Kitchen Mysteries_ Revealing the Science of Cooking Part 2

Lemon juice or vinegar adds water to the already const.i.tuted emulsion. The droplets have more s.p.a.ce into which to flow. The mayonnaise is more fluid. Simultaneously, it turns whiter. Perhaps the droplets are dispersing the light differently, resulting in this effect, but that remains to be proven.

How Much Mayonnaise Can Be Prepared with a Single Egg Yolk?

The amount of mayonnaise that can be made with a single egg yolk depends on the quant.i.ty of water present. Traditional recipes generally indicate that if there is too much oil for the quant.i.ty of yolk used, the sauce decomposes. They recommend using, at the most, one to two deciliters (3.38 to 6.76 ounces) of oil per egg yolk.

Nevertheless, my American friend Harold McGee, author of the very popular book On Food and Cooking On Food and Cooking (Scribner and Sons), has prepared up to twenty-four liters (25.37 quarts) of mayonnaise with a single egg yolk. Naturally, he had the aid of science. Knowing that oil arranges itself into droplets in a continuous phase of water, he figured that the small quant.i.ty of water normally contributed by the egg yolk (about a half teaspoon per yolk) was not enough to prepare a large emulsion. Thus, to maintain the separated oil droplets in the aqueous phase, he added water as he added oil. More precisely, for each cup of oil, he advises adding two or three teaspoons of water. (Scribner and Sons), has prepared up to twenty-four liters (25.37 quarts) of mayonnaise with a single egg yolk. Naturally, he had the aid of science. Knowing that oil arranges itself into droplets in a continuous phase of water, he figured that the small quant.i.ty of water normally contributed by the egg yolk (about a half teaspoon per yolk) was not enough to prepare a large emulsion. Thus, to maintain the separated oil droplets in the aqueous phase, he added water as he added oil. More precisely, for each cup of oil, he advises adding two or three teaspoons of water.20 Since a large egg yolk contains enough surface-active molecules to emulsify many quarts of mayonnaise and since too much egg yolk gives the mayonnaise a taste of raw egg that some find disagreeable, I suggest that, when you wish to prepare a small quant.i.ty of mayonnaise, you do not use the whole yolk-a drop is enough to make a big bowl of mayonnaise-and you begin the sauce with lemon, vinegar, or plain water, adding a few finely chopped herbs for flavor.

Why Must Mayonnaise Be Beaten Vigorously?

It is necessary to break up the oil into little droplets and make them migrate in the water, carrying the surfactants.21 Now, the lower the temperature, the greater the difference between the miscibility of the water and oil. If you congeal the oil by cooling it too much, you will no longer be able to divide it into droplets. For the same reason, you must warm the b.u.t.ter used in preparing a bearnaise or a hollandaise sauce, two other emulsions in which the egg, again, provides the surfactants. Now, the lower the temperature, the greater the difference between the miscibility of the water and oil. If you congeal the oil by cooling it too much, you will no longer be able to divide it into droplets. For the same reason, you must warm the b.u.t.ter used in preparing a bearnaise or a hollandaise sauce, two other emulsions in which the egg, again, provides the surfactants.

Why Can't the Oil Be Poured In All at Once?

Cla.s.sically, recipes indicate that the vinegar (please, no mustard, otherwise your mayonnaise is no longer a mayonnaise: it is a "remoulade") must be mixed first, then the egg yolk, and finally the oil must be added, slowly, while whisking vigorously. Why add the oil to the aqueous phase, rather than the other way around? First, because it is necessary to separate the oil into microscopic droplets, which is much easier if one begins with a drop of oil in water, rather than vice versa. Second, because the surface-active molecules coat the drops of oil most quickly and consistently if the surfactant is initially present in large proportions (it is initially present in the form of micelles, spheres at the center of which all the hydrophobic tails of surface-active molecules have gathered).

The first task is to produce small, well-separated drops. As long as there is more water than oil, large drops can escape the action of the whisk, and oil rises to the surface. When the volume of incorporated oil is equal to the initial volume of water and seasonings, the drops mutually prevent one another from rising, and the emulsion begins to stabilize. Then, as one continues to add oil, the small drops serve to break up the big ones, impeding their flow.

Why Does Mayonnaise Curdle?

Mayonnaise turns because it flocculates: the oil droplets merge with one another and separate from the aqueous phase. Generally, this catastrophe takes place either because the ingredients are too cold or because the emulsion does not contain enough water for the quant.i.ty of oil added.

