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Lamb cooking physics


cdh
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As everybody here, I'm sure, knows, when a cut of beef's internal temp gets to 140F, it can in no way be described as blood rare....

So... Why is it that lamb, when taken to the same temp, still manages to be almost raw and bloody? What is it about lamb protein that resists the denaturing power of heat? Do we have any food physicists who could take a whack at that question?

Christopher D. Holst aka "cdh"

Learn to brew beer with my eGCI course

Chris Holst, Attorney-at-Lunch

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As everybody here, I'm sure, knows, when a cut of beef's internal temp gets to 140F, it can in no way be described as blood rare....

So...  Why is it that lamb, when taken to the same temp, still manages to be almost raw and bloody?  What is it about lamb protein that resists the denaturing power of heat?  Do we have any food physicists who could take a whack at that question?

How are you measuring the temperature? If you're using a thermometer, have you calibrated it?

Are you giving it time to rest so the juices redistribute back into the meat? Without this extra time, even a medium-cooked piece of meat will leak raw red juices.

How does it feel when you cut through it? I mean to touch it with your fingers. Does it feel like raw meat? How much resistance does it give?

Drink!

I refuse to spend my life worrying about what I eat. There is no pleasure worth forgoing just for an extra three years in the geriatric ward. --John Mortimera

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Hello CDH,

Two questions I have for you is what cut of meat are you using and what cooking method. If you are using a saddle or rack eye you can try and cook it in a water bath with a temperature of about 140 f. If you have a cryo vac ( hope I spelled that right) you can seal the meat and cook until you acheive an internal temp of the same whic will give you an all around even color and texture as well as a perfect medium rare. This is one technique I used at The Fat Duck In England. Another is if you slowly rissole the cut of meat with brown butter to acheive the caramelization effect so many care to have, and then slowly cook in a 2oo f oven for around 20 minutes. This is on a 16/18 oz. rack eye or equivalent to a loin cut. Hope to be of some help.

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If you have a cryo vac ( hope I spelled that right) you can seal the meat and cook until you acheive an internal temp of the same whic will give you an all around even color and texture as well as a perfect medium rare.

Hello mjmchef,

I like this idea! I want to try it. How hot was your oven? Any idea how hot it can be before the plastic starts melting? (I know it can go in boiling water so it should be at least 212F.

Thanks!

Drink!

I refuse to spend my life worrying about what I eat. There is no pleasure worth forgoing just for an extra three years in the geriatric ward. --John Mortimera

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Since we're getting into the mechanics of cooking now, rather than just the physics of why lamb behaves as it does, here's the story that prompted the question:

A rack of lamb, previously frozen, was defrosted and thrown on the grill with the probe of a Pyrex instant read digital thermometer firmly planted in the center of the meat, away from the bones. Grilling commenced, and the internal temp rose. When it got to 140F, I pulled the rack off the grill and whacked off a chop. Said chop was nearly raw in its texture and appearance. This got me thinking "Beef at 140 is never anywhere near this raw... what's up?" so did a little research. Said research (the table of donenesses that came with said Pyrex thermometer) indicated that medium rare lamb was achieved at internal temp of 180F... Huh? What is it about lamb protein that is so radically different than beef protein that it needs a full 60 Farenheit degrees more heat to acheive the same level of denatured-ness?

So I posed the question here, which WHT took a stab at... Is lamb protein really more dense? (Time to bust out with a scale and a graduated cylinder...) How would the density of a protein affect the temperature at which it denatures? How would internal fat content affect the temperature at which a protein denatures? What's up with lamb flesh???

Lamb! The Amazing Asbestos Animal!

Edited by cdh (log)

Christopher D. Holst aka "cdh"

Learn to brew beer with my eGCI course

Chris Holst, Attorney-at-Lunch

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Density and fat content aside, I think we can assume that there would not be a significant variation from one lamb to the next. My references (and experience) say rare lamb is 135 - 140F, and 180 is beyond well-done.

I suspect your thermometer. You seem to have be careful about placement, so I wonder if it is reading accurately. Have you checked it?

Dave Scantland
Executive director
dscantland@eGstaff.org
eG Ethics signatory

Eat more chicken skin.

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I've not done side-by-side comparisons with the thermometer and any others, but it has worked fine in all other kinds of applications...In boiling water it reads 211, and in cooked pork loin it says 160... it even tells me that my melted sugar is 350 when it starts looking and smelling like nice dark caramel...

But at 140 lamb is still rarer than rare beef, which is 10-15 degrees cooler. What's up with the lamb?

I agree that the recommended 180 on the chart must be a misprint... but that still doesn't get the lamb off the hook for cooking differently.

Christopher D. Holst aka "cdh"

Learn to brew beer with my eGCI course

Chris Holst, Attorney-at-Lunch

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It was, indeed, a bone-in rack approximately 6 inches long (8 ribs). The probe, which is about 4 inches long was inserted into the center of the loin, to a depth of approximately 3 inches in, on a plane orthogonal to the bones' axis. (I think that is the right word, but my cartesian vocab is quite rusty...)

edit: correction of cartesian speak

Edited by cdh (log)

Christopher D. Holst aka "cdh"

Learn to brew beer with my eGCI course

Chris Holst, Attorney-at-Lunch

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Here's what I found . . .

