114 replies to this topic

[ChefDanBrown]

Ther was one variation on cooking liquid that I didn't get to do during the seminar, but I'm driven to investigate. I'd like to know if anyone has any experience with braising in milk, I believe it was pork chops that I read about in Marcel Hazan's book, but I can't remember for sure. If anyone has recipes or experience in this area (the one area I'm really concerned about is the milk curdling if it's heated with the dish, and I'm not sure if avoiding other acids or heating the milk separately is the smartest way to tackle this one), can you please share it with me? If not, I guess I'll just go for it, although another braised meat is definitely going to have to wait a week or two.

[Wolfert]

Dan: Perhaps this recipe for a Basque version might be of interest to you: Porc Frais au lait or PORK COOKED IN MILK

I haven't made it in years, but I do remember liking it very much.
There is a Venetian dish called arrosto di maiale al latte (pork loin braised in milk), described by Elizabeth David, which is somewhat similar to this one. I’m not sure where the recipe originated, but it appears prominently in Maïté Escurignan’s marvelous work on Basque cookery.
Though red meats become more succulent and tender when cooked slowly in liquid, white meats, such as pork or veal, sometimes end up stringy and without much taste. Here is a recipe that solves that problem: a pork loin is submerged in flavored milk and slowly cooked at a low temperature. The small quantity of butterfat in the milk “swims” through the meat, and the milk keeps the loin totally moist.
Unlike in many braises, the pork is not browned first. Long, slow simmering in a fatty substance will make the lean meat juicy, and, at the same time, the meat will be virtually fat-free when removed from the cooking medium. Only after the cooking do you brown the pork.
•Begin 1 to 2 days in advance
SERVES 6

3 to 3 1/2 pounds boneless center-cut pork loin, trimmed of excess fat
2 garlic cloves, cut into slivers
Coarse kosher salt
1/4 cup finely chopped carrots
1/4 cup finely chopped onions
2 tablespoons finely sliced leek (white part only)
2 tablespoons unsalted butter
1 quart whole milk
1/4 teaspoon ground white pepper
Herb bouquet: 3 sprigs parsley, 1 sprig thyme, and 1 bay leaf tied together
1 tablespoon chopped fresh parsley
1. A day or 2 IN ADVANCE, stud the pork loin with slivers of garlic. Rub the surface of the pork loin with salt; cover loosely and keep refrigerated.
2. About 4 HOURS BEFORE SERVING, preheat the oven to 300°F. In a 3- or 4-quart flameproof casserole, cook the carrots and onions in the butter over moderately low heat until soft but not brown, about 5 minutes. Place the pork roast on top of the vegetables.
3. In a saucepan, heat the milk until bubbles appear around the edge of the pan; pour over the pork. Add the pepper and herb bouquet. Cover and place on the lowest rack of the oven to cook for 3 hours. Turn the meat every hour so that it cooks evenly.
4. Remove the casserole and raise the oven temperature to 375°F. Transfer the meat, fat side up, to a large baking dish and return to the oven. Roast uncovered until browned, about 20 minutes.
5. Meanwhile, strain the milk cooking juices, pushing down on the milk solids that have separated out in the cooking. Quickly chill in larger bowl of ice and water or put in the freezer so the fat rises to surface. Remove and discard fat.
6. Return the sauce to the casserole and bring to a boil with a metal spoon on the bottom to prevent boiling over. Reduce by two thirds, about 15 minutes. Season with salt and pepper to taste.
7. Slice the meat and arrange on a serving platter. Spoon the sauce over the slices and sprinkle with chopped parsley.

c\Wolfert. 1983, 2005

[Smithy]

So the conclusion seems to be that the meat doesn't taste much different depending on how it was browned or even whether it was browned.  However, do you think the sauce would be different?

The sauce seemed to be different in my test. I plan a more careful series of tests to confirm this, but I thought the sauce from deglazing the stovetop steel (not nonstick) pan was richer, more complex and darker than the other sauces.

For that matter, I also thought there were some differences in the meat texture and taste - but they were admittedly minor, not as noticeable as the sauce differences. I'll know more tonight when I reheat the samples.

It's tonight. I didn't label the samples. One sample is more tender than the others, but I don't know which one it is, except that it is one of the meats that had been browned beforehand.

How do I know? By the juices, or sauces, whatever you want to call them. (I haven't bothered reducing them, so they're runny but flavorful.) Three are indistinguishable. The fourth is different in appearance, texture, and to some degree taste. It was like this last night too, and even though I've lost the labels I know that this one dish had the unseared meat.

The unbrowned-meat sauce separates readily into two layers, with the top layer a clear, maybe golden, maybe colorless, liquid. (It's difficult to be sure of the color, given the small sample.) It gives the bowl juice a halo effect, of light golden color around the reddish sauce. The browned-meat sauces all are more homogenous, with no halo from having a clear layer floating atop a darker layer. The juices look somehow more coagulated. I can taste the wine, meat juice and spices in all 4 samples, but the unbrowned-meat-braise-juice tastes, erm, lighter somehow. I tried to photograph the differences, but now as I'm previewing the post I don't think they came out. I won't bother casual readers with them, but they're in my Braising Lab 3+ album in case anyone else is interested enough to look.

I poured the juices into small glasses to see how they'd separate. The top layer of the unbrowned-meat juice was clearer than the layer below and the top layer of the browned-meat juices was cloudier than the layer below.

I haven't a clue of the chemistry behind what I'm seeing, or what it might mean for making a sauce, or what it says about the braising method. Either setup tastes fine, but they're different. Why? Enquiring minds want to know!

[...tm...]