To salvage mayonnaise that has curdled, cookbooks recommend adding another egg yolk, as if the problem were caused by the oil. But it is sometimes enough to add water and beat vigorously. You'll save an egg, but you'll need elbow grease. A better solution is to wait until the oil and water separate. Pour off the oil, and then add it back drop by drop, whipping continuously: all the useful molecules were present but not in the right configuration; you only have to rearrange them.

The Egg's Incarnations Essential Accessories The egg is the unrecognized star of cooking. In his Almanach des gourmands Almanach des gourmands, Grimod de la Reyniere celebrated it in these terms: "The egg is to cooking as the articles are to speech, that is to say, such an indispensable necessity that the most skillful cook will renounce his art if he is forbidden to use them."

How true! Its whites, beaten into stiff peaks, merit their own chapter. Souffles, which they cause to rise, require the examination of so many principles of physics that, again, a complete chapter will be necessary if we are to master them. And the hard-boiled egg, though its preparation seems within the range of the least skilled novice, requires much care to be truly good.

Nevertheless, the importance of eggs in cooking is often underestimated. First of all, the egg is indispensable anytime you want to give a dish a specific form. You break an egg, whole or not, into a container that is then heated. The egg, possibly with some filling, takes the form of the container and retains it after being cooked.

Second, when its whites are beaten into stiff peaks, the egg provides the foamy element in recipes for meringues and souffles, in mousses that are cooked, and also in recipes for the various chocolate or Grand Marnier mousses that are served cold and not cooked.

Next, eggs can form permanent gels that trap solid elements, as in, for example, clafoutis (a type of fruit tart) or quiche.

Finally, the egg is used for its surface-active compounds in various sauces: mayonnaise, bearnaise, hollandaise, gravy, and so on.22 In all these uses, the egg is an accessory ... an essential accessory. In all these uses, the egg is an accessory ... an essential accessory.

In other dishes, the egg is not just an accessory but a princ.i.p.al player: think of boiled eggs, omelets, and eggs mimosa, for example.

Why is it so versatile? First of all, the yolk is about half water, one-third lipids (lecithin and cholesterol among them), and 15 percent proteins. The white, on the other hand, is nearly all water, since it contains only 10 percent proteins (primarily ovalb.u.min and conalb.u.min).

How does knowledge of this composition serve us? It lets us answer all the following questions.

How Can You Tell a Raw Egg from a Cooked Egg?

In a refrigerator shared by an entire family, cooked eggs are frequently mixed up with raw ones. They have the same ma.s.s (weigh them to convince yourself of this), the same color, the same surface appearance. How to distinguish them?

When in doubt, remember that a raw egg is a viscous liquid. If you make it spin, you turn only the sh.e.l.l. The inside of the egg remains semi-immobile, exactly like coffee when one turns the cup. Because of the friction between the liquid and the sh.e.l.l, a raw egg quickly loses speed, while inside the liquid slowly begins to move. A raw egg spins with difficulty and then, released, slows down. On the other hand, a hard-cooked egg, all of a piece like a spinning top, turns easily and for a long time as soon as it is set in motion. If you have no egg available for comparison, spin your mystery egg and then stop it by just touching and releasing it. A cooked egg will remain still. A raw egg will continue to spin when released because of the motion of the egg white within the sh.e.l.l.

Why Does an Egg Cook?

Let us consider the simple case of the fried egg. A priori, cooking an egg is a complex operation. Think about it: all those different molecules! Nevertheless, an examination of the egg's composition shows us that what we have here, at a first approximation, is only a mixture of proteins and water.

The water behaves as expected. When it is heated, its temperature increases steadily until, at 100C (212F), it boils, forming bubbles.

On the other hand, the proteins are molecules a.n.a.logous to long strings, often folded back on themselves because of forces that come into play between the atoms of a single molecule. When they are heated, these weak forces are broken, and since each broken bond leaves two atoms hard-pressed for companions, the heating encourages encounters between the forsaken ones, which can thus form bonds even if they do not belong to the same molecule. Moreover, some particular parts of proteins, made of one sulfur atom and one hydrogen atom, can link when the proteins are denatured. They make specific bonds called disulfide bridges responsible for coagulation.

