Food safety question for the scientists

[Jenise]

Tomorrow I'm doing this rib cookoff at Bill Spohn's, and I was there today as well discussing our methods etc with a couple other 'contestants'. And I was asked how I was going to keep mine warm between my house and Bill's, which are about 90 minutes apart (only half that in miles, but there's an international border to cross and no direct roads). I said no problem allowing the racks, which would leave my house fully cooked and right off the equipment, to cool to room temp during the ride, and then crisp them up on Bill's barbecue for service.

That somehow got one guy's wife extremely excited. I protested that where it was far more desirable to not have to let them cool, an hour or two of cooling to room temperature simply wasn't to my mind an issue. She then brought up that she's a dietician and mentioned the word 'bacteria'. Which, I'm ashamed to admit annoyed me, so I said, "Then please don't eat my ribs. Wouldn't wish to poison you." And then someone changed the subject.

Well, here I am a few hours later and I stand by my belief that an hour or two of cooling to room temp isn't going to be a problem. What I *would* worry a lot more about is putting meat that hadn't completey cooled into refrigeration.

So my question: isn't room temp for the relatively short time involved okay? Would I really be better off keeping the meat slightly warm in an igloo chest?

To me, it sounds like what you are doing is fine.

BUT I am a biochemist and not a microbiologist...

I do know that when Keller has you make broth, he has you plunge the pot into ice when it comes off the stove.

???

[Jenise]

Frank, Bob and I discussed this on the way home today. Bob pointed out the many buffet type dinners we've done for parties where various forms of cooked meat sits on open trays for a few hours until someone finishes the last bite, and no one's ever gotten sick on my food. Nor have I gotten sick on anyone else's in the same circumstances. Mind you, anything left over at the end of the night gets tossed.

I'm much leerier of any kind of dairy product that sits around which is why I don't serve that kind of thing unless I can keep it cold, nor do I partake when others do.

Anyway, I guess what I'm saying is that I care a lot about the food I serve and am reasonably cautious I think, but I don't know exactly at what point bacteria starts growing. Would be useful to know.

IANAFSS (I am not a food safety scientist,) but I agree with Frank.

Your ribs will be bacteria-free when cooking is completed at your house. If you immediately place them in a clean, covered container for the ride, you should be fine. The tiny amount of bacteria that will be trapped with your meat a) won't have time to multiply enough to become problematic, b) will be confined to the surface of the meat and therefore, c) will be destroyed by the crisping process at Bill's.

Our friend Wikipedia says food stored in the danger zone of 40F - 140F for more than four hours should be discarded. I think your time starts when the ribs come off Bill's barbie.

Are you kicking Bill's ass tomorrow, or is he not competing?

[David M. Bueker]

If the dietician was actually right we would all have died off years ago...

[Jenise]

Okay, thanks guys! And Jim, the Wikipedia tidbit was especially helpful. Oh, and no Bill's not competing. He's hosting, and one of the judges.

I've had this issue come up a few time, Janise. I have always found it effective to line a small, well-insulated cooler with aluminum foil and place the ribs in it, hot off the grill. Then cover the meats with another layer of foil and throw it in the trunk. When I arrive at my destination the ribs are still hot/warm. No one has gotten sick! Just a thought.

food stored in the danger zone of 40F - 140F for more than four hours should be discarded. I think your time starts when the ribs come off Bill's barbie.

If 41F is unsafe, then I'd guess a lot of the home fridges in US have spoiled food. Most are set for 38-40, but top shelf and door probably are a couple degrees warmer. Just allowing for mechanical variance means a fair percentage will be over 40.
I've heard the real danger zone for rapid growth is I think between 65 and 120F, but for 2 hours, I wouldn't worry about it. Of course, I eat unpasteurized cheeses and sushi too.

Joanne's idea is what some of my groups do to transport hot food (though if you are using something like an Igloo as opposed to a commercial Cambro type carrier, I'd put towel or cardboard against walls- hot pans could conceivably damage plastic)

[Jenise]

Dale and Jo Ann, yes that's what I'll do. I know I wouldn't be poisoning anyone the other way, but at least walking in the door I'll look as good as possible to those who would otherwise question.

