The Fresh Loaf

A Community of Amateur Bakers and Artisan Bread Enthusiasts.

The perils of relying on internal temperature

suave's picture
suave

The perils of relying on internal temperature

So, I was thumbing through a copy The Science of Good Cooking by Cook's Illustrated and came upon a description of this experiment:

"We commonly advise checking the internal temperature of a loaf of bread before making the decision to pull it from the oven. A properly baked loaf should register a temperature between 195 and 210 degrees on an instant read thermometer depending upon the type of bread. But is internal temperature by itself sufficient proof that bread fully baked?
We placed temperature probes in the center of two loaves of rustic Italian bread and monitored them as they baked.  Halfway into the baking time, the internal temperature of the loaves had already passed 200 degrees, and they reached the optimal 210 degrees a full 15 minutes before the end of the recommended baking time. We pulled one loaf from the oven as soon as it neared 210 degrees and left the other in the oven for the recommended baking time. (The temperature of the longer-baked loaf never rose above 210, because the moisture it contains, even when fully baked, prevents it from going past the boiling point of water, or 212 degrees.) The differences between the two loaves were dramatic: The loaf removed early had a pale, soft crust and a gummy interior, while the loaf that baked for the full hour had a nicely browned, crisp crust and a perfectly baked crumb. 
The takeaway? Internal temperature is less useful than appearance as a sign of a well-baked loaf."

This mirrors my personal belief - if the breads looks right, it is done.   Of course I also have experience on my side which allows me to set the proper baking time and temperature for a particular loaf, and tell what looks right. 

gary.turner's picture
gary.turner

I suspect one or both of two errors.  1) Did they support the probe in a manner to keep the tip centered in the loaf?  2) How did they prevent the probe from conducting heat from the oven to its own measuring tip.

Concerning #1, did the tip migrate down to the hearth or at least very close?  On #2 it may be the external part of the probe was at the oven's temp, say 400℉, and the dough chilled it to below water's boiling point as the heat was conducted inward.

A more robust experiment would take eight loaves and bake them one at a time each loaf being measured (probed, for you Area 51 fans) at a different time, e.g. 5, 10, 15, 20, 25, 30, 35 and 40 minutes.  Obviously, measures at the beginning could be skipped in the interest of practicality.

cheers,

gary

suave's picture
suave

Oh, I don't think for a second their experiment is perfect - I would want to see how this works for different doughs and hydrations, as well as for different loaf sizes and shapes.  One thing that does not bother me is whether CI tried to reproduce their results.

gary.turner's picture
gary.turner

If it's not reproducible, it's not science, it's only screwing around.

g

suave's picture
suave

If you read CI you know that they are not one-n-done sort of folks.  I'd be seriously surprised if they did not repeat it several times.

Laurentius's picture
Laurentius

Please show your crumb shot.

suave's picture
suave

crumb shots?

KathyF's picture
KathyF

I have been fooled... more than once... by a loaf that "looked done". I do find it odd that they reached full temp so early. I have pulled loaves and measured the temperature when it looked done and found them to be too low.

suave's picture
suave

I do not remember off hand who exactly, may be Joe Ortiz, may be Maggie Glezer has the following advice for beginner bakers - if you think the loaf is done give another 5-10 minutes.

dabrownman's picture
dabrownman

Mini Oven!

suave's picture
suave

"I would just advise new bakers to bake their bread until you judge it to be done, then give it 5 more minutes!"

Maggie Glezer in Artisan Baking

dabrownman's picture
dabrownman

Looks dome but it tests 190 F - but it never thumps right at 190 F.  love that thump!

Happy Bsking

Laurentius's picture
Laurentius

Hi Suave,

Sorry, so caught in the reading was thinking that it was your research.

barryvabeach's picture
barryvabeach

I only bake 100% whole wheat, but I nearly always use a thermometer  ( lately I have been using the DOT wired probe thermometer from Thermapen )  I set the thermometer to 200 F, center the probe,  and usually pull the loaf shortly after it stops beeping - say maybe 201 to 205.  I have never had a gummy crumb so I can't agree with their position.   My limited experience is that the color of the crust is more closely related to the temperature of the oven then the degree of doneness.  

dabrownman's picture
dabrownman

but gave up on it for this very reason.  When it looks done and thumps done I call it done.  Never failed me yet like a probe at 210 F does on occasion.  Nice [post.

Bob S.'s picture
Bob S.

For consistent results, use an accurate oven thermometer. Oven thermostats can be inaccurate and sometimes fail to keep the oven temperature at the desired level. Once a stable oven environment is established, the baking time and temperature can be adjusted to achieve the desired crust and crumb properties. I prefer a bulb type of thermometer over the dial type:

http://www.taylorusa.com/kitchen/thermometers/5-commercial-oven-guide-thermometer.html

Mini Oven's picture
Mini Oven

I have to agree that the oven temp determines the crust colour as soon as enough moisture has left the crust.  But the thermometer is a good check to see if the centre of the loaf has gotten up to the right temp.  If the crumb temp is "not done" and the crust look is "done," it normally indicates the oven is too hot for that particular bread.   If the loaf is "done" but looks pale, the oven temp is too low (although I can think of many other reasons for a pale crust.)   The crumb shot should tell more about the distribution of heat directed at the loaf. 

Picking up the loaf to check the weight (before looking at the bottom)  will also tell me if enough water has evaporated from the loaf.  Too heavy, and I would also be inclined to pop it back into the oven.  A slight squeeze tells me more about the middle of the loaf too.  And if the loaf has a specific density that reminds me more of my swollen feet than what I'm expecting in my loaf, I'm also inclined to pop it back into the oven and let more moisture bake out of the loaf.  (I only wish it worked with my feet.)

Aroma is another indicator but that too is dependant on the temperature of the oven.  Lower temps generate more varieties of aroma.  High temps burn them off.  A loaf that smells done will also underline the decision that the loaf is baked properly.   

The point I'm making, add up all the factors of what constitutes a well baked loaf and don't rely on only one factor, like internal temp OR crust colour.  

rgconner's picture
rgconner

New here but...

seems weight would be the better indicator. If you know the weight and the hydration ratio, you can work out how much it should weigh when the right amount of water has been driven off.

How you get a scale to work in the oven is the gotcha...