The Food Lab's all about clearing up culinary misinformation; separating the old wives' tales from the old wives that keep telling them.
So here are the six most common and egregious food myths I commonly encounter, and the truth behind them. You can use this information to either improve your cooking, or to sound like a pompous windbag at your next cocktail party.
1. Moist Cooking Methods Give you Moister Results Than Dry Cooking Methods
It makes sense, right? Cook meat in a moist environment (braise it, boil it, simmer it, steam it), and you'll end up with meat that's moisture if you cook it in a dry environment (roast, saute, grill, barbecue, broil, or fry). Unfortunately, it doesn't work that way. The amount of moisture that a piece of meat retains is pretty much only related to the temperature it is cooked to. Basically, under a microscope, a hunk of meat looks like a bunch of liquid-filled straws bound together into bundles. The straws are filled to capacity with liquid when the meat is raw. As it cooks, the walls of those straws contract, squeezing liquid out of them—whether or not they are in a moist or dry environment.
It's easiest to think of it as squeezing out a tube of toothpaste. Whether you do it in the air or under water, just as much toothpaste gets squeezed out. You can boil a steak until it's dry just as easily as you can roast it until it's dry*.
What does help keep moist, on the other hand, is brining. Soaking raw meat in a salt water solution fundamentally changes the shape of its proteins, allowing them to retain more moisture than they're able to naturally. Of course, the tradeoff is that the extra liquid in the meat also somewhat dilutes its flavor.
*Even easier, in fact, since the water in a boiling pot has a much higher specific heat capacity than the air in a hot oven does.
2. Frying at a Higher Temperature Prevents Food From Absorbing Oil
Next to myth number 4 below, this is probably the most widely circulated food myth from home cooks and great chefs alike, and it's easy to see why. There's no denying that frying food at a low temperature—say below 300°F or so—leads to greasy end results, and that upping the temp to 350°F or above will infinitely improve your food's crispness. But does "greasy-tasting" necessarily equate to "more grease"?
The common explanation is that when you put food in hot oil, the pressure exerted by the bubbles of water vapor rapidly leaving the food prevents the oil from entering the food. And it seems to make sense. But the thing is, the vast majority of the oil that gets absorbed into fried foods happens not while it's inside the hot oil, but within the first few seconds after it is removed from the oil.
"What comes in to fill those holes? The only thing that can: the oil on the surface of the food."
If you look at a French fry under a microscope, here what's happening. While it's being fried, the water inside the food is rapidly expanding and converting to steam. Much of this water escapes, leaving small, steam-filled cavities in the food. As soon as the food is removed from the oil, it rapidly drops in temperature. The steam inside condenses back into water, leaving large vacuum-filled holes in its structure. What comes in to fill those holes? The only thing that can: the oil on the surface of the food.
In fact, the amount of oil that a piece of food absorbs is directly proportional to the temperature it is cooked at.
So the sensation of greasiness you get when eating poorly fried food? It's the combination of oil and the moisture left on or near the surface of the food that causes that. Well-fried food should be nearly water-free on its surface, giving it a cleaner, less greasy mouthfeel.
3. When Grilling, It's Best to Flip Just Once in the Middle
Common backyard know-how dictates that burgers and steaks should only be flipped once, half way through cooking. But has anyone ever bothered questioning why we do this? Does it actually create a noticeable improvement in the way your meat comes out?
Turns out the answer is an emphatic no! Flipping your meat multiple times produces meat that's noticeably more evenly cooked (there's about 40% less overcooked meat in a burger flipped every 15 seconds vs. one flipped once), browns just as well (just don't expect distinct hash marks), and to top it all off, ends up cooking in about 2/3rds of the time. Faster and better? You betcha!
Moral of the story: if you see your buddy doing that multiple flip thing, don't get on their case. They're doing good.
4. Searing "Locks In" Juices
This is the oldest one in the book, and still gets repeated—by many highly respected cookbook authors and chefs!—to this day. It's been conclusively proven false many times, including in our own post on How to Cook a Perfect Prime Rib, where we found that when roasting a standing roast, it in fact lost 1.68% more juice if it was seared before roasting rather than after! The same is true for pork roasts, steaks, hamburgers, chicken cutlets, you name it.
On the other hand, searing does improve flavor by catalyzing the Maillard browning reactions, a series of chemical reactions that rapidly take place when proteins and sugars are heated to around 300°F or so, improving the flavor and texture of the dish. But in almost all cases, it's better to sear the food after it's roasted, not at the start.
5. Pasta Must Be Cooked in Massive Amounts of Boiling Water
Well, this one is actually true, but only if you are dealing with really fresh (as in you rolled it yourself) pasta. With dried pasta, as long as the pasta is completely covered in water, it'll cook just fine. People cite the fact that a large pot of water will lose less heat than a small pot of water when you add pasta to it, but this is in fact not true. There is a difference between heat (energy) and temperature (a value based on how much energy a given amount of a given substance holds).
So, it's indeed true that a large pot of water will show a smaller decrease in temperature than a small pot of water, but the amount of energy needed to bring that water back up to a boil when you add the pasta to it is exactly the same, no matter how much water you have. In fact, because a small pot loses less energy to the outside environment because of its smaller surface area, it will actually return to a boil faster than a large pot of water will.
Moreover, you don't even need to keep the water all that hot. Cover your pasta with boiling water, bring it back to a boil, put a lid on it, and remove it from the heat. It'll cook just as fast and evenly as a pot that's kept at a rolling boil for the entire duration of cooking, plus it'll shave a few pennies off your gas bill!
6. Salting Beans During Cooking Will Make Them Tough
Most of us have been told at some point in our culinary careers that salting beans will cause them to toughen. It's incredible that this little bit of culinary mis-wisdom still lingers, for it couldn't be further from the truth. A simple side-by-side test can prove to you conclusively that salting beans (both the water used to soak them in and the water used to cook them) actually tenderizes the skins.
It's got to do with magnesium and calcium, two ions found in the bean skins that help keep the structure of the beans' skin intact. When you soak the beans in salt water, sodium ions end up replacing some of the magnesium and calcium, effectively softening the skins. Your beans come out creamier, better seasoned, and have a much smaller likelihood of exploding while cooking.
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