Ther was one variation on cooking liquid that I didn't get to do during the seminar, but I'm driven to investigate. I'd like to know if anyone has any experience with braising in milk, I believe it was pork chops that I read about in Marcel Hazan's book, but I can't remember for sure. If anyone has recipes or experience in this area (the one area I'm really concerned about is the milk curdling if it's heated with the dish, and I'm not sure if avoiding other acids or heating the milk separately is the smartest way to tackle this one), can you please share it with me? If not, I guess I'll just go for it, although another braised meat is definitely going to have to wait a week or two.

Meat braised in milk is a common fallback recipe for me. I've done many cuts of pork, beef, and chicken leg quarters. I was just going to say that I liked the chicken the best, but I hink that is just because that is the last one in my memory. Lefovers are especially good and fairly versatile--they can be served over any sort of starch--pasta, mashed potatoes, rice, bread, etc.

Anyway, I usually brown the meat on the stovetop, set aside while I sautee a mirepoix (sometimes plus garlic and root vegetables), then add meat back to the pan, add milk about halfway up, and bring up to a simmer, then place in a 300 degree oven for about two hours. The milk is usually somewhat chunky at this point, but even if it isn't I take the meat out (and pick it from the bone, if necessary) and blend the milk/aromatics. I usually reduce the milk sauce on the stovetop for a little bit before serving. This not only make the sauce a bit thicker, it caramelizes it a bit, which is epecially good with pork.

Now that I think about it, I think I did like the chicken best because a lot of gelatin was produced as I braised it with the skin, cartilage, and bones. It was seriously like some sort of meaty-milk jello mold in the refrigerator the next day. And that's a good thing.

[Fat Guy]

"Meaty Milk Jell-O, now available in the Kosher section."

There are a number of braising liquid permutations I'd have liked to try given unlimited identical vessels and oven space. One that I've seen recommended by a number of trustworthy sources -- and I've been served some good examples -- is to use no actual liquid at all but, rather, a large quantity of sliced onions as a bed for the meat. As they heat and exude liquid, they braise and flavor the meat, and they "melt" and combine with the meat juices to become a wonderful sauce. Beer is, of course, an important variation, as in beer braised short ribs. Then there are all the issues of the mirepoix, its composition, should you sweat it, salt it, etc.

However, what I think we learned in the lab -- though I don't by any means think this is an absolute -- is that variants in the braising liquid are much more important to your sauce than they are to your meat. Perhaps this is so obvious it didn't even need to be said, but to me meat braised in any liquid tastes at least close to the same meat braised in any other liquid. It's when you make that liquid into a sauce, or you start doing intensive glazing with the liquid, or you slice up a brisket and submerge it in the liquid and reheat it, that the liquid becomes most important.

[Wolfert]

I haven't a clue of the chemistry behind what I'm seeing, or what it might mean for making a sauce, or what it says about the braising method. Either setup tastes fine, but they're different. Why? Enquiring minds want to know

In the French Southwest, I learned a neat trick to extract from the scum-like bottom layer of solids from your cooled down sauce all its wonderfully intense flavor, and end up with a clear sauce rich enough to coat a spoon lightly.

Here is how to do it: after straining the sauce and pressing down on all the solids with the back of a spoon; cool the entire sauce down; remove all the fat that rises; discard or save for cooking; put the remaining liquid (scum and clear) in a small wide saucepan; and set over heat to bring to a boil. Now, shove the saucepan half off the heat and cook at a slow boil, skimming off all the scum-like solids that rise to the top on the cool side of the liquid for about 10 minutes, or until reduced enough to coat a spoon lightly.

This really works though it might take longer than 10 minutes if you have lots of sauce.

Edited by Wolfert, 20 February 2005 - 08:51 AM.

[Bella S.F.]

Lean meat such as leg of lamb and rack of lamb are better roasted, steamed, or grilled. The shank, the shoulder and the neck with the bone in are the ideal cuts for Moroccan tagines.

A question for you. I recently made a cassoulet and then an "Afghani Lamb and Onion Stew". Both recipes called for lamb shoulder. I called two different butchers and each told me that they did not carry lamb shoulder, but that I could/should use leg of lamb. They both said that the meat would be more tender. I did, and both dishes were quite wonderful. However, I am wondering now if I should have tried harder to find lamb shoulder. Would there have been any difference? I know... I need to find a better butcher.

Thanks!

[Ducky]

This is a brilliant thread - which I discovered too late to participate. One question: Are there some conclusions about braising of general application that could be made after all these experiments? Or is the conclusion that the vagaries of equipment, cuts of meat and method make it difficult to formulate any conclusions of general application?

[slkinsey]

It seems at least somewhat clear from the experiments, which in all cases favored heavy metal vessels over aluminum foil and in most cases favored the heaviest vessel (Le Creuset) over others, that for whatever reason (and a few theories have been bandied about) the materials with greater heat capacity provide better braising. If you have more stuff in the oven, this will also have an effect related to heat capacity I think.

I should add, however, that weight is not the only factor in heat capacity. The nature of the material is also important. According to this list of engineering material properties the heat capacities of the materials I used are, in J/kg*°C:

Aluminum 963.00
Borosilicate glass 710.00
Iron 440.00

In other words, the borosilicate glass (which is I think the basis of the materials we call Pyrex and Corningware) has half again as much heat capacity per kilogram as iron, and aluminum has more than double the heat capacity of iron. So an aluminum pot weighing 1 kg has more heat capacity than a cast-iron pot weighing 2 kg. This is why I think my aluminum (Calphalon) and glass (Corningware) vessels, though smaller and lighter than the iron (Le Creuset) vessel, did so well at braising, such that I didn't detect any real difference in final product.

