I cooked a beef tenderloin today - why would my new Thermapen register 148 F. when just the tip was inserted at the fattest part of the meat but 119 F when inserted in the skinny end of the roast?
There was no way the meat was at 148 - it was between Blue and very rare, but I ended up relying on touch.
My Thermapen registers 212 Degrees when inserted in boiling water so it must be me (I am just inserting the skinny tip).
The salesman where I bought it could not help - he just confirmed I was using it properly.
Can anyone help?
America's Test Kitchen often sings the praises of the Thermapen, and I own one myself. Interestingly enough, I was listening to an ATK podcast earlier this week and a caller phoned in to ask about what appeared to be inaccurate readings with the pricey Thermapen. Chris Kimball and Bridget Lancaster said they often get inconsistent readings and recommended a few things. (1) Test the meat in a few places; (2) slide the probe into the meat a little more than half way and then pull it back just a little; (3) be sure to slide the probe into the meat from the side, not from the top. They said that when they're showing something like cooking a steak to medium rare, and they're looking for a reading of, say, 130 degrees, it might take many steaks and many temperature readings before they get the one they actually show on TV; everything else is edited out.
Your Thermapen is probably very accurate (use the ice water test that ellabee recommends), and if it's not it can be calibrated, but there are temperature variations in any given piece of cooked meat or poultry.
These more expensive and sensitive sensors are more sensitive to these variations in the temperature. A less sensitive thermometer (e.g. a dial type) averages the temperature over the bottom 1/2" or more of the probe, while the Thermapen records the temperature at the bottom 1/8" of a narrower tip.
" just the tip was inserted at the fattest part of the meat " - just the tip? You are supposed to insert it till the tip is in middle of the fattest part. The idea it to measure the temperature of the part that will take the longest to cook.
From an online Thermapen manual:
"The micro-thermocouple sensor is located at the tip of the probe shaft.
Minimum immersion is only 1/8" (3 mm). For best results immerse or
penetrate the probe into the food item so the probe tip is in the place
you want to measure. In food, this should normally be the thickest part. "