The Science Behind Aquafaba Foam: How to Achieve Perfect Egg White Meringues

Welcome to a deep dive into the science of aquafaba and how it can be used to make perfect meringues. While traditionally egg whites are used to create meringues, aquafaba offers a fantastic alternative that can be enjoyed by those concerned with egg usage or allergies.

Composition of Legumes and Aquafaba

Aquafaba is the liquid that is left after legumes, such as chickpeas (garbanzo beans), have been cooked. According to Wikipedia, legume seeds are primarily composed of 19% protein, 61% carbohydrates, 6% lipids, and 14% water. When you cook legumes, the water-soluble protein and sugar migrate to the cooking water, specifically the aquafaba.

Protein Denaturation and Foaming

When protein is heated, it undergoes a process called denaturation, where it loses its natural shape and becomes more reactive and sticky. As you heat the aquafaba in an open container, air is entrapped, creating an unstable interface between air and water. This interface needs to be stabilized by a surface-active component, predominantly composed of proteins, to form a stable foam.

The protein molecules in aquafaba attach to the surface of air bubbles and stabilize them. However, as the foam stabilizes, the liquid gradually drains from the foam, causing the bubbles to come closer together and eventually merge. This is why foam stability decreases over time. Nonetheless, the high protein content of aquafaba plays a crucial role in stabilizing the foam compared to fats, which often destabilize it.

Factors Affecting Foam Stability

Making meringues with aquafaba is similar to traditional egg white meringues, but with a few key differences. Here are the steps to follow:

Ingredients and Preparation

One can of chickpeas, about 3/4 cup of liquid aquafaba. Make sure to drain the chickpeas well. Sugar (about 2/3 cup) Vanilla or almond extract (1 tsp) Piping bag and star tip or two tablespoons for shaping Parchment-lined sheet pans

Process

Drain the can of chickpeas and reserve about 3/4 cup of the liquid. Beat the reserved liquid in a stand mixer until stiff peaks form. Gradually add sugar, 1 tablespoon at a time, while continuing to beat the mixture to ensure it remains glossy. Add vanilla or almond extract after the sugar. If using a piping bag, pipe the mixture onto the prepared sheet pans. If not, use two tablespoons to make mounds. Bake in a preheated 250°F (120°C) oven for 90 minutes to 2 hours, checking when the meringues are dry to the touch. Allow the meringues to cool and enjoy!

Storing the meringues in an airtight container helps preserve their texture and freshness.

Now that you know the science behind making meringues with aquafaba, feel free to experiment and enjoy the delicious results. And if you have any questions, feel free to ask – I'm here to help!