Hardware & Software: Kitchen Thermometers
Like many of you, most of what I know about cooking is self-taught. Yes, I've had classes and some serious schooling, and it's all certainly helped, but mostly I've learned by being inspired by a recipe, wrecking a fair share of ingredients because I simply didn't know what I was doing, and then trying again until I got it right. It's an apt metaphor for lots of things in life, where you can substitute recipe and ingredients for any number of circumstances and if we're patient, or determined enough, we eventually learn. But knowledge often erases the memory of ignorance, so that once we know something it can be nearly impossible to remember what it was like when we didn't. Can we remember when we couldn't read? Or ride a bike/drive a car/change a lightbulb/know how to fight with a cable company?
However, I do remember what it was like to try to cook a roast without a thermometer. It was so frustrating for me as a young cook because a roast seemed so simple to make -- you put it in a pan, add a little salt and pepper, and stick it in a hot oven and after leaving it alone for some period of time, it was ready to eat. But nearly always, my roasts came out overcooked and tasteless. Plus the meats we roast the most -- legs of lamb, whole turkeys, beef tenderloins, pork loins -- are pricey, and cooking on a budget, I simply couldn't afford to ruin expensive ingredients.
So I gave up trying. For years I only cooked meats that were in smaller pieces, like lamb shanks, or beef stew or turkey burgers. Still, I longed to have success with something that every other home cook seemed to know how to do. And then I found the answer: I needed a meat thermometer. I haven't had a failed roast since.
The fact is that without a thermometer it's nearly impossible to accurately gauge the state of doneness when roasting large pieces of protein, whether it's a whole ham or a thick salmon fillet. Looking at it or touching it won't reveal the state of things deep inside.
Checking a roast by cutting into it will ruin it because its juices will all flow out. Here's why: when you cook anything with heat, any internal moisture will be drawn to its surface where the temperature is highest. So if you cut into a roast (or a steak or chop or chicken breast) while still very hot, the juices will escape and you'll be left with a dry, tough piece of meat. This is why recipes always instruct us to let a just-cooked piece of meat rest, giving its juices a chance to settle back and redistribute (the larger the piece the longer the resting time -- three or four minutes is fine for a single chicken breast but a whole chicken should be given about ten minutes, a Thanksgiving turkey closer to twenty). Plus as it rests, the meat will continue to cook a bit; more on this in a moment.
Back to thermometers. These are essential kitchen tools for anyone who uses heat, which is just about any home cook. Thermometers are not just for roasts. They're also used to manage the temperature of water for poaching fish, to successfully bloom active dry yeast, to turn sugar and water into a perfect caramel, to deep fry crispy fried potatoes or crunchy calamari, and to know for sure that when you set your oven to 325º F that in fact, that's what you're getting.
They're also not just for heat. If your refrigerator is unreliable or if you keep a stocked freezer, a thermometer is essential for food safety and preservation. And for any oenophiles with a wine fridge, a thermometer can make all the difference when storing anything valuable.
In other words thermometers give you data and when you're working with delicate or costly ingredients, more data will give you more control.
Types of Cooking Thermometers
An instant thermometer is not exactly instant; you usually get a reading within five to 10 seconds. Most are about six inches long with a gauge on one end and a sharp point at the other. Sometimes the gauge is digital while others have a dial face, and many come with a plastic holder to protect the stem. Most are not waterproof but they clean easily by just wiping with a damp cloth. Taylor is a good brand and the one that I have, which has a dial face, has worked effectively for about eight or so years with the same unchangeable battery.
The long nail-like metal stem lets you make a very small pierce into the meat (avoiding any bone, which will give you a false reading) to find out what's actually going on deep inside. Some skilled (and brave) cooks will then remove the stem and touch it to their lips to feel how hot the insides are; I'm timid with this method but I will touch the stem's tip with my fingers immediately after removing it from the meat.
When using an instant thermometer with a whole chicken, remember that the dark meat, which has more fat, will take a bit longer to cook than the white breast meat. Your internal temperature target (see the list below) will be 165° F but check both the breast and the leg or thigh. It will help when roasting a whole chicken or turkey to put the pan legs-end side first, where the oven is slightly hotter and will cook a little faster, with the breast-side facing the oven door.
I don't use an instant thermometer with a steak or chops because the size of the meat is smaller and I want to avoid piercing the surface (see above about the juices). Instead I encourage anyone who pan cooks or broils steaks and chops to learn how to tell doneness with your fingertips, not a thermometer. See our link to an article, with photos, that can help you learn how to do this.
A final point on instant thermometers: as I've written before, when I travel and rent an apartment instead of staying in a hotel, I always include an instant thermometer in the cooking kit I bring with me (along with little bags of favorite spices, my chef's knife, and a long piece of butcher's twine). When I'm in an unfamiliar kitchen with an untested oven and food shopping in unfamiliar markets, I know that at the very least I can roast a chicken. If I'm in Europe I set the oven to 180º or 200º C (350º or 400º F) and use my thermometer to check for doneness. Even in a foreign kitchen, a chicken cooked to 165º F is perfect.
