Cooking Myths

by Craig Good
February 10, 2015

One of the things that distinguishes homo sapiens from the rest of the Animal Kingdom is that we are the species that cooks. Countless millennia of growing, hunting, preparing, processing, and cooking our food has produced a lot of folk wisdom. Some is based on solid science, and some is just plain made up. Because preparing food should be rewarding, fun, and safe, grab an apron and join me in the kitchen. See if you can guess which cooking tips are myth, true, or somewhere in between.

There's no way we can cover them all, but we'll try to catch a lot of common ones. Let's start with some myths about equipment and technique, and then march through the pantry by category.

Equipment and technique

Grilling causes cancer — MYTH

This myth seems to stem from the discovery of the presence of Acrylamide in some burned foods. Later it was found to be naturally occurring in many foods. While it has been linked to toxic effects on the nervous system and fertility, the FDA and the World Health Organization found that intake would have to be some 500 times that found in an average diet to impact the nervous system, and 2,000 times to affect fertility.

Cooking in aluminum pots and pans causes Alzheimer's — MYTH

No link has been found between aluminum cookware and Alzheimer's. It does appear that Alzheimer's sufferers have higher concentrations of aluminum in their brains, but if aluminum exposure were the cause then Alzheimer's would be more prevalent in people with very high exposure to aluminum. And it isn't. Besides, your cookware is not a major source of aluminum intake compared to other common sources.

You should use non-reactive bowls and pans for acidic foods like sourdough and tomato sauce — TRUE

Cooking or preparing acidic foods in aluminum, copper, or other reactive metals can both damage the cookware and impart a metallic taste or odd color to your food. Prepare in plastic or glass bowls, and cook in either stainless steel or non-stick pans instead.

Plastic cutting boards have fewer germs than wooden ones — TRUE

It turns out that the study claiming wood has fairly decent anti-bacterial properties was flawed, failing to account for bacteria hiding inside the wood and away from the surface. Wooden boards are not allowed in commercial kitchens. But are they safe for home? Well, they can be. Kept clean and well maintained, either one is a perfectly good food prep surface. The most important safety tip is to avoid cross contamination. Use separate boards for raw meats and vegetables.

Whip cream and egg whites in a copper bowl if you have one, never in a plastic one — TRUE

Besides good heat conductivity to keep its contents cold, trace copper ions give a more stable foam. But oil molecules on the surface of plastic interfere with foam development.

The microwave oven was invented when a Magnetron melted the candy in a guy's pocket — TRUE

One day radar engineer Percy Spencer noticed that the candy bar in his pocket had melted when he stood in front of an active radar. He wasn't the first to notice the effect, but he was the first to try the next logical step: Popcorn. He later enclosed the magnetron in a metal box to contain the radiation, and the microwave oven was born. Now you know why it was called the Radarange.

Microwave ovens destroy nutrients — MYTH

The only thing the non-ionizing radiation of a microwave oven can do to food is make it hotter. In fact, it's so gentle that it's one of the best methods, along with steaming, for preserving nutrients while cooking.

You should never heat baby formula in a microwave oven — TRUE

It's not because it damages the nutrients. Microwaves heat unevenly, and since there's no stirring from convection sometimes part of the liquid is very hot while the surrounding liquid is cooler. So the risk to baby is getting scalded.

Alcohol completely evaporates from food when you cook it. — MYTH

Ethanol does boil at a lower temperature than water, but also binds with other compounds. Depending on the recipe and technique, as much as 85% of the alcohol can remain. Only very long cook times, upwards of 3 hours, are likely to remove it all.

Salt is just salt — MIXED

Sure, chemically it's just Sodium Chloride. But the grain size between table salt and Kosher salt is so different that if a recipe calls specifically for one, you really don't want to substitute. A teaspoon of table salt is a lot saltier than a teaspoon of Kosher because it weighs more.

Vinegar never goes bad — TRUE

Cook's Illustrated magazine tested 12-year-old balsamic. It was fine. Old vinegar will have a harmless sediment. Stir it up, filter it out, or just ignore it. Don't throw away old vinegar.

Fruits and Vegetables

Limes have lots of Vitamin C — MIXED

Like all citrus, they have some. But only half as much as lemons.

Cooking vegetables robs them of nutrition — MYTH

The "raw is better" idea is really another facet of the naturalistic fallacy. Enthusiasts will point out that raw vegetables have all their enzymes intact. While this is true, the acids in your stomach will dispatch any that weren't rinsed away when you washed them. (You do wash your vegetables, I hope.) Besides, the plants need the enzymes to grow, but they're of no particular use to you. On the contrary, cooking food is why humans extract nutrients from our food more efficiently than our poor simian cousins, some of whom have to spend a third of their day chewing.

Brightly colored vegetables are the most nutritious — MYTH

While much colorful produce is rich with nutrients, many pale veggies are packed with goodness.

Grains

Bread goes stale because it dries out — MYTH

Actually it's just the opposite. The bread is absorbing moisture, actually getting heavier. The moisture causes the starch granules to crystalize, hardening the bread. That's why you don't keep it in the refrigerator, and why a brief visit to the oven can soften it again.

