Animal Fats: Better Cooking Through Science 02

[Chris Amirault]

This is the second topic in our series, "Better Cooking Through Science." The purpose of this series is to talk, ask, and learn about an important concept in food science, how that concept functions in specific foods and recipes, and what you can and should do in your own cooking to incorporate those insights into better practices. If it works, we can all figure out how to tackle seemingly challenging scientific knowledge and bend it to our uses!

The first topic on the series, on emulsions, is here. In this topic, we're hoping to get the skinny on fat. I admit to being totally confused about animal fat and its components, and the news media isn't particularly helpful on the subject either. However, as always, Harold McGee's On Food and Cooking: The Science and Lore of the Kitchen is coming through when all others fail; most of the material I quote here is from pages 797-802. (I haven't checked Shirley Corriher's Cookwise: The Secrets of Cooking Revealed yet, but I will tonight at home.)

Fats (and oils) are lipids, and lipids have a lot of useful characteristics for cooking. For one, they taste good and feel lovely on most people's tongues. They can provide a tenderizing effect: think of the velvety consistency of a well-made duck confit.

Fats, of course, have gotten a bum rap, in part due to another beneficial property, namely, their ability to store a lot more chemical energy than most substances. (That energy is measured in calories, of course.) In addition, depending on the various proportions of saturated, monounsaturated, and (trans-)polyunsaturated fats -- and your reading of current research -- a large foundation of animal fats isn't probably the basis of a healthy diet. Thankfully, however, this isn't "Healthy Eating Through Science" but "Better Cooking Through Science," so I'm not going to try to unravel any of these carbon chains. Instead, let's focus on something we all know and love.

Fats are fantastic media for heating foods. Anyone who's ever eaten pancakes cooked on a non-stick skillet without fat knows that the microscopic distance between the pan and the food is in fact a vast, tasteless gulf that must be filled with something. Water works, but just for a few seconds on a hot surface, at which point it turns to steam and evaporates; adding more water than can evaporate is poaching, which has its own limitations.

Since lipids by their very definition are unlike water, they can form boundaries between organic compounds that include water (vegetable matter, meat protein) and the cooking surface. The stove then heats the fat to temperatures much higher than the boiling point of water, transferring that heat energy though the fat via convection currents. Evenly distributed across the item's surface, fats are crucial aids in the drying, crisping, and browning of your hash browns and pork chop, effects achieved by the Maillard effect and caramelization, both of which require higher temperatures than 212F/100C.

More fun fat facts:

• Fats don't have sharply defined melting points (think of your butter in the fridge, on the counter in winter, and next to the stove).
  
• Fats that are more saturated are more stable in relationship to the oxygen in air (think of dry-aged beef) whereas the more unsaturated fats are more likely to go rancid (think of dry-aged chicken skin).
  
• Free fatty acids are the pests behind smoke points -- the more free acids, the less stable the fat, and thus the lower the smoke point -- and because fat breaks down a bit more each time you deep-fry, the quality of the oil deteriorates and the smoke point lowers.
  
• Searing that steak in fat on both sides doesn't "seal in the juices," but you know that, don't you?
  

Any animal fats can be rendered in order to provide a pure cooking medium; many Society members boast proudly of their collections of schmaltz (rendered chicken fat), duck fat, lard (rendered pork fat) and others bumping around the back of their fridge. For years I had used fifi's method for rendering fat (click here), but I've discovered a more efficient and controllable method that I've posted to RecipeGullet here. Creating an emulsion of fat and water before rendering is a particularly useful technique if you want to get the most out of duck or chicken skin and don't want cracklin's or gribenes to snack on at the end.

I still have lots of questions even after reading up. For example, what precisely causes food to taste unpleasantly greasy, and what can you do to avoid it? What kinds of fat have affinities for what sorts of cooking tasks? (For example, busboy will tell anyone who listens that potatoes and duck fat are a marriage made in nirvana.) There's likely a lot more questions out there, and hopefully a few of us can figure out answers and share tips.

