Why It Works
- Cream of tartar helps to stabilize the foam, which results in a voluminous meringue frosting.
- Cream of tartar also helps to prevent browning due to caramelization of sugars and Maillard reactions.
- Heat helps denature the proteins in the aquafaba, helping to produce a more stable foam.
Aquafaba, the cooking liquid left behind from cooked beans, is a multifaceted gift to cooks. Similar to egg whites, the proteins present in aquafaba give it the ability to produce foams when combined with sugar and aerated vigorously. When baked, the foam produces meringue cookies that are practically indistinguishable from their egg-based counterparts. I wanted to see if the proteins in aquafaba could be manipulated even further to produce frostings for cakes and pies—an aquafaba meringue frosting that was egg-free!
Here’s what I knew:
- Aquafaba and egg whites produce foams because of water-soluble proteins that belong to the albumin and globulin families of proteins.
- In egg-based meringue frostings, the sugar and egg whites are heated then aerated vigorously to help the proteins in the egg white denature and change their shape. The foam that forms is stable and also takes on a satiny sheen. Ovalbumin in egg whites denatures at 183.2°F (84°C), so this became the endpoint temperature for my recipe.
Based on these two pieces of information, I hypothesized that the proteins in aquafaba might behave similarly if I heated them with the sugar.
I tested the idea out, along with a couple other ideas I had to improve the stability of an aquafaba-based meringue, and you can read about those experiments by clicking the link below. Long story short, by heating a mixture of aquafaba and sugar to 183°F (84°C) and then adding cream of tartar, an acid, you can produce a beautiful, fluffy, satiny, egg-less meringue that holds its shape and loft for hours, perfect for topping cakes and pies of all kinds. I also found that by adding strongly aromatic ingredients, like cardamom or coffee, you can mask much of aquafaba's "beany" flavor and aroma; and, if you use a brand of canned chickpeas that uses kombu, a seaweed, as part of its cooking process, the resulting meringue is even more stable.
- 1/2 cup (120ml; 130g) aquafaba (see note)
- 1/2 cup (100g) superfine sugar
- 1/4 teaspoon ground green cardamom
- 1/4 teaspoon cream of tartar
In a 2-quart saucepan, combine aquafaba with sugar and cardamom. Set over medium-low heat and cook, stirring and scraping with a silicone spatula, until mixture reaches 183°F (84°C).
Remove from heat and immediately scrape mixture into the bowl of a stand mixer fitted with the whisk. Add the cream of tartar and whisk at high speed until satiny white, stiff peaks form, about 15 minutes.
Frost cakes as desired with the meringue frosting.
Aquafaba is the cooking liquid collected from beans (in this case chickpeas). We recommend using aquafaba from canned chickpeas for reliable and consistent results. Please note that while home-cooked chickpeas can produce aquafaba that works, you may end up with varying results depending on how much water was used to cook the beans and how they were cooked. One 15-ounce can of chickpeas gives about 2/3 cup (160g) aquafaba.
Make-Ahead and Storage
This frosting can be refrigerated in an airtight container for up to 3 days.