KUKpro is the First and Only Temperature Profiling Meat Thermometer with 12 Sensors

The Consistently Inconsistent Turkey


Have you ever thought about preparing a turkey feast for the holidays but you didn’t even know where to start, let alone where to place the thermometer?  If so, then this Study is for you.

There’s nothing like preparing a meal for guests that can result in both, some of the most rewarding and most frustrating experiences of our lives.  With all the well intentioned mis-information on the internet, it’s no wonder so many turkeys turn out consistently inconsistent.  In today’s blog we are going to share with you the results of our research into why, despite the home chef’s best intentions, turkey’s are so regularly under and overcooked, and oddly enough why both often happen to the same turkey.  These are our two priorities for cooking turkey:

Priority #1: Nobody Gets Sick

Priority #2: Cook The Perfect Turkey

Note: if you accomplish #2, Nobody is likely to get sick

 Cooking Without a Thermometer – “Winging” It!

 Don’t do it! #1 is more likely if you do this! This is the only reason a turkey should ever be overcooked…or the battery in your thermometer died! To cook your turkey without a thermometer and rely on a timer based upon oven temperature and weight alone, you risk the chance of undercooking and/or overcooking it.  There are far too many variables at play to risk cooking without a thermometer particularly if you are not well versed in the art.  Is your bird fully thawed?  Does your oven run hotter or cooler than it is set for? Is your turkey stuffed with enough herbs, etc. to restrict airflow through the cavity? Most of the overcooked turkeys we’ve all heard about are likely the result of cooking without a thermometer, otherwise, they would have been pulled out of the oven when the thermometer reached 165°, right?  I’m sure more than enough turkeys cooked without a thermometer have also been undercooked.  Having said that, using a thermometer alone does not guarantee the perfectly cooked turkey.

Cooking With a Thermometer

using a thermometer alone does not guarantee the perfectly cooked turkey either. For example, you have a 16 lb. turkey and you place your thermometer into your bird but miss the thermal center (the cold spot). Your thermometer will reach 165° before the center is fully cooked and you will pull your bird out of the oven to rest too early.  When you finally go to carve it, you will find it’s raw in the center so you will have to chuck it back in the oven for a while longer, sometimes a long while longer only to serve your guests a dry turkey because all its juices have dried up after a second cooking. Not to mention the over-cooked side dishes, dried out breads and the stress this has all brought upon you – did I mention the horror stories we’ve all heard about.

Invariably, there are as many ways to prepare a turkey as there are guests sitting at your table.  It doesn’t matter whether your turkey is 10 lbs. or 20 lbs., fresh or frozen, baked or grilled, Porchetta-spiced or Garlic Herb-Butter marinated, there is only one commonality between all turkeys and that is the peak internal temperature your turkey must reach before it is served.  And that temperature is debatable too if you can believe it! At  165° for 10 seconds, there is a 7-log reduction in pathogens according to the USDA.  Did you know you can also kill the same pathogens at a lower temperature, provided your bird maintains that temperature for a longer period?

Here is an excerpt from the USDA’s Poultry Pasteurization Tables for reference. There are other variables that affect these values so it is best to refer to the actual tables. 

              F         Chicken     unit    .    .    .     Turkey   unit

           155            44.2         sec                            1.2      min

           156            35             sec                         59          sec

           157            27.7         sec                         47.9      sec

           158            21.9         sec                         38.8      sec

           159            17.3         sec                         31.5      sec

           160            13.7         sec                         25.6      sec

           161            10.8         sec                         20.8      sec

           162          <10.0         sec                         16.9      sec

           163          <10.0         sec                         13.7      sec

           164          <10.0         sec                         11.1      sec

           165          <10.0         sec                       <10.0      sec

 

This means you can cook the cold spot of a turkey, provided you know where it is, to 155 degrees Fahrenheit and hold it at least at that temperature for 1.2 minutes (1 minute 12 seconds) and it is as healthy as if it had reached 165 degrees Fahrenheit for 10 seconds.

That’s great! Now all you have to do is align your single sensor thermometer’s sensing element with the coldest part of your turkey, otherwise, your thermometer will tell you it is done too early and you will pull your turkey out of the oven to rest while it is still raw but we already knew that, right?  OK, so where should we place the thermometer? 

Probe Placement

The problem #1: Where to measure?

The problem #2: How to measure…correctly?

You’ve seen it, I’ve seen it, we have all seen it. Thermometers coming out of every part of a turkey.  What the heck? Which thermometer is telling the truth?

 

Simply put, you have two choices when measuring your turkey’s temperature, the breast and the thigh, however, turkey breasts and thighs cook at different rates.  Not only that, but measuring them in various ways often leads to different results. So this is what we did.  We placed two KUKpro thermometers in the breast (one horizontal and one vertical) and we placed two KUKpro thermometers in the thigh (one vertical and one horizontal). Did we mention each KUKpro thermometer has 12 sensors in 1 probe?