This would also tend to support the notion that, by weight, aluminum is the most desirable material for braising. It has far greater heat capacity per kilogram than any of the other commonly used cookware materials. In addition to the ones listed above, copper is 385.00 and steel runs from 419.00 to 503.00 depending on the alloy.

Steven,

If I may, I will suggest my eGCI class on cookware for a more comprehensible and accurate description of what heat capacity is and how it applies to cookware.

Here is a quotation from the relevant section:

Heat Capacity

Thus far we have mostly been talking about heat in its pure scientific sense: as it relates to the transfer of thermal energy.  Now, we will turn out attention to the second meaning of heat, as it relates to internal thermal energy.  Every object  -- for our purposes, every chunk of metal -- can not only be described as being at a certain temperature, but also as holding a certain amount of heat.  For example, if we have a one pound piece of iron and a five pound piece of iron, both at 200 degrees C, it doesn’t take too much thinking to wrap our minds around the idea that the 5 pound piece of iron is holding more heat than the smaller piece.  This is easily understood by nothing more than the fact that it had to sit on the stove a lot longer before it came up to temperature.  A more scientific experiment would be to drop each piece of iron into equal sized containers of water and measure how much the temperature of the water goes up in each container.  If you do this experiment, you will find that the water in the container with the large piece of iron is significantly warmer than the water in the container with the smaller piece.  This is because the large piece of iron stores more heat than the small piece, even at the same temperature.

As it turns out, various materials differ in their ability to store heat.  In other words, some materials can hold more heat at a given temperature than others.  For example, a one pound chunk of aluminum holds a lot more heat than a one pound chunk of copper at the same temperature.  The scientific term that quantifies a material’s heat storage capabilities is called Specific Heat.  Specific heat is the amount of heat it takes to raise one unit of a substance by one degree.  The most common way specific heat is expressed is the amount of heat, measured in Joules it takes to raise one gram of a substance by one degree Kelvin, or: Joules per gram per degree Kelvin (J/g K).  That said, you may also see specific heat expressed as British thermal units per pound per degree Fahrenheit (Btu/lb F) or calories per gram per degree Celsius (cal/g C) and so forth depending on the measurement system used.  We’ll stick with good old J/g K for this article.

Confused yet?  It gets even more complicated. We also need to settle on a reference standard.  Specific heat is not an absolute measurement like a meter or a kilogram.  A meter is an absolute quantity -- something that is a meter long is a meter long and something that is two meters long is twice the length of a meter.  Temperature systems, on the other hand, work differently.  Take the Celsius scale, for example...  the values of 1 and 100 are arbitrarily set at the freezing and boiling points of water.  Why?  Why are there 100 units between the freezing and boiling points of water?  Is 20C twice as hot as 10C?  How?  Well, as it so happens, water has an unusual ability to hold a lot of heat, so scientists have arbitrarily designated the specific heat of water as 1.  Thus, all specific heat measurements are given relative to the specific heat of good old H2O.  The illustration below lists the specific heat values for the most commonly used cookware materials.



As we can see, aluminum has a very high specific heat indeed – over double that of iron.  This would lead us to conclude that a one pound chunk of aluminum holds more heat than a one pound chunk of iron at the same temperature.  But wait...  cast iron is supposed to hold the most heat, right?  Yes and no.  It is true that the chunk of aluminum holds more than the chunk of iron, but we haven’t accounted for the density of the materials.  The illustration below shows the density of the same materials.



OK... now we can see that iron is a lot more dense than aluminum.  A one pound piece of aluminum would be almost three times the size of a one pound piece of iron.  Since cookware is described in terms of its thickness (i.e., the volume of the materials rather than the weight) it is more useful for us to understand the heat carrying capabilities of a given volume of metal rather than a given mass of metal.  To obtain these figures, we can simply multiply the specific heat by the density to arrive at specific heat per cubic centimeter.



Now the picture looks completely different, doesn’t it?  Aluminum is way down there on the bottom, iron and copper are in the middle, and steel is up at the top.  These are much more useful numbers that more accurately reflect the way materials are deployed in cookware.  A understanding of these numbers can take us a long way towards understanding the difference between a 3 mm thick aluminum bottom and a 7 mm thick aluminum bottom -- also between a 3 mm thick aluminum bottom and a 2 mm thick copper bottom.  This is because we can use these numbers to understand the Heat Capacity of various cookware.

Heat Capacity is the term we will use to describe the total heat holding capabilities of an entire piece of cookware.  For example, if we have an 11 inch sauté pan with a 7 mm thick aluminum bottom, we can calculate the heat capacity of that base.  If I plug in a radius of 14 centimeters (half of the 11 inch diameter) and a height of .7 centimeters into this handy online calculator we get a volume of 431 cubic centimeters.  Multiplying that by the specific heat per cc number from above, we get an overall heat capacity of 1043.  Now let us compare this aluminum bottom to a copper bottom at 2.5 mm.  The volume of the copper bottom is much smaller -- only 154 cubic centimeters.  Using the number for copper from above, we arrive at an overall heat capacity of 531, or around half that of the aluminum bottom.  This may seem fairly esoteric, but in fact we have just used materials data to compare a 67 dollar Sitram Profisserie sauté pan with a 7 mm aluminum base to a 140 dollar Sitram Catering sauté pan with a 2.5 mm copper base.  What does this tell you?  It tells you that you’re better off buying the cheaper pan if you want a sauté pan with a high heat capacity so you can dump a whole bunch of stuff into it all at the same time.

A good way to conceptualize heat capacity is to return to our “heat bucket” illustration from above.