Thus, when an egg's temperature increases, the b.a.l.l.s of string that are the proteins begin to form chains without unwinding significantly. The liquid turns solid, but the various kinds of proteins do not all coagulate at the same temperature. One forms a network at 61C (141F), another at 70C (158F), and so on. For each temperature, there is a specific culinary result, and the higher the temperature reached, the harder the egg, because the greater the number of protein networks that trap water molecules. In the end, when all proteins are coagulated and the water is lost, the egg white becomes rubbery.

Moral: When you are frying an egg, stop cooking it as soon as it turns opaque. Beyond that point, your egg will no longer be worth its salt.

Why Does the Egg Yolk Cook More Slowly than the White?

Cooks know that the yolk of an egg, fried or soft-boiled, cooks much more slowly than the white. This is partly because the major proteins in the yolks coagulate at a temperature seven degrees higher than that at which those in the whites coagulate. To complicate matters further, when boiling eggs, the white protects the yolk, causing its temperature to rise more slowly.

The famous three-minute recommendation for cooking soft-boiled eggs corresponds to the time during which the temperature increases in the various parts of an egg immersed in boiling water. After three minutes, the outside reaches 100C (212F) and the core reaches about 70C (158F), depending on the size of the egg. It takes a minute longer for the temperature of the egg yolk to rise the seven degrees necessary for its coagulation.

We must now ask, why not bake eggs in a 65C (149F) oven for an extended period of time (slightly more than an hour for a 60-gram egg [just over two ounces]), rather than remaining at the mercy of an egg timer? We would be sure of a perfectly cooked egg white and a perfectly runny yolk, with no risk of failure!

Why Won't the Egg White Closest to the Yolk Cook?

Anyone who has fried an egg has encountered this phenomenon: surrounding the yolk, part of the egg white refuses to coagulate.

That is because the protein in the egg white called ovomucin coagulates with more difficulty than the other proteins; this is what gives the egg white in contact with the yolk its viscosity.

How to get it to cook without letting the rest of the egg white become rubbery (see the question "Why Does an Egg Cook?")?

Salt and acids (vinegar, lemon juice, etc.) promote the cooking of a solution of proteins in water because their electrically charged atoms, or ions, come to surround the atoms possessing the complementary electrical charge in the proteins. These similar electrical charges are normally responsible for the winding and dispersing of the proteins. In the presence of complementary ions, the proteins can unwind, come together, and form bonds more easily. In other words, the proteins cook at a lower temperature in the presence of salt or acids. When cooking a fried egg, you can obtain a h.o.m.ogeneous white by salting the white around the yolk.

In the extreme, you can almost cook an egg by immersing it in vinegar, without heating it. The acid's ions prompt the weak bonds to break, so that the abandoned atoms can combine with the abandoned atoms of other molecules. The egg coagulates. This explanation also answers the following question.

Why Add Vinegar to the Water When Poaching an Egg?

Adding vinegar to the cooking water when poaching an egg accelerates the coagulation of the part of the egg that is in contact with the boiling solution. The outside part of the egg coagulates immediately, constraining the rest of the egg, which can thus form a ma.s.s without dispersing into the solution. Salt is said to do the same, but experimenting will prove vinegar's superior effectiveness.

Likewise, there is an advantage to adding a little vinegar to the water used for soft-boiling eggs. If the sh.e.l.l cracks, the egg white coagulates immediately, sealing the leak (another solution for avoiding cracks is to make a small pin hole in each end of the egg; in that way, the air that expands does not break the egg and escapes without causing damage).

The Odorous Mysteries of the Hard-Cooked Egg Those who know how to cook sometimes forget this: you can can cook a hard-boiled egg badly! cook a hard-boiled egg badly!

Let us turn to Madame Saint-Ange, author of a long-standing cooking column whose excellent advice was collected in book form by Larousse in 1927: It is a very common mistake to think that there is no risk of overcooking when it is a matter of hard-boiled eggs and that therefore it does not matter how long they remain in the boiling water after they have become hard. An overcooked hard-boiled egg is tough; the yolk is rimmed with green, the white gives off an unpleasant odor, and the whole thing gives the impression of an egg that is not fresh.Another mistake: putting eggs in lukewarm or even cold water, and only then bringing it to a boil. The result is a faulty distribution of the white around the yolk, not achieving an attractive roundness or, in the case of stuffed eggs, attractive white cups of a regular thickness.

