Let Them Eat Foam

The Kitchen



    When last we visited The Egg Files [The Egg
Files II
, we investigated that orb's unique ability to convert almost any liquid into a viscous victual. This particular power dwells in the yolk meaning that the albumins or whites were left out of the dessert drama. Once the custard was consumed, the whites were, of course, individually frozen in ice cube trays. Later on that same day, Paul bagged and tagged them for later use.

[From The Egg Files]


1 cup cream
(or half & half)
   2 eggs__

bacon  leeks  gruyére

3 eggs + 3 yolks

proteins    sugar

    Locked away inside these translucent cubes, one of the most formidable and versatile powers in the kitchen universe lays waiting, waiting to be converted into foam. Believe it or not, a simple foam of fresh or frozen egg whites is the embarkation point for a culinary journey dotted with dozens of delicious destinations.
    Meringues, soufflés and mousses lie upon this road as does many a cake, one of which is so impossibly light, so ethereally delicious, so amazingly versatile, so ridiculously easy to make—not to mention completely fat-free—that many refer to it simply as angel food. Hmm. Having never dined with angels, I just call it good eats.

The Driveway

    Whether it's floating on your beer, topping your pie, or cleansing your car, a foam is simply a collection of small bubbles. And a bubble is just a pocket of gas surrounded by a thin layer of liquid which is surrounded by more air. "Duh," you say? Well I tell you what. You blow some. [hands glass of water and a straw to the "camera," bubbling sounds are made, but no bubbles remain] Yeah. You see, pure water, any pure liquid for that matter, can not be bubbled. The reason is surface tension. You see, water molecules are so attracted to each other that when faced with an alien environment, like air, any body of water will shape itself as to expose as few of its molecules as possible to that environment. Now, the shape that exposes the fewest molecules is, of course, a sphere. Okay? This is the bubble's geometric doppelganger. [pops balloon full of water]
    Now to turn water into foam we must break the surface tension and that means adding molecules which can infiltrate the water and get it to relax a little. Now the list of potential additives is long. As we all remember from Fight Club, everyday soap is made from fat treated with a caustic alkaline like lye. The problem is, soapy foams like this aren't very stable and they tend to taste like soap. So their culinary usefulness is limited to pot scrubbing.
    Egg whites foam fabulously because their water already contains the necessary additives in the form of proteins. There's so many, in fact, that you can add even more water and still harvest bubbles aplenty. Give that a try. [hands glass of water with egg whites and a straw to the "camera," bubbling sounds are made, big bubbles are formed] And, of course, eggs don't taste like soap. Of course, you wouldn't want to drink it right now. Blah.

"Foam" comes from the Germanic "faimaz",
which derives ultimately from the Latin "spuma".

The Kitchen

    Time to meet the software. Headlining for Team Dry, sugar, one and three quarters cups of sugar. Now why so much? Well, here's the thing. This cake does not have any fat in it, okay? And a cake with no fat and a lot of egg whites will end up like [bounces a rubber ball] ...

1 3/4 Cups sugar

Without sugar an angel food cake is essentially a hard cooked egg.

... only it won't taste nearly as good as that. By adding all of this sugar, we're going to provide some tenderizing and that's going to make a nice, moist cake.
    Now what would really be great is to have fine sugar. Fine sugar dissolves very quickly and it's nice and light. It's easy to work into light batters. The thing is, who wants to go out and buy fine sugar? Nobody. So make your own. Two minutes in the food processor.

Unlike confectioners sugar, fine sugar does not
contain corn starch or any other additives.

    Since the crystals now take up less space, one and three quarter cups has become one and a quarter to one and a half, depending on your food processor. Now about half of this, roughly, gets sifted with a quarter teaspoon of salt and one cup of cake flour. Now what makes 'cake flour' cake flour? Well, it's made from weak or soft wheat which doesn't contain much in the way of protein. No protein, no gluten. No gluten, no chewiness. Cake flour is also is very finely milled. Put these things together and you've got a flour capable of producing a very soft and light cake.

1 3/4 Cups becomes 1 1/2 cups

sift half with
1/4 tsp salt
1 Cup cake flour

Swans Down

    Now when this dry stuff faces the foam to come there won't be much in the way of mixing so it is important that the sugar and flour are integrated and aerated. Sifting now and then again into the batter will do the trick.