[Mallet]

Why do I consistently get better browning when I use rendered pork fat vs. oil or butter?

[Kent Wang]

Why do animal fats, especially duck fat, taste better? What trace elements give duck fat its duck-ful character? Why have I never heard of rendered beef fat?

[Fat Guy]

Rendered beef fat (and rendered bovine fat --sheep, horse -- in general) is known as tallow. It's not currently a very popular ingredient, but it was commonplace in the days before the health lobbyists pressured food corporations to replace animal fats with the trans fats they're now lobbying to ban. Tallow is probably the best medium for making fries -- the old McDonald's formula, when the fries were excellent, consisted mostly of tallow (93% tallow and 7% cottonseed oil according to various online sources). Tallow was also often seen on food product labels, and under the old labeling system could just be part of the "animal and/or vegetable fats" description -- I believe Oreos were made this way for about a zillion years prior to the switch to vegetable fat that ruined them; Fig Newtons too. Tallow is no longer used very much in candle-making, but it is still a common ingredient in bar soap.

[Kent Wang]

Ah, yes, tallow was the term I was looking for. I found more information in the Wikipedia article.

Just to nitpick, sheep (ovines) are indeed bovines but horses (equines) are not.

[jackal10]

Mention should be made of the current view that trans-fats are evil, but saturated fats have been redeemed, especially if you eat garlic and drink red wine...

Butter and Goose fat are particularly beneficial, and good to cook with.

[Adam Balic]

Why do animal fats, especially duck fat, taste better? What trace elements give duck fat its duck-ful character? Why have I never heard of rendered beef fat?

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In the UK at least rendered beef fat is sold in most supermarkets and butchers as "dripping". This was literally drippings at one point, the liquid that fell from a roasting joint, so this included aqueous liquids as well. While you can still buy this at some butchers, the common form is rendered fat. It sits on the shelf next to the lard (rendered pork fat) and the sold vegetable fats.

Tallow is rendered fat, but isn't a term usually associated with food consumption here.

[Adam Balic]

Why do animal fats, especially duck fat, taste better? What trace elements give duck fat its duck-ful character? Why have I never heard of rendered beef fat?

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Many flavour componants are fat soluble, Mcgee mentions that fatty acids in grass end up in in the fat and give beef a characteristic flavour. Which is why goose tastes similar to beef as they also graze on grass.

[jeniac42]

Anything cooked in bacon fat is guaranteed to taste 100% better than it did before you put it in the pan.

I don't have a lot of experience with rendering animal fats, and am thinking I should perhaps start saving my trimmings and start a collection. Chris, your method looks interesting and easy; do you recommend chilling or freezing the skin and fat before putting it in the food processor?

It does seem that the flavor of the animal seems to concentrate itself in the fat. I don't enjoy working with raw poultry much, and birds aren't my favorite form of meat, though I do enjoy them now and then. And in particular, there is a certain smell to poultry fat that can induce my gag reflex. This doesn't seem to apply as much when I can source well-raised animals, but I still wouldn't say I like the smell.

On the other hand, venison (the deer version, this from northern MI) meat smells sweet to me, but the fat is definitely gamey. If there is too much of it present, it ruins the taste of the dish for me; I won't eat it as I would pork fat - it doesn't soften in the same way, and it seems to harbor that unpleasant taste and smell.

I now feel like I need to get out the old copy of McGee and have a lookthrough.

[bigcat39]

In December, I proudly rendered 14 lbs of real, honest to god leaf lard, the stuff was still warm when I picked it up at the processors plant. I have a ton of pics if anyone is interested.

[Shalmanese]

In the 4 months since I've moved to America, I've gone through 500mL of Extra Virgin Olive Oil, 200mL of peanut oil, 300mL of duck fat, 400gm of butter and around 700gm of bacon fat. Pretty much all of the EVOO was used in salad dressings so virtually all my cooking is done with animal fats.

