A temperature reading that is off by several degrees can ruin a dish. I rely on meat/fry/candy thermometers to ensure that meats are cooked just right, jams have reached their setting point, or that oil is hot enough to fry in. In Manila, we have several food thermometers, many of them gifts from friends that know I like to cook, and I use them often. I also have independent thermometers for our ovens, which can be surprisingly mercurial, and heat unevenly and inaccurately. At any rate, these little gadgets can themselves be totally inaccurate, so here’s a quick tip I once read somewhere on how to calibrate your thermometers. Blitz several ice cubes and a bit of water in a blender, transfer the slush to a glass and plunge in a meat thermometer. It should register somewhere around 32.5 to 33.5F. Just above freezing, or melting point. If you get that reading, you have a pretty accurate thermometer, like the one up top, the first one we ever bought, have had for 10+ years and it continues to work beautifully…
Our candy or jam thermometer, however, which I have noticed on several occasions does not seem to reach the proper setting point of sugar/jam, turns out to be 10F off the mark! To find out, I put it in nearly boiling water that was transfered to a cup, and compared the temperature to already vetted first thermometer. The larger thermometer was giving me a reading that was 10F less than the smaller thermometer. Arrggh! If you want to be really accurate, you can plunge your themometer into just boiling water and you should be a reading of 212F. No need to throw out the bad thermometer, just adjust by 10F or so the next time you use it.
Finally, I tested this fancy, schmancy “Sur La Table” digital thermometer and it was quite accurate. So if you have food thermometers in your household, take a couple of minutes to make sure they are calibrated, so you don’t ruin a good roast, or burn a batch of jam… :)