Temperature Probe Insertion – Timing, and other considerations

Discussion in 'General Discussion' started by dcarch, Jul 9, 2013.

  1. dcarch

    dcarch Smoking Fanatic

    Posted by  Chef JimmyJ on “Temperature Probe Insertion Question –  Timing” http://www.smokingmeatforums.com/t/...obe-insertion-question-timing/20#post_1016128

    “Since you guys are HIJACKING THIS THREAD!...And I am a major contributor to answering the OP's question, I will add my observation...

    What is the point of building a Thermal Probe that conducts Heat? Are the sensors not Heat Isolated from the rest of the probe and the probe non-conductive? If not then ALL metal Probes would conduct heat to the meat, especially that in contact with the senor AND the sensor itself!  There would not be a single accurate thermometer with a Metal Probe...Not to mention in this senario, Corporate customer demand and therm manufacturer profit savings would have switched to sturdy non-conductive Plastic Probes with just Metal Tips, years ago. I can see, maybe, a cheap probe thermometer conducting heat and being off a few degrees but the metal is very thin and there is just not enough Thermal Mass to make a significant difference. Additionally, I highly doubt general statements about conduction are valid. During my Electronics Controls and Measurement days, I was not always a Chef, all the Industrial and Medical equipment I worked on and with, had Metal Therm Probes and had better be thermally isolated and highly accurate or there would be huge Costs to our clients from manufacturing inferior Product, Malfunctioning Control Systems and worthless Test Equipment. ------------------- Please make your Closing Statements and move on starting a New Thread on the subject if you wish to continue, in a civil manner of course...JJ”

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    Spinning off from the above thread.

    Here is a quick experiment to illustrate my point on that thread:

    I wrapped some paper towel around the shaft of a typical  probe thermometer about 1 ½” away from the tip. I poured 212F water just over the paper towel. In about 5 minutes, the tip measured temperature change from 76F to 89F.

    I would assume that the temperature rise is mostly due to the metal conductivity of the shaft.

    Imagine the situation of a thermometer probe in a 350F cooker, not 212F environment, for 4 to 5 hours or more into the meat, not 5 minutes, how much thermal distortion the conductivity of the metal can possibly introduce.

    However, this does not mean probe thermometers are useless or not accurate, all it means is to have the best designed fastest electronics, and the smallest probe; the smaller the metal construction the better the thermal characteristics (note the probe size of Thermapen) and don’t take too long to take your measurements. Read the thermometer's spec and see how long it says for the thermometer to register a correct reading and don't take much long that that. Just MHO.

    I have also done a lot of sous vide cooking. In sous vide, as you probably know, people are concerned with 1 degree accuracy.


  2. chef jimmyj

    chef jimmyj Smoking Guru Staff Member Moderator Group Lead OTBS Member

    It is still a non-issue in our world. Look at it this way...An 8 Lb Butt allows a 6" probe to be buried up to the bent. You have determined that the probe conducts heat. But the meat is 40*F. As the probe heats, the conducted energy raises the temp Very slowly in fact at or just slightly higher than the same pace as the heat energy is absorbed by the entire surface. To put a number on it for discussion sake. After 15 minutes 1/4" of the meat surface has risen 10*F and maybe 11*F surrounding the top 1/4" of the Probe shaft...The remaining 6" of meat is still 40*F and sucks heat off the remaining 6" of the probe, therefore the Sensor still read 40*F. Each 15 minutes the temp continues to rise but is conducted Slowly from the Surface toward the Center with any conducted heat energy On the Probe being sucked off by the colder center of the meat. The heat energy from the environment and the probe continues to move from surface to center until the Center of the meat reaches a temp 5-10*F below the desired finished IT, to Rest, then continues to rise to the desired finished IT. This is Carryover Cooking. The energy at the hotter Surface continues to conduct to the center until equilibrium is reached.  We KNOW this because when you measure with the MAV Probe, in the meat the whole time, and an Instant read right next to it, they will be the same or very close, at 1 min, 1 hour and 10 hours...Many of us double check our IT's and have proven this...By your premise if we want to Rapid Cool a 8 Lb Roast we could quickly do this by putting a hunk of Ice against the Probe!...Probe conduction is insignificant. 

    Now where the conduction of a hunk of steel punched into or actually through a hunk of meat is on a Rotisserie! A 3/8" to 1/2" rod of steel with a foot of exposed steel on each side of the roast absolutely conducts heat to the center of the roast at a faster pace then the energy conducts from the surface to the center...JJ
  3. s2k9k

    s2k9k AMNPS Test Group

    dcarch, Nice experiment but I think to make it relevant to the point you are trying to make you need to put the tip in a 40* solid mass then pour the 212* water over the paper towel.

    I really don't care what a remote meat probe left in the meat reads, most of the time I don't use one, it's just a general guideline to let me know when the meat is starting to get close to done. I rely on instant read therms probed in all parts of the piece of meat and also the tenderness of the meat.