McGee (p. 87) in On Food & Cooking:

Beef: 60% water / 18% protein / 22% fat

Lamb: 56% water / 16% protein / 28% fat

Aidells & Kelly (p. 481) in The Complete Meat Cookbook:

Rack of Lamb Doneness . . .

Blood-rare 115*F to 125*F

Rare 125*F to 130*F

Medium-rare 130*F to 140*F

Medium 140*F to 150*F

Edit: removed unneeded apostrophe

Edited by MatthewB (log)
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I just reskimmed the McGee chapter about meat and the only thing I found pertaining to this is that the myoglobin in meat isn't destroyed until about 140F - therefore the red color. Maybe lamb has more myoglobin? Lamb does have more fat (and more unsaturated fat) and less protein than beef.

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I've not done side-by-side comparisons with the thermometer and any others, but it has worked fine in all other kinds of applications...In boiling water it reads 211, and in cooked pork loin it says 160... it even tells me that my melted sugar is 350 when it starts looking and smelling like nice dark caramel... 

But at 140 lamb is still rarer than rare beef, which is 10-15 degrees cooler.  What's up with the lamb?

I agree that the recommended 180 on the chart must be a misprint... but that still doesn't get the lamb off the hook for cooking differently.

Although you would expect the manufacturer to compensate for it in the more important ranges, digital thermometers often exhibit non-linear responses.

Off-hand, I can't think of a standard that would let you check it in say, the 125 to 150 range, other than another thermometer. Any thoughts?

I'm not letting lamb off the hook yet. But I'm not convinced that you're really looking at 140 lamb, especially with what Matthew looked up.

Dave Scantland
Executive director
dscantland@eGstaff.org
eG Ethics signatory

Eat more chicken skin.

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Maybe lamb has more myoglobin? Lamb does have more fat (and more unsaturated fat) and less protein than beef.

Actually lamb has less myoglobin than beef, with 6 milligrams per gram of lamb, whereas beef has 8 mg/gram, and pork, that other white meat, 2 mg/gram.

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Off-hand, I can't think of a standard that would let you check it in say, the 125 to 150 range, other than another thermometer. Any thoughts?

I suggest that cdh go "Steingarten" on us . . .

Go buy about 30 different thermometers (do your research first).

Then, buy about 20 different racks of lamb.

Do your work.

Report your findings. :cool:

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Maybe lamb has more myoglobin? Lamb does have more fat (and more unsaturated fat) and less protein than beef.

Actually lamb has less myoglobin than beef, with 6 milligrams per gram of lamb, whereas beef has 8 mg/gram, and pork, that other white meat, 2 mg/gram.

Oh well, I tried.

I serve my rare lamb at 120, just like my beef, anyway.

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And bill it all to the MatthewB Charitable Foundation For The Advancement of Culinary Science?

I wish. I truly do! :biggrin:

More seriously, do you have a Thermapen?

I'd think that might be the best way to get an accurate temp when grilling. Use the remote probe when BBQ'ing.

My hunch--just a hunch--is that the probe moving whilst grilling and the tip (the tip is where the temp is read) touched bone.

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I've not done side-by-side comparisons with the thermometer and any others, but it has worked fine in all other kinds of applications...In boiling water it reads 211, and in cooked pork loin it says 160... it even tells me that my melted sugar is 350 when it starts looking and smelling like nice dark caramel... 

But at 140 lamb is still rarer than rare beef, which is 10-15 degrees cooler.  What's up with the lamb?

I agree that the recommended 180 on the chart must be a misprint... but that still doesn't get the lamb off the hook for cooking differently.

The short answer is fat helps to ttranfer heat. Meat is a lot slower to do this. added moisture has to be reduced befor heat can be effectivly transfered.

Living hard will take its toll...
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The short answer is fat helps to ttranfer heat. Meat is a lot slower to do this. added moisture has to be reduced befor heat can be effectivly transfered.

But McGee's numbers seem to indicate that there's not a big difference between the composition of beef & lamb.

Am I missing something?

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You're missing the same thing I am: an understanding of what it is about lamb flesh that makes it cook so differently from beef and pork.

WHT's explanations, sorry to say, seem relevant to a question like "I put my lamb into a 350F oven for x minutes and it is still looks and feels raw... however, when under the same conditions, beef would be medium." That is a heat transfer question, to which WHT is providing heat transfer answers.

My question is "When lamb's internal temperature is 140F, it still looks and feels pretty damn raw, while beef or pork at the same temperature are much more cooked." I don't care how long, or by what means the internal temp got to where it is... I care about how the material behaves at a given temperature, and why it does so.

Christopher D. Holst aka "cdh"

Learn to brew beer with my eGCI course

Chris Holst, Attorney-at-Lunch

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cdh,

If a suitable answer doesn't arrive by next weekend (I'm out of town this weekend), I'd be willing to grill a rack of lamb to 130*F--according to my thermometers--and take pictures.

You game for the same on your end?

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