Kitchen Myths

Facts and fiction about food and cooking, by Peter Aitken

Category Archives: Equipment

A pressure gauge on your propane tank is useful

Many folks have paid for a pressure gauge on their propane tanks in the mistaken belief that it tells you how much propane is left. Me too, I got one before I figured out that it is useless. How come? High school physics class to the rescue!

In the tank, the propane is mostly liquid. At the top of the tank, above the liquid propane, is gaseous propane. When you open the valve, some of the propane gas is released, and some of the liquid vaporizes to maintain what physicists call the vapor pressure – the pressure at which liquid and gaseous propane are in equilibrium. As long as there is some liquid propane in the tank, this pressure remains the same (although it does vary with temperature, being higher when the temperature is warmer). Whether 95% full or 5% full, the pressure is the same. Only when there is no more liquid propane in the tank will the pressure shown on your gauge drop. You can tell how much propane is left by weighing the tank, but that’s a bother. You can also tell by feeling the side of the tank when it is in use (when your grill is on). At some place the tank will be colder below, warmer above. That’s the level of the liquid propane. Bottom line? Keep an extra tank on hand.

Sharp knives make cutting your fingers more likely

A sharp knife cuts more easily, so this make sense – right? But, it is not true. With a sharp knife, cutting is easily done and nothing needs to be forced. And it’s the forcing that causes cuts, when you have to press down hard and the knife slips onto your finger. Ouch! With a really sharp knife, your cutting can be smooth and relaxed, with less danger of cuts. So, keep your knives sharp!

When baking muffins, fill empty cups with water for even baking

Suppose you have a 12-cup muffin tin and enough batter for only, say, six muffins. This myth says to fill the empty cups with water or you’ll get uneven baking and your tin might warp. It does no harm, but it’s a waste of time and has no effect whatever on the evenness of cooking. Why would it? Even with all 12 cups full of batter, most of them are not adjacent to another cup on one or two sides and things cook perfectly fine. If your tin warps, that’s a sign of low quality, and maybe you need a replacement.

There is one scenario where putting water in the empty cups makes sense—if you have already greased them. Baking an empty, greased cup makes for hard cleanup!

All pressure cookers are created equal

Pressure cookers work because they allow you to cook food in water or steam above the usual boiling point of 100 degrees C (212 F). Under pressure that is higher than normal, water boils at higher temperatures, and these higher temperatures cook your food faster and, sometimes, better. But, how much extra pressure—that’s the question.

At normal atmospheric pressure, water boils at 100 degrees C (212 degrees F). If your pressure cooker raises the pressure by 7 PSI (pounds per square inch), the temperature goes up to 112 degrees C.  An increase of 15 PSI gives you 120 degrees, and a 37 PSI increase in pressure gives you 140 degrees C.  The higher the pressure, the faster your food will cook. There’s no practical way to measure the pressure in your cooker, so, be warned: the timing in pressure cooker recipes may need to be modified based on the characteristics of your cooker. After a few tries, you should be able to get a feel for whether your cooker is faster or slower than typical.

You cannot do serious cooking in a microwave

This is one of the very silliest myths but it refuses to die out. There are a lot of people who use their microwave for nothing but boiling water and reheating leftovers and they are really missing out on a lot. I suspect that this myth got its start when microwaves were a new tool and a lot of awful microwave recipe books were published. Some people tried to use their microwave as a general purpose stove and oven replacement rather than as a more specialized tool that is well suited for some jobs but not at all useful for others. For example, you would not want to use a microwave for a roast beef, fried potatoes, or baking bread, but it works just great for things like rice, poached fish, and steamed veggies. I find it particularly handy for making polenta and risotto, with results that are every bit as good as the stovetop with much less work and worry. If you want to expand your microwave repertoire I highly recommend The Microwave Gourmet by Barbara Kafka. Another excellent book is The Moghul Microwave by Julie Sahni (Indian dishes).

