (https://www.restaurantnz.co.nz/wp-content/uploads/2017/07/burger-tip-sheet-for-chefs-2.pdf ).
The problem with colour and “doneness”
One problem is that it can be quite difficult to tell when meat is properly cooked just by looking at it. Some colleagues of mine published a review on just this subject a little while ago (http://onlinelibrary.wiley.com/wol1/doi/10.1111/j.1750-3841.2006.00029.x/abstract ). The only real definitive way of doing it is with a thermometer and a timer. The same problem applies to other chef/regulator stand offs, like chicken livers-more another time perhaps.
This sort of issue will always lead to clash between some people in the food industry and regulators, and has some similarities with the whole raw milk debate. It is especially tricky for regulators to allow the industry to express itself yet ensure that public health is not put at risk. It is also an area which is quite complicated and it will be difficult for chefs to show the efficacy of their alternative methods to the stated criteria. How will they demonstrate the 10,000-fold kill over the whole process which is required by the FSA?