Gas or Charcoal?
By Robert L. Wolke
Wednesday, July 7, 2004; Page F01
I never write about politics in this column. But this is an election year, this is The Washington Post, and I cannot remain silent any longer. The most vital issue facing our nation is so critical, and the two candidates so contrasting, that I cannot resist asserting my position on this, the most contentiously debated concern of our time: Which is better for grilling? Charcoal or gas?
I hereby express my wholehearted endorsement of charcoal.
Caution: The opinions expressed in this column are inflammatory. Reader discretion is advised.
I have 11 grilling cookbooks on my shelves, but they all shrewdly gloss over two important points: that grilling and barbecuing are not the same thing, and that all fuels are not created equal.
Recognizing that almost no one understands the distinction between grilling and barbecuing, the cookbooks include both kinds of recipes to appeal to as many backyard cooks as possible. And because a majority of all "barbecue grills" (a name that only compounds the confusion) in the United States are gas-fired, the authors stifle their unanimous conviction (which they would admit only under oath) that charcoal is clearly superior to gas for grilling. An author cannot afford to lose a major segment of his or her potential readers, many of whom have shelled out big bucks for Brobdingnagian stainless steel, 18-wheeler gas grills equipped with everything but cruise control and global positioning systems.
In true grilling, the food is placed within several inches of a very hot (500 to 1,000 degrees), smoke-free fire and cooked quickly. Think of steaks, chops, hamburgers, kebabs, sausages, chicken parts and shrimp, to name the most commonly grilled foods. Barbecuing, on the other hand, consists of long (several hours), slow, relatively low-temperature (300 to 350 degrees) cooking, with the food confined in a pit or some sort of enclosure along with a smoky fire. Think of beef or pork ribs, pork shoulder or brisket being slathered with top-secret sauces by men wearing cowboy hats.
For grilling, which is the subject of this column, there are three kinds of fuels: lump charcoal, briquettes and gas.
If wood is heated in the absence of oxygen (a process called destructive distillation), it can't burn. Instead, it decomposes. First, its water is driven off. Then its carbohydrates (mainly cellulose and lignin) begin to break down into methyl alcohol (therefore known as wood alcohol), acetic acid, acetone, formaldehyde and many other smokes and gases. Eventually, nothing is left but virtually pure carbon. That's lump charcoal.
For at least 4,000 years, people have been making charcoal from wood, for use as a cooking fuel. Today's commercial lump charcoal, still retaining the shapes of the wood chunks it was made from, burns hot and clean, with minimal amounts of smoke. It therefore earns my vote (and the secret ballots of most grilling experts) as the best possible fuel for grilling.
Briquettes -- and I won't call them charcoal briquettes because they contain so much other stuff besides charcoal -- were invented and patented by one Orin F. Stafford, a professor at the University of Oregon. Henry Ford then built a plant to manufacture them on a grand scale, thereby turning the waste sawdust and wood scraps from his Model T plant into a profitable product.
Originally, briquettes were made from powdered charcoal, compressed and bound with starch. But today, they're not that simple. According to a 2000 publication of the Kingsford Products Co., heir to Ford's charcoal company, their briquettes contain wood charcoal, mineral char (a soft, brown coal), mineral carbon (graphite), limestone (to produce that nice coating of white ash), starch (as binder), borax (helps release the briquettes from the molds), sawdust (for easier ignition) and sodium nitrate, which releases oxygen when heated and speeds the burn.
Personally, I would rather not have tar-laden coal, starch, borax and sawdust burning beneath my steak.
The fuel used in modern gas grills is either methane (natural gas) or propane, two hydrocarbons whose molecules are made of carbon atoms and hydrogen atoms. And that's the difference between solid charcoal and gaseous fuels: the hydrogen atoms. While charcoal burns completely to produce only carbon dioxide, an odorless, tasteless gas, methane and propane produce both carbon dioxide and water vapor. (Hold a transparent glass plate briefly above a gas flame and you'll see it fog up with condensed water.)
Each molecule of burned propane produces four molecules of water. In a typical 40,000-Btu-per-hour gas grill, that translates to 1 1/2 quarts of water being given off per hour. The bottom surface of the meat is thus being steamed, and its temperature cannot get as high as with dry-burning charcoal. No wonder you can't quite achieve that flavorful, seared, brown crust that charcoal produces.
When Heat Meets Meat
Grilling mavens distinguish between two techniques: direct grilling, where the meat is placed directly above a bed of charcoal, and indirect grilling, where the charcoal pile is off to one side.
In the direct method, the heat reaches the meat by both convection (rising hot air) and radiation (infrared rays). In the indirect method, since the meat isn't directly above the heat source, the heat reaches the meat predominantly by radiation. (The third heat transmission mechanism, conduction, doesn't play much of a role in either grilling or barbecuing.)
The meat therefore doesn't attain as high a temperature in the indirect method and cooks more slowly. If the cooking apparatus is covered, the rising hot air from the coals is trapped and circulates throughout the enclosure, making it into a sort of convection oven. Throw in a few chips of moistened hardwood and you can smoke the food at the same time.
Whoops! In that last paragraph we've slipped from grilling into barbecuing. It's easy to do, because the same equipment can be used for both.
So I urge you to vote for charcoal over propane. There's no fuel like an old fuel.
Robert L. Wolke (www.professorscience.com) is professor emeritus of chemistry at the University of Pittsburgh and the author, most recently, of "What Einstein Told His Cook: Kitchen Science Explained" (W. W. Norton, hardcover, $25.95). He can be reached at email@example.com.
© 2004 The Washington Post Company