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Editor's note: The following is an edited excerpt from a chapter in Modernist Cuisine: The Art and Science of Cooking (The Cooking Lab, 2011), a six-volume set consisting of 2,348 pages of text and photography.
Scientific research on foodborne pathogens provides the foundation for all food safety rules. Generally speaking, two kinds of research inform us about issues of food safety. The first is laboratory experimentation: for example, testing how much heat will kill a pathogen or render it harmless. Data from these experiments tell us the fundamental facts about pathogens of interest. The second kind of research is investigation of specific outbreaks of foodborne illness.
You might think that scientific evidence would constitute the “last word” when food safety rules are made, but in fact it’s only the beginning. Policy makers take many other factors into consideration, including tradition, cultural trends, political expediency, and pressure from industry.To some extent, it’s reasonable to apply these modifiers because public health, not scientific purity, is the ultimate goal of food safety regulations. But this approach sometimes imposes arbitrary and scientifically indefensible restrictions that limit food choices, confuse the public, and prevent cooks from preparing the highest-quality meals.
To complicate matters, some guesswork and compromise are inevitable in setting safety standards. Take, for example, the way in which health officials decide how much the pathogen count should be reduced when heating food. In the preceding chapter, we reviewed the terminology used to describe these reductions.Killing 90% of the pathogens within a specific food, for example, is called a 1D reduction (where D stands for “decimal,” or factor of 10). Killing 99 percent of the pathogens is referred to as a 2D reduction, killing 99.99 percent is termed a 4D reduction, and so forth.
Cooks achieve these reductions by maintaining food at a given temperature for a corresponding length of time. The practical impact of an elevated D level is a longer cooking time at a particular temperature. If a 1D reduction requires 18 minutes at 54.4 degrees C / 130 degrees F , then a 5D reduction would take five times as long, or 90 minutes, and a 6.5D reduction would take 6.5 times as long, or 117 minutes. Clearly, the D levels targeted for food can have a profound effect on the manner and quality of cooking.
What D level should regulators choose to ensure food safety? If the food contains no pathogens to begin with, then it’s not necessary to kill pathogens to any D level! Highly contaminated food, on the other hand, might need processing to a very high D level. Right away, you can see that decisions about pathogen-reduction levels are inherently arbitrary because they require guessing the initial level of contamination. That guess can be supported by the results of scientific studies measuring the number of foodborne pathogens present under the various conditions that cooks encounter. But it’s still a guess.
Many people don’t realize that authorities rely on guesswork to develop these standards. Chefs, cookbook authors, and public health officials often make dogmatic statements that food cooked to
a standard is “safe,” but food cooked less than the standard is “unsafe.” That can never be literally true. No matter what the standard is, if the food is highly contaminated, it might still be unsafe (especially owing to cross-contamination). And on the other hand, if the food is not contaminated, then eating it raw won’t hurt you.
All food safety standards deal in probabilities. Reaching a higher standard (i.e., cooking food longer or at a higher temperature) will make the food less likely to be unsafe, and targeting a lower standard will make it a bit more likely. But there are no guarantees and no absolutes.
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9 Comments
Add CommentWell that explains why the time i accidentally cooked my pork roast to the internal temperature of rare/medium rare beef (140 F) it was so good !
Reply | Report Abuse | Link to thisFantastic article - thanks.
Reply | Report Abuse | Link to thisPersonally, I love a rare hamburger (red, not pink). And I'm frustrated by the refusal of most restaraunts to cook it that way. Generally, even if they say they cook to order and will cook it rare, it comes out medium or worse.
I even had a T bone steak recently which I ordered rare come out more like medium. Nothing unusual there, except the cook claimed that the local health inspector was requiring that steaks need to be cooked to 125 internal temperature!
I believe that these over-cautious public health recommendations are also applied to handling pets. This in turn causes some people to consider pets necessarily "dirty". This is untrue for well cared for pets [there should be no other standards really]. Thus many people who own pets are at a disadvantage in many parts of their lives such as finding housing and in court disputes.
Reply | Report Abuse | Link to thisAs the authors point out in the book, it's important to keep in mind that ground meat (or meat tenderized by puncturing) is more susceptible to contamination because external surfaces are mixed into the interior of the food. Any bacteria that get onto the outside of the meat during handling can thus be spread throughout the meat, which doesn't happen in intact muscle meats like well-butchered steaks.
Reply | Report Abuse | Link to thisIt is thus riskier to eat ground beef that is rare, and if you don't have complete confidence in the hygiene of the butchering and handling that went into the preparation of the ground meat, the safest course is to cook the meat longer or to a higher temperature.
I plan to grill a steak for dinner tonight. Seared on the outside and running red when cut. If it don't bleed it's burnt! As for pork, pink inside running clear juices on the plate is just fine. I also prefer limp bacon. Runny eggs go great with it. Sushi is also a part of my diet. If Big Brother doesn't like it, he can shove it.
Reply | Report Abuse | Link to thisBig Brother isn't forcing your hand in your own kitchen. You are free to take your own risks there, this article discuses regulations for food manufacturers and restaurants.
Reply | Report Abuse | Link to thisWhile I agree that many of the regulations are arbitrarily assigned and influenced by factors other than safety, I can't help but think that I'd rather not risk a food-borne illness (especially for someone who's immunocompromised) just for the sake of a slightly more delicious pork chop.
Reply | Report Abuse | Link to thisI'd rather be overcooking food than risking undercooking (due to faulty thermometers, cooks who don't know any better, etc.) because the food safety guidelines are right on the cusp of safety.
I think the bigger issue is how food manufacturers may be taking advantage of these extreme cooking guidelines to be more slack with their microbial control. If they know it'll be cooked to a 12D level of destruction, what's the incentive to use good manufacturing processes?
I am grateful that this article is here because I too love a rare steak, carpaccio, and sushi, but as wayt pointed out, ground beef is an exception.
Reply | Report Abuse | Link to thisGround beef is probably not safe unless you see it ground for yourself by a butcher you trust. Any given pound of commercially-produced ground beef can and does contain pathogens from literally thousands of cows, usually dairy cattle worn out by several years of filthy conditions, rBGH, antibiotics, and chronic low-level infection. To that, add scrap meat from all over the country, and grind. It's a food safety nightmare.
Because of this the meat packing industry has (once again!) started to use ammonia gas to "disinfect" ground beef, a practice exposed by Upton Sinclair's The Jungle, which detailed the horrific conditions for humans, animals, and our food in the meatpacking industry of the time. Legislation ensued, and for perhaps 50 years we had reasonable standards for meatpackers. This has since been undone, and now we're back (once again!) to having immigrants paid in dirt perform this work, on lines whose speed has been increased again and again, rendering it impossible for even the most conscientious gutter to ensure that there isn't shit in the meat. We're right back where we were at the start of the 20th Century in terms of labor and animal abuse, and right back where we were in terms of food safety.
I encourage all readers to purchase their meat from smaller, more local vendors -- the reward in taste, nutrition (e.g. grass-fed meat), and safety is more than worth it. If you are reading this article to begin with, you are likely to notice and appreciate the difference!
Readers of this article might be interested in my response to this excerpt posted here: http://barfblog.foodsafety.ksu.edu/blog/147413/11/03/27/more-modernist-cuisine-and-bad-microbial-food-safety-colbert-careful-clostridiu
Reply | Report Abuse | Link to thisIn short, while I agree that some standards today are inconsistent, the authors do make some microbiological errors that would lead to food safety problems.