Grilling and The First Law of Thermodynamics


I’m going to start giving meat thermometers as birthday presents. The best gifts are the ones you didn’t know you needed, and it has become apparent that my friends need meat thermometers.

In the last week, two different people asked me how long it took to grill a particular slab of meat. The first slab was a bacon-wrapped pork tenderloin and the other was a delectably marinated chuck roast. In hopes of recreating the results I had achieved, they asked about cooking time and assumed I would provide a simple answer in the form of a whole number. I’m sorry, but it doesn’t work like that.

You can ask someone how long it took him or her to run a marathon, but the answer will be useless in providing information about how long it will take you to run a marathon. A marathon is done after you travel 26.2 miles, whether you do it in a world-class two and a half hours or a somewhat more glacial eight. In this analogy, you are the slab of meat being cooked. Some people run like rib eye steaks, and some of us are slow and low pork shoulders, and your culinary race ends when you reach a specific temperature. Time is not a good way to measure doneness.

My first lesson on doneness vs. cooking time came on a Friday evening when I was a teenager, and my parents were going out to dinner, leaving me to cook a hamburger for myself. I had mastered the sandwich arts, but this was to be my first experience cooking a protein over heat. I knew the basic process: heat up frying pan, put burger in pan, cook one side, flip to the other side, transfer to bun. But I didn’t know how long it would take for the meat to transform from raw to delicious. When I asked how long to cook the burger, my mom said, “Until it’s done.” She was, in fact, a teacher, and this lesson, while infuriating to a hungry teenager, was foundational to my gastronomic education. Cooking time can be an effective means of determining doneness when baking with precisely measured, homogeneous ingredients in carefully controlled conditions, but it’s not so simple when grilling pigs, cows, fish, and fowl over open flame.

Like most craftwork, experience is the best classroom. The more you grill, the more you learn. Recipes can’t teach you the pain of overcooked $15 per pound rib eyes or the humiliation arising from undercooked salmon fillets that you have to “finish” in the microwave. Through those, and other, early failures, I learned the differences between indirect and direct heat, and open or closed lid cooking. Later, I came to understand the idiosyncrasies of my grill and how to exploit them to achieve the ideal Maillard reaction. And I have wondered at the miracle of carry-over.  The craft of grilling is complex and exciting.  There’s a lot to learn about doneness.

Through my long apprenticeship, I have learned in gross terms how long a particular slab will will take – steak: couple minutes per side; four pound beef roast: couple hours – but the specific finishing time is unknowable. Doneness knows no timer.

Some grilling enthusiasts swear by the “poke” test, judging doneness according to how squishy the meat feels. Poking works pretty well for boneless chicken breasts. If it’s squishy, keep cooking, as there’s nothing less yummy than Salmonella. In general, however, poking is not a reliable yardstick. For thicker cuts, there’s just too much mass to properly assess squishiness. For thinner cuts, by the time you can feel that it’s done, it’s overdone. A good meat thermometer can spare you many unpleasant overdone experiences.

A meat thermometer allows you to measure the internal temperature of the slab you’re cooking. There are lots of handy guides available online to tell you how hot various cuts of meat should get before they can be considered done. You need to know – again, through experience – how done you like your food to be cooked, but once you know that you like a medium rare roast, all you need to do is get that internal temperature up to 125°. It might take an hour or it might take three, but it will be beautifully pink in the middle.

I have used several different thermometers and learned three important lessons:

  1. Instant-read thermometers are called that for a reason.

An instant-read thermometer is designed to be inserted into a slab to measure its current temperature, and then quickly removed. The last time I left an instant-read thermometer inserted in a roast while it cooked in the smoky confines of my grill, the plastic dial at the top of the thermometer melted off. I wasn’t sure about the roast, but the thermometer was, without question, done.

  1. Vinyl is a type of plastic.

Having destroyed my instant-read thermometer, I upgraded to a probe thermometer specifically designed to be left in the meat. The probe was connected to a digital temperature display via a vinyl-insulated cord. It worked well, allowing me to monitor the temperature throughout the cooking process. Over time, however, the vinyl broke down due to the heat of the grill. Once the plastic melted off, leaving the bare wires exposed, the accuracy of the gauge was compromised.

  1. Thermal conduction can be terminal.

I upgraded from a vinyl-coated wire to one with metallic mesh-insulation. While it was more durable than vinyl, it was also more susceptible to heat transference. On first usage, with smug self-assurance, I carelessly let the metal-wrapped cord lay too close to the flame, in full contact with the grill grate. I believe the thermometer achieved a state of thermal equilibrium with the air temperature of the grill, and the digital read-out quickly spiked to 400° and stayed there. Forever. I checked on it recently, and the thermometer still insists that the ambient air temperature of my kitchen is similar to the surface of Venus.

I got another metal-clad probe thermometer and have taken care not to let it get overheated. Also, I was given a very cool dual-thermometer rig made by Maverick for Christmas. I can now measure the internal temperature of the meat and the ambient temperature of the grill. I’m still learning how to use some of the temperature programming features, but it’s a very sexy device.

The meat thermometer is my essential grilling tool. It’s the secret of my success in producing perfectly done steaks, roasts, chops, briskets, and shoulders.  It has also left me unable to answer the simple question, “how long do you cook it?” Despite the flawed question, the correct answers are as follows:

  1. Bacon-wrapped pork tenderloin, 150°
  2. Marinated chuck roast, 125°

Let me know if you’ve got a birthday coming up. I may be able to get a discount on bulk purchases.


3 thoughts on “Grilling and The First Law of Thermodynamics

  1. Were I of the modernist bent, I would long ago have graphed out the time/temperature relationship which is not linear but distinctly curved. The internal temperature of the roasted object follows a low-slope rise during the first hours, followed by an abrupt upward hook toward, through, and past perfection. The timing of this sudden spike toward inedibility is directly proportional to the cost of the cut and the complexity of the side dishes, a conspiracy of ingredients designed to thwart the best laid dinner plans. Needless to say, I still have much to learn.

    • You may not have suffered through the most debilitating temperature challenge: the plateau. When you slow smoke brisket or pork shoulder, the temperature rise often stalls when it reaches 130 degrees or so. It can stay there for hours before moving again. It’s quite maddening. We all have much to learn.

  2. […] to make use of the highest-tech grilling gear in my pit boss toolbox when cooking the pork loins: the dual probe remote thermometer rig that I wrote about previously. The ambient air temperature probe let me know that my grill was running hotter than I planned […]

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