While heavy cream requires cold temperatures to whip properly, egg whites are best whipped at room temperature or above (60°C / 140°F maxi-mum), without reaching coagulation tempera-ture (62°C / 145°F). The reasoning behind this principle is that the globulin (a protein found in egg whites) is more relaxed at warmer tem-peratures than when it is cold. Cold egg whites can certainly be foamed to full volume without a hitch, since the whipping action (friction) will warm them up rather quickly, but warmer egg whites will foam much faster. Some chefs like to use older egg whites because they claim
that they are looser (thinner) and are therefore easier to whip. All eggs are alkaline, especially the egg white portion (at a pH of 8 when they are at peak freshness), and they become more alkaline as they age, but alkalinity is only good is for obtaining volume quickly, not for stability.
Increased alkalinity negatively affects the stability of a foam. A fresh egg white will produce a much more stable foam, but it will take longer to reach its maximum volume. When the egg whites are beaten, the globulin proteins, which are tangled in their original state, will unfold easily into strands. These strands group around the inter-face of the bubble, trapping it. A solid network of protein strands holds water and air in place, evenly suspending the bubbles in the liquid.
The ideal vessel for whipping egg whites is made of copper and silver, because these met-als react with the sulfur present in egg whites to form very strong and stable protein bonds very quickly. The downside of using copper is that it can be hard to maintain, because it needs to be specially cleaned after each use. Lemon juice and salt do a beautiful job of cleaning. The bowl should be properly washed before applying the
Egg whites can be whipped using a variety of hot or cold methods, yielding a strong, versatile aerator. These egg whites are whipped to stiff peaks.
lemon juice and salt. Once the lemon juice and salt have cleaned the bowl, rinse out with cold water and dry thoroughly. This procedure might need to be repeated before using the bowl again.
A good substitute for a copper bowl is add-ing food-grade copper powder;1 gram/.035 oz per 1,000 grams/2 pounds 3.27 ounces of egg whites yields excellent results. Stainless steel bowls are also recommended and are much more economical. However, the foam will take longer to form because egg whites do not react with stainless steel. Never, ever use a plastic bowl to whip egg whites, because the surface of plastic is porous and can harbor debris (and fat), which can hinder foaming signifi cantly (see below). Whatever material you choose, make sure that the bowl will be big enough to hold eight times the volume of the egg whites. If you are whipping by hand, use a balloon whisk or a piano whisk, which will incorporate air much more effi ciently than a stiff French whisk.
Cream of tartar and even lemon juice can be used to help stabilize egg white foams. They are both acids that enforce the sulfur and hydrogen bonds that contribute to effective foaming (in egg whites only). When they are not used, the sulfur found in egg whites tends to separate itself from the hydrogen. Acid keeps these bonds together throughout the whipping process. Another effect of acid on proteins is that it promotes coagula-tion. (Think of what happens when raw fi sh (a protein) is marinated in lime juice (an acid) to make seviche. The lime juice “cooks” the fi sh.) After the protein strands unfold because of the agitation from whipping, the cream of tartar coag-ulates the protein that surrounds the air bubble, trapping it more effectively. Of course, it is a very small amount that is added to the egg white (15 grams/.53 ounces of cream of tartar per 1,000 grams/2 pounds 3.27 ounces of egg whites), and it is added at the beginning of the whipping process. The coagulation effect is minimal, but is suffi cient for stabilizing purposes. If too much acid is added, it could fl avor the foam, and then the amount of acid could over-coagulate the pro-teins before they have enough time to unfold and trap air bubbles.
Egg whites are beaten to three different peaks, each one with its own particular stiffness.
The stages are soft peak, medium peak, and stiff peak. In order to determine the peak, the whisk or whip that is being used is taken out of the bowl and held upward. The meringue that is at the top of the whisk or whip will show the stage of the peak. At soft peak, the foam retains some of its shape but the peak droops down quickly. At me-dium peak, the meringue peak will slowly droop down halfway, without drooping all the way down.
At stiff peak, the egg whites have increased in vol-ume eightfold from their original volvol-ume, and the peak will hold without drooping at all (see photo at left). When egg whites are over-whipped, the proteins are over-coagulated, forming bonds that are too tight, and instead of stabilizing the foam, they squeeze the water out between the bubbles, sending the bubbles up to the surface while the water separates to the bottom of the bowl.