The illustration above shows the difference between two otherwise similar cooking vessels made with different amounts of the same material.  Because they are made from the same material, the thermal conductivity (as illustrated by the size of the faucets) is the same.  As we can see, the pan made with more material has a larger heat bucket and is able to hold more heat at a given temperature -- it has a larger heat capacity.

Where this pokes a hole in your "aluminum is best for braising due to heat capacity" argument is that, while aluminum does have a higher heat capacity then iron by weight, iron is so much more dense than aluminum that an iron vessel with approximately the same dimensions as an aluminum vessel will have a far greater heat capacity. In order for an aluminum braising pot to have the same (not better, just the same) heat capacity as an iron braising pot of the same size, it would have to be quite a bit thicker. Iron also has the significant advantage for low/slow cooking of having relatively poor thermal conductivity (aluminum has fairly high thermal conductivity). This means that, if the heat is removed from two "equal" braising pots, the aluminum pot will cool down more rapidly. Iron's low conductivity is especially beneficial for those who have an electric stove and wish to braise on the stovetop: although the burner may cycle on and off, the actual temperature of a heavy iron pot won't change that much.

[Wolfert]

Please somehow fit in braising in claypots. I've been braising in claypots for forty-five years and just might be able to offer some commentary from time to time.

[Smithy]

Please somehow fit in braising in claypots. I've been braising in claypots for forty-five years and just might be able to offer some commentary from time to time.

I don't know whether you were addressing that request to slkinsey in particular, but if you weren't, I will. I didn't much like my clay pot braising results the first night, but as the nights progressed and I continued recombining the meat and juice and reheating them in their pot, that sample became one of my favorites. I doubt that the clay has either the heat content or heat conductivity of the metals. Therefore I think there must be something else going on to explain the clay pot results, and I'm guessing it's related to the way the pores inside the pot exchange moisture and flavors with the meat and juice. What does the materials expert think?

I certainly plan to do more braising in the clay pot vs. the Le Creuset and All-Clad, to see what happens as my technique and control improve. It may be that certain flavor combinations benefit more from the earthy pot flavor than others do.

I have a clay pot question right away, for Ms. Wolfert: do they take on the flavors of the foods cooked in them to the point that you reserve some for certain types of food? If so, which do you segregate?

Finally, thank you Wolfert for the note above about clarifying the sauce. That's a neat trick, and I have a lot of juice on which to try it.

Edited by Smithy, 20 February 2005 - 12:22 PM.

[Smithy]

This is a brilliant thread - which I discovered too late to participate. One question: Are there some conclusions about braising of general application that could be made after all these experiments? Or is the conclusion that the vagaries of equipment, cuts of meat and method make it difficult to formulate any conclusions of general application?

Ducky, as noted in Fat Guy's post to which slkinsey responded in the post right after yours, we all had more satisfactory results in cookware with a higher heat capacity. For ease of figuring you can take that as "more massive" but that isn't the whole story, as slkinsey's explained so well. Beyond that it got down to technique, equipment and to some extent personal taste. I had better results in the oven; a couple of the others did better on stovetop. I think I was the only person who tried a clay pot, and I really liked that too.

[Wolfert]

I have a clay pot question right away, for Ms. Wolfert: do they take on the flavors of the foods cooked in them to the point that you reserve some for certain types of food? If so, which do you segregate

I should explain that I only know the cooking of the Mediterranean and the French Southwest and their claypot cooking styles.

In Morocco, fish is almost always cooked in an unglazed pot called a tagra (see photo below). Not because of fear of flavor transfer but the shape is more 'fish-like'



Before I can share what I know about claypot cooking I need to know which pot you were using. So many types of glazes, clays, additions of such minerals as mica, and shapes have a lot to do with the outcome of your braise.

[Smithy]

I have a clay pot question right away, for Ms. Wolfert: do they take on the flavors of the foods cooked in them to the point that you reserve some for certain types of food? If so, which do you segregate

I should explain that I only know the cooking of the Mediterranean and the French Southwest and their claypot cooking styles.

In Morocco, fish is almost always cooked in an unglazed pot called a tagra (see photo below). Not because of fear of flavor transfer but the shape is more 'fish-like'



Before I can share what I know about claypot cooking I need to know which pot you were using. So many types of glazes, clays, additions of such minerals as mica, and shapes have a lot to do with the outcome of your braise.

Well, I can answer some of those questions, but my Egyptian isn't good enough to have all the answers!

In Egypt they call this particular pot a tagine, pronounced more or less "DAjin" with a broad 'a' as in 'ahh', and I picked it and the smaller bowls up because I like using them for moussaka. This type of clay cookware is as common as dirt around Luxor, and fortunately as cheap. They're unglazed. I think the clay must come from the stuff mined for the many potteries now - from somewhere near Aswan? can't remember where. Some potters closer to Cairo told me that the present conservation rules forbid using arable land from the Nile Valley for getting clay, so dry material is mined in the desert, brought in sacks of dry powder to the valley factories, and then mixed with water to make pottery clay.

The initial cure involves coating the pot interior with molasses ("asl aswad") and cooking it in the oven in low heat for a long time. Temperature and time eluded our language skills. I've managed so far not to break anything. I think really well-seasoned pots may have a heavier coating.

Here are a top view of the larger pot that I used as well as one of the individual bowls. That's an orange in front, for size comparison. The side view of the tagine gives a better idea of its shape.



And yes, I know this is totally different than a Moroccan tagine. Someday I hope to lay my hands on one of those babies. I've never seen them in Egypt.

Edited to correct a trivial detail on the mining and shipping process, and an incorrect pronunciation note.

Edited by Smithy, 20 February 2005 - 10:15 PM.

