Yes, kids, it’s that time again…
Is it just me, or are the weeks flying by? It seems like the minute I get one of these posts up, there’s another Tuesday barreling down the road. But considering how many things I want to get to about fats, I guess that’s a good thing. This is a pretty long post, but hey, you've got a long holiday weekend coming up and maybe a couple extra minutes to read something that just might make you a little smarter (and healthier!) than you were before.
If this is your first time here, welcome! And second, check out the previous posts in this series. In part 1, I explained that every fat and oil is a combination of saturated, monounsaturated, and polyunsaturated fatty acids, so when we say “animal fat is saturated fat,” it’s true but it sure isn’t the whole story. In part 2, I introduced some very basic biochemistry of fats. I showed the shapes of a few examples of different fatty acids, and explained that those shapes help determine some of the properties of those fatty acids – like whether they’re solid (like butter) or liquid (like canola oil) at room temperature.
At the risk of scaring you away, I’m afraid I have to give you just a little more lipid chemistry 101 this week. (What is this “lipid” I speak of? That’s the term the biochem geeks—um, I mean professionals—use when they refer to fats and oils. For the sake of simplicity, I’ll just use “fats,” but remember, when I say “fats,” I mean fats and oils. The pros usually use fats for solid lipids, like butter and lard, and oils for liquids, like soybean or flax oil. And for the record, I mean no offense when I say biochem geeks. I consider myself one proudly, in fact.)
Like I said in the previous posts, in order to stand a chance in the daunting task of putting a few nails in the coffin of six decades of misleading, misconstrued, and just plain wrong information about dietary fat, we’ve got to stick to the facts. We’ve got to put aside the media hype, the magazine headlines, and even dear, sweet Dr. Oz’s food-company-sponsored agenda. We need to forget everything we think we know and start from scratch. Remember—once upon a time, all the “experts” (except Copernicus, and Galileo) were convinced the Earth was flat. They were convinced the Earth was the center of the universe, and that the sun revolved around us instead of the other way around. They were sure. They were so sure, in fact, that anyone who disagreed with them was excommunicated and/or killed. Nice, huh?
|Yeah, I'm pretty sure it's round. |
What else do you think they might be wrong about??
And they were wrong, weren’t they? Now, it’s bad enough when scientific authorities get things wrong when it comes to astronomy. But when it comes to our health—how we feel every day and the overall quality (and quantity!) of our lives, they don’t just get things wrong. They get them dead wrong.
So let’s close the Skinny Bitch and Kind Diet books and open up our minds, shall we?
Continuing where I left off in part 2 of this series, let’s get back to talking about how the chemical structures of fatty acids give them their shapes and also determine what happens to them when we cook and/or eat them. Don’t get skeered – I’ve done the hard part. I’ve sifted through the textbooks. All you have to do it sit back and soak up some nifty info.
You know what they say: Go big or go home.
And if we’re gonna start big, we might as well start with the granddaddy of ‘em all: saturated fat. (Yes, you know my line…cue the scary music…) Here’s an analogy I think will help us make sense of this stuff. Let’s think of fats as a glass jar with fragile glass marbles inside it. If the jar is completely filled with marbles, that’s like a saturated fat. The jar is packed full with marbles. They’re in there so tightly that there’s no room for any of them to move around, even if you grab the jar and give it a good, hard shake. The marbles inside are stable. They’re not going anywhere. You’ll recall from the last post that saturated fats have no double bonds between carbon atoms. They are saturated with hydrogen atoms instead, hence the term saturated fat. No double bonds, no room in the jar, no chipped marbles.
If we take just one marble out of the jar, we have a monounsaturated fat. Now, if you were to shake the jar, the marbles have a tiny bit of room to move around. There’s a little “give” or “play” there, that the completely filled jar didn’t have, right? You could do some damage to the marbles if you shook the jar. Not a lot of damage, of course, because there’s only a little bit of room for them to move, so they won’t bump into each other and chip all that much. A monounsaturated fat has just one double bond—one place for things to get a little dicey.
Now, let’s take a bunch of marbles out of the jar and give what’s left a good shake. There’s a lot more room for them to bang around in there, chip, shatter, and generally get messed up, right? (And yes, “generally get messed up” is the official scientific term.) The jar that’s missing a few marbles (hehheh) is like a polyunsaturated fat. There are multiple double bonds—multiple places where things can go wrong under certain circumstances. What are those circumstances? Patience, grasshoppers. Keep reading.
|Better a broken glass than broken arteries. |
(More on that in future posts.)
