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Thermometers

Thermometers are some of the most essential tools in your kitchen. I can’t emphasize enough how important they are. Thermometers take the randomness and guesswork out of cooking; they will do more to ensure that you consistently get the results you are looking for than any other tool.

Ideally you will have four thermometers in your kitchen:

  • An oven thermometer. The built-in thermostat in your oven is very unreliable, and only gets worse over time. Also, oven thermostats stop telling you any useful information once they think your oven is pre-heated, whereas we would like constant updates on the temperature in our oven: we open the door from time to time, we add and remove things, and sometimes we change the temperature setting midway. Go buy an oven thermometer, put it in your oven in a place where you can read it through the window in the oven door (i.e. without opening the door), and leave it there. If your oven allows for it, re-calibrate the built-in thermostat to match what the thermometer tells you the real temperature is.
  • Thermometers in both your refrigerator and freezer.  Preferably simultaneously, because in many refrigerators adjusting the temperature of one will also affect the either. If you’re lucky enough to have an expensive refrigerator or freezer, it might have a built-in thermostat; these are certainly more reliable than oven thermostats, but they are still worth validating before you put too much trust in them.
  • A hand-held thermometer with a three-to-five-inch needle that can be inserted into something to read its internal temperature (the sensor is at the tip). You can use this with liquids, thick cuts of meat, and baked goods alike.

In time as you expand your cooking, you might need a high-temperature or “candy” thermometer, which looks like a big held-held thermometer but can take readings at much higher temperatures than most hand-helds. As the name suggests, they are useful for making sweets, but they are also very useful for taking the temperature of oil that you intend to use for deep-frying. Candy thermometers often have a clip that allows for attaching them to the side of a pot so that you can be continuously checking the temperature hands-free.

Thermometer mechanisms

There are three types of thermometer mechanisms:  mechanical dial, mercury, and digital.

Mechanical dial thermostats have a small metal coil inside that expands and contracts based upon the temperature. They are calibrated to be accurate when they are first manufactured, but over time they quickly lose their accuracy – and especially if they are subject to frequent cycles of warming and cooling, such as in an oven. They are the cheapest thermometers in every sense of the word: least expensive to manufacture, least expensive to buy, and worth the least. Don’t buy them.

Mercury-based thermometers are very accurate, are in fact older technology than dial thermometers, and are fairly inexpensive. You can readily find them for refrigerators, freezers, and candy thermometers; they are harder (but not impossible) to find for ovens and handheld thermometers. Their one downside is that they are fairly slow to render a reading; it can take up to a few minutes for them to adjust when placed in a new environment. As such, they are not very practical for hand-held thermometers. Also, if they break (which they won’t if you’re reasonably careful), you risk spilling mercury, which is poisonous, in your kitchen and onto your food. These are great options for your refrigerator and freezer where they can be put in place and left alone.

Digital thermometers have come a long way in the last five to ten years. The first generation often weren’t any better than mechanical dial thermometers: of variable accuracy and slow to return a reading. Mostly this was due to design and manufacturing choices: accurate, quick-to-respond electronic temperature sensors have existed for decades, but so do cheaper, less accurate, slower sensors. Also, the heat-transfer qualities of the metal probe surrounding the sensor matters a lot: if it doesn’t quickly and efficiently let heat pass through, then the sensor can give false (or slow) readings.

Digital handheld insertion thermometers

The gold standard for digital handheld thermometers is made by ThermoWorks. Their products are reliable, highly accurate, durable, and give a nearly instant temperature reading. They are also pricy, but for years they were by far the best one out there; it’s what every professional chef carried in their shirt pocket. Many still do, and their products are still best of breed, but there are competitors catching up quickly at much lower price-points. You can’t go wrong buying a ThermoWorks Thermapen (and it’s a great item to add to your birthday or holiday gift wish list), but I recommend reading the latest product reviews because you will likely find a less expensive competitor that is almost as good. Beware, though, of claims that a thermometer is “instant read”; many claim to be, few truly are.

You can also find digital refrigerator and oven thermometers.