[andiesenji]

When I was working in Southwest France back in the late 70's and early 80's, I studied briefly with a chef named André Guillot, now gone about 10 years. He used to give cooking courses for chefs and enthusiatic cooks in Santons in Provence.
    Among his most famous fans  were Marc Meneau, Gerard Vie, Jean Marie Amat, Emil Jung and Richard Olney. In fact,  we formed an Association of the Friends of Andre Guillot to keep his name alive, but alas he is almost forgotten today.
    One of his most memorable tips for salting meat included the following:" lightly salt the meat the minute you bring it home. If you do this, you will hardly need to salt later, and in the end you’ll use half as much salt as you would normally. Lightly salted meat will tenderize and mature in flavor when stored overnight in the refrigerator. "

  He also taught me that though some blood will run out, he considered it insignificant. In fact, he  suggested that meat be coated lightly with grape-seed oil right after the salting to keep it from drying out; he prefered grape-seed oil, because it smoked at a much higher temperature than other oils.

I wonder if this was a process taught years ago but that somehow fell out of favor. The first classes in the French method of cooking that I attended were taught by a Chef Gregoire.
He was quite adamant about salting meat as soon as it was cut. (We started out by getting instruction in how to cut portions of meats from large pieces.) The meat was salted then placed in a colander set in a pan in the refrigerator for a couple of hours, then rinsed, oiled and wrapped for use in our recipes the following day. (Our classes were on Monday and Tuesday, the two days his restaurant was closed.)
I don't recall that any of us ever asked him specifically why we were to do this. We were all so in awe of this man that we accepted just about everything he told us as gospel. One classmate did mention that the process was similar to koshering and the Chef replied that if we bought kosher meat we could skip the salting process as it was already sans sang.

[Fat Guy]

Where this pokes a hole in your "aluminum is best for braising due to heat capacity" argument is that, while aluminum does have a higher heat capacity then iron by weight, iron is so much more dense than aluminum that an iron vessel with approximately the same dimensions as an aluminum vessel will have a far greater heat capacity. 

The quote above -- "aluminum is best for braising due to heat capacity" -- does not come from me. What I said was: "by weight, aluminum is the most desirable material for braising." If you take an aluminum pot and a cast-iron pot of the same internal diameter and height, the aluminum pot can weigh half as much yet have the same heat capacity as the cast iron. The walls of the aluminum pot will be thicker, of course.

Conductivity may be important as well, especially if the "insulation" hypothesis holds true, however it is worth noting that if it is important the Corningware and Pyrex must be by far the best materials -- their thermal conductivity is worse than that of cast iron by something like a factor of 70.

[Wolfert]

Smithy: your pots are beautiful.

I need to re-read the whole thread to refresh my memory but the shallow round one with a good cover probably stood up to the best Staub.

Meantime, check out www.tagines.com for very inexpensive unglazed tagines. The one from Ourika has some mica in it and really holds heat and cooks meat beautifully on top of the stove using a flame tamer if you have electric burners or very low heat over gas.

The one from the Rif is great for cooking a chicken whole among other things. This also should be used on top of the stove. I also bake cakes in the bottom part in the oven.

Here is my recipe for home-curing an unglazed tagine from Morocco:Soak both parts of the tagine in water to cover for 3 or 4 hours; Drain and dry; Rub top and bottom inside and out with olive oil; Put on gloves and rub wood ash (from the fireplace) all over the two parts; and set in a 250 oven and let bake overnight.

Cool down the two parts, wipe away the excess ash, rub again with olive oil and let dry in the oven for an hour or two. Wash and dry the two parts and you are now ready to braise Moroccan style in a tagine on top of the stove.

Edited by Wolfert, 20 February 2005 - 03:09 PM.

[slkinsey]

If you take an aluminum pot and a cast-iron pot of the same internal diameter and height, the aluminum pot can weigh half as much yet have the same heat capacity as the cast iron. The walls of the aluminum pot will be thicker, of course.

What I am suggesting is that, in the real world, the walls of a Calphalon pot will never be thick enough that it has the same heat capacity as a Staub pot of the same internal diameter and height. Of some significance is the fact that the traditional enameled cast iron casserole has a very heavy iron lid, which adds to the overall thermal capacity of the pan.

Conductivity may be important as well, especially if the "insulation" hypothesis holds true, however it is worth noting that if it is important the Corningware and Pyrex must be by far the best materials -- their thermal conductivity is worse than that of cast iron by something like a factor of 70.

Yes, that might be true in certain circumstances. The deal with Corningware and Pyrex is that they have a low thermal capacity per unit volume because they have low density compared to metal. As a result they would need to be gigantically thick in order to match a cooking vessel with the same internal diameter and height in either iron or aluminum.


What I'm reading from the lab results in terms of cooking vessels is that the traditional vessels seem to be the best choices. That means heavy enameled cast iron (and perhaps also clay/ceramic, for different reasons).

[Fat Guy]

I agree with that, but I might also suggest that the "real world" may be making the wrong choice based on tradition rather than engineering: it is possible that a superior braising vessel could be made out of anodized aluminum and would be half as heavy (not to mention probably half as expensive) as its enameled cast-iron equivalent. And while the walls would be beefy, it's not as though they'd be a foot thick.

[ahr]

The side walls of a Calphalon Commercial 2.5 quart low-rise (8.5x3") saucepan, which I bought mostly because it cost only $17, are fully 3/8" thick. I'll bet it will do a heckuva stovetop braise-for-one (or -two).

[Fat Guy]

The saucepans are the thickest Calphalon pieces. My Dutch ovens and saucepan are from the same Calphalon series -- Professional Nonstick II -- and the saucepan has got to be twice as thick as the Dutch ovens. I wish they made all Calphalon pieces super-thick. I remember the original anodized aluminum Calphalon pieces, very beefy and with those great flat handles. Since then, every Calphalon design "innovation" has been a step backwards.

