The Science of Meringue!
In our recipe, the first step (after preheating your oven and lining the baking sheets) is to separate the egg whites from the yolks and beat those whites. The egg whites are separated before beating because the yolk has fat in it, while the white is just proteins. The whites are made up of 88% water, 0.2 % fat, 11% protein (Rocculi). After that, you have to leave the eggs out at room temperature for at least half an hour. The eggs will whip up bigger if they are left out and come to room temperature. It is imperative that no yolk is present in your egg whites when beating them. This is because the protein in the egg white is what coats the air bubbles formed by beating the eggs, and if the yolk was included the fat from it would get in the way of this process, and interfere with how to protiens line up and coat the bubbles. It is important that the bubbles are properly coated with and protected by the proteins because this is what will help give the meringue volume (Rhodes).
Beating the egg yolks is best done with a mixer with a whisk attachment, in a medium bowl. The egg whites are going to expand much beyond their original size, so it is important that the bowl used will fit it all. It is also suggested that you do not use plastic bowls, and they can contain fat residue even after washing, which as stated before, will interfere with the expansion of the egg whites (Rhodes). The egg whites expand because when we beat the eggs, air bubbles are forming and the eggs are undergoing a physical change. All of the expansion is from the addition of air. This is why beating the egg whites for the correct amount of time is crucial for meringue (Rocculi).
Cream of tartar is a byproduct of wine and grape juice processing. The addition of cream of tartar to the eggs before beating is done to stabilize the foam before it gets started. This happens because when the eggs are beaten, the protein changes shape to form around the water in the whites and the air. As you let it sit, the protein starts to change back, releasing the air and water. The egg whites contain sulfur, which will start forming strong bonds as the meringue sits. The acid in the cream of tartar stops the sulfur bonds from forming in the egg whites, helping the meringue stay fluffy and dry for longer. (Oldham)
Vanilla extract is also added for flavor, and it acts similar to salt in a savory recipe. It brings out the natural flavors in the ingredients, and is the flavoring for these vanilla meringues. Without the vanilla extract, the cookies would taste bland and just like plain sugar. (White)
The addition of salt into the meringue mixture is primarily for flavor purposes. Adding salt to sweets seems counter intuitive but it actually helps our taste buds perceive sweetness better! Adding salt to sweet baked goods like meringues, helps cancel out any bitter flavors that may oppose the sweetness of the dish, so it’s always good to add a small amount of salt to sweet dishes (Berenstein).
This mixture should be beaten until it becomes frothy. It is important to start adding the sugar when the mixture is already partly beaten because the addition of sugar can get in the way of the formation of the bubbles. When the mixture is starting to froth up, start adding the sugar slowly in small increments to mitigate the loss of bubbles from this addition. After the sugar is all added, the egg whites should be beaten until they are forming stiff peaks. This means that when you remove the beater, the peak that forms will stay upright. If the peaks are drooping, you have to keep mixing. Be careful to check frequently, because over beating can make the mixture separate the water from the rest of the molecules, leaving wet and very dry clumps of egg, which would make bad cookies.
After this is done, you should put the meringue into a piping bag and pipe the cookies on parchment paper. They should be an inch in diameter and two inches apart from each other. The parchment paper is used because the cookies can be very sticky on the baking sheet and it will be easier for you to remove them if it is lined. The cookies are piped because it would be impossible to make uniform cookies with a less precise method because the meringue is sticky.
The meringues are baked in an oven because they need heat all around them to cook properly and keep their shape. The heat transfer is convection, which means the hot air and cold air circulate around the oven and heat all parts of the food equally.
For our recipe modification, we wanted to explore the importance of beating the egg whites for the proper amount of time. To explore this concept we beat some of the egg white mixture for a longer amount of time than suggested. This resulted in the foam mixture collapsing and becoming clumpy, and grainy. When over mixed the egg whites were no longer glossy and created stiff peaks, rather they became almost chunky, without any structure to be able to form a cookie.
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Berenstein, Nadia. “Grapefruit And Salt: The Science Behind This Unlikely Power Couple.”
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Institution, 20 Jan. 2012, www.smithsonianmag.com/arts-culture/meringue-chemistry-the-secrets-of-fluff-23039746/.
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White, C. (2019, December 24). Why Do You Add Vanilla Extract Last When Baking? Retrieved