The environmental equivalents to shaking the jar are light, air, and heat. When fats are exposed to any or all of these three things, biochemical nastiness might ensue. (Again, the official scientific term. And you thought science was scary!) If we think about how fats are processed—that is, how they get from their original source and into the bottle, tub, or other package at the store—we’ll see that they are, in fact, exposed to all three. Don’t worry, I’ll make it quick.
Let’s start with animal fats, like cream, butter, beef tallow, and lard. These do not require much processing before they’re ready to cook with and/or eat. If you milk a cow, bam, you’ve got cream. (Let the milk sit awhile undisturbed and the cream rises to the top. No processing there.) Shake that cream up a lot until it solidifies and you’ve got butter. Also not a lot of wacky hijinks involved. As for beef tallow, lard, or schmaltz (chicken fat, or Jewish gold, if you prefer), those are pretty easy to come by, too. After an animal is slaughtered, you can take some of the fat off straight as is and render it down, or you can boil the bones and a little bit of the meat and you’ll end up with a good bit of it solidified at the top of your stockpot. (Unfortunately, this is pretty much the only way to get beef tallow or lard these days, unless you live near a farm or have an especially savvy vendor at the farmer’s market. The big chain supermarkets don’t exactly keep this stuff on hand. More’s the pity, although you can sometimes find lard at a good Latin American market.) Long story short, animal fat is fairly straightforward. What you see is what you get.
Now let’s talk seed and nut oils. These are also relatively easy to get…provided you have a huge mechanical press of some sort. Nuts and seeds are pretty high in fat. If you gather enough of them and squeeze, press, and crush them hard enough, the oil will come out. (“Expeller pressed” or “mechanically pressed” on the label usually means that this is how the oil was extracted. If you don’t see these words, chances are the oils were extracted using this more traditional, low-tech method but also with chemical solvents and industrial machinery that can come at these poor nuts and seeds with so much pressure and chemical shenanigans that the oil has no choice but to come out.)
Moving along, we’ve got vegetable oils—and I use the term loosely. Corn is more of a grain, and soybeans are legumes. I wouldn’t call either a vegetable. Don’t be fooled by Wesson or Crisco labels that say “vegetable oil” on the bottle. These are soybean oil. (Have you ever heard of “broccoli oil,” or “eggplant oil? Me neither.) Think about an ear of corn. I don’t know about you, but when I think about rich sources of fat, corn doesn’t immediately come to mind. In fact, if I had to name the ten fattiest foods I could think of, corn wouldn’t come close to making the list. (It wouldn’t even make the top twenty, actually.) Neither would soybeans, for that matter. Think of a nice, green edamame pod or a bright yellow or white ear of corn. Now think of the translucent, odorless bottle of oil you find at the supermarket. How much chemical manipulation do you think it takes to get bushels of corn or soybeans to resemble those oils? If you said “a lot,” you’re right. (I would say a “shit-ton,” but this is a family show.) It takes an incredible amount of processing to extract oil from corn and beans. (And aren’t they always saying we should eat fewer processed foods? But we’re supposed to avoid animal fats and stick to all the vegetable oils, right? I guess we’re damned if we do and damned if we don’t. Hmmm…) If it takes extraordinary measures to get oil out of things that really are fatty, like peanuts and sunflower seeds, what must it take to get bottles of the stuff from corn, for goodness sake?
|Where do your fats come from?|
Let’s think about what happens between, say, a truckload of safflower seeds, and the bottle of safflower oil you can buy from your neighborhood store. In order to get the oil out, the seeds are subjected to mechanical pressures you could never replicate in your home kitchen. (Or basement workshop, garage lab, or wherever it is you do your wacky home food experiments.) This pressure creates friction, and friction creates heat, right? (We can verify this scientifically by recalling a greeting card I once saw: “I tried to take up jogging once, but my thighs rubbed together so much my underwear caught on fire.” HA!! So yeah – pressure --> friction --> heat.) And in a factory setting, what else is this oil exposed to? Unless the extraction is somehow being done in a vacuum (and it’s not), it’s exposed to light and air. So we’ve got the trifecta of things that can damage the unsaturated fats. ‘Cuz remember: the saturated fats do not have the double bonds, which is where the damage will typically occur.
