Temperature carry-over


 
T

Tyler Davis

New member
I have noticed that my readings actually drop ~5 degrees immediately after taking the meat off the smoker. This is with an accurate, calibrated digital probe. I wonder if there is some effect where the juices are boiling, then cool down as soon as the meat is taken off. I still do the foil-tent/resting phase, but it makes it hard to predict when it is truly done. Has anyone else had this problem?
 
To be honest, I've never left a temp probe in a bbq cut after pulling off the smoker, so no, I've never had that "problem".
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Finished temps are just guidelines of when to check for tenderness. Learning when to pull for optimum tenderness comes from experience and/or learning from someone that truly knows what they're doing. Books and bbq forums are only so much help, but I'm kind of surprised that videos aren't suggested more often. Honestly, you might try doing some youtube searches, starting with "Chris Lilly pork butts".
 
The cut in question was actually a whole turkey. I have a better "feel" for a pork butt and when it is ready to be pulled. With poultry the only thing I know to try is to twist the leg joint and see if if breaks easily. But sometimes that can be deceptive if the skin is crispy and holding the leg joint in place.
 
A turkey, huh? You probably would've gotten just as many or more responses on the turkey forum.

Anyway, I do go by temp when cooking turkeys, but have never had an issue with the temp falling like that if I recall. Maybe your probe tip was touching a bone or reached all the way into the cavity? I suggest leaving the probe in the breast, not the thigh, and you might learn some more turkey temp tips here: http://www.thermoworks.com/blog/2010/11/turkey-temps/
 
Welcome Tyler,

Carry-over cooking is dependant on cooking temp and mass (quantity of meat). The higher the cooking temp the more carry-over you'll have.
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">wonder if there is some effect where the juices are boiling </div></BLOCKQUOTE>
Shouldn't be 'boiling' otherwise you'd have an internal temp of approx 212 which would make for a very dry bird. I would suspect the probe is somehow moving as you pull the meat off and exposing it to cooler temps. I've not experienced an immediate drop in temps like that.

Paul
 
Your probe might be picking some ambient temperatures from the cooker. I have a couple of cheap grocery store probe thermometers and they always drop in temp when I pull the meat off. It's almost like the heat of the cooker is traveling down the probe from the exposed area outside of the meat. If that makes any sense.
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Travis D:
Your probe might be picking some ambient temperatures from the cooker. I have a couple of cheap grocery store probe thermometers and they always drop in temp when I pull the meat off. It's almost like the heat of the cooker is traveling down the probe from the exposed area outside of the meat. If that makes any sense. </div></BLOCKQUOTE>

Yeah that's the best explanation I can think of. Even in a Maverick probe, there is no thermal isolation to prevent heat from traveling down the probe to the tip, which will tend to give high readings as long as it is on the smoker.
 
If the probes used are analog (typical bimetal thermometers) this is a common problem. These 'meat thermometers' should not be used to check meat for safe internal temps because they only use an average of the temp along the stem - often 2-2.5 inches of the stem, from the tip - and thus are highly influenced by ambient temps if the entire probe is not buried in the meat, something usually impossible to do.
 
Again, I'm not using bimetallic thermometer. I use a digital Maverick and a digital ProAccurate thermometer. However, the physics is the same, in that heat will travel down the length of the probe and give a temperature reading that is higher than the probe tip, but lower than the ambient hot smoker air.
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">the physics is the same, </div></BLOCKQUOTE>
It isn't. That is not how thermistor and thermocouple thermometers work, which is why either is better for checking safe internals.

Juices don't 'boil'. In poultry one can see a drop or immediate stability when the bird is removed. Temps don't often rise in poultry as its structure is different.
 
I understand that the actual thermistor is in the probe tip, but the temperature of that tip is influenced by the rest of the probe temeprature upstream. That is, the probe tip is not perfectly thermally isolated from the sheath.
 
It doesn't need to be sheathed. In a thermistor, the measurement occurs at the resistor that is attached to the electronic circuit at the tip. Thermocouple measurement occurs at the 'cold junction', also at the tip.

In both cases it is what is going on at the measurement point - not elsewhere - which determines the temp reading. This is why these types of therms are used where safety and accuracy are most critical, like in food safety and medical devices.
 
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