Transcript: Thermometer

Food Science
Episode “Thermometers”

Dr. Kiky Sanford: Hi I am Dr. Kiky Sanford, and you are watching food science, today we are talking about infrared thermometers. You are probably familiar with this thing called a kitchen thermometer. You stick it in to whatever food you want to cook, and it tells you how hot that food is inside.

But what if you wanted to know how hot the food s on the outside. Or say you wanted to know how hot your grill surface is. Well you don’t want to touch it because you an end up burned. That’s why science as come up with this handy little gadget called the infrared thermometer. Lots of recipes require that you bring cooking surfaces to particular surfaces.

Like if you want to sear your meat the best temperature is 232 degrees Celsius, exactly. Now I want to make pancakes, and it requires a pretty narrow temperature range. To test the griddle a lot of people will take water and see if it skittles across the surface. If it does they will usually decide that hey the griddles ready to go.

The problem is that water skittles across a wide temperature range, from about 160, to 230 degrees Celsius. I don’t need that wide of rage to make my pancakes, remember I need it very narrow. So I can use my infrared thermometer to tell how hot my griddle is to a tenth of a degree without even touching it. I just push a button and point a thermometer and it tells me that my thermometer is 184.4 degrees Celsius. Perfect for pancakes, but how does it work?

It has an optical sensor, see right here this little thing right here that looks like it should be a laser beam but it’s not unfortunately. I wish it were a laser beam. You point it at a surface and the optical sensor reads the black body radiation that’s emitted from the object in the infrared range of the electromagnetic spectrum.

It is a little bit longer in wavelength than the color red, the color reds the longest wavelength in light that we can actually see. The best thing to do is hold your thermometer close to the surface of the object that you are measuring because each infrared thermometer has its own D-S ratio. That’s distance to surface area. Mine is 1 to 1.

I wonder if my griddle is really ready for these pancakes lets measure it again, looks just about right. Let’s make pancakes. Ah-ha, but remember its not just food, its science.