And, yes, by all means cover the whole thing with a heavy towel. I left out that part -- which further maintains the warmth. But, then, I don't insulate the entire thermal environment, because I don't include pots or pans, just the food item. However, I have discovered that if you are transporting a ham or turkey, you can insulate a large grocery bag with a thicket of newspapers on all sides, then with towels and a well, foil-wrapped piece of meat. Then place the paper bag in a plastic bag that you can securely tie around. This will keep a piece of meat hot for 2 hours. I've done this numerous times and it really works!

Wow, the silliness promulgated in the name of "food safety" knows no bounds, does it? OK, I am no food scientist, either, but like Frank I have a decent training in the sciences with a few courses in bacteriology thrown in. Smoking and salting were techniques developed to retard bacterial spoilage of cooked meats. If you used a dry rub and smoked your ribs, a few hours at room temperature presents no particular difficulty at all. To go further, I'd have no qualms about eating a grilled steak that's sat at room temperature for two hours, either. The real concern regards the transport and storage of uncooked meats, most especially the ground ones. In those cases, a few hours at room temperature can be quite problematic because of the rapid doubling times of bacterial populations at room temp. It's an apples and oranges situation with cooked meats, though, because the pathogenic bacteria present in the uncooked meat arise from the slaughtering and processing plants. You're not going to reintroduce E. Coli onto a cooked steak unless you make a habit of not washing your hands after going to the bathroom.

Sorry for the rant, but I find food-related paranoia of the misinformed particularly vexatious.

Mark Lipton

My wife who is a registered dietitian says rule of thumb is two hours for leaving meat out at room temp. CA law says meat on a restaurant buffet must be removed after two hours. So she sees no problem with what Jenise did. She does have a masters in nutrition from UC Cal Long Beach. Of course what's the air temp, etc, there can be extenuating circumstances for personal decisions.

FWIW, we had 4 differnt takes on dry rub ribs, and Jenise's was delicious!

And so far I haven't had any reports of any of the participants expiring!

If the dietician was actually right we would all have died off years ago...

If she were right, then Old Country Buffet would be guilty of much greater crimes than just bad food.

[Jenise]

It's an apples and oranges situation with cooked meats, though, because the pathogenic bacteria present in the uncooked meat arise from the slaughtering and processing plants. You're not going to reintroduce E. Coli onto a cooked steak unless you make a habit of not washing your hands after going to the bathroom.

Agreed re uncooked meats, and if that's what I'd been talking about transporting I'd have understood the concern. But we're talking not only cooked but well-done meat here, which is why I was so surprised by the concern. Thanks for the validation.

[Jenise]

FWIW, we had 4 differnt takes on dry rub ribs, and Jenise's was delicious!

And so far I haven't had any reports of any of the participants expiring!

And talk about validation--a report from the front. Thanks!

I'm so curious...did the dietitian eat any of the ribs?

She realized that there were bacteria on the door handles of her car, and never made it out of her house...

She realized that there were bacteria on the door handles of her car, and never made it out of her house...

I wonder what she'll do when someone does a skin culture of her skin? S. aureus and S. epidermis??? Run for the hills!

