Marlene Parrish - What Einstein Told His Cook 2

Here is an oversimplified account of the complex chemical reactions that take place when you cut an onion.

Neither the tear gas compound T nor the pungency compounds exist as such in the uncut onion. They are formed when the cells are broken open by cutting or chewing, at which time the enzyme alliinase (A) and a group of compounds known as S-alk(en)yl cysteine sulfoxides (S), which until then had been isolated from each other in different parts of the onion’s cells, are liberated. They then react with each other to form the tear gas: A + S T.

A different set of alliinase-activated reactions produces a mixture of ammonia, pyruvic acid, and unstable sulfenic acids. The sulfenic acids react further to form a number of flavor and pungency compounds, primarily alkylthiosulfinates.

The amount of pyruvic acid formed in the last two reactions is generally used as an index of pungency, but only because it is stable and easy to measure in the laboratory. It is not itself responsible for the pungency of onions.

And now for a few of what Dave Letterman might call “stupid onion tricks,” measures that are often claimed to prevent tears while cutting onions. After reading my parenthetical comments, you can decide how much sense the tricks make.

Cut the stem end off before the root end. (Any onion with half an IQ will remember the cutting order and behave accordingly.)

Let a stream of cold water run in the sink while you do the cutting. (When the onion vapors see the water they will rush toward the sink to drown, even if it’s halfway across the room.)

Clamp a wooden match between your teeth. (You’ll never notice your eyes stinging if you bite on the match head.)

Keep a piece of bread in your mouth. (And make sure to chew it ostentatiously, so the onion will know it’s there.)

Wear contact lenses to protect your corneas.

If you wear contact lenses, remove them because the irritating vapors can get behind them, preventing the tears from washing them out.

Cut or chop your onions under water. You may either fill the sink with water and do your cutting beneath the surface, or put on your scuba gear and take the job to the swimming pool. (These methods should work, except for the little problem of the onion pieces floating away before you can collect them.)

But seriously, folks, here’s the most practical and effective method of all (fanfare, please, Maestro): Chill the onions in the refrigerator for a couple of hours before cutting. This slows down the chemical reaction that produces the tear gas and lowers its vapor pressure (its tendency to float around).

Best of all, just learn how to dice an onion as quickly and efficiently as the chefs do, and there won’t be time for the irritating vapors to bother your eyes very much. Several cookbooks illustrate the technique. And remember that using a very sharp knife will break fewer cells and produce less tear gas.

An effective, inexpensive knife sharpener made by Fiskars of Finland. The ingeniously angled abrasive wheels remove a minimal amount of metal. Available by the name “ASPEKT” at IKEA.

And speaking of sharp knives, everyone swears by his or her pet sharpening device, sometimes to the point that swearing can actually occur when two chefs defend their favorite methods. But I have found that a fancy, expensive sharpener isn’t at all necessary. The inexpensive device shown in the illustration on the preceding page does an excellent job, especially if you follow it with a few swipes on a “sharpening steel,” which straightens out any microscopically wavy edge left by the sharpener.

THE FOODIE’S FICTIONARY:Leek—a hole in the bucket

GEORGIA ON MY MIND

Why are Vidalia onions so much sweeter than other onions?

T erroir .

Permit me to explain.

Vidalias aren’t unique in their mildness. There are several brands of mild onions grown in other parts of the country, including the Maui, Walla Walla, Texas 1015, and OSO. Note that I have called them “mild,” not “sweet.” They don’t necessarily contain more sugar than other onions; they simply contain lesser amounts of both the pungent-tasting and tear-producing compounds.

In the case of Vidalia, Georgia, a town on the state’s southern coastal plain, the mildness of the onions has been attributed to a dearth of sulfur in the area’s sandy loam soils. Because both the pungency chemicals and the tear-producing chemicals are compounds of sulfur (see chapter 3), sulfur-deprived plants are presumably able to manufacture less of them.

Regardless of soil, weather, and cultivation conditions, any plant is the species and variety it is because the genes in its seeds tell it to manufacture precisely the proper proteins, enzymes, and hormones, and nothing a farmer can do will change that. Vidalia onions, for example, are all of the variety called yellow granex.

But that’s heredity, and as everyone knows, an organism’s characteristics are shaped by both heredity and environment. A multitude of environmental factors, such as the amounts of various nutrients in the soil; the soil’s texture and drainage; its micro-flora and -fauna; its proportions of sand, rock, and clay; the land’s slope; the growing temperatures; the amounts of rain, wind, and sun—in sum, a plant’s entire micro-milieu, short of the phase of the moon at planting time—can lead to subtle differences in the ultimate fruit or vegetable. (That’s no joke about the phase of the moon. Vintners who practice so-called biodynamic winemaking reportedly wait until the moon has waned before removing the sediment from their wines. They believe that inasmuch as the full moon draws up the tides, it would obviously draw the sediment upward and keep it from settling. What could be more logical?)

French winemakers have lumped all of these variables and imponderables (usually excluding the phases of the moon), along with a healthy measure of Gallic shrug and a soupçon of mysticism, into the concept of terroir, which is now modishly being applied to virtually all fruits and vegetables. But there is nothing profound about terroir , which literally refers to an agricultural region or territory. It is merely a summation of all the peculiarities of a particular local growing environment. And anyone who has traveled in France knows that on the other side of every hill or around every bend may be lurking a very different microclimate.

Let us return now to Vidalia, Georgia, where the Vidalia Onion is a registered trademark of the Georgia Department of Agriculture and where a state law decrees the characteristics the onions must have in order to wear that jealously guarded label. A vigorous marketing campaign encouraging us to “eat ’em like an apple” (but why would we want to, may I ask?) undoubtedly plays a role in gilding the onion, so to speak. And no one can deny that economics and politics are central ingredients in the onion’s reputation. Quite a few lawsuits have been fought along the lines of “My onion is more Vidalia than your onion.”

Clearly, not every acre of farmland within the officially sanctioned and virtually sanctified twenty-county Vidalia Onion region of southeastern Georgia can contain exactly the same amount of sulfur in the soil. Thus, sulfur cannot be the only factor. Lacking credible scientific evidence, I’m willing to chalk it all up to a je ne sais quoi factor. In other words, I believe in terroirism .

THE FOODIE’S FICTIONARY: Bain marie —Mary needs a bath