Sometimes egg whites take too long to whip or do not whip at all. The following factors might be the culprits:
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• Salt: Salt decreases the foam’s stability and prolongs whipping time by weakening protein bonds. Salt needs a place to go too, and lodging itself between protein bonds is just as good a place as any other. But salt in small amounts is necessary for fl avor. It will disperse itself very well in the foam; in small amounts it does no harm at all.
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• Fat: Fat molecules, from ingredients like oil and egg yolks, hinder proper foaming because they will interfere with egg white proteins while they are trying to latch on to an air bub-ble. While it is possible to obtain a good foam even with a small amount of egg yolk or other fat present, the whites will take longer to whip and the foam will not be very stable. It will quickly defl ate.
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• Water: Some water can actually help produce a very good foam because it lightens the viscosity of egg whites, but too much water will dilute the egg whites to the point where the ratio of proteins to water is too small for a good foam (very few proteins to too much water).
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• Sugar: Care must be taken to add sugar to egg whites at the right time. If they are added too early (before beginning to whip), the sugar will weigh down the foam and will drastically slow down the foaming process. For specifi c instructions on how to add sugar to each type of meringue, continue reading.
The combination of sugar and egg whites will result in a meringue, where the typical ratio of sugar to egg whites is 2:1. There are three basic types of meringues: French or Common, Italian, and Swiss. One practice that will create a more stable foam is to add powdered egg whites to the foam. The recommended amount to add is 1 percent of the total weight of the egg whites.
Powdered egg whites contain all the protein and none of the water of fresh egg whites. The addi-tion of proteins will create a much more stable foam because there will be more proteins trap-ping the air bubbles, therefore reinforcing the bubble walls further. It will not affect the fl avor or consistency of the meringue. Be careful not to confuse powdered egg whites with meringue powder, which contains large amounts of sugar.
FRENCH OR COMMON MERINGUE (UNCOOKED) The egg whites must be at room temperature when beginning the French meringue. Add cream of tartar and begin whip-ping at high speed. Once the egg whites have quadrupled in volume, pour the sugar in slowly down the side of the mixing bowl. If the sugar is added all at once, it will defl ate the already formed foam and the whipping time will be greatly increased. Some pastry chefs will opt to pour the sugar in when the egg whites are al-most done whipping. While this will reduce de-fl ation and whipping time, it will not dissolve the sugar, resulting in a grainy foam that is not very stable. Use a very fi ne granulated sugar (such as superfi ne or baker’s) so that it can be easily incorporated and quickly dissolved in the egg whites. The larger the sugar crystal, the longer it takes to dissolve.
Check the peak by taking the whip or whisk out of the bowl and standing it upright. If the
peak does not move, you have obtained maxi-mum volume. If the peak leans downward, you have not obtained enough volume. Continue to whip until you reach maximum volume. If the foam looks grainy and not smooth, you have over-whipped your egg whites, and at this point there is nothing you can do to fi x them. Start over; egg whites are not that expensive.
This meringue is not considered food safe unless pasteurized egg whites are used. Pasteur-ized egg whites usually contain stabilizers, which make for very good foams, but keep in mind that they whip much faster because of this, and over-whipping can easily occur. For the frozen desserts in this book that contain a French me-ringue, always use pasteurized egg whites.
A combination of sugars can also be used to make French meringue. You can make a me-ringue that is one part egg whites, one part gran-ulated sugar, and one part confectioners’ sugar.
The confectioners’ sugar needs to be sifted and should be added once the egg whites have been whipped with the granulated sugar to stiff peaks, since granulated sugar takes longer to dissolve into the egg whites and confectioners’ sugar will dissolve almost on contact. Confectioners’
sugar is a great stabilizer, but it won’t produce very good results if this meringue is used for any other purpose than to make crisp meringues in the oven. Since 3 percent of the total weight of the sugar is cornstarch, which is added to keep the sugar’s very fi ne crystals from absorbing too much moisture from the environment, French meringues with confectioners’ sugar will make the frozen dessert taste mealy because you taste the uncooked starch.