 This test was really important to us so we made a special test apparatus that we can connect 4 KUKpro probes up to in order to collect all this great data. With 48 sensors in one turkey, we’re going to study the crap out of this bird!

 

We ended up using 3 KUKpro probes with the test apparatus and used the fourth with our standard KUKpro Puck and KUKpro app just for fun! We inserted the fourth into the breast (vertical) because that was the one we really wanted to monitor as this is where most people place their probe or at least where I have always placed mine.

 

Before we start, let’s take a look at exactly how a turkey cooks.

Probably the single most frustrating part of cooking a turkey is ensuring your thermometer is measuring the coldest part, or the “thermal center” of your turkey.  To understand this more fully, as a turkey cooks it develops a temperature profile with the hottest temperature being on the exterior and the coldest, located somewhere within.  Intuitively, it seems obvious that the coldest part of the turkey is the center of the meat.  While this may be more true with steak it is not necessarily true with turkey. The thermal center of your turkey is determined by several variables including oven temperature, breast thickness, internal starting temperature (did you bring it to room temperature or is the cavity still full of little icy bits?), bone and even by the free movement of air into and out of the cavity as well as how much “stuff” you choose to place inside the cavity to impart more flavor to your meal. That is to say, the thermal center of your turkey is a mystery, no two turkeys are the same and what most people don’t realize is that the thermal center location varies and can even, in certain circumstances, move.

Seriously? Yes, it almost makes us want to throw in the towel – no wonder so many people have…or never even pick it up to begin with! And no wonder so many turkeys initially come out of the oven with raw centers.

 Okay, enough theory, let’s get down to business!

Planning Your Cook

Now that our turkey is thawed (or should be) and we know something about probe placement we can move on to cooking.  Here we have to balance the estimated cook time and temperature with the size of our turkey. This chart, provided by the U.S. Department of Health and Human Services provides cooking times for turkeys cooked at 325 degrees F.  Note – most recipes call for cooking turkeys in ovens set at 325 or 350 degrees and others for finishing for 1 hour at 400° to crisp the skin. These are estimations only and should be used for planning your general cook time. The actual cook time should be determined using a thermometer.

 

 Cooking Your Turkey

Now we have our thermometers placed for cooking and we cook…and we cook…and we cook, until, viola – our app tells us it’s close to time to pull our bird. Note the cold spot temperature at the tip is auto selected as the “LOW” temperature and is compared to the “TARGET” temperature. When the “LOW” temperature matches the “TARGET” an audible alarm sounds to alert you your turkey is ready.

 

 This screenshot shows us we still have 4 degrees to go but we’re close (the breast meat is actually fine to eat now as it has been above 150 degrees for more than a few minutes but we need to let the thigh do the same). We should also mention, and this is very important, the KUKpro thermometer was inserted all the way to the bone. This is important for two reasons:

  1. It shows the cold spot in the turkey breast is beyond the middle of the thickest part of the breast and adjacent to the bone. no wonder we hear so many raw turkey horror stories – It’s easy to miss the cold spot with a single sensor thermometer.
  2. It shows there’s about 10 degrees of difference ½ inch from the cold spot – makes sense, if everyone is missing the cold spot they’re going to be serving raw turkey.

 Here’s some really good data on heat conduction through bone (see link below). Spoiler alert: bird bone is light and full of air so helps to insulate the breast meat from the hotter cavity temperature while pork bone is more dense and more readily conducts heat. Single sensor thermometers may show a warmer temperature than what the meat actually is if it is touching pork bone but that’s not the case if it is touching poultry bone.

https://genuineideas.com/ArticlesIndex/tothebone.html

So we waited until 165 degrees and checked the rest of our sensors on the laptop.  The coldest temperature, in the thigh as expected, has been above 150 degrees for more than enough time to be rendered safe, according to the USDA’s Poultry Pasteurization Tables.

Here’s what we got, a beautiful turkey:

 

…and boy did it taste good!

Here’s some interesting data.  We are going to standardize the take-aways from each of the 4 thermometer plots to make for easier comparisons between sensor placement - it’s a lot of data and can be overwhelming. We will describe,

  1. The temperature gradient between the 11 sensors in the meat
  2. Location of the cold spot
  3. Temperature variation ½ inch from cold spot, in case you miss it
  4. Rest Period Carry-Over Cook (how many degrees in 20 mins)

 

This first graph is from the Turkey Breast (Vertical) probe using the mobile app.

Temperature Gradient over 2” when cold spot reached 165°:

                        55° F

Cold Spot Location:

                        sensor 1 (the tip)

 Temperature Variation 1/2 inch from cold spot:

                        9° F

Rest Period (Carry-Over Cook): 

                        11° increase in 20 minutes

General Notes:

Ambient sensor shows minor variations from gas turning on and off, maintaining the oven at 350° F.

