What Einstein Told His Cook (4 page)

Among the most voracious electron snatchers are the so-called free radicals, atoms or molecules that desperately need another electron and will snatch one from almost anything it encounters. (Electrons like to exist in pairs, and a free radical is an atom or molecule that has an unpaired electron desperately seeking a partner.) Thus, free radicals can oxidize vital life molecules, slowing down the body, causing premature aging, and possibly even heart disease and cancer. The problem is that a certain number of free radicals occur naturally in the body from a variety of causes.

Antioxidants to the rescue! An antioxidant is an atom or molecule that can neutralize a free radical by giving it the electron it wants before it steals one from something vital. Among the antioxidants we obtain from our foods are vitamins C and E, beta-carotene (which turns into vitamin A in the body), and those ten-syllable tongue-twisters you see on the labels of many fat-containing products to keep them from turning rancid by oxidation, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT).

Back for a moment to sulfites. We should note that some people, especially asthmatics, are very sensitive to sulfites, which can cause headache, hives, dizziness, and difficulty in breathing within minutes of eating them. The FDA requires specific labeling of products that contain sulfites—and there are many, from beer and wine to baked goods, dried fruits, processed seafoods, syrups, and vinegars. Search the labels for sulfur dioxide or any chemical whose name ends in-sulfite.

TREACLE, TREACLE, IN THE JAR, HOW I WONDER WHAT YOU ARE

What are those sweet syrups called treacle and sorghum, and how are they different from cane syrup?

C
ane syrup
is simply clarified sugar-cane juice, boiled down to a syrup in much the same way maple syrup is made by boiling down the thin, sucrose-rich sap of the North American sugar maple and black maple trees. Black birch trees also have a sweet sap that can be boiled down into a syrup.

Treacle
is a term used mainly in Great Britain. Dark treacle is similar to blackstrap molasses and has blackstrap’s somewhat bitter taste. Light treacle, also known as golden syrup (a significant improvement in nomenclature), is essentially cane syrup. The most popular brand, Lyle’s Golden Syrup, can be found in American specialty stores.

Sorghum
is made neither from sugar cane nor sugar beets, but from a grass-like cereal grain plant with tall, strong stalks. It is grown around the world in hot, dry climates, mostly for use as hay and fodder. But some varieties have a sweet juice in the pith inside the stalks that can be boiled down into a syrup. The resulting product is called either sorghum molasses or sorghum syrup or sometimes just plain sorghum.

A TIGHT SQUEEZE?

My recipe for fondant tells me to dissolve two cups of sugar in one cup of water. It won’t fit, will it?

W
hy didn’t you try it?

Add two cups of sugar to one cup of water in a saucepan and stir while heating slightly. You’ll see that all the sugar will dissolve.

One of the reasons is very simple: Sugar molecules can squeeze into empty spaces between the water molecules, so they are not really taking up much new space. When you get right down to the submicroscopic level, water isn’t a densely packed pile of molecules. It’s a somewhat open latticework, with the molecules connected to one another in tangled strings. The holes in this latticework can accommodate a surprising number of dissolved particles. This is especially true of sugar, because sugar molecules are built in such a way that they just love to associate with (Techspeak: hydrogen-bond to) water molecules, and that makes sugar very mixable with water. As a matter of fact, with heating, you can coax more than two pounds (5 cups!) of sugar to dissolve in a single cup of water. Of course, by the time you get that far, it’s not clear whether you’re dealing with a boiling solution of sugar in water or with bubbling melted sugar containing a little water.

A snapshot of the arrangement of H
₂
O molecules in water. The dashed lines represent hydrogen bonds, which are continually breaking and re-forming between molecules.

And that’s how candy was born.

Yet another reason is that two cups of sugar is considerably less sugar than it seems. Sugar molecules are both heavier and bulkier than water molecules, so there won’t be as many of them in a pound or in a cup. Also, the sugar is in granulated form, rather than in the form of a liquid, and the grains don’t settle down into the cup as tightly as you might think. The surprising result is that a cup of sugar contains only about one twenty-fifth as many molecules as there are in a cup of water. That means that in your two-cups-of-sugar-in-one-cup-of-water solution, there is only one molecule of sugar for every twelve molecules of water. Not such a big deal, after all.