The consequences of the first mistake are simple to explain. When eggs are cooked too long, the egg's proteins, which contain sulfur atoms, release a gas called dihydrogen sulfide, the infamous odor of rotten eggs. This gas reacts with iron ions present in the egg's ovotranferrin (iron-carrying) proteins and thus gives it its greenish color.

To cook hard-boiled eggs properly, immerse them in water that is already boiling, allow the water to return to a boil, and let the eggs cook for ten minutes. Then put the eggs immediately into cold water. That will make them easier to sh.e.l.l. And again, if you want to be really modern, bake your eggs in a well-moderated oven, set at any temperature you choose, depending on how well done you like your eggs.

The Liquids in Eggs Omelets, quiches, and the various flans are mixtures of egg whites, yolks, and a liquid (milk, water etc.). The more abundant the additional liquid, the longer the cooking time. But the heat must be evenly distributed during cooking. If the temperature in a specific spot is too high, those dreaded lumps will form.

The remedy? A pinch of flour or starch. At a high enough temperature, the long molecules of the flour pa.s.s into solution and, for reasons still unknown, block the aggregation of the egg's proteins. We will come across this effect again with regard to sauces thickened with egg yolks. It is also what lets us succeed at sabayon, custard, and the like.

A Successful Souffle?

A Foam Beginning with a Liquid?

How to succeed at souffle every time? Some souffle magicians tirelessly repeat the techniques that, one day, just out of luck, guaranteed them their success. I make no claims to helping them. But what about the rest of us, whose luck has not led us to the appropriate sleight of hand? We will obtain good results more reliably if we truly understand what a souffle is and how its const.i.tuent parts react.

A souffle is always a foam of egg whites with some preparation added: an herbed bechamel sauce for savory souffles or a mixture of milk or pureed fruit and sugar for dessert souffles. The essential ingredient is the egg white, which must be whipped until stiff and to which the preparation must be added without "breaking up the foam," so that it then rises with heating and retains its risen shape after being taken out of the oven.

Let us first examine this egg white, which we whip into stiff peaks. It is a matter of a mixture of water and proteins, into which we want to introduce air bubbles. Why does an egg white foam even though water itself will not retain air? Because egg white contains proteins (essentially ovomucin and conalb.u.min) that, in addition to bonding simultaneously to air and water (they are surface-active), make the egg white viscous and stabilize the air bubbles introduced.

In effect, these proteins, each with a part that bonds to water and a part that repels it, tend to position themselves at the water-air interface, that is, at the border between the air and the water. In the same way that, in a mayonnaise emulsion, the surfactants of the egg yolk coat the oil droplets and disperse them in the water, the proteins of the egg white coat the air bubbles and allow their dispersion in the water of the egg white.

When we begin to whip the egg whites, the air bubbles are large, but the more we whip, the smaller the bubbles become.

This effect increases the stabilization of the bubbles, because the force of gravity, which normally tends to make the less dense parts of the foam (the air bubbles) rise and the liquid sink, soon becomes inferior to the force of surface tension, which is responsible for the cohesion of the air and the liquid. In other words, foam well whipped for a long time, composed of many small bubbles, is more stable than foam poorly whipped by a lazy cook.

Why does a soap solution form much less solid foam than egg whites do? Because soap molecules are generally much smaller than egg white proteins. Egg whites, more viscous than soap solutions, flow with difficulty along the interbubble surfaces. This effect is reinforced by the bonds that are established between the proteins that come to coat the surface of the bubbles. Globular proteins are long threads folded back on themselves by the forces between some of their atoms. When a solution of globular proteins is whipped, these long threads unwind, but the widowed atoms tend to reform bonds. Since they bond indiscriminately with other widowed atoms of the same protein or with widowed atoms of neighboring proteins, the neighboring proteins bond together and rigidify the water-air interface.

When Are Egg Whites Whipped Enough?

Here are a few simple formulas. For those good at calculations, first of all you will want to know that, in your vessel, an egg of 3.5 centiliters (1.18 ounces), well beaten, produces a white of 15 centiliters (5.07 ounces). an egg of 3.5 centiliters (1.18 ounces), well beaten, produces a white of 15 centiliters (5.07 ounces).

As for the more pragmatic, you will want to stop whipping when, removing your foam-filled whisk from the bowl and turning it upside down, you see that the foam remains attached to it in a solid ma.s.s taking the shape of pointed tuft, like a clown's wig.

Another trick: the egg white is whipped stiffly enough for a souffle when it will support the weight of an egg in its sh.e.l.l!