FYI, check out this link: The International Dutch Oven Society.

Also, 12" Anodized Aluminum Dutch Oven from Clavey River Equipment: "These new 12" Dutch Ovens offer the cooking qualities of cast iron but with half the weight." Could just be hype, but the theory does seem at least somewhat sound.

[slkinsey]

I agree with that, but I might also suggest that the "real world" may be making the wrong choice based on tradition rather than engineering: it is possible that a superior braising vessel could be made out of anodized aluminum and would be half as heavy (not to mention probably half as expensive) as its enameled cast-iron equivalent. And while the walls would be beefy, it's not as though they'd be a foot thick.

It's definitely true that one could construct an aluminum braising vessel that would have the same heat capacity as a similar iron braising vessel with the same internal dimensions without getting too whacky with the thickness. I did a few calculations and came up with the following:

• To have the same heat capacity, the body of an aluminum pan has to be 45% thicker than the body an iron pan
• However, since iron braising pans have heavy lids that increase the overall thermal mass considerably while aluminum braising pans do not, an aluminum braising pan has to be twice as thick as an iron braising pan to have the same thermal capacity.
• At the same heat capacity, the iron pan will weigh almost twice as much.
• With the lid removed, the iron pan weighs about 50% more than the aluminum pan.
• With a representative amount of braising material inside (e.g, 5 cm of liquid in an 28 cm diameter x 14 cm height casserole) the iron pan is around 55% heavier than the aluminum pan with the lid on, and around 27% heavier with the lid off.

In the real world, of course, even a seemingly small difference like 27% can be significant because it is the absolute differences that matter. If one loaded pan weighs 4.5 pounds more than the other, that is likely to be what matters most when someone is trying to lift the pan. This is overall an advantage for aluminum.

That's just the heat capacity, however. To my mind, there is an advantage to be gained in low/slow cooking by having a cooking vessel with lower thermal conductivity. For most any cooking task there are one or two optimal combinations of heat capacity and thermal conductivity. If we make the iron and aluminum vessels have the same heat capacity, then the main variable is thermal conductivity (3003 aluminum alloy is around 1.63 W/cm K compared to 0.8 for iron). On the other hand, some people love clay and ceramic for braising. These materials don't have anywhere near the heat capacity per cc of iron and aluminum, but may make up for that in the context of oven braising by having extremely low thermal conductivity.

My other nitpick with anodized aluminum is that it's extremely difficult to keep clean. This is something that will become a factor in the context of low/slow dishes where food items may cook on to the surfaces of the pan for a long time. One of the nice things about enameled cast iron is that you can soak it overnight in the sink and most everything will come off. With anodized aluminum, I find that I have to scrub and scrub and scrub and scrub to get it clean.

[Fat Guy]

Most anodized aluminum cookware comes either with anodized aluminum lids or with stainless steel lids. My glass-lidded Calphalon Professional Nonstick II cookware is a difficult-to-find exception.

I don't have a totally firm grasp on how a vessel's heat capacity relates to the metal's specific heat capacity and the construction of a Dutch oven. I understand that twice as much of the same metal will give the vessel double the heat capacity, but in terms of practical effect I'm not sure what that means for a braise. For example, what is the relevance of the lid's thermal capacity? Is the lid somehow radiating heat back into the environment of the vessel's interior? I thought the idea of the lid was mostly just to keep the steam in -- assuming it wouldn't crush it, if you put a 5-pound iron lid on an aluminum foil braising tray, would that increase in overall vessel heat capacity actually make a big difference?

Also, just as the liquid and pot contents contribute to weight, they should contribute to heat capacity. Water has a pretty good heat capacity, I think. I wonder if, the more braising liquid you use, the less the vessel matters.

I'm also wondering whether there's a point at which enough is enough in terms of heat capacity. For example, a 15-pound iron pot may braise better than a 5-pound iron pot, but will a 500-pound iron pot braise any better than the 15-pound one?

In terms of thermal conductivity, I'm wondering how this becomes important. In an oven, it should be a pretty minor consideration within reasonable tolerances. On the stovetop, it would seem to promote even heating but be problematic on electric cooktops that cycle -- again assuming the cycle speed and conductivity combine to make a difference.

[ahr]

Some questions that occurred to me over the course of the seminar:

Did the immersed parts of partially immersed samples differ in texture and/or taste from the fully immersed samples? From the interior of the unimmersed parts of the same samples (to discount for greater exterior caramelization)?

Was the crappiness of FG's foil-tray samples due to a higher ratio of liquid to total vessel volume? If not, then what?

Why is it assumed that temperature stability during cooking (i.e., a vessel with high heat capacity) is beneficial, when reheating experiments showed that cooling and reheating improved flavor? Perhaps fluctuation is a good thing, so long as the high end does not substantially exceed a simmer.

BTW, my old MagPro pots have cast-aluminum covers substantially heavier than the flimsy things accompanying Calphalon, All-Clad, and similar current cookware.

[slkinsey]

I don't have a totally firm grasp on how a vessel's heat capacity relates to the metal's specific heat capacity and the construction of a Dutch oven.

I'm not quite sure what you're asking here. A cooking vessel's overall heat capacity is determined by the specific heat and the amount of the materials of which the cooking vessel is composed. Since iron has a higher specific heat than aluminum by volume, a 1x10x10 cm piece of iron at a given temperature holds more thermal energy than a 1x10x10 cm piece of aluminum. In order for the aluminum piece to hold the same amount of thermal energy, it would have to be 1.45 cm thick.

FWIW, technically a "Dutch oven" is not really what we're talking about. Those are designed (usually with feet and a special lid) to be used in cooking with live coals.

