🥚 What Eggs Really Do in Baking (and how to best substitute)

Have you ever cracked an egg into your brownie batter and thought, “What exactly is this doing in here?” I used to wonder the same thing. Sure, it adds moisture, but that can’t be all, right?

This month, we’re cracking the science wide open (pun absolutely intended) to talk about the real role eggs play in baking—and how to replace them when needed without ending up with a crumbly mess.

Let’s dig in.

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First What Are Eggs Made Of?

From a food science standpoint, an egg is a compact, functional powerhouse:

Inside, it’s made up of two very different parts:

• The egg white: mostly water and protein (~90% water and ~10% proteins, mostly ovalbumin)

• The yolk: contains fat, protein, and a magical ingredient called lecithin (more on that later)

This mix of proteins, fats, and water means eggs perform multiple roles in your baked goods—sometimes all at once.

Let’s break it down further:

1. Structure: Protein Coagulation

Think of a cake like a house. Eggs are like the beams holding everything up.

When you bake, the heat causes egg proteins to unfold and then stick together. This process, called coagulation, gives your cake the structure it needs to stand tall and not collapse like a sad soufflé.

Too little egg? Your bake might crumble. Too much? You get a tough, rubbery bite.

More of a scientific breakdown:

Egg proteins (egg white begin coagulating at 60°C (140°F), and yolk proteins at ~65°C (149°F) denature when heated. This means they unfold from their native globular shape and begin forming new bonds with other proteins—aka coagulation.

That’s why underbaked custards are runny: not enough protein bonding. And why overbaking leads to rubbery textures: too much cross-linking.

2. Leavening: Foam Formation & Stabilization

Ever whip egg whites into stiff peaks for a meringue or sponge cake?

That’s protein magic happening. Egg whites are great at holding onto air bubbles. When you bake them, that air expands and gives you those light, airy textures we all love.

Stabilizing that foam often requires:

• Acid (like cream of tartar) to lower pH and slow coagulation

• Sugar to delay foam collapse

3. Moisture Retention

Eggs are full of water. That water hydrates your flour, dissolves your sugar, and keeps your bake from becoming dry.

The fats in the yolk also help make your baked goods tender. That’s why yolk-heavy recipes (like pound cake or custards) taste so rich

Removing eggs without replacing this moisture can lead to dry or crumbly bakes.

4. Emulsification: Making Fat and Water Play Nice

Oil and water don’t mix but an egg yolk can help suspend them together. The yolk contains lecithin (it is both hydrophilic [water-loving] and hydrophobic [fat-loving]), which acts as an emulsifier. It keeps your batter smooth and uniform, so your cakes bake up uniform instead of uneven or lumpy and reducing curdling.

5. Flavor and Color

Egg yolks give richness and a golden hue to things like yellow cake and brioche. And during baking, eggs help with browning through a phenomenon known as the Maillard reaction - a complex browning process between amino acids (in eggs) and sugars.

Yolks contribute:

• Richness from fats

• Yellow/orange pigmentation (from xanthophylls and carotenoids)

• Subtle umami from sulfur-containing amino acids

⚠️ One thing to note: no single substitute does everything an egg does. You might need to combine them. Like, use aquafaba for lift plus a little oil for richness.

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Key Takeaway: In a Shell...Eggs Are Everything🥚

• Eggs are baking’s multitasker. They give structure, hold air, add moisture, blend oil and water, and boost flavor and color. But when needed, you can swap them—smartly and science-fully.

• With some food science knowledge, you can simulate their effects using smart, purposeful substitutes.

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🥕 Italian Carrot Cake Recipe (Torta di Carote)

This Italian-style carrot cake is more delicate or fluffy than the American version. Instead of heavy spices, nuts, or a rich cream cheese frosting, this cake is all about letting the sweet, earthy flavor of carrots shine. Made with finely grated carrots, almond flour, and whipped egg whites, it has a soft, tender crumb that’s moist yet airy. A simple dusting of powdered sugar keeps it elegant and not overly sweet, though you can drizzle it with honey or syrup if you like for sweeter moister cake that becomes slightly more dense.

