My mechanical meat thermometer is taking an average of the meat and air temperature

Question

I have two "good cook" brand mechanical instant read meat thermometers. I use my small oven broiler to cook steak to medium rare. However, after cooking for a while, taking the meat out and measuring it with both thermometers, the temperature never reaches above 120. In the end, the meat is quite dry and obviously ruined.

I did a test with a boiling cup of water. If I only dip the probe tip into the water, the thermometer doesn't read 100 C but rather something much lower (consistent reading on both thermometers). If I immerse the entire probe in the boiling water, it would read close to 100C.

I suspect that these probes actually average the temperature over the entire length of the probe. But this would mean that I cannot really rely on these thermometers to diagnose welldone-ness. Had anyone else ran into this issue?

I suppose I could re-calibrate the temperature reading at which my steak is considered rare, most likely a reading of around 100 F on these thermos.

Answer 1

You are right that mechanical probes sense temperature along the length of the probe, so they are only accurate if they are almost completely embedded in the food. Electric probes on the other hand have a thermocouple at the tip of the probe, so they are much more accurate. I suggest you get a digital probe instead.

Answer 2

I have always found mechanical thermometers hard to work with. The problem with them is as you noticed, unless a considerable portion of the probe is inserted it’s hard to get a reliable reading.

I’m not sure if recalibration could help. When you recalibrate, say using boiling water, your readings on the thermometer will also be affected by the ambient temperature around the probe (which will be somewhere between the room temp and 100C). However, when you use it in the oven, say while roasting some meat, the calibrated reading on the thermometer will account for the ambient temperature at the time of calibration, but your actual reading will be affected by the oven temperature.

Unless you calibrate it for different environments, I don’t think that’s going to be useful.