The more air between the flour granules, the
fewer bubbles will be broken in the final batter.

    On to the wet works. A dozen large egg whites. Whether fresh or thawed like these, they need to be at room temperature, okay? Cold whites aren't flexible so they don't whip well. Add to this a third of a cup of warm water. Now when working with these, the most important thing is that there be no fat anywhere in sight [hand appears with eye dropper full of egg yolk] especially egg yolks. You see, a single cc of yolk will drastically damage the white's growth potential. Why? Tell you later.

1 dozen large egg whites

1/3 cup warm H2O

AB: Now get that stuff out of here.

    Okay, since a drop of yellow could ruin a whole carton of whites, do practice safe separation by using three containers. Begin by separating the white into a custard or tea cup in the middle. Move the yolk into a holding tank. Then after screening for yellow flecks, move the white out of quarantine and into its own holding tank. This way any renegade yolk will be isolated in the middle cup. You can throw it away or cook an omelet. Either way, if any yolk does show up in that middle cup, you'll have to start with a clean cup.

    To up the flavor ante, add a teaspoon of chemical X, extract that is. Any kind you like. I think orange sounds good today. There we go.

1 tsp chemical X (tract)

    Last but not least, to help the whites on their way to greatness we'll add a teaspoon and a half of cream of tartar. Now one day when I was a kid, I mixed up a few tablespoons of this stuff and put it on my fish sticks. I wish somebody had taken the time to explain that this is not freeze-dried tartar sauce but partially neutralized and finely ground version of tartaric acid crystals harvested from the inside of barrels where wine's fermented. You often see them on the underside of corks. Anyway, as a mild acid it will add just enough hydrogen atoms to the whites to stabilize the foam.

1 1/2 tsp cream of tartar

    Okay. As for the hardware, aside from the usual measuring menagerie and various vessels, we will employ a large balloon whisk, an electric hand mixer, a rubber spatula, a tube pan—more on the tube part later—and a whipping bowl. You know what? Let's go bowling.

As is true of so many American desserts, angel food
was invented in the early 1800s by the Pennsylvania Dutch

Bed, Bath & Beyond: Dunwoody, GA - 11:58 am

GUEST: W, Equipment Specialist

    Simple though they may seem, shopping for a bowl is not an easy thing. That's because there are actually bowls designed for work and then bowls designed to just hold things and I pity the poor fool that confuses the two.
    For instance, say that you were to take your egg whites and attempt to whip them up inside this plastic bowl. Okay. Plastic molecules are very, very close to fat polymers. Matter of fact, they're so close to one another that they attract each other and that means that even after four maybe five hard washings there still will be a layer of fat adhesed [sic] to the inside of this bowl. And I don't need to tell you what'll happen if a little bit fat comes in contact with a perfectly good egg foam ... [senses W].
    She's back there isn't she? So why don't we help our good friend W and logically rearrange the bowl department?

W: Perhaps I should rearrange you ...
AB: You know, you're right. Most of this stuff is absolutely superfluous. I mean, come on. There are a lot better containers for a dragging slaw to the Halloween Hoe-Down in wouldn't you agree? And what about this? Glass. Glass bowls. You know what they do? They break. I mean, besides, maybe ... not, not even a Jell-O mold. You know, what I think we've got to do here is really re-think the role of the work bowl. Maybe if we resorted ...
W: Nope. Wait. Hold it. Hold it. Hold it. If I help you will you just leave without a struggle?
AB: A struggle? W, I've got oven mitts bigger than you, girl.
W: Security, aisle five.
AB: Security? Since when do ...
SECURITY: [rounds corner]

    I didn't know they let those guys moonlight.