Some home cooks prefer a probe thermometer that is inserted into and then left in the meat for the duration of the cooking, with a cord running out of the oven to connect to a gauge and an alarm. Such thermometers let you set a temperature goal so you don't have to worry about checking the meat too soon or too late. But I find that most roasts are forgiving and there isn't a precise time of doneness. It's not like a sheet of cookies for which five minutes of unchecked cooking is the difference between cooked and burned. You have some latitude with your pork loin so I stick with my instant thermometer.
I don't grill, but I have friends who do, and I've seen how a probe thermometer with an external monitor can be extremely useful and effective with a gas grill. It lets you avoid having to repeatedly open and close the grill's hood to check the progress of cooking and you don't have to put your hand inside, making it safer.
Most deep fat/candy thermometers are attached to a metal plate with a temperature gauge printed on it. This kind of thermometer is designed so to clip onto the side of a pot that contains a very hot liquid -- perhaps oil or rendered lard for deep fat frying, or a sugar syrup that will be cooked to become caramel, candy, or icing. This kind of thermometer is safer to use -- once placed inside and attached to the pot, you don't have to touch it again because you can easily watch the temperature rise and know when whatever you're cooking is at its designated heat without having to insert or remove the thermometer, risking a serious burn. For example, deep fat frying is usually done with the fat at 375° F. Likewise if you're boiling sugar syrup to a soft (235º F) or hard (250º F) ball stage -- you can easily monitor the cooking and turn off the heat when you're at your goal.
There are instant deep fat/candy thermometers that read temperatures higher than the instant kind you'd use for meat or poultry but in my view they're more dangerous to use because you have to reach into the hot pot, so if you prefer this style, be cautious. Most deep fat/candy thermometers -- both clip on and instant -- cost about $8 to $12.
Oven thermometers are in my view essential for any home cook -- even if you've got a fancy stove or high-end wall ovens. In most cases, ovens are factory calibrated to proper temperature controls, but you'd be surprised how often you think you've set your oven to 350º F, when it fact it is 345º F or 355º F. Even if your stove's LED display says it's 350º F, you can't be sure until you test it with a thermometer.
Perhaps you think five degrees is no big deal. In fact it can be, especially if you're working at lower temperatures for a long, slow braise but your oven is too high and thus cooking too fast; or if you're trying to get a rise out of a soufflé at a higher temperature but instead it deflates. Likewise if you're cooking something that starts at a high heat and then finishes at a lower one -- how can you know you've hit your marks without a thermometer? An oven thermometer costs less than $8 so if you've never measured yours, or if you've just bought a new stove, it's worth the small investment to check what you have. If it's a new stove and the temperature is off more than one or two degrees, ask for a service call; if you've had your stove for a while and the warranty is expired, just make a note of any temperature difference and adjust for it every time you use your oven.
Refrigerator, freezer and wine cooler thermometers, which also cost less than $10 each, are useful the same way oven thermometers are: you learn what in fact is going on and if necessary, you can make adjustments. If your refrigerator is running too high, you're wasting electricity plus you can be damaging your food. A small example -- I really love cottage cheese and always have some on hand for a quick lunch, but my previous refrigerator constantly froze it and I assure you that frozen cottage cheese is, well, yucky. There was no digital temperature indicator so I got a thermometer and little by little, adjusted the fridge's temperature knob until I got it to a steady 39º - 40º F. No more ruined cottage cheese.
Wine cooler thermometers can be equally important if you've got valuable bottles kept in a temperature-controlled space or refrigerator.
Using A Thermometer When Cooking Fish
It can be tricky to know when thick pieces of fish, such as salmon fillets, are fully cooked. Cutting into a piece doesn't do as much harm as if you did the same thing to a piece of beef because it doesn't have the same juices, but you still want to avoid messing up the fish as you try to figure if it's done. So use an instant thermometer, carefully inserted into the thickest section. Just avoid making contact with the pan, which will skew your reading. Our adaptation for Miso-Glazed Salmon from The America's Test Kitchen Menu Cookbook is a superbly flavored and easy way to cook salmon and it recommends using an instant thermometer to make sure it's perfectly done.
In another recipe, this one for Tricolor Salad alla Splendido by Jeff Gordinier and published by The New York Times, makes a confit of fresh tuna in olive oil that is kept at a steady temperature so that it poaches and not overcooks. Use your instant thermometer to manage the temperature and the tuna will be tender, tasty and luscious -- or as the recipe calls it -- splendido!
Temperature Targets
Okay, so you have your thermometer, instant or not. What exactly are you aiming for? This list of target temperatures combines guidelines from the USDA with ones published by Martha Stewart with the slightly lower targets often used by professional and restaurant kitchens. Note how every temperature target is before resting; this means the internal temperature at the point when you take the item out of the oven. An ingredient will continue to cook and its internal temperature will continue to rise while it rests. When a food is especially large, such as a fifteen or twenty-pound Thanksgiving turkey, its internal temperature can rise as much as ten degrees while it rests, especially if you have it tented with foil, so always keep this in mind when you set your target temperatures.
Ground meats have higher temperature targets because they can be more vulnerable to bacteria.