I understand that twice as much of the same metal will give the vessel double the heat capacity, but in terms of practical effect I'm not sure what that means for a braise.

Here's something that I had posted earlier:

I then thought about parallels in other types of cooking, and realized that in baking the mass/thermal capacity of a baking surface makes a big difference. Given a 300 degree F oven, a thin metal cookie sheet performs very differently from, say, a baking stone. The reason for this, as I understand it, is that the baking stone absorbs heat from the oven and radiates it into the food, whereas the thin metal sheet mostly just transfers the ambient heat. As a result, there is  what appears to be an amplification of heat.

It's actually a little more complicated than that. Theoretically, a hot baking surface (thin sheet or thick stone) conducts (not radiates) heat into the cookies. How much heat it conducts into the cookies depends on how much heat it can hold. Since the thin cookie sheet has a minimal heat capacity and the baking stone has a high heat capacity, the stone conducts way more heat into the cookies. As a result, the cookies on the preheated stone should cook much faster (and much more on the bottom).

This is for a hot baking stone, though. What about a cold stone put into a hot oven? Well, the flip side of thermal capacity is that the higher the capacity, the longer it takes to fill up with heat. If a cold thin cookie sheet and a cold baking stone go into the oven, there is a good chance that the cookies on the thin sheet will bake faster. This is because the stone has to suck up a lot of heat before it can effectively conduct heat back into the cookies (for a while it may actually absorb heat from the cookies). I have experienced this phenonenon many times while baking pies because I have a metal pie pan (low thermal capacity) and a ceramic pie pan (higher thermal capacity). The pie in the metal pan always cooks faster.

How does this translate into oven braising? It could work in several ways.

First, the pans with a higher thermal capacity work to keep the heat more even as the oven cycles on and off. Some people noted that the liquid in the foil container stopped simmering when the oven door was opened. This is because, when the oven stopped pouring heat into the cooking vessel, the foil container didn't have stored heat to fall back on and maintain the heat.

Second, unlike when baking cookies, the braising vessels are in the oven long enough to come up to temperature completely long before the food is finished cooking. This means that they are all "filled up" with heat and conducting heat into the food inside, which is more efficient. It is likely that the heavier pans gave plenty of heat to the food items by direct conduction from the pan to the meat (as opposed to from the liquid to the meat), whereas the thin pans didn't have any extra heat to give this way.

Third is the question of thermal conductivity. Boria_A noted that his copper vessel came up to temperature the fastest and stayed the hottest. This is not a surprise, because copper has excellent thermal conductivity at around 4.01 W/cm K. The aluminum and iron vessels also appear to have heated very well (it's harder to say much about the ceramic and pyrex vessels because they are much smaller than their metal counterparts). For the foil vessels, the metal part is so small and inconsequential in terms of thermal capacity relative to the contents that the thermal conductivity is effectively the thermal conductivity of the contents: mostly water. Well, water has terrible thermal conductivity, coming in at around 0.0058 W/cm K.

The transfer of heat from the oven to the cooking vessel by conduction through the air and by radiation is incredibly inefficient. So it appears that there may be a real advantage to having a cooking vessel that is able to store a lot of heat and thus "free itself" from the constraints of this method of heat transfer, and instead rely upon its own inherrent heat properties to cook the contents inside of it.

For example, what is the relevance of the lid's thermal capacity? Is the lid somehow radiating heat back into the environment of the vessel's interior? I thought the idea of the lid was mostly just to keep the steam in -- assuming it wouldn't crush it, if you put a 5-pound iron lid on an aluminum foil braising tray, would that increase in overall vessel heat capacity actually make a big difference?

When the pan is all of one (or reasonably similar) construction, the thermal capacity of the lid effectively adds to the thermal capacity of the cooking vessel. It's all available heat that can be conducted from the lid down to the sides, etc. The lid does radiate some heat back into the environment, but I am not sure that this is nearly as significant as the contribution to the overall thermal capacity. The problems with the "iron lid with aluminum tray" model are 1. that it isn't all of one construction; and 2. that the most important part is the weakest part in terms of thermal properties. If, on the other hand, you added a 5 pound iron lid to a cooking vessel with reasonably good and reasonably similar properties (e.g., thick cast aluminum) it would make a difference, I think. The other advantage of a heavy lid is that it is more effective at keeping the steam inside.

Also, just as the liquid and pot contents contribute to weight, they should contribute to heat capacity. Water has a pretty good heat capacity, I think. I wonder if, the more braising liquid you use, the less the vessel matters.

By mass, water has an excellent heat capacity. In fact, as explained above, it is the reference standard: water has a specific heat of 1. By volume, however, water's specific heat is nov very good. It's still 1, whereas aluminum 3003 alloy has 2.44 J/cm^3 K and iron us up at 3.53. This is because aluminum and iron are much more dense than water. The Law of Dulong and Petit relates thermal capacity to density in telling us that most materials have the same heat capacity per mole.

You are correct, however, in suggesting that it is possible to use enough water to largely mitigate the differences between otherwise similar cooking vessels made from different materials with respect to oven braising. I think it would end up being a lot of liquid, though. Your experiment used far less than the real-world amounts in the various cooking vessels you tested, not really using them the way they were designed to be used. This may be one reason behind some of the observed differences. It's possible that the aluminum and iron casseroles, and perhaps even the foil tray, would produce much more similar results if each one had held 20 short ribs in 5 cm of liquid instead of 2 short ribs in 1.5 cm of liquid. FWIW, I am not entirely convinced we would find wide differences had the various cooking vessels been fully loaded.

