© Randal Oulton
Thermometers come in many different varieties and scales. The choice isn’t just between Fahrenheit or Celsius: some of the simpler ones are not really thermometers at all. They just show ranges — rare, medium, burnt-offering, etc. Some have mercury in them, but most are pure metal these days because it is safer (and cheaper.) Some are so high-tech they’re even fun (toys for boys.)
Digital ones require batteries. Dial ones are also called “analog.”
Digital ones are better for checking thinner foods — they are the ones that food safety experts recommend for checking hamburgers. Large-dial ones are better for large pieces of meat.
When using a mercury Thermometer, keep it upright while cooking and while it is hot. If you lay it down, the heated mercury may separate into small beads and render the thermometer useless in the future. Always let glass thermometers cool completely before cleaning or they may shatter.
What all thermometers have had in common is that they had to touch the food to work. This leads to the possibility of cross-contamination. We need a Thermometer that you can just point at something on the grill, click a button to shoot and presto, there’s your temperature, with no surface contact needed. There are now (since about 1998) infra-red thermometers that do something like this, except they have one show-stopping limitation: they can only measure the surface temperature of food, and, given the nature of how infra-red rays work, it’s not likely that this limitation can be overcome with this technology.
From time to time, check the accuracy of your food thermometers. Bring some water to a rolling boil, put the thermometer skewer two inches (5 cm) in, not allowing it to touch the bottom, and hold it there. If there’s a lot of steam, mind the steam: you may even want to put an oven glove on. Hold it there: after 30 seconds, an Instant Read Meat Thermometer should be reading 212 F (100 C). An Oven Safe Meat Thermometer may take up to two minutes to show the correct temperature. If your dial-type Thermometer is off and has a nut underneath the dial part, then you can “calibrate” it by adjusting the nut. If your Thermometer is designed so that you can’t calibrate it in this way, then you need to plan in the future to take into account how much it is off by, or pitch it and buy a new one.
Blewitt, Tom. Infrared thermometers help food safety professionals prevent foodborne illness. Melville, NY: Engineering Services, Underwriters Laboratories Inc., 1999.
Health Canada. “Food Safety Tips for Using Food Thermometers”. Publication P0285E-03. March 2003.
USDA Food Safety and Inspection Service. The Thermy™ Campaign. May 2002.