What do I mean by “damage”? In chemical terms, I mean oxidation, but in terms of what you’d detect with your nose and mouth, it means one thing: rancidity. Ever have a bottle of oil or a jar of nuts sit around a little too long and go bad? And it takes on that nasty smell and taste? That’s rancidity. And it happens because light, heat, and/or air has wreaked havoc with those double bonds. This is why we can keep bacon fat in a glass jar or metal coffee can on the counter practically forever and it won’t go bad. (Well, we don’t do this, of course, because we’ve been made absolutely terrified of animal fats, but our great grandmothers were gettin’ their cook on long before anyone from the government was in their faces telling them what they should and shouldn’t eat. I’m a born-and-rasied New Yorker, but even I know that a blue Maxwell House can half full of saved bacon grease is a staple of most Midwest kitchen counters, and anyplace else where they have a lick of sense about good cooking.)
Do you see what this means? Polyunsaturated oils—the jars with lots of marbles missing—are “messed up” before they even leave the factory! Point of failure #1. I know, I know. You’re wondering why they don’t look funny or smell “off” when you open a bottle of one. Well, part of the processing cavalcade includes filtering, bleaching, and deodorizing, so the bottle of oil you bring home is translucent and generally odorless and even flavorless. That doesn’t mean it’s not rancid; it just means you don’t realize it. (Except for olive oil, which is over 70% monounsaturated, about 15% saturated, and therefore much less prone to rancidity. Most people like their olive oil to have a strong flavor, especially if they shell out big money for the good stuff.)
So these fragile polyunsaturated oils are damaged before they even get to the store. But what happens when they are in the store? They sit on shelves in clear plastic or glass bottles, where they’re exposed to more light. Twenty-four-seven, in some cases! Point of failure #2. (Except for a few brands of olive oil that you can find in metal containers or very dark glass. But there are also the ones sold in clear glass so we can all see how pretty and pristine and dark green the oil is, eh? Marketing genius, yes, but also good chemistry!)
What’s point of failure #3—and possibly 4? Let’s say you go to the store, where you buy a bottle of “vegetable oil.” It’s already been exposed to lots of heat, light, and air, then more light, and now you bring it home to make dinner. Maybe you’re making a stir-fry, so you put a couple tablespoons in a pan to heat up while you prep your veggies. Now the oil’s getting heated—for a second time. (Never mind the light and air. At this point, those are small potatoes compared to the heat.) High heat is a death knell for these fragile polyunsaturated fats. Want to wreck soybean, corn, cottonseed, canola, and safflower oils? Heat them. Want to wreck your health? Eat them after you’ve heated them. (But that’s a completely different ballgame right there. Like I said, one piece of craziness at a time.)
And think about a restaurant where they deep fry in this stuff! They use these polyunsaturated oils over and over again, heating them repeatedly. Whoa, momma! See, the funny thing about fried foods in restaurants is that they’re not “bad for you” because they’re fried – it’s because of the kind of oil they’re fried in! (Almost always soy, sometimes canola, cottonseed, or peanut. Of those three, I’m most comfortable with peanut.) I’ve heard that Food Network celebrity chef Michael Symon uses lard in all his restaurants, and if you’ve ever seen any of this shows, you know the man loves his animal fats. If you can find a restaurant using natural, mostly saturated fats for frying, go ahead…order what you want!
Bottom line: Saturated fats are best for cooking. Especially high heat cooking. They’re the least prone to oxidizing in the bottle, in the frying pan, and in your body. You can use the most monounsaturated olive, peanut, and sesame oils for cooking too, but for everyday use you’re better off with the saturates. For an AWESOME cheat sheet on all this, check out this one by Diane Sanfilippo. She’s also got great explanations of fats here and here, and you might learn a thing or two I didn’t get into in today’s post. (And she’s much more to the point than I am, so no worries about having to read something as long as this!)
If you’re thinking that there’s another kind of fat besides saturated, monounsaturated, and polyunsaturated, you’re right. (Pat yourself on the back, I’ll wait.) Let’s not forget the über-nasty trans fats. What are they and why is there so much bad press about them? Tune in next week.
In the meantime, have a question about fats—or anything nutrition/food/health related? Leave a comment or send me an email. I love hearing from you!