AB: All right. You win. Call off the dogs.
W: [holds him back] So, what are you mangling today?
AB: Egg whites, actually.
W: We should talk copper.
AB: Oh now, come on. I've heard of that whole copper/egg-white thing was just a bunch of malark ...
W: Scientific fact?
AB: Scientific fact. Yes. Absolutely. What I heard.
W: Egg whites actually pick up copper ions from the bowl.
AB: Hmm. That means that those ions very well could block bonding sites on the egg proteins. That would prevent other proteins from joining on, thus preventing over-coagulation. I like it.
W: Traditional copper bowls are also easier to whip in because of their round bottoms. Nothing does egg whites better.
AB: [looks at price tag] Right. Uh, well what if I was looking for more every-day kind of bowl.
W: If you mean bowls that you can actually work with ...
AB: Yeah.
W: ... beat up with a hand-mixers, ...
AB: Right.
W: ... use as double boilers, ...
AB: Every day.
W: ... put in the oven and temper chocolate with, ...
AB: Whenever possible.
W: ... use as molds and, of course, mix in ...
AB: Right.
W: ... then you can't go wrong with stainless steel nesters. You can find anywhere from 3 to 6 in a set.
AB: Well, I guess more is better, right?
W: Actually, better is better than more. And if you're really going to work them there are some things you need to look for.
AB: Like what?
W: Well first you want stainless and you want heavy. Feel that.
AB: Woo. Stout.
W: Notice the shape of the bowl, the angle of the curve and the narrow bottom makes for easier mixing.
AB: Um, hm.
W: And the straight sides keep the work in the bowl and not on the counter.
AB: Ah, it doesn't slop out. Nice.
W: And it also has a handle so you can put it in a sauce pan and use it as a double boiler. Or, you can use it as a lid.
AB: Of course you could just carry it. Ha, ha, ha, ha. What about a spout.
W: That's up to you, but I think they get in the way more than they help.
AB: I see. Well, I have to say, uh, W, once again you have bowled me over. Heh, heh. You know, I'm really all set on stainless steel bowls to tell you the truth. But hey, if you're willing to talk discount on this little copper number here, I brought money this time. Really, it's ...
W: Security.
S: [advances]
AB: Not exactly the copper I had in mind.

Although copper is toxic in large amounts, copper
bowls are safe for whipping egg whites and cream.

The Kitchen

    Now regardless of the function of the final foam, I like to start egg foams with a hand whisk. It's better at getting the whole viscous mass moving and once you've got it in motion it'll start to build itself into a froth and a froth is the first step on the way to a foam. There. Look. In just a couple of seconds we've got a nice, big base of bubbles. Now it's time to move in with the heavy artillery. Go with your hand mixer on medium speed.
    You know, now would be a really good time to get down inside there and see what's going on. Go ahead. Get close. Go ahead.


    Here we have a foam. Just a few thousand bubbles being maintained by little more than the viscosity of the surrounding liquid. But as they are agitated by the mixer, they're going to divide and grow into lots of smaller bubbles. As the mixer invites even more air to the party, more bubbles will be created. This is where even a speck of egg yolk can wreak havoc by greasing up the bonding points on the proteins. If that happens ... [pops a balloon]. By the way, now's a good time to sprinkle on some sugar.

The Kitchen

    Sprinkle on the reserved sugar just a tablespoon at a time. It'll take it a couple of minutes to work it all the way in. Now in the meantime, the beaters are still breaking up all those big bubbles into little bitty bubbles and more and more air is being worked into the mix. You can help by not keeping the beaters egg-merged all of the way down. Bring them up to the surface every now and then so that they can grab hold of air.
    Now you'll notice that we're starting to get trailing. You can see the pattern, kind of like a rooster tail of the beaters moving through the eggs. That means that we've got a successful foam going here. It's completely opaque, it's snowy, looks good. But, it's nowhere close to done. How can you tell? Dig in and take a look. No back bone. No cling. We're not there yet. But it'll happen very quickly.


    Now that a good bit of air has been incorporated into our foam, certain egg proteins begin to unwind and form a mesh around the bubbles. Now some of these proteins dry and harden when exposed to air. Rub your hand on egg whites sometime and then let it dry for a minute and you'll see what I mean. As these proteins stiffen, so, too, does our foam. Sometimes, in fact, this happens long before the foam has reached its full volume. But that is not going to happen to us because we added water right at the beginning.

The Kitchen

    Now we're talking. These are called peaks. But as you can tell by gravity's effect, they're still slightly soft peaks. Still, we're at a point where good eggs can go bad even with the protection of the cream of tartar and the water. So I'm going to turn the speed down on the mixer at this point because if I don't, what is now nice and smooth and creamy will become hard and dry and yuck. [is shown a plate of hard, dry foam] What happened there?


    Whip it good but don't whip it too long or else the proteins will squeeze together so tight that ... [squeezes and pops a balloon]. Game over.