In each of these cases, it is a matter of forming very small bubbles, so that the s.p.a.ces between the bubbles are as narrow as possible, making it difficult for liquid to flow there, or, to put it another way, making the bubbles very stable.

Be careful! There is a danger of beating the whites too much, which separates the water from the proteins and makes the whites "weep." But this risk is not great if you beat the eggs by hand. Amateur cooks tend to whip too little rather than too much. Professionals will add sugar as a safeguard, but science still cannot explain their sleight of hand.

Why Must We Avoid Getting Yolk in the Whites?

Egg whites polluted with yolks or with fatty substances rise with more difficulty (it seems) than do pure egg whites. Why is this true? Because the yolks contain small surface-active molecules that bond to the long proteins of the whites and hamper the development of a network of the egg white proteins, weakening the water-air interface. Moreover, the fats in the yolk bond with the hydrophobic parts of the egg white proteins and thus reduce the availability of these latter to coat the air bubbles. On the other hand, when the foam is well formed, and when the egg white proteins have bonded among themselves and are properly distributed at the water-air interface, the lipids of the yolks can be added without causing harm. Places for them are no longer available.

Thus be careful with plastic bowls and, in general, containers to which fats stick. Such utensils have a harmful, if not to say disastrous, effect when whipping egg whites, because fat molecules that remain on their surfaces have the same effect as the fats in egg yolk.

What About Salt or Acid?

Many cookbooks recommend adding a little vinegar or salt to egg whites before beating them. This addition is supposed to help the foam rise and make the stiffened egg whites firmer. Is that true?

First of all, acids certainly react with whipped egg whites because their hydrogen ions (H+) break the weak intramolecular bonds that are responsible for the proteins folding. For example, when hydrogen ions are abundant, they come in close contact with the oxygen atoms that would normally be linked to the hydrogen atoms of the same molecule. A sixteenth of a teaspoon of vinegar or lemon juice per egg white increases tenfold the concentration of the hydrogen ions, which, as small atoms of hydrogen bearing a positive electrical charge, further prevent the acid groups of the proteins from losing their hydrogen atoms and becoming electrically charged. In the presence of an acid, the proteins repel one another less. Acids also facilitate the coagulation of the proteins around the bubbles and stabilize these latter, though only to a limited extent.

Salt acts in an identical fas.h.i.+on, but it does not alter the dissociation of the proteins. Its ions simply come to surround the electrically charged atoms of the proteins, which weakens their electrostatic repulsion and facilitates their coagulation. Again, the effect is limited. Practically speaking, adding vinegar or salt is not of great value. It's best to stick to whipping.

A Careful Mix What to do with egg whites after they have been beaten until stiff? If we consult them, cookbooks will suggest using them in a bechamel sauce, along with the yolks and minced, chopped, or pureed vegetables, cheese, meat, or fish. Or they may be mixed into a milk batter or with fruit puree that has been cooked and sweetened.

I would add, from experience, that mixing yolks into a basic preparation must be done away from heat, after the preparation has cooled (otherwise the yolks get cooked).

Should yolks be added two by two, as advised in certain good cookbooks? I have no idea why it should be so, but I did have a chance to test this advice in 1980, when Sunday after Sunday I inflicted on my friends the Roquefort souffle that I was trying to perfect. I tried everything: adding all the yolks at once, adding them one by one, three by three. I obtained the best result when I added the yolks two by two. The cooks seemed right, but the mystery remained (I know now that the two-by-two trick is no use; I probably just finally learned how to make this souffle as I was experimenting). This experience encouraged me to begin collecting and investigating similar culinary old wives' tales, proverbs, and sayings. I now have more than twenty-five thousand of them, for French cooking alone, and they are being systematically studied in the laboratory, as part of molecular gastronomy. And because molecular gastronomy is growing in popularity all over the world, I am pleased to say that people in many countries are now scrutinizing their own cuisines, collecting this old wealth of knowledge before it falls victim to modernization worldwide.

Now, back to our souffle. Having thus mixed the yolks into the basic preparation, now comes the problem of adding the whites to the mixture. The difficulty of the operation stems from the fact that the egg whites are delicate and of a very different viscosity from that of the preparation, so they do not mix well.