I pretty much never use pre-rendered fats anymore. If I am searing chuck for a braise, I will trim all the large chunks of fat off and render that in the pan while I prep everything else. I then use the rendered beef fat to sear the meat and pour off any excess into the bin. Most other dishes, I'll start with a rasher or 2 of bacon and render it out in the same manner. One great tip I've found is to use far more fat than is actually needed to sear something. The extra fat tempers any hot spots you have in the pan and gets deep into the nooks and crannies of the meat giving a superior sear. Once you've finished searing, just pour any excess fat out and let it cool before disposing of it.

The taste of animal fat just cant be beat for getting warm, rich flavours into a dish when used judiciously.

[FoodMan]

Fat and heart health:

Is it a good rule of thumb to say that the softer the animal fat is the healthier it can be? Basically lard (pork fat once rendered) is nice and soft at room temperature, where as beef fat is very much solid. This means beef fat is more saturated, ergo worse for your heart arteries than lard. Similar comparisons can be made with duck fat versus butter....

I know I've read this in a couple of places including one of Jeffrey Steigarten's books and it makes sense, but would like to think what everyone's take on it is.

[Dave the Cook]

. . . . .

what precisely causes food to taste unpleasantly greasy, and what can you do to avoid it? . . . .

←

In short, poor temperature control. As you noted in your post, fat can get hotter than water; this simple point is essential to understanding what happens when you fry something. When moisture-laden food (most food is mostly water) comes in contact with properly heated fat, steam is created. As long as the temperature remains high enough, and as long as there is water close enough to the surface of the food to be heated by the fat, release of steam prevents fat from getting into the food. If the temperature drops too low to precipitate boiling, or if moisture is depleted, fat floods in.

So: don't crowd the pan (or pot, if you're deep frying); make sure your fat is hot enough; and make sure that large items are close to room temperature, so as not to cause a rapid drop in fat temperature. It also helps to use a heavy pan; its heat capacity helps prevent severe temperature drop.

When shallow frying, use enough fat to allow full contact with the surface of the food. If you try to minimize fat in the finished product by using minimal fat in the pan, you will often end up with something that is burned, greasy, soggy, or a combination of all three. Imagine frying something with an irregular profile -- like a breaded chicken thigh -- in too little fat: where the food contacts the pan directly, it will burn; where it's in contact with fat, moisture in the meat will dissipate long before the meat is cooked -- these areas will take in fat, and the breading will be greasy; where the food contacts neither pan nor fat, the water near the surface of the food will still get hot enough to steam, but without fat to carry the moisture away, the surface turns soggy. As a rule of thumb, use enough fat to come halfway up the sides of the food -- this provides buoyancy (as well as a temperature buffer), so your food is less likely to burn.

Finally, when shallow frying breaded items, watch the top of your food. When moisture appears, turn it over -- once only.

[hummingbirdkiss]

the single best apple pie I have ever made had a goose fat crust ..it was so flaky and perfectly cooked ..the taste was to die for around the apple filling ..it heald up perfectly!!!

I rendered it myself and used it in a basic pastry recipe

if I could have goose fat around when I needed it ..I would be very happy ....

[infernooo]

In the 4 months since I've moved to America, I've gone through 500mL of Extra Virgin Olive Oil, 200mL of peanut oil, 300mL of duck fat, 400gm of butter and around 700gm of bacon fat. Pretty much all of the EVOO was used in salad dressings so virtually all my cooking is done with animal fats.

I pretty much never use pre-rendered fats anymore. If I am searing chuck for a braise, I will trim all the large chunks of fat off and render that in the pan while I prep everything else. I then use the rendered beef fat to sear the meat and pour off any excess into the bin. Most other dishes, I'll start with a rasher or 2 of bacon and render it out in the same manner. One great tip I've found is to use far more fat than is actually needed to sear something. The extra fat tempers any hot spots you have in the pan and gets deep into the nooks and crannies of the meat giving a superior sear. Once you've finished searing, just pour any excess fat out and let it cool before disposing of it.