Oven was opened a little more than half way through to place foil over the breast meat – the 12th sensor is affected by this because airflow is disrupted. 

Cooling is apparent in shallow sensors while deeper sensors continue to rise during the rest period. This is the carry-over cooking.

Now for the horizontally placed breast thermometer:

 

 

Temperature Gradient when the breast cold spot reached 165°:

                        14° F

Cold Spot Location:

                        sensor 1 (the tip)

Temperature Variation 1/2 inch from cold spot: 

                        3° F

 Rest Period (Carry-Over Cook):

                        11° increase in 20 minutes

General Notes:

The 12th sensor looks like it is either in the turkey or very near the surface. This graph is notably different from the first.  The temperature of the first 11 sensors are much more closely packed than the first graph.  This makes sense as the first graph is from the vertical thermometer which passed through all the temperature gradients from the outer skin to the rib cage while this thermometer, going through the meat horizontally, was meant to stay within a narrower temperature gradient internal to the turkey. In fact, the vertical probe sensors passed through a 55 degree gradient while the horizontal gradient was only 14 degrees. That 14 degree gradient was across a little more than 2 inches though so a single sensor thermometer may still have a hard time capturing the cold spot.  Again, it is becoming clear why so many turkeys end up making a return trip to the oven. Even so, it should be noted the cold spot in the horizontal and vertical probes matched to within 0.1 degree.

 Now for the vertically placed thigh thermometer:

 

Temperature Gradient when the breast cold spot reached 165°:

                        10° F

Cold Spot Location:

                        sensor 9

Temperature Variation 1/2 inch from cold spot:

                        3° F

Rest Period (Carry-Over Cook):

                        11° increase in 20 minutes

The first thing to note is we lost some data when I opened the oven to tent the turkey and the circuit board fell off the counter and disconnected one of the sensors as can be seen in the plot.  It dangled from the other two probe wires but they were ok. Luckily that sensor wasn’t in the cold spot and it appeared it recovered some time after.

The other thing to note here is that the vertical thigh cold spot only just reaches 160 degrees before the rest period. 

Now for the horizontally placed thigh thermometer:

 

 

Temperature Gradient when the breast cold spot reached 165°:

                        5° F 

Cold Spot Location: 

                        sensor 1 (the tip)

Temperature Variation 1/2 inch from cold spot:

                        1° F

Rest Period (Carry-Over Cook):

                         9° increase in 20 minutes 

The horizontal thigh cold spot measured 155 degrees when the breast reached 165.  The temperature gradient was 5 degrees across a 2-inch span. This is the smallest gradient yet implying this would be a good option from which to measure with a single sensor thermometer and with only one degree of separation a half inch away.

Sensor Location

Gradient (11 Sensors)

Gradient (1/2 inch from cold spot)

Cold Spot Location

Carry-Over Cook

Breast (Vertical)

55 Degrees

9 Degrees

Sensor #1 (The Tip)

11 Degrees

Breast (Horizontal)

14 Degrees

3 Degrees

Sensor #1 (The Tip)

11 Degrees

Thigh (Vertical)

10 Degrees

3 Degrees

Sensor #9

11 Degrees

Thigh (Horizontal)

5 Degrees

1 Degree

Sensor #1 (The Tip)

9 Degrees

 

Conclusion

With 48 sensors in a single turkey, the KUKpro thermometer has shown:

  1. the breast meat has the largest temperature gradient when measured vertically from the surface to the rib cage. This provides for the largest opportunity for error in measurement as indicated by the 9° gradient only ½ inch away.
  2. The cold spot is closer to the rib cage than the center of the breast meat. It is clear the breast meat is heated primarily from the exterior of the turkey and not the body cavity but counter-intuitive to what we have all heard, “set your thermometer in the middle of the thickest part of the breast”.
  3. The breast meat is better measured horizontally. While there is still opportunity for error with a single sensor thermometer, it is greatly reduced.
  4. While measuring the breast meat with a thermometer may be sufficient for getting the breast meat cooked correctly, the thigh meat cooks slower and must also be monitored closely.
  5. Tenting of the breast meat earlier in the cooking process will prevent the breast meat from getting done too early (way before the thigh meat).
  6. Given the carry-over cooking of 11°, it would be safe to pull the turkey earlier than 165°, provided the thigh meat has also been sufficiently cooked according to the USDA’s Poultry Pasteurization Tables.

A question we have:

Can anyone provide insight to the graph, “Turkey Thigh – Vertical”? There is a very interesting jump in temperature early on and then an obvious decrease.  This is fascinating and we aren’t quite sure why.

I think a lot of people get lucky because they overcook their breast meat by not removing it from the oven until the breast reaches 165 degrees.  This results in an overdone breast due to carry-over cooking but allows time for the thigh to rise to a temperature that is sufficient to satisfy the USDA’s Poultry Pasteurization Tables. That is to say, I think before KUKpro, I was lucky…most of the time!

 

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