Ingredients:

• 2 cups (202g) blanched almond flour

• ⅔ cup (89g) all-purpose flour

• 1 tablespoon (14g) baking powder

• 1¼ cups (235g) organic cane sugar

• 1 tablespoon grappa (optional, but lovely)

• 5 large eggs, separated

• 3 large carrots (313g), finely grated (about 4 cups)

• 1 teaspoon vanilla extract

• ¼ teaspoon kosher salt

• Powdered sugar, for dusting

• (Optional: warm maple syrup, honey, or simple syrup for drizzling)

Instructions:

1. Preheat your oven to 350°F (175°C). Lightly grease a 9-inch cake pan and line the bottom with parchment paper.

2. Separate the egg whites from the yolks. In a large bowl, whisk the sugar and egg yolks together until pale and doubled in volume. Stir in the vanilla and grappa. Fold in the grated carrots.

3. In another bowl, whisk together the almond flour, all-purpose flour, and baking powder.

4. In a clean bowl, beat the egg whites with the salt until stiff peaks form (about 3 minutes).

5. Fold the carrot mixture into the dry ingredients until just combined. Gently fold in half of the whipped egg whites until incorporated, then fold in the remaining half until no white streaks remain. Take care not to deflate the batter.

6. Pour the batter into your prepared cake pan and smooth the top. Bake for 55–60 minutes, rotating halfway through, until the top is golden brown and the edges begin to pull away from the pan.

7. Cool completely on a wire rack. Dust with powdered sugar before serving. For extra moisture and sweetness, drizzle with warm maple syrup, honey, or simple syrup.
   

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🥕 Vegan or Egg-Free Substitute (for all 5 eggs):

How to Substitute Eggs the Carrot Cake Recipe
To properly substitute eggs, it helps to understand how they function in the recipe. The egg whites are whipped to incorporate air, so we’ll want a substitute that can do the same. Aquafaba (the liquid from canned chickpeas) is ideal — its unique protein-to-water structure allows it to trap and hold air much like egg whites.

For the yolks, which contribute richness, structure, and binding, you’ll want a substitute that mimics those roles. Ground flaxseed (1 tablespoon flaxseed meal + 2.5 tablespoons water per yolk) or cornstarch (1 tablespoon mixed with 2 tablespoons water) are great options here, helping bind the batter while adding a bit of body and texture.

Aquafaba + Flax (Best for Closest Texture Match)

• For the 5 egg yolks:
  Replace with 3 tablespoons flaxseed meal + 9 tablespoons water (let sit 5–10 minutes to gel).

• For the 5 egg whites:
  Replace with ½ cup aquafaba (liquid from canned chickpeas), whipped until stiff peaks form — just like egg whites!

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🍪 Chewy Chocolate Chip Cookie Recipe

I found this recipe at a community recipe box tucked inside a Julia Child exhibit at a museum wedged between family recipes from the 1960s.From the kitchen of UK Rittershausen, Newport, VT.

Naturally, I had to try them. And they were exactly what you hope to find at a recipe swap: buttery, chewy, packed with rich chocolate, and just nostalgic..They have crisp edges, soft middles, and a melt-in-your-mouth texture that makes people go quiet after the first bite.

They feel old-fashioned in the best way — the kind of cookie someone’s been making for decades, passed along through handwritten cards and now it’s yours.

Ingredients:

• 2 sticks (1 cup) unsalted butter, melted

• 1 cup dark brown sugar, packed

• 1/2 cup white sugar

• 2 large eggs

• 1 tsp baking soda

• ½ tsp salt

• 1 tsp vanilla extract (homemade if you have it!)

• 2½ cups all-purpose flour

• 2 cups chocolate chips

Instructions:

1. In a large mixing bowl, pour the melted butter over the brown sugar.

2. Sprinkle in the baking soda and salt. Mix until well combined.

3. Beat the eggs in a separate bowl, then add them to the butter-sugar mixture along with the vanilla. Mix until smooth.

4. Add the flour gradually, ½ to 1 cup at a time, mixing after each addition until a dough forms.

5. Stir in the chocolate chips.

6. Scoop the dough into walnut-sized balls and place on a parchment-lined baking sheet.

7. Bake at 350°F (175°C) for 10–12 minutes, or until the edges are lightly golden.

8. Let cool slightly on the tray before transferring to a wire rack.

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Want to learn more? Have a questions? Reply and let me know—I always love talking about the science behind baking.

Stay Sweet,
Sarah @HalfBatchBaking