    I think someone who relies on one probe in only one place in the meat and when that one very small section of the meat shows their desired temp they call it done is someone who could be turning out much better product than what they are.
    Last edited: Jul 9, 2013
  4. dcarch

    dcarch Smoking Fanatic

    Just like the folks in the not-too-old good-old-days, after a while, you really don't need a thermometer to cook, unless you are making candy. Experience works.

    However, I am alarmed by so many I have seen, including so-called chefs on TV, sticking a cheap probe thermometer into 1/2" thick burger meat, or 3/4" thick chicken breast and hope that the readings will guarantee them safe eating for the family. This is the whole point of my posts: that is, metal conductivity of temperature probes can be a significant factor in the measurement of thin cuts of meat cooked at high temperature for a long time.

    Last edited: Jul 9, 2013
  5. s2k9k

    s2k9k AMNPS Test Group

    I think if you cook a 1/2" thick hamburger at high temps for a long time you probably don't have to worry about it being undercooked.
  6. Hello.  I have read both posts.  I have been grillin and smokin for almost 40 yrs. I know the thought; if you have been doing it WRONG for 40 years it's still wrong.  I don't mince words when I know what I am talkin about.  You are wrong and Chef JJ is correct.  The temperature sensing tip is isolated and reads the true temp of the meat if properly inserted.  Write it up any which way you want and do as you wish.  I will not argue.  Good luck.  Keep Smokin!

  7. dcarch

    dcarch Smoking Fanatic

    LOL! Even I re-read my post before I push "Submit", still I didn't see what I was really trying to say can come out the wrong way.

    I was trying to say:

    "This is the whole point of my posts: that is, metal conductivity of temperature probes can be a significant factor in the measurement of thin cuts of meat cooked at high temperature and for thin cuts of meat to be cooked for a long time."

  8. dcarch

    dcarch Smoking Fanatic

    Utilizing metal pins to conduct heat into the center of meat to facilitate cooking is nothing new. I have a whole bunch of these heat pins.

    Now I also use a different technology to do the same thing.

    If you open up your laptop computer, you may find the CPU's heat is dissipated using a tube which is called a “Heat Pipe”.  Applying the law of thermal dynamics and  phase transition, a heat pipe is a very efficient heat (BTU) mover. Without it, your laptop will be fried in minutes.

    There are a lot of these laptop heat pipes very inexpensive on the surplus market. I have a whole bunch of them which I fashioned into heat pins for cooking. It cuts down the time required to get the center of large cuts of meat up to temperature, and resting time also.


  9. shannon127

    shannon127 Smoking Fanatic OTBS Member

    I just use my pinky finger. 
  10. jarjarchef

    jarjarchef Master of the Pit OTBS Member

    Why would you cook a thin piece of meat on high heat with a probe in it?

    I would have to say Dave and Chef Jimmy have made some very good points.
  11. chef jimmyj

    chef jimmyj Smoking Guru Staff Member Moderator Group Lead OTBS Member

    This is just SILLY! By design thin cuts of meat are Cut to be cooked very QUICKLY by direct contact with a Heat Source for a short period!!! Not only would it be impractical to stick a slow " Leave in the Meat " Therm Probe in a cut less than 1" because of the difficulty of Centering it...UNDER NO CIRCUMSTANCES would ANY part of the metal probe come in contact with the Heated Surface with the exception of the small amount of Infrared energy the shiny metal would absorb, which is again a Moot Point for reasons already stated multiple times and ways!!! How could it possibly CONDUCT heat to the Meat and be Inaccurate!?!?! Thin Tender Cuts like, Chicken Breast, Beef Steaks from the Rib, Short Loin, Tender Loin and Sirloin and Pork Chops from Center cut Loins, are NEVER EVER Cooked for a Long time! Additionally ONLY Chicken Breast represents any risk if not cooked above 160*F, which in the Thickest Breast I have ever seen at 14 Ounces for a single lobe was 1 1/2" Thick and cooked in only 5 minutes per side. Beyond 1 1/2" we are no longer talking THIN CUTS!...I missed a few days of Thermodynamics Class back in Engineering School. Am I missing something here as well?...JJ
  12. s2k9k

    s2k9k AMNPS Test Group

    I am so confused!!!
  13. shannon127

    shannon127 Smoking Fanatic OTBS Member

    I am cooking steak-ums, what temp should they be heated to? 
  14. chef jimmyj

    chef jimmyj Smoking Guru Staff Member Moderator Group Lead OTBS Member

    [​IMG]    I have not had Steak-ums since the late 70's!!!....JJ
  15. s2k9k

    s2k9k AMNPS Test Group

    120 for rare....130 for med rare.....140.........................................................................but always check your probe in boiling water for accuracy before inserting into a steak-um!
  16. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    I just had to look up Steak-Umm.... I must have grown up "deprived" or "depraved"....    I'd cook the $h!t out of them, then add lots of sauce.....  of course they would need liquid smoke.....  mesquite flavored liquid smoke....  and garlic.... lots of garlic....


    Though he's got 33 patents in the food industry, Gagliardi is best-known for Steak-Umm, an imitation meat product. And at 82, he's still ahead of his industry's curve.


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