Beef/Rare
USDA Guidelines (before resting): n/a
Restaurant Kitchens (before resting): 115° F
Beef/Medium-Rare
USDA Guidelines (before resting): 145° F
Restaurant Kitchens (before resting): 120° F to 130° F
Beef/ Medium
USDA Guidelines (before resting): 160° F
Restaurant Kitchens (before resting): 140° F
Beef/Medium-Well
USDA Guidelines (before resting): n/a
Restaurant Kitchens (before resting): 150° F
Beef/Well-Done
USDA Guidelines (before resting): 170° F
Restaurant Kitchens (before resting): 155° F to 160° F
Ground Beef
USDA Guidelines (before resting): 160° F
Restaurant Kitchens (before resting): 160° F
Pork/Medium
USDA Guidelines (before resting): 160° F
Restaurant Kitchens (before resting): 145° F
Pork/Well-Done
USDA Guidelines (before resting): 170° F
Restaurant Kitchens (before resting): 160° F
Ground Pork
USDA Guidelines (before resting): 160° F
Restaurant Kitchens (before resting): 160° F
Lamb/Rare
USDA Guidelines (before resting): n/a
Restaurant Kitchens (before resting): 110° F to 115° F
Lamb/Medium-Rare
USDA Guidelines (before resting): 145° F
Restaurant Kitchens (before resting): 130° F
Lamb/Medium
USDA Guidelines (before resting): 160° F
Restaurant Kitchens (before resting): 140° F
Lamb/Medium-Well
USDA Guidelines (before resting): n/a
Restaurant Kitchens (before resting): 145° F to 150° F
Lamb/Well-Done
USDA Guidelines (before resting): 160° F
Restaurant Kitchens (before resting): 150° F to 155° F
Ground Lamb
USDA Guidelines (before resting): 170° F
Restaurant Kitchens (before resting): 160° F
Poultry/Whole Bird, Thighs, Legs, Wings, Ground Poultry (chicken, turkey, duck)
USDA Guidelines (before resting): 165° F
Restaurant Kitchens (before resting): 165° F
Boneless Chicken Breasts
USDA Guidelines (before resting): 165° F
Restaurant Kitchens (before resting): 160° F
These targets for poultry are often the subject of debate around Thanksgiving and many home cooks prefer to cook their turkeys to 155º F or 160º F and then let the bird rest for 20 minutes, during which time the internal temperature will rise another ten degrees. The most important clue to whether your bird is done is if any of the juices run red when you finally cut into it. Given that under-done poultry can make us ill, I err on the higher side and still aim at 165º F and let it rest for a minimum of 15 minutes, longer if the bird is more than fifteen pounds.
Cooking duck is a bit more complicated. The target of 165º F is good for a whole duck and for individual legs using a confit method. But duck breasts are often safely cooked and eaten rare or medium rare, meaning you can cook the breast to about 130º F before resting. If you are pan cooking individual breasts, try to avoid piercing them with a thermometer and instead use the touch method in order to avoid letting all the juice out.
Other Cooking Temperature Targets
110º F - 120º F Cooked saltwater fish
120º F Cooked freshwater fish (to kill parasites)
140º F Oil temperature to poach or confit fish, e.g., tuna
180º F Water temperature for poaching fish
192º F - 210º F Oil temperature to confit duck legs, i.e., confit de canard
375º F Pan temperature for pan frying fish
450º F Best oven broiler temperature for broiling fish
Oven Temperatures
Sometimes you'll hear a chef refer to cooking in a "hot oven" or a "slow oven." What does this mean? Since most home ovens have a range of 200° F to 500° F, such terms generally describe the relative state of the heat. Here's a general guideline:
200º - 250º F Very slow, very cool, or warm
250º - 300º F Slow or cool
300º - 350º F Very moderate
350º - 375º F Moderate
375º - 400º F Moderately hot to hot
425º - 450º F Hot to very hot
450º - 500º F Very hot
550º F Most broiler temperatures
1000º F Self-cleaning oven temperature when cleaning
Broilers in most residential stoves cook at a single level or temperature. Getting a more robust performance out of a broiler requires either pre-heating the broiler so that the air in the oven itself becomes hotter or else by putting a broiler-proof pan, e.g., a cast iron pan, into the oven with the broiler on and letting the pan pre-heat. For example, I use this method when broiling swordfish so that the hot grill pan cooks the underside and the broiler above cooks the top surface -- making it unnecessary to turn the fish over.
Converting Fahrenheit Degrees to Celsius/Centigrade Degrees
If you need to convert a degree from Celsius/Centigrade to Fahrenheit, multiply by 9, divide by 5, and add 32. Or you can use this online calculator.
In my experience in cooking in kitchens in countries that use Celsius -- for example, if you are on holiday in Europe -- set your oven to 180º C if your goal is 350º F, and to 200º C if your goal is 400º F.
Let me bring this back to something simple: Understanding how heat (or cold) affects ingredients and learning how to astutely manage temperature will make you a more confident and successful cook. The first step in doing this is to have the device that gives you accurate data -- a thermometer. It's a small investment that can pay you back the first time you don't wreck a chicken.
