Baking without eggs: How to use aquafaba to make meringues

Humans

You don't need eggs to make meringues, pancakes and a host of other baked goods. If you know the science behind it, there are ingredients such as aquafaba that can do the same job

By Sam Wong

15 April 2020

What you need

400g can of chickpeas

Lemon juice

Sugar

I DON鈥橳 know what it is like for you, but in my neighbourhood it has been hard to buy eggs since The Event, so I have been searching for substitutes to use in baking.

Eggs have several important roles in baked foods. They bind ingredients, contribute moisture and trap bubbles, helping to create light textures. Vegan bakers and those with egg allergies have found a range of alternatives to fulfil these functions.

Perhaps surprisingly, most of these aren鈥檛 rich in fat and protein like eggs, but consist principally of carbohydrates 鈥� specifically polysaccharides, which are chains of sugar molecules. These can link together to form networks, just like the structures formed by broken-down egg proteins.

Chia seeds and flax seeds are among the most common vegan egg substitutes. Polysaccharides in the seed coat form a gummy gel when mixed with water, which binds mixtures and traps water.

Starchy fruits and vegetables can also work well. Try swapping eggs for mashed banana when making pancakes, for instance.

Egg whites have a rare ability to form stable foams 鈥� important for making meringues, souffl茅s and other airy desserts. When egg whites are beaten, the physical stress makes globular proteins unfold and bond together, reinforcing bubbles in the liquid. One crucial protein, ovalbumin, is relatively immune to beating, but when subjected to heat, it unfolds and coagulates, giving permanent stability to the cooked foam.

A few years ago, someone discovered a substitute: the liquid found in tins of beans, dubbed aquafaba. Almost any beans seem to work, but chickpea liquid has a less beany taste than others.

During cooking, soluble carbohydrates and proteins diffuse out of the beans. There has been little research into which ones are responsible for the liquid鈥檚 foaming properties, but saponins may be important. These sugar-derived molecules have water-attracting and water-repelling parts 鈥� just like egg white proteins 鈥� which may collect at bubble walls and stabilise bubbles.

Egg foams can break if the proteins bind together too tightly and squeeze out water, and the same can happen with aquafaba. A little acid, in the form of lemon juice or cream of tartar, helps to stabilise them. The hydrogen ions in the acid stop proteins from shedding their own hydrogens and forming strong sulphur-sulphur bonds.

To make aquafaba meringues, line a baking tray with greaseproof paper. Take the liquid from a 400-gram tin of chickpeas, add a tablespoon of lemon juice and whisk until very stiff. One spoonful at a time, whisk in 125 grams of sugar. Place spoonfuls of meringue on the baking tray. Bake at 110掳C for 90 minutes, then turn the oven off but leave the meringues inside until cool. Serve with coconut yogurt and fruit.

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