The taste of animal fat just cant be beat for getting warm, rich flavours into a dish when used judiciously.

←

Shalmanese: Have you found that US bacon is far more fatty than AU bacon? As you know, our fattiest cuts are the "middle bacon" with fat and rind attached, and the "normal" bacon is short cut which is pretty much just the loin (very lean). The middle bacon seems to be the loin with a little bit of the belly attached to the end.

[Adam Balic]

In the 4 months since I've moved to America, I've gone through 500mL of Extra Virgin Olive Oil, 200mL of peanut oil, 300mL of duck fat, 400gm of butter and around 700gm of bacon fat. Pretty much all of the EVOO was used in salad dressings so virtually all my cooking is done with animal fats.

I pretty much never use pre-rendered fats anymore. If I am searing chuck for a braise, I will trim all the large chunks of fat off and render that in the pan while I prep everything else. I then use the rendered beef fat to sear the meat and pour off any excess into the bin. Most other dishes, I'll start with a rasher or 2 of bacon and render it out in the same manner. One great tip I've found is to use far more fat than is actually needed to sear something. The extra fat tempers any hot spots you have in the pan and gets deep into the nooks and crannies of the meat giving a superior sear. Once you've finished searing, just pour any excess fat out and let it cool before disposing of it.

The taste of animal fat just cant be beat for getting warm, rich flavours into a dish when used judiciously.

←

Shalmanese: Have you found that US bacon is far more fatty than AU bacon? As you know, our fattiest cuts are the "middle bacon" with fat and rind attached, and the "normal" bacon is short cut which is pretty much just the loin (very lean). The middle bacon seems to be the loin with a little bit of the belly attached to the end.

←

Australian meat in general is extremely (far too lean). I've discussed this with various people and the consensus seems to be that the main factor is the modern health consciences diet, with part of the driving force behind this being the very successful decade of heart awareness campaigns.

So yesterday I was at the Prahran market watching the butchers cut all the fat off the steaks and roasts. Rib roasts seem popular, but most of the roasts I saw had all of the external fat removed. I can't see any conventional domestic way of cooking a joint like this without it being very dry. Another thing to note is the huge amount of marinaded meat that is sold, in part to counteract the tendency of very lean meat to dry out.

Like the UK, pig growers receive finacial penalties if there is too much fat on the carcass, depending on where you are it can be as low as 11 mm of fat. There has also been a move promote breeds of pig that have more muscle bundles. Much of the loin cut bacon you get now will have this little round fillet sitting in the fat layer, 20 years ago this feature was very rare. If you have access to cookbooks from around the '30's you will see streaky bacon that is mostly fat with a few pink stripes of meat, not the reverse is true.

[Shalmanese]

Yes, US bacon is generally significantly fattier than Australian.

[Chris Amirault]

I don't have a lot of experience with rendering animal fats, and am thinking I should perhaps start saving my trimmings and start a collection.  Chris, your method looks interesting and easy; do you recommend chilling or freezing the skin and fat before putting it in the food processor?

←

There's really no need to do that. It's not as if you're making an emulsion for, say, a sausage; you're beating water next to fat molecules to make the rendering speedier. In fact, you want the emulsion to break and release the liquid fat.

Fat and heart health:

Is it a good rule of thumb to say that the softer the animal fat is the healthier it can be?

←

My sense is that, yes, this is more or less true, simply because your body, which sits at about 98.6F most of the time, will process anything that's in a liquid state at that temperature more effectively than it will process something that isn't. However, I'm far from certain, and my quick research suggests that it's not a rule of thumb. (This doesn't make any sense at all, of course, with oils.)

[Shalmanese]

My sense is that, yes, this is more or less true, simply because your body, which sits at about 98.6F most of the time, will process anything that's in a liquid state at that temperature more effectively than it will process something that isn't. However, I'm far from certain, and my quick research suggests that it's not a rule of thumb. (This doesn't make any sense at all, of course, with oils.)