Beware: not only is overcoagulation
irreversible, it renders egg whites useless.

The Kitchen

    And we have achieved medium peaks. Now this is as far as I'm willing to take angel food cake. Remember, these bubbles still have to be elastic enough to expand in the oven and we still have some dry ingredients to go in. By the way, if we had added another cup of sugar to this and beat it all the way to stiff peaks, we'd be talking about meringue, but that's another show.

Stand mixers can be used for beating egg whites, but they
tend to allow unbeaten white to pool at the bottom of the bowl.

The Kitchen

    Folding time. The goal? Integrate this dry stuff into this wet stuff while destroying as few of the bubbles as possible. Now you may remember we put this move on Mr. Mousse in our film-noir classic, Art of Darkness. Start by sifting on just enough of the flour mixture to dust the top of the foam. There. Now fold. Straight down with a rubber spatula, up the side and over. Turn the bowl a quarter and repeat working your way around. Just like that.

Some Pennsylvania Dutch bakers keep a
clean fly swatter just for folding batters.

    Now you've got a new surface, sift on some more. The goal? Do this with the fewest motions possible. There. It still looks like a bit of a shaggy mess but that's okay. You don't want to over-fold. Now, it's imperative you get this straight to the pan. Add the batter in dollops. Don't really try to pour it in or you'll flatten it out.

    Now what's with the tube? Support. This batter's going to double in volume but only if it's got something to climb, to hold on to. Without a structure, here in the middle the cake would just be sink, sank, sunk. The tube also provides for even heat contact and that will ensure even baking. Now there are several different styles of tube pan but all that's really important is that the center tube comes up beyond the edge of the pan. Now this one also breaks in to two parts which is sweet.                                      _
    Now once everything is in don't try to smooth it out with your spatula. Don't bang it up and down or you'll just lose air. Just give the pan a couple of gentle spins. There. Now straight into a 350 degree oven for 35 minutes. No peeking.

350° oven


    Now that it's in the oven, this foam will continue to increase in volume. That's because the air in each bubble is going to expand from the heat. Now that's okay with this mesh because it's flexible. The problem is when it gets hot enough this mesh is going to fall apart. Luckily we've already got another one standing by to take its place, ovalbumin, the last of the great egg-white proteins. With this protein in place it doesn't matter if the water in the bubble walls evaporates as steam. The foam will remain stable and that is how angel food works.


Other proteins responsible for albumin foaming include
conalbumin, ovomucin, and of course the globulins.

The Kitchen

    Ah, that is what angel food cake should look like. But to be sure it's done, got to give it the skewer right down the middle. Perfect. Not bone dry. You don't want it to be completely dry. Now the problem now is that if we cool this upright the cake's going to fall because until it really sets it can't even support its own weight. That is where the tall tube comes in. Put a pan on top and gently flip it over. Now suspended just like that, in two or three hours the foam is going to set and it will stay that way forever ... well, almost forever.

Never, ever, grease or lubricate an angel food pan or it
will fall out of the inverted pan before it has a chance to set.

The Kitchen

    The one down side to not being able to lube up the pan is that the cake is going to stick. But you know that if it didn't stick, it wouldn't be able to climb up the sides. And if it couldn't climb up the sides, well, it wouldn't be angel food, would it? There. I just usually cut all the way around with my thinnest serrated blade which just happens to be the blade from my electric knife. Now, behold the wonders of the two piece tube pan. There. Now all you have to do is cut away the base. I just usually turn the pan against the knife like that. It doesn't take much. Ah.
    Now the next cut is extremely important because it's the first one you're actually going to eat and I like a nice healthy slice. Now unfortunately you can't smell this. This is extremely fragrant. It is unbearably light and, I have to say, ... mmm ... delicious. And, of course, add to that the fact that it is very easy to make, it works and plays well with others and, hey, it contains no fat. None. Zero. Zip.
    Now I can't speak for those for whom this divine device is named but you know what? I know good eats when I see it and when I taste it. See you next time. Mmm.


    [voice over] Ladies and gentleman. The part of the microscopic foam was played by 526 white latex balloons. Although they were handled with the utmost care, regretfully two balloons perished during the production.

Proof Reading help from Jon Loonin & Sue Libretti

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Last Edited on 08/27/2010