TWO KINDS OF BROWNING

Recipes sometimes tell me to caramelize chopped onions, meaning to sauté them until they are soft and lightly browned. Does “caramelize” mean simply to brown something? And what’s the connection, if any, to caramel candy?

T
he word
caramelize
is used for the browning of a variety of foods, but strictly speaking, caramelizing means the heat-induced browning of a food that contains sugars, but no proteins.

When pure table sugar (sucrose) is heated to about 365ºF it melts into a colorless liquid. On further heating it turns yellow, then light brown and in quick succession darker and darker browns. In the process it develops a unique, sweetly pungent, increasingly bitter taste. That’s caramelization. It is exploited in making a wide range of sweets, from caramel syrups to caramel candies to peanut brittle.

Caramelization entails a series of complex chemical reactions that still aren’t completely understood by chemists. But they begin when the sugar is dehydrated and end with the formation of polymers—large molecules made up of many smaller molecules bound together into long chains. Some of these large molecules have bitter flavors and are responsible for the brown color. If the heating is carried too far, the sugar decomposes into water vapor and black carbon, as when you get too impatient while toasting a marshmallow. (Hey, kids: It should
not
catch fire.)

On the other hand, when small amounts of sugars or starches (which, remember, are made up of sugar units) are heated in the presence of proteins or amino acids (the building blocks of proteins), a different set of high-temperature chemical reactions takes place: the Maillard reactions, named after the French biochemist Louis Camille Maillard (1878–1936), who characterized the first step in the process. Part of the sugar molecule (Techspeak: its aldehyde group) reacts with the nitrogen part of the protein molecule (Tech-speak: an amino group), after which follow a series of complex reactions that lead to brown polymers and many highly flavored, as-yet unidentified chemicals. Food scientists are still having international research conferences to figure out the Maillard reactions in detail.

Maillard reactions are responsible for the good flavor of heat-browned, carbohydrate-and protein-containing foods such as grilled and roasted meats (yes, there are sugars in meats), bread crusts, and onions. “Caramelized” onions do indeed taste sweet, because in addition to the Maillard reactions, heating makes some of their starch break down into free sugars, which can then truly caramelize. Moreover, many recipes for caramelized onions prime the pump by including a teaspoonful of sugar.

The moral of the story is that the word
caramelization
should be reserved for the browning of sugar—any kind of sugar—in the absence of protein. When sugars or starches occur together with proteins, as they do in onions, breads, and meats, the browning is mostly due to Monsieur Maillard, not to caramelization.

The “caramel color” that you see on the labels of cola soft drinks, low-quality soy sauces, and many other foods is made by heating sugar solutions with an ammonium compound. Ammonium compounds act just like the amino groups in proteins. So in a sense, the “caramel color” is really a sort of Maillard color.

CORNY, BUT SWEET

So many prepared foods list “corn sweeteners” or “corn syrup” on the label. How do they get all that sweetness out of corn?

I
know what you’re thinking. The corn that you bought at the farmers’ market the other day wasn’t really “as sweet as sugar,” as the vendor promised, was it?

“Sweet corn” does indeed contain more sugar than “cow corn,” but even in the new sugar-enhanced and supersweet varieties it’s precious little compared with sugar cane or sugar beets. Why is it that corn-derived sugar is so widely used instead of cane or beet sugar?

Two reasons, one economic and one chemical.

We don’t produce nearly enough cane or beet sugar in the United States to satisfy our 275 million sweet teeth, so we have to import some. In fact, we import about sixty times more sugar then we export. But much of this imported sugar comes from countries that have never won awards for crop reliability, political stability, or love for Uncle Sam, so sugar importing has always been a bit of a gamble. On the other hand, right here at home we produce enormous amounts of corn—ton for ton, more than six thousand times as much corn as sugar cane. So if we could only get our sugar fix from home-grown corn, the problem would be solved.

Well, we can. But we’re not limited to corn’s meager allotment of sugar. Through the magic of chemistry, we can actually make sugar out of cornstarch. There’s lots more starch than sugar in corn.

What do we find inside the corn kernel’s cupboard? If we take away the water from a kernel of corn, the remainder will be about 84 percent carbohydrates, a family of biochemicals that includes sugars, starches, and cellulose. The cellulose is in the kernel’s hull. But starch is the main component of all the other stuff outside the cob.