Madame Saint-Ange advises pouring the lighter preparation (the beaten egg whites) over the heavier one and then cutting through both with a spatula, as if cutting a tart, bringing the heavier preparation up from the bottom and over the egg whites and repeating that operation while turning the bowl until the two preparations are thoroughly blended. Other chefs draw the heavier preparation up by beginning from the far side of the bowl and sc.r.a.ping along the bottom of the mixing bowl, depositing the preparation drawn from below over the top of the whites and turning the bowl with each sc.r.a.pe. Of course, to withstand this kind of treatment, the egg whites must be firm.

Now the mixture is poured into souffle molds that have been b.u.t.tered (so the souffle will not stick) and floured (so that it can rise easily), being careful to fill the molds only two-thirds full (so that they only moderately overflow when the souffles rise).

In a souffle prepared like this, its success is due to the ovalb.u.min in the egg white (50 percent of the egg white), which is not denatured during the mixing and coagulates when cooked, thus limiting the expansion of the air bubbles, which would otherwise eventually explode.

Souffles were said to rise because the air bubbles swell under the action of heating (the air expands), but a simple calculation shows that this effect can only explain a swelling of 30 percent at the most (even considering the increase in pressure, which I have not measured). If the souffle doubles or even triples in volume, that is because the water evaporates and the resulting vapor enlarges the bubbles. Again, the coagulation of the egg proteins traps the bubbles within the ma.s.s for good.

Why Must the Oven Door Remain Closed While the Souffle Is Baking?

Egg proteins that have not yet coagulated have not yet formed a rigid armature. Till they do, it is the souffle bubbles, in equilibrium with the oven air, that support the weight of the preparation. If the oven door is opened before coagulation occurs, the sudden drop in temperature causes the air bubbles to contract and the vapor bubble to recondense, and the souffle falls. Then, after the door is closed again, the walls of the bubbles coagulate before the bubbles can reinflate.

At What Temperature Must the Souffle Bake?

The question posed in this heading requires an evasive answer. A souffle has to bake at a temperature high enough for the proteins to coagulate before the bubbles begin to explode and the foam collapses but low enough for the interior to rise before that same coagulation prevents it from doing so. By experimenting, chefs have determined that the ideal temperature is about 200C (392F) for obtaining a moist center with a golden crust and about 150C (302F) for achieving more uniform results.

The baking time depends on the size of the souffle. Often it is recommended that large souffles should bake for twenty-five to thirty minutes, and small ones for fifteen minutes.

One final trick: for a nice even souffle crust, put the souffle under the broiler for a few moments before baking it. The top will form a solid roof, which will then rise uniformly, lifted by the air and vapor bubbles.

How Do You Avoid a Fallen Souffle?

Ah ha! That is the great souffle question! Some chefs advise preparing souffles in advance, before the guests arrive, and placing them in a warm water bath until it is time to bake them. The gentle heat of the water will cause the souffles to rise very slowly, and-a scientific mystery-they will not fall after being baked. Is this good advice?

In collaboration with Nicholas Kurti, I have studied the rising of souffles and especially the validity of this advice. We prepared a cheese bechamel sauce, beat egg whites until stiff, and proceeded to mix them together. We then filled many small porcelain souffle ramekins with this mixture and began by baking just one of these souffles. Its volume had tripled, and it was perfectly baked after twenty-five minutes in a 180C (356F) oven. Coming out of the oven, the souffle was beautiful, but it fell.

One of the other ramekins was placed in the refrigerator, another in the freezer, and the last two were left at room temperature. Later, the ramekin in the freezer was taken out, and when it had reached room temperature it was baked at the same time as the souffle that had been in the refrigerator. It rose a bit better, but the result was less interesting than the first souffle we baked. The last two souffles were baked at the same time as well, but one of them was first placed in a warm water bath and the other one was not. They did not yield the expected results.

This series of experiments is open to criticism. The souffle in the warm water bath had been kept in the refrigerator before this recommended treatment. Thus I repeated the experiment many times, putting the souffle mixture in the warm water bath immediately after mixing the whites and the cheese bechamel sauce, and testing different temperatures and lengths of time for the water bath before baking. These souffles never rose as well as the souffles baked immediately. It is true that the cheese souffles kept in the water bath did not fall-but that was because they did not rise.

This experiment offers the following important information: to make a beautiful souffle, do not wait to bake it. Putting it in the freezer is only a stopgap measure, as is any time in a warm water bath.

Three Rules for a Successful Souffle There are three rules to keep in mind for a successful souffle, all based on the fact that a souffle swells primarily because of water vaporization.