Mark Lipton

OK Jenise, you asked for it. Here is some of the science of bacteriological spoilage. First, the way bacteria grow means that the growth patterns tend to be not linear ( 2 * x hours ), not quadratic/polynomial ( x^2 ), but exponential ( 2^x ). Bear with me, you don't have to know the math to appreciate the difference. The thing to remember is that the population is doubling every so many minutes. This is the property that allows a tiny vial of yeast to produce enough offspring to ferment five gallons of beer within a couple days. (Yeast is a fungus, but all one-celled organisms grow in roughly the same fashion).
Our brains are typically suited to linear thinking, so it's understandable that we think, if 2 hours is OK, another hour will only add 50% more. However, the exponential nature means that you'll get a third more bacteria growth in the third hour than the first two put together. And the fourth hour will have a third more than that. Exponential is very, very fast, faster than makes sense to our linear brains. It's the reason why getting paid 1 penny the first day, 2 the second, 4 the third, 8 the fourth, etc. seems like it's not going to be very much money, but on the last day of the month you get paid over $10 million.
However, what you have control over is the "base" of the exponent (I've been using 2). That's where temperature comes in. At 0F/-18C (what your freezer is supposed to be at), the exponent is very close to 1. Stuff can spoil, but from a practical standpoint everything in there is in suspended animation. When you get above roughly 38F / 3C, though, the doubling time goes from days or weeks to hours. Furthermore, the rough rule of thumb is that for every increase of 18F/10C degrees, the rate doubles. Yes, you get a doubling of your doubling. Very fast becomes very very fast. Right around body temperature is where that rate hits its maximum (thus why one proofs yeast in 100-110F/38-43C water). Above that, the rate starts to slow again because the bacterium is having trouble resisting the effects of cooking, and about at 140F/60C the rate goes below what it was in the fridge.
So, that's the math behind the "danger zone." I hope it wasn't too bad. This kind of math is what's behind the new USDA rules on pork, because they were able to run computer simulations of various cooking processes and establish that any pork cooked to 140F/60C was safe.
The thought of all those bacteria doubling and quadrupling is pretty scary, but it also means that the "danger zone" is not really a big red band in which bacteria run rampant. It's a range, where the middle is quite dangerous, and the edges much less so. In other words, if you can keep those ribs, Jenise, at 130F/54C, or cool them to 50F/10C, you'll be a lot better off. The rules for food service are made so that poorly paid and trained employees can remember just two temperatures and a time to guide them, but if you as a home cook with a thermometer are conscientious, you can do better.
The other issue is the intial bacterial load. As mentioned above, ribs are among the most sanitary foods, cooked to a very high temperature with salt, spices, and sugar that are all hostile to growth. You can make beef jerky safely at room temperature! Similarly, I have no problem leaving a pot of boiled beans out overnight as long as the cover keeps any microorganisms from falling in. The "danger zone" is also partially a safety factor to minimize the impact of a careless cross-contamination.

While I knew this in principal from long ago bacterial genetics courses, this was a very nice synopsis of growth vs. temperature, Walter.

I have to wonder (because I don't recall) what the difference in terms of initial sterilization might be between ribs that are cooked quickly and hot over a BBQ, and ribs that are slowly smoked for 6 hours at temps of maybe 200 F. Would both be equally efficient at rendering the meat essentially sterile, so that all one needed to worry about is reinoculation with something from the environment (or perhaps new growth of any latent bacteria not destroyed by the 200 F)?

While I knew this in principal from long ago bacterial genetics courses, this was a very nice synopsis of growth vs. temperature, Walter.

I have to wonder (because I don't recall) what the difference in terms of initial sterilization might be between ribs that are cooked quickly and hot over a BBQ, and ribs that are slowly smoked for 6 hours at temps of maybe 200 F. Would both be equally efficient at rendering the meat essentially sterile, so that all one needed to worry about is reinoculation with something from the environment (or perhaps new growth of any latent bacteria not destroyed by the 200 F)?

I'm not Walt, but either cooking process will eliminate bacterial populations, which will immediately then recolonize the food as it cools. The smoke is a not insignificant factor, too, as it's not a hospitable environment for microbiota.

Mark Lipton

Thank you, Walt, that was concise and, um, er, digestible!

Our brains are typically suited to linear thinking,

Not to hijack the thread completely -- but I have to point out that by some recent analysis, the way we perceive numbers has more to do with logarithmic thinking. When you are five years old, it is an eternity until your next birthday. When you are 50, that's not so true any more. In perceiving quantities, we seem to look at ratios rather than amounts.

Nice discussion of this on RadioLab's podcast "Numbers"

http://www.radiolab.org/2009/nov/30/