Hot pan, cold oil to prevent sticking

This mantra is repeated by many people as the best way to prevent food from sticking to the pan when sautéing or stir frying. The idea is that you heat up the pan first then add the cold oil and almost immediately add the food. This works of course, so it is not a myth in that it is untrue. It is, however, false to think that this is the only or the best way to prevent sticking. What you really want is “hot pan, hot oil” and that’s what you are actually getting because the cold oil heats up almost instantly when added to the hot pan. You’ll get the same results if you heat the oil along with the pan rather than adding the oil at the last minute. In fact some cooks prefer this technique because the appearance of the oil in the pan can give you some indication of when the pan has reached the proper temperature.

There is one situation where you don’t want to heat the oil in the pan, and that’s when you need a super-hot pan for searing a steak or similar tasks. It has nothing to do with sticking, however, but with the oil burning. Your pan is likely to reach 600 degrees and that is well above the smoke point of any cooking oil, so your oil will start to smoke and decompose well before the pan is ready. My approach is to not add oil to the pan at all, but rub it on the steak – patted dry first, of course – just before putting the steak in the pan.

You must use a serrated knife to slice ripe tomatoes

You certainly can use a serrated knife for ripe tomatoes, but there’s no need to. If you find yourself always turning to a serrated knife for this task it is probably because your straight-edged knives are not sharp enough. A well-sharpened regular knife will make paper-thin slices from a ripe tomato—in fact, some people use this as a test for a knife’s sharpness.

Gas cooktops are better than electric

It’s become almost an article of faith that gas cooktops are better than electric, and that any “serious” cook should aspire to owning one. This belief does not stand up to intelligent scrutiny, however. Gas cooktops are fine, of course, but when comparing them to electric you will see that there’s no overall objective superiority. Let’s take a look at some of the ways gas and electric can differ–and then a brief look at induction cooking: Read more of this post

Avoid aluminum cookware because of Alzheimer’s disease

This myth got its start a number of years ago when medical researchers found elevated levels of aluminum in diseased tissue from the brains of Alzheimer’s patients (dead ones, I hope). One logical possibility (but not the only one) was that the raised aluminum level was responsible for causing the disease. Get exposed to too much aluminum, from your job perhaps or your cookware, and you would have a better chance of coming down with this awful disease. People started avoiding aluminum cookware, and some still are – unnecessarily it turns out. Subsequent research has failed to show any connection between aluminum exposure and Alzheimer’s, and it is believed that the elevated aluminum in the brains of Alzheimer’s patients is a result of the disease process. In other words, high aluminum levels do not cause Alzheimer’s, but rather Alzheimer’s causes high aluminum levels.

Heating a pan prevents food from sticking by closing cracks in the metal

Most cooks know that you should start with a hot pan to prevent or minimize food sticking. You may hear a bizarre theory that goes something like this: food sticks to pans because it seeps into minute cracks and pits in the pan and then solidifies when heated, becoming stuck. If you heat the pan before adding the food, the metal expands and fills in the microscopic cracks and holes in the pan’s surface or at least makes them smaller. With fewer or smaller surface defects for the food to grab onto it is less likely to stick.

Unfortunately whoever came up with this idea knew nothing about the physical properties of metals. When metal expands due to heating, each individual atom vibrates faster and faster and thus takes up more space. The result is the same as if each atom simply got a bit bigger, and the result is that the entire piece of metal, defects, holes and all, gets bigger. Thus, if you heat a donut-shaped piece of metal, the outer diameter gets bigger and so does the diameter of the hole. You have probably used this fact yourself when trying to get a metal screw lid off a glass jar. Running hot water over the lid expands the entire lid and loosens its grip on the jar, making it easier to remove. So, heating a pan would cause these hypothetical surface cracks to get larger, not smaller.

You can’t wash cast iron cookware with soap

This myth seems to make sense—after all, you use fat to season cast iron and soap removes fat, case closed, right? It’s not that simple.

The seasoning layer on the surface of the pan is formed when the pan is heated while in contact with some fat or oil. This may happen during normal cooking or during a special seasoning process that many people use with a new pan. The result is a chemical reaction in which that fat polymerizes, meaning that multiple individual fat molecules join together to form larger molecules. It is these larger polymer molecules that bind to the metal of the pan and form the seasoning. And, guess what, the polymer is not dissolved by soap. So, it’s perfectly OK to use a mild soap on your cast iron if you are so inclined. Never use harsh detergent, put the pan in the dishwasher, or scrub with an abrasive, however, as these will take off the coating.

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