I'm also wondering whether there's a point at which enough is enough in terms of heat capacity. For example, a 15-pound iron pot may braise better than a 5-pound iron pot, but will a 500-pound iron pot braise any better than the 15-pound one?

Yes, there is obviously a reasonable limit (although having an infinite heat source would theoretically be ideal). But we have to be careful not to do the old reductio ad absurdum thing. It's possible that a 30 pound braising pot would perform better than a 15 pound one with the same volume capacity. There does come a practical limit, of course. In the real world there is a tradeoff with thermal conductivity and heat capacity. A 500 pound iron pot would be prohibitively difficult to heat and would therefore probably be a less effective braising pot.

In terms of thermal conductivity, I'm wondering how this becomes important. In an oven, it should be a pretty minor consideration within reasonable tolerances. On the stovetop, it would seem to promote even heating but be problematic on electric cooktops that cycle -- again assuming the cycle speed and conductivity combine to make a difference.

Well, clearly it is important on the stovetop. How important it is in the oven is more difficult to say. The principle behind using a high thermal capacity/low conductivity cooking vessel is that once it hits the target temperature, it likes to stay there. Also, if two cooking vessels have the same heat capacity and different thermal conductivity, the vessel with lower thermal conductivity should come up to temperature more slowly all other things being equal. How significant this is in the context of an oven's extremely inefficient heat transfer is more difficult to say.

[Fat Guy]

I might have to order one of these: the retailer I always recommend for stockpots, A. Best Kitchen, has heavy duty "braziers" made from 3004 aluminum alloy in a thickness of 6.4 mm -- that's a little more than 1/4". The 8-quart is only $49, plus $8.94 for the lid if you want it, which I don't because it takes a 10" lid and I already have more 10" lids than I can shake a stick at. Seems they're offering free shipping on this item as well.

Then again, I might have to order one of these: there is a super sale on the Calphalon 8.5-quart "saucier" at Amazon right now. Only $33.88, and free shipping. The claimed list price on this pot is $180.

[slkinsey]

I might have to order one of these: the retailer I always recommend for stockpots, A. Best Kitchen, has heavy duty "braziers" made from 3004 aluminum alloy in a thickness of 6.4 mm -- that's a little more than 1/4".

6.4 mm is an awesome thickness for aluminum. Unfortunately I wouldn't recommend this for braising because it's raw aluminum. Well, to be more precise I wouldn't recommend it for braising if you ever want to braise using anything acidic, like wine, tomato paste, etc. Even most meat stocks are somewhat acidic, coming in at atound pH 5.5 (7 is neutral). This is the real weakness of aluminum. You can often find aluminum at amazingly thick gauges and at ridiculously low prices... but raw aluminum is very reactive and therefore has a lot of limitations.

Then again, I might have to order one of these: there is a super sale on the Calphalon 8.5-quart "saucier" at Amazon right now. Only $33.88, and free shipping. The claimed list price on this pot is $180.

Seems like a good deal for people who like Calphalon. I don't know why they call it a "saucier" when it's clearly not for making sauces (looks like a rondeau to me), but that's neither here nor there. Of course it's probably only about half as thick as the Johnson Rose casserole, and I would have serious concerns about warping at that size if you use it to brown meats on the stove. On the other hand, it is more compatible with acidic products than the Johnson Rose casserole.

[Smithy]

What does "3004 aluminum alloy" mean, and might it be less reactive than raw aluminum?

[slkinsey]

What does "3004 aluminum alloy" mean, and might it be less reactive than raw aluminum?

The aluminum used in cookware is typically not pure aluminum, rather it is aluminum alloyed with other metals. The "3000 series" aluminum alloys are the ones most commonly employed in non-cast aluminum cookware. The other metals presumably make the metal easier to work with and may provide other desirable properties (e.g., hardness), but they also unfortunately reduce the thermal conductivity somewhat. Here is the composition specification for a 3003 and a 3004 aluminum alloy:

 3003 Aluminum Alloy                  3004 Aluminum Alloy
Component        Wt. %               Component        Wt. %
----------------------               ----------------------
Al           96.7 - 99               Al         95.5 - 98.2
Cu          0.05 - 0.2               Cu            Max 0.25
Fe             Max 0.7               Fe             Max 0.7
                                      Mg           0.8 - 1.3
Mn             1 - 1.5               Mn             1 - 1.5
Other, each   Max 0.05               Other, each   Max 0.05
Other, total  Max 0.15               Other, total  Max 0.15
Si             Max 0.6               Si             Max 0.3
Zn             Max 0.1               Zn            Max 0.25

For the most part, when we say "aluminum cookware" we are really saying "aluminum alloy cookware." And while the alloys may be less reactive than pure aluminum, they're still plenty reactive.

[zeitoun]

Sorry if i'm chiming in a little too late however I would like to begin by saying that this is the first seminar I have been reading along since it began. Even though I have not participated in it (and I hope to next time), I found it so informative and enlightening on many aspects. Thanks Fat Guy and everyone else for your participation and intense labor!!

My question has to do with parchment lids during braising (if this was discussed anywhere, please direct me towards the appropriate link). I have seen many recipes call for it in both stovetop and oven braising. I assume regular lids were used during all the EGullet braising labs, yet I was hoping to see some commentary on the benefits and disadvantages associated with the use of parchment lids instead. From what I have observed during my braising experiences, it seems that parchment lids do allow more braising liquid to evaporate than regular tighter lids. In addition, I have always assumed that they were of greater use in the oven since they prevented whatever piece of meat not submerged to remain somewhat moist and not to crust. Yet, and as I stated earlier, their use is also suggested for stovetop braising. Could anyone tell me what is the primary reason for the use of parchment lids vs. regular lids in braising?