Flashcards in CONCEPT 21: WHIPPED EGG WHITES NEED STABILIZERS Deck (65):
Describe whipped egg whites.
A billowy mound of cloud-like foam.
How do egg whites go from liquid to foam when whipped?
As an egg white is beaten, its protein unfold and bond to create a mesh-like network that coats and reinforces the surface of air bubbles produced in the water from egg whites (90% H2O). The unfurled proteins increase viscosity of the water surrounding any air bubbles, enhancing their stability.
What happens if egg whites are under-beaten?
Foam won't be stable.
What happens if egg whites are over-beaten?
The foam will become too rigid and rupture, squeezing out the liquid contained in the whites.
What will yolks do to egg whites when creating a foam?
They will coats the proteins, much like in a custard, and prevent them from unfolding and bonding.
What do oils and fat do to the air bubbles of a foam?
Fats and oils take up valuable space on air bubbles, disrupting the network of protective proteins and causing foam to deflate.
Why don't foams last?
Water eventually succumbs to gravity and begins to drain away.
Will starch help stabilize egg white like a custard?
What two ingredients help stabilize whipped egg whites?
Sugar and cream of tartar.
What two ways does sugar help stabilize egg white foam?
It slows the unfolding of egg proteins, delaying the formation of foam and protecting against over whipping. Two, it dissolves in the liquid surrounding the air bubbles, forming a thick and viscous syrup that is slow to drain.
Can sugar be added in the beginning of whipping? Why?
No, it interferes with the protein's ability to cross-link; fewer proteins will bond and trap air, resulting in a foam that is less voluminous.
What happens if you add sugar too late?
Sugar has less water to dissolve in, creating a gritty texture and a tendency to form drops of sugar syrup during baking.
When is the right moment to add sugar?
When the foam is frothy and bubbly but not quite firm enough to hold a peak; right before soft peak.
How does cream of tartar create better foam?
It's an acid that alters the electrical charge on the proteins of egg whites, reducing the interactions between protein molecules.
Does whipping take longer with cream of tartar?
Yes, but produces a much more stable foam.
Why are stabile foams important?
Whipped egg white can revert, at least partially, to their liquid state over time. This is what happens when the meringue topping on pie "weeps."
TEST KITCHEN: FOAM WITH CREAM OF TARTAR AND WITHOUT.
Regular foam lost 23mL of water in 60 minutes; cream of tartar lost less than half of that #, 9mL.
How can you minimize stickiness of meringue cookies on a humid or rainy day?
Allow meringues to cool in a turned-off oven for an additional hour.
Two basic ingredients in meringue cookies.
Egg whites and sugar.
How many types of meringue are there? What are they?
Italian, Swiss and French.
What is an Italian meringue?
Hot syrup is poured into the egg whites as they are beaten.
What is a Swiss meringue?
Heats the egg whites with the sugar.
What is a French meringue?
Egg whites are whipped with sugar alone.
What is the difference between meringue cooking when using French instead of Italian?
Italian meringues are dense and candy like.
What happens to meringues as they bake if sufficient sugar isn't added? Why?
Without sufficient sugar, the meringues will lose moisture too quickly and collapse.
What are the twin-stabilizers for meringues?
Sugar and cornstarch.
To guarantee uniform shape, what should you use?
Substitute for pastry bag?
Zipper-lock bag with end cut off or parchment paper.
Oven temp and techniques for meringue cookies.
225 degree oven for an hour, followed by another hour in the turned-off oven.
In their raw state, tiny bubbles that form a meringue get their structure from what two things?
Cross-linking of egg white proteins and the water that occupies virtually all the space between the bubbles.
What is happening as a meringue bakes?
Its moisture slowly evaporates, weakening its structure. At the same time, ovalbumin is becoming stronger by bonding with other proteins, providing additional structure for the foam.
What does sugar have a tendency to hold on to as meringues bake? How does this help?
What does cornstarch add to meringue cookies?
It shares the water clinging property of sugar and allows you to cut back on sugar if overly sweet; it doesn't compromise structure.
Recipe for meringue cookies.
3/4 C (5 1/4oz) sugar
2 TBSP cornstarch
4 Large egg whites
If sugar is lumpy should you break it up with grease-free fingers?
Yes, any residual fat from butter or chocolate might hinder whipping the whites.
Brown sugar offers sweetness and what?
A hint of smokiness from the molasses.
What ingredient in brown sugar is slightly acidic? What could this eliminate in making foam?
Molasses could eliminate the use of cream of tartar.
When folding egg whites with chocolate to bake, what happens when nothing has been added to them?
They collapse under the chocolates weight, giving the cake a dense, brick-like structure.
When folding egg whites with chocolate to bake, what happens when they've been beaten almost rigid?
This will make the cake unappealingly dry; beating them will only make the cake more dense.
When is sugar added if the final product should be soft peak instead of stiff?
Add 1/2 after it becomes frothy (30 sec) and combine; add the other half after combined.
What happens when mousse cake is baked at 350?
It turns into a giant mushroom that collapses after cooking.
What happens when mousse cake is baked at 300?
Causes the cakes exterior to be overdone with a raw center.
What's the right temp to bake a mousse cake?
In a water bath at 325 degrees.
Safest way to separate eggs?
Cracking then in a smaller bow, while cold, and then separating.
Should plastic wrap on covered, cracked eggs be touching their tops? Why?
Yes, so they don't dry out.
Cream of tartar is also known as what?
potassium bitartrate or potassium acid tartrate.
Cream of tartar is a byproduct of what?
Two main ingredients in baking powder.
Cream of tartar and baking soda.
Cream of tartar's acidic nature does what to egg whites?
Lowers the pH, altering the electrical charge on proteins, encouraging them to unfold; thus creating more volume, greater stability and a glossier appearance.
Why is Italian meringue a better choice for lemon meringue pie?
The hot syrup cooks the whites and transforms them into a soft, smooth meringue that is stable enough to resist weeping while baking; French doesn't always cook through and weeping is a greater risk.
Does angel food cake use oil or butter?
What can make an angel food cake somewhat heavy?
Sugar, even if it's confectioners' or granulated.
How to you avoid an acceptably heavy angel food cake?
Process granulated sugar in the food processor until powdery; it will dissolve much faster and won't deflate the egg whites.
How can you get away with sifting dry goods for angel food cake just once?
Process flour with half the sugar to aerate.
How many batches should you add flour into egg-white foam? Why?
Three batches won't deflate the egg whites.
How should you cool and angel food cake? Why?
Angel food cake should be flipped upside down so they aren't crushed by their own weight.
What is bouillie?
A paste made from flour and milk.
When folding the foam into a soufflé, what makes them more resilient to a heavy hand?
Sugar makes the foam more stable.
What technique give a soufflé a high, even rise? Why?
After pouring, trace a circle in the batter with your finger, 1/2 inch from the edge of the dish; it breaks surface tension.
Describe the taste of a finished soufflé.
Very creamy in the middle and firm around the outside, almost like a pudding cake.
Good indication a soufflé is done cooking.
The center isn't completely solid or liquid-y, but still quite loose and very moist. Once you can smell a soufflé it's about ready to come out.
Do copper bowls help make whipped egg whites stable?
What do "copper egg whites" do for a soufflé?
Soufflé has greater volume, flavor is less eggy and a light golden crust.
Science of copper bowls and egg whites.
When whipped, copper ions combine with conalbumin and slow the coagulation process; foam is more stable because it takes longer to whip. Because the foam is more stable, it can better tolerate expansion in the oven.