←

Pretty much all fats are liquid at 98.6F. If this were not the case, they would have a very unpleasant mouthfeel as they would not melt and release flavour when you ate them.

The melting point for a fat is an indirect proxy of the amount of saturation. Saturated fats can pack in much more closely to each other and form tighter bonds so they have a higher melting point.

[Dave the Cook]

The saturated/unsaturated picture is complicated. Fats with high percentages of saturated fats (and this includes all animal fats) often have significant mono- and polyunsaturated content as well. By the same token, there seems to be a widespread belief that all vegetable-based oils are innocent (though palm and coconut are often exempted). But the fact is that all fats are combinations of the three types. Look at the percentages, and it's not so clear:

Chicken fat: 45% monounsaturated; 21% polyunsaturated; 30% saturated

Beef tallow: 42; 4; 50

Lard: 46; 12; 40

Compare those numbers with some popular vegetable oils:

Soybean: 24% monounsaturated; 58% polyunsaturated; 15% saturated

Cottonseed: 18; 52; 26

Safflower: 12; 75; 9

[chiantiglace]

Why do I consistently get better browning when I use rendered pork fat vs. oil or butter?

←

Probably because the saturated fat is able to absorb more surface area during cooking and also clings (like cooked sugar) to the meat.

[chiantiglace]

Why do animal fats, especially duck fat, taste better? What trace elements give duck fat its duck-ful character? Why have I never heard of rendered beef fat?

←

Many wild and lean muscle tissue carry unpleasant tasting fats. I will trim quite a bit of fat off of a wild duck to keep it from tasting foul.

it all depends on how the animal is raised and fed. Thats where the cages come in to play, so that these animals aren't running wild picking up random organisms in the fields.

[chiantiglace]

Mention should be made of the current view that trans-fats are evil, but saturated fats have been redeemed, especially if you eat garlic and drink red wine...

Butter and Goose fat are particularly beneficial, and good to cook with.

←

I dont think saturated fats have been redeemed, I think people relize now that they aren't as bad as their once replacements. The saturated fats are still linked to many diseases, so it is more important to pick up mono and poly unsaturated fats, preferrably the ones with the double carbon bond at the omega-3 placement.

I believe McDonalds has replaced its oil with fully hygrogenated soybean oil, that is cut with remaining un-hygrogenated oil to produce the proper consistency. I could be wrong about this though.

Soybean oil may not be the best oil to choose as a replacemtn either. Soybean oil contains I much greater ratio of omega 6 to omega three fatty acids. Even though omega 6 fatty acids are good for human health and cellular structure, we already consumer far more than omega - 3's on average, and this can lead to arachidonic acid, because desaturase ends up converting remaining linoleic acids (omega-6) if there aren't enough alpha-linoleic acids (omega-3) to compensate the proper ratio.

[Baggy]

I wonder if anyone else has noticed how the ‘healthy’ fats breakdown very quickly and start to give off eye-stinging fumes?

For example, deep frying with sunflower oil starts to leach nasties within a couple of times of using the oil. Duck fat quickly evaporates, but the smell is appetizing and, apart from coating everything in the kitchen, it doesn’t hurt the eyes.

Generally, I think animal fats tend to have higher smoke points and tend to go syrupy when they are past their prime.

My major bugbear in rancid fats though, is salmon. Cooked as a confit at around 40C it tastes succulent and wonderful. Grilled or pan fried it stinks…

Back to the main subject though, fats with a higher smoking point, but not necessarily melting point, give a shorter crust in pastry and, in bread making, a greater lift in the oven. Breads made with olive oil are pleasing from a marketing point of view, but a whole meal loaf made with lard (tallow) has a pleasant sweet odour, at least 10% greater volume and goes stale less quickly.

[Chris Amirault]

Why do I consistently get better browning when I use rendered pork fat vs. oil or butter?

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Probably because the saturated fat is able to absorb more surface area during cooking and also clings (like cooked sugar) to the meat.

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I'm not sure I follow this. What does "absorb more surface area" mean?