Beans make you fart — TRUE

Indeed beans, and a long list of other foods high in fiber and/or polysaccharides, can contribute to flatulence. This can be mitigated by soaking, ingesting a sugar-digesting enzyme such as the one found in a product called Beano, and other techniques.

Pasta

There are a lot of myths about pasta and its preparation. Here are some common ones.

Salting the water makes it boil faster — MYTH

You do want to salt the water for flavor, but the change in boiling point is so tiny that you need lab equipment to find it.

Put a lid on the pot to make it boil faster — MIXED

This makes a tiny bit of difference, but only after the water is close to the boiling point. Feel free to start the heat and then look for the lid.

Adding olive oil keeps the pasta from sticking, or the water from boiling over — MYTH

Oil and water don't mix. It won't prevent boiling over, but will give you slimy pasta that sauce doesn't want to stick to. And it's a waste of olive oil.

You should never rinse your pasta — TRUE

You want that starchy water to act as an emulsifier to help your sauce adhere to the pasta.

You need a large pot of boiling water to cook pasta — MYTH

Surprisingly, you not only don't need much water, but it doesn't even have to be boiling the whole time! Chef J. Kenji López-Alt developed a wonderful technique for cooking dry pasta that I'll link to in the show transcript.

Dairy

European eggs don't need refrigeration — TRUE

But their eggs are sold unwashed, and Europeans tend to buy in small quantities and consume their eggs quickly.

Cheese never goes bad - you can just cut off the mold — MIXED

Hard cheeses are usually fine for quite a while under the mold. Soft cheeses, like bleu cheese, not so much. Cheese stores best cool and dry, not sealed in a bag where it can collect moisture.

Raw milk is healthy — MYTH

What it really is, is risky. Their are no significant nutritional advantages to raw milk, and the serious health risks aren't worth the small flavor advantage. Raw milk enthusiasts typically represent another facet of the naturalistic, "raw is better" fallacy.

Poultry

Never wash your chicken — TRUE

Poultry is the only meat commonly processed with the skin on. That's why it can harbor dangerous microbes such as salmonella. If you wash it, you aren't disinfecting it at all, but spreading germs all over the sink, your hands, and the kitchen. Cooking it is the best way to pasteurize it.

Seafood

Lobsters scream when you boil them — MYTH

That sound is steam rapidly escaping their shells. The separate question, do they feel pain, is still unsettled. Many think that such a simple nervous system is incapable of it. While some scientists find that they do feel pain, other scientists question the validity of their methods. The answer for now seems to be we just don't know.

Fish comes from an environment about the same temperature as your refrigerator, which is why it spoils faster than meat — TRUE

Keeping fish properly chilled is important for both safety and flavor. That's why good fish shops pack it in ice for you.

Finally, we come to the subject of some of the most prevalent food myths out there.

Meat

Pork needs to be cooked well-done — MYTH

The risk of trichinosis has all but vanished in the United States and many other parts of the world. The USDA has even revised the minimum safe temperature for pork downward to 145° F (63° C).

Leftover meat needs to be reheated — MIXED

It's safe to eat cold leftovers if they were rapidly cooled after cooking. Bacteria in the presence of air can reproduce in a temperature range between 40° F and 140° F (5° C - 60°C). If it stayed out on the counter for a couple of hours before hitting the fridge, consider a thorough reheat.

Red juice leaking from a burger means it's not safe — MYTH

No, that's not blood, and no, it doesn't mean the burger is undercooked. The doneness of meat is entirely a function of temperature. Beef that isn't overcooked should still have plenty of juices. It's true that ground meat is safer cooked all the way to medium, or 140° F (60° C) than at medium rare. Steaks are safe at medium rare (132° F, 55°C) because the interior hasn't been exposed to the air. Once beef passes medium, it's really not getting any safer or any better cooked. The proteins are just contracting, getting tougher, and squeezing out the juices — along with a lot of the flavor.

You can test the doneness of steak by pressing it with a finger — MYTH

While experienced chefs appear to get away with this, an instant-read thermometer inserted into it is the only way to accurately know how done a piece of meat is.

Don't turn a steak with a fork, or cut it open to check it, or the juices will run out — MYTH

This is trivially proven by weighing the steaks before and after. They aren't bags and they don't spring leaks.

Last, but certainly not least, here is what I think must be the most stubborn and pervasive kitchen myth of all:

Searing meat seals in the juices — MYTH

Quite the opposite is the case. Heating meat always causes proteins to contract, which always squeezes out some juices. What that quick sear does is provoke the Maillard reaction. This is the same chemical change that happens when you toast bread or brown food in general. Amino acids and sugars react to form hundreds of flavor compounds, giving just about anything a real flavor boost.

I don't know about you, but this is making me really hungry. So as long as we're in the kitchen, let's get cooking. Bon apetit, be safe, and when you hear something about cooking that "everybody knows", it pays to be skeptical.

By Craig Good