What Einstein Kept Under His Hat: Secrets of Science in the Kitchen (49 page)

Not often realized is the fact that all flavoring additives, natural or artificial, are made by humans. To make an artificial flavor, a flavor chemist (called a flavorist) in a laboratory has to select and blend the right chemical compounds in the right proportions to simulate a natural flavor. And to make a natural flavor, someone in another laboratory or factory has to extract and distill or concentrate the flavor compounds from the raw plant or animal materials.

An even less appreciated fact is that in many cases the man-made flavoring chemicals are identical to Nature’s flavoring chemicals. For example, one of the primary flavor chemicals in bananas is isoamyl acetate, which can be made synthetically and used as a (rather poor) imitation of banana flavor.

Most natural flavors, however, are much more complex than that. Some thirty-seven different chemical compounds have been identified in the flavor of mangoes, and more than eight hundred in the aroma of coffee. To imitate the effects of these natural flavors on the palate, a flavorist must blend a dozen or more chemicals, no single one of which hits the flavor nail directly on the head.

An interesting case is the vanilla bean, most of whose natural flavor comes from its 2 percent content of vanillin, known to chemists by its nickname, 4-hydroxy-3-methoxy benzaldehyde. If this and the other natural vanilla flavors are extracted into alcohol, the product may legally be labeled Pure Vanilla Extract, a “natural” flavoring. But if the product contains synthetic vanillin, which can be made by any of several processes, it must be labeled Imitation Vanilla Flavoring.

But get this: If the synthetic vanillin was made not by combining chemicals in a laboratory but by allowing bacteria to ferment ferulic acid, a chemical obtained from corn or rice, it may be labeled Natural Vanilla Flavor, because fermentation is a “natural” process. The vanillin obtained by the fermentation, however, is absolutely identical to the vanillin made in the lab.

The bottom-line issue for cooks is “Does artificial vanilla flavoring taste as good as natural vanilla flavoring?” Well, in taste panels convened by
Cook’s Illustrated
magazine over a period of several years, the imitation vanilla flavoring was actually preferred over the natural product. So there!

I have observed an interesting phenomenon with milk and orange juice cartons. After I pour out the “last” drops, I can always come back later and pour out more liquid. What’s going on?

....

S
o you’ve noticed that, too, eh? It happens when you’re “emptying” all sorts of containers, including cocktail shakers and wine bottles. I hadn’t given it much thought, but you have inspired me to figure out what really
is
going on.

What’s undoubtedly happening is that as you “empty” the container, some of the liquid encounters microscopic rough spots or non-wettable spots on the container’s inside surface. These spots hold back small drops of the liquid, which remain stuck there as long as the container continues to be inverted. But when you return it to its upright position, the small drops can slide back down, because the path had been smooth up until they encountered those snags. So the drops do slide back down, joining their brethren at the bottom to form a pool. The pool is now heavier than any individual drop, so when you invert the container again the pool can steamroller right down past the rough spots.

I hope you are happier for understanding that. I know I am.

I am curious about marshmallow. Ever since I was a kid I’ve wondered how that sweet, puffy substance with such an odd name and texture was ever invented. Is it really old?

....

T
he modern version is only about a hundred years old, but it’s a new take on a several-thousand-year-old treat.

The magical material we call marshmallow is named after the marsh mallow plant (
Althaea officinalis
), whose roots contain a sweet, gummy sap that has been used as a confection and for its supposed medicinal properties for some four thousand years.

In the late nineteenth century, when candy makers were unable to keep up with demand for the real thing, an imitation marshmallow was concocted from sugar, starch, and gelatin. Today, most marshmallow candies are made from corn syrup, sugar, modified starch, and gelatin. (Modified starch is starch that has been treated chemically or physically to improve its characteristics for manufacturing purposes, such as by making it able to mix with and thicken cold water.)

The most pleasurable characteristic of marshmallow is its uniquely soft, pillowy texture, unmatched by any other food. To make it, a hot (240°F or 116°C) mixture of corn syrup, sugar, water, and gelatin is whipped vigorously into a frothy foam until it is two to three times its original volume. Zillions of microscopic air bubbles remain trapped as the mixture cools and the gelatin sets. The result is a solid foam that is only 35 to 45 percent as dense as water.

Technically, a foam is a suspension of gas bubbles in a liquid. The bubbles are so tiny (they are of
colloidal
size) that they never rise to the surface; they stay suspended in the liquid. Often, as in the case of marshmallow, polystyrene foam (trademarked Styrofoam), and baked meringues, we still call it a foam after the liquid has solidified or dried. Foams can be stabilized—the air bubbles prevented from coalescing into bigger bubbles—by emulsifying agents such as soaps and certain proteins. In foods, we prefer the protein stabilizers: gelatin, the casein in whipped cream, and the albumins in egg-white meringues can all do the job.

The most familiar brands of marshmallow confections, Campfire and Jet-Puffed, are in the shape of small cylinders about an inch in diameter and an inch long. Why that shape? In marshmallow factories the liquid foam is piped through a long, one-inch-diameter tube as it cools, and the emerging rope is then chopped into approximately one-inch lengths. (In case anyone ever asks you, Campfires are an eighth of an inch wider and an eighth of an inch shorter than Jet-Puffed marshmallows.)

