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Aquafaba & Other Hopes for Delicious Egg-free Meringues

Photo credit: veganbaking.net (vegan-baking/Flickr)

Photo credit: veganbaking.net (vegan-baking/Flickr)

Meringues are one of the few desserts that are simple yet elegant works of art. They are also precursors to other impressive, albeit considerably more complicated, desserts such as baked Alaska, lemon meringue pies, and macarons. At the bare minimum, all you need to make a fluffy meringue is egg whites, sugar, and an electric mixer—or an egg beater and some arm power. For vegans, this egg-containing dessert is not an option—but why should vegans (and those with egg allergies) miss out on this sweet, airy dollop of heaven?

To make a decent egg-free meringue, it helps to understand the meringue at the molecular level. How does a liquid get whipped into a cloud-like solid?

Egg whites, comprising 90% water, are undeniably runny. The other 10% consists of proteins, which play a major role in the fluid-to-fluff transformation. Mechanical stress from rigorously beating the egg whites causes the egg white proteins to denature, unfold from their natural structure. This exposes various amino acids, the building blocks of proteins, to the rapidly aerating environment. Some of the amino acids are hydrophobic (water-fearing), and some are hydrophilic (water-loving). As the egg whites are whipped, hydrogen bonds form between the hydrophilic amino acids and water in the egg whites. The hydrophobic amino acids prefer to be exposed to the air that is quickly beaten into the liquid mixture. Air ends up trapped in the meshwork of denatured proteins within the developing foam, and so the longer the mixture is beaten, the fluffier it gets. To retain the trapped air bubbles and generate peaks that stand up straight, sugar is added as a stabilizer. And eccola! Una nuvola dolce nella ciotola; a fluffy meringue is ready to bake or prepare into macarons or boccone dolce.

To create an equally amazing and delicious vegan counterpart, the egg whites would have to be substituted with an ingredient that has both water-loving and water-fearing parts. Logic may think to search for a plant-based protein alternative, but French chef Joël Roessel discovered that chickpea brine works perfectly well as a vegan egg-white substitute [1]. Coined aquafaba by Goose Wohlt (Latin for “bean water”), the leftover water from a can of chickpeas can be combined with sugar and whisked into a vegan meringue that surprisingly tastes nothing like beans. Of all the possible substitutions, why does aquafaba work in lieu of egg whites?

Photo credit: getselfsufficient/Flickr

Water leftover from cooking chickpeas, also known as aquafaba, can be used in lieu of egg whites. Photo credit: getselfsufficient/Flickr

Anne Rieder, a scientist at the Norwegian food research institute Nofima, analyzed aquafaba and revealed that the bean water contains equal amounts of proteins and carbohydrates [2]. The function of proteins in the aquafaba are similar for meringue-making; Rieber suggests that the carbohydrates may serve as an additional stabilizer by increasing the viscosity of the water portion of the foam.

To create foams like meringues, Kent Kirshenbaum, a professor at NYU, was inspired by chemistry to invent a foaming agent that is rich in saponins, currently awaiting patent approval. Saponins are a class of chemicals found in plants, including beans like chickpeas. The name derives from the soapwort plant, Saponaria, which contains the Latin root for soap, sapo; this is a fitting name, given the compound’s propensity to foam when shaken in water [3]. Like the amino acids of proteins, saponin molecules contain a hydrophobic and a hydrophilic moiety that enables them to interact with both air and water.

Whatever the reason for avoiding eggs, at least you won’t have to forfeit the heavenly delight that is a lightweight meringue cookie.

References cited

  1. Aquafaba history.” The Official Aquafaba Website.
  2. Aquafaba, what is its chemical composition?Frie kaker.
  3. Saponins.” Cornell University Department of Animal Sciences.

Alice PhungAbout the author: Alice Phung once had her sights set on an English degree, but eventually switched over to chemistry and hasn’t looked back since.

Read more by Alice Phung


Apple Pie with Peanut Butter Mousse

The Science of Pie – May 19, 2013
People’s Choice Award
Elan Kramer, Caleb Turner (Team “Insert Team Name Here”)

This student duo thought outside the box with this creative apple and peanut butter pie. To create the ultimate peanut butter experience, the team experimented with the effect of egg white content on the texture and density of the peanut butter mousse.

TeamInsertTeamNameHere

photos courtesy of Patrick Tran

Egg white content affects mousse texture. (A, B) Team “Insert Team Name Here” visualized the air bubbles incorporated into peanut butter mousses prepared with different amounts of egg whites. (C) Using image processing techniques, they calculated the mean (red) and median (blue) air bubble areas as a function of egg white content. Their results show that there is indeed an optimal egg white content for creating an light, airy mousse. (D) An egg white is made up of many proteins suspended in water. Whipping incorporates air bubbles into the egg whites, causing the proteins to unfold as they are exposed to air. Denatured proteins [link to ceviche recipe] form networks at the liquid/air interfaces that stabilize air bubbles within the egg white foam.

The Recipe
Frozen apple pie with peanut butter mousse

1 large store-bought graham cracker crust

For the apple layer:
2 tbsp unsalted butter
3 firm-textured cooking apples*, peeled, cored, and sliced
¼ cup granulated sugar
1 tsp fresh lemon juice
2 tbsp powdered sugar
*Team “Insert Team Name Here” used Pink Lady and Granny Smith apples

For the peanut butter mousse:
1 cup heavy cream
8 ounces cream cheese, softened
1 cup smooth peanut butter
¾ cup granulated sugar
½ cup firmly packed light brown sugar
2 tsp pure vanilla extract
2 large egg whites

For the topping:
1 cup heavy cream
1 tbsp powdered sugar
½ cup finely chopped salted dry-roasted peanuts
2 graham crackers, crushed
1 1/2 tsp cinnamon

To prepare the apple layer, melt the butter in a large sautée pan. Stir in the apples and granulated sugar and cook over medium heat, stirring often, until tender, about 5 minutes. Stir in the lemon juice and powdered sugar and cook, stirring, for 1 minute longer. Remove from the heat and refrigerate.

To make the peanut butter cloud layer, use an electric mixer to whip the heavy cream until it holds semi-firm peaks. Cover and refrigerate.

Using the mixer, beat the cream cheese and peanut butter together until smooth. Gradually beat in the sugars, then the vanilla. The mixture will be lumpy, like cookie dough. Add the whipped cream to the peanut butter mixture, slowly blending them together with the electric mixer until smooth.

Clean and dry the beaters. Using a clean bowl, beat the egg whites until they hold stiff peaks. Fold the whites into the peanut butter mixture with a rubber spatula until evenly blended. Put mixture into the pie crust, cover loosely with aluminum foil and freeze for at least 5 hours.

When you’re ready to serve the pie, take it out of the freezer and top with the refrigerated apples. For the topping, add the powdered sugar and 1/2 teaspoon to the cream and use an immersion blender or mixer to whip. Spread over the top of the pie and sprinkle with peanuts, graham cracker crumbs, and remaining cinnamon.

Recipe adapted from Cookstr: Frozen Apple and Peanut Butter Cloud Pie