French meringues are usually added to another ingredient (e.g., souffl és, French maca-rons), but they can also be dried in the oven to obtain a crisp meringue, or even poached or steamed (e.g. fl oating island).
ITALIAN MERINGUE (COOKED) Italian ringue can be the most complicated of me-ringues to produce. It consists of cooking sugar to 121°C / 250°F, or the “soft ball” stage, using the wet method (combining the sugar in a pot
with enough water to moisten all the sugar to obtain the consistency of wet sand). While the sugar is reaching the soft-ball stage, room-tem-perature egg whites and cream of tartar need to be whipped to the stiff-peak stage. When the sugar is at the right temperature and the egg whites have reached their maximum volume (stiff peaks), the sugar syrup is poured down the side of the bowl as the egg whites continue to whip. Once all of the sugar is incorporated, the mixture needs to continue to whip until it has cooled down to room temperature. This me-ringue is considered to be pasteurized because the heat from the sugar will eliminate any bac-teria. It is also a very stable meringue because the heat from the sugar coagulates the proteins in the egg whites, which traps the air bubbles almost immediately. Remember that coagulated proteins will keep the air bubbles trapped better than “soft” proteins.
The tricky part is coordinating the cooking of the sugar with the whipping of the egg whites.
No matter how experienced you are, it is almost impossible to do so. But there are ways of con-trolling both the cooking sugar and the whipping egg whites. Begin whipping the egg whites on medium speed at the same time you start cook-ing your sugar. Have an ice bath ready. It should be big enough to comfortably fi t the pot in which you are cooking the sugar. When your sugar has reached 115°C / 240°F, increase the speed of the mixer to high. When the sugar reaches 121°C / 250°F, take the pot off the heat and shock it in the ice bath. This will keep the sugar at a liquid consistency, but cooking will be stopped. Wait for your egg whites to reach stiff peaks and im-mediately pour the sugar down the side of the bowl and whip until the foam has cooled to room temperature.
This meringue has many uses, from straightforward crisp meringues to marshmal-lows and, more important for us, parfaits. The only inconvenience when it comes to an Italian meringue is not really an inconvenience, it is merely the fact that it is more technically ad-vanced than other meringues and it takes a few tries to get it right; for the same reason, it is really
easy to make a mistake. Typically a foam that has gone wrong is impossible to fi x and you will need to start over again.
SWISS MERINGUE (COOKED) Swiss meringue is simply a cooked French meringue. It consists of combining sugar, egg whites, and cream of tartar in a mixing bowl, and then placing this bowl over a hot water bath. The mixture is con-stantly whisked until it reaches a temperature between 57°C / 135°F and 60°C / 140°F. Do not exceed 60°C / 140°F to prevent over-coagulating the egg whites (remember that egg white pro-teins cook at 62°C / 145°F), but do not stop at a temperature lower than 57°C / 135°F, because bacteria will not die below those temperatures, and part of the purpose of cooking egg whites like this is to pasteurize them. Of course, if you are using pasteurized egg whites you do not need to worry about bacteria, just overcooking.
If using pasteurized egg whites, heat them to 60°C / 140°F, which will warm up the egg whites and dissolve the sugar at the same time.
The meringue can be taken off the heat once the sugar has dissolved and the desired temperature has been reached. Some pastry chefs opt to whip the foam directly over the hot water bath until it reaches stiff peaks. That is a good idea if you are making very small amounts, but for larger amounts it is more effi cient to fi n-ish the whipping process in a mixer. This way it will whip to stiff peaks and cool down much faster.
This meringue is food safe, and it can be added to other ingredients or dried in the oven to obtain a crisp meringue.
MERINGUE WEEPING Meringue weeping is characterized by small droplets of water that accumulate on the surface of the meringue.
Weeping is caused by over- or under-whipping the egg whites and by the sugar not having been completely dissolved into the egg whites. This weeping is seen only when baking plain me-ringues of any kind (French, Italian, Swiss), and it can be triggered by high oven temperatures.
For this reason weeping will not be evident in a
meringue that will not be baked. Weeping will also make the meringue crack while it bakes (or dries) in an oven.