By measuring and weighing them carefully (okay, so I’m a nut), I have calculated (a) that Campfire marshmallows are 23 percent puffier (less dense) than Jet-Puffed, and (b) that the 90 million pounds of marshmallows consumed annually in the United States would make a single marshmallow 30 yards in diameter and as tall as the Washington Monument.

The texture of marshmallow can be controlled by adjusting the proportions of ingredients and the amount of whipping. It ranges from the semiliquid Marshmallow Fluff to the more elastic and chewier marshmallows that can stand up to being coated with chocolate. That’s why chocolate-covered marshmallow candies are never as soft inside as you expect them to be.

You cannot have read this far without thinking about toasting marshmallows on a stick over a campfire, right? The fire’s heat both melts the gelatin and caramelizes the sugar, producing a hot, caramel-flavored goo that yin-yangs your tongue with heat and sweet. But as in all cooking, there is a right way and a wrong way.

Wrong way: Hold the marshmallow just above the flames until it catches fire, and let it burn until it has a crisp, black crust. Don’t be deterred by the fact that the crust is made of indigestible carbon laced with bitter-tasting and undoubtedly carcinogenic tars.

Right way: Wait until the fire has died down to glowing coals and then hold the marshmallow high over them, rotating it until it slowly develops a nice uniform tan color. (Patience, patience.) If it should catch fire, blow it out immediately, let it cool for a few seconds, and resume toasting.

In the Boy Scouts I learned to search out and cut a long green twig that wouldn’t catch fire. Today, you can buy a package of 30-inch-long Smorstix that are, according to the Smorstix website (
http://www.smorstix.com
), “made of 100% untreated white birch without any additives, dirt or grime.” With these, you can supposedly toast your marshmallows with a clear environmental conscience instead of “trampl[ing] the underbrush and damag[ing] trees and forests” (in Smorstix’s words) during your search for a toasting stick.

Ah, for the simpler, politically incorrect days of my youth!

My female readers are likely to know why Smorstix were so named: for s’mores, the Girl Scouts’ traditional campfire dessert made (according to the recipe in a 1927 Girl Scout manual) by inserting two toasted marshmallows between halves of a Hershey bar sandwiched between graham crackers. The hot, gooey marshmallow melts the chocolate, making even more goo.

For those who don’t have access to a campfire, I (don’t blame Marlene for it) have created Marshmallow Zaps, an indoor alternative to fire-roasted marshmallows.

Lately, many of the better food stores have been carrying a wide assortment of chocolate bars from different countries. Some of my friends are comparing and discussing their merits as if they were wines. Mostly, they talk about “percents,” but percents of what? Also, I find the ingredient lists on the wrappers to be confusing. Can you help me sort these things out so I can be as snobbish as my friends?

....

A
mericans seem to have discovered only a few years ago that “chocolate” doesn’t have to mean Hershey bars and Whitman Samplers; they learned that serious chocolate bars, as distinguished from candy bars, could open a whole new world of flavors. There are now dozens of dark chocolate bars on the market from both American and foreign manufacturers. Among foodies, chocolate tastings threaten to replace wine tastings as entertaining and educational activities.

The ingredient lists on the wrappers can indeed be perplexing, because most of the ingredients go by a number of aliases. So let’s look closely at what is in a serious bar of dark chocolate.

It all starts with cacao (ka-KAH-oh), not cocoa (KO-ko), beans. Cacao beans are the seeds of the fruit of the tropical tree
Theobroma cacao
. (
Theobroma
literally means “food of the gods,” a name obviously chosen by a chocophile taxonomist.) The bitter cacao bean was enjoyed as a spice by the Mayans and Aztecs, but only after it made its way to Europe was it sweetened with sugar.

The percentage number on a bar’s wrapper is the percentage of the bar’s weight that actually came from the cacao bean. That is, it’s the bar’s content of honest-to-goodness cacao bean components. Natural cacao beans contain 54 percent fat by weight; the other 46 percent is hard, solid vegetable matter. Thus, the percentage number on the wrapper of a chocolate bar is the sum of its cacao fat (called cocoa butter in the United States) and its cacao solids.

The rest of a chocolate bar is almost entirely sugar, so a “75%” chocolate bar will contain about 25 percent sugar. Thus, the higher the percentage number on the wrapper, the less sweet, more bitter, and more complex the flavor. Minor ingredients, usually present at less than one percent, may include vanilla or vanillin (an artificial flavor) and lecithin, an emulsifier obtained from soybeans that enhances the chocolate’s smoothness and creaminess.

Here, then, are the three major components of a quality chocolate bar, together with their aliases. My preferred names (and I wish the world would standardize upon them or their translations) are in boldface.

•
 
Chocolate liquor,
cacao, cacao mass, cacao paste, or cacao liquor: By any of these names, this is the “raw material” of chocolate: ground-up cacao beans. It is often referred to as a paste or liquor because the friction of grinding melts the dense fat, and what comes out of the grinding machine is a glistening brown paste. The percentage of chocolate liquor in a bar is the percentage of actual chocolate.