The kitchen chemist is back, BABY! And really into watercolor cakes. I made this one with completely natural food coloring!
Introduction: I don't really have a problem with artificial food dyes. Anyways, they're everywhere: in hot dogs, cereal, maraschino cherries, mouthwash, even fresh oranges. And the FDA regulates color additives to ensure they're safe. But if you want to avoid processed dyes derived from petroleum (or worse, bugs), you could make your own food coloring using natural food pigments. Like carotenoids, which give carrots and sweet potatoes their orange color. Or anthocyanins, which make blueberries all purple-y. Or chlorophyll, which make leafy greens so green. But just note that some natural dyes aren't as vivid or exciting as the synthetic ones. Also, note that blue is notoriously difficult to achieve with natural dyes. (Synthetic blue food coloring is made out of the same indigo dye used in your blue jeans.) Let's color!
Materials:
Natural food coloring:
- blueberries
- raspberries - beets
- carrots
- spinach powder (next time, I'd use fresh spinach or basil)
- spirulina powder (next time, I'd skip this)
Carrot cake (very slightly adapted from the King Arthur Flour recipe):
- 1 1/2 cups vegetable oil
- 2 cups granulated sugar
- 1 teaspoon salt
- 4 large eggs
- 1 tablespoon cinnamon
- 1/2 teaspoon ginger
- 2 cups all-purpose flour
- 2 teaspoons baking soda
- 3 cups grated carrots
Frosting:
- 1 stick unsalted butter, at room temperature
- 2 8-ounce packages of cream cheese, at room temperature
- 1/4 teaspoon salt
- 2 teaspoons vanilla extract
- 1 16-ounce box of confectioners' sugar
Methods: Make the natural food dyes first. If you don't use them right away, you can freeze them in ice cube molds and then defrost in the fridge before using.
Purple: In a small saucepan over medium heat, boil some blueberries in a small amount of water. Simmer to reduce the liquid. Use some cheese cloth to strain out the berries. (You can also try purple cabbage if you're so inclined.)
Pink: In a small saucepan over medium heat, boil some raspberries in a small amount of water. Simmer to reduce the liquid. Strain out the berries. (Strawberries or cranberries would also work.)
Red: Cut up a beet or two. In a small saucepan over medium heat, boil the beets in a small amount of water. Remove the beet chunks and simmer to reduce the liquid.
Orange: Cut up some carrots. In a small saucepan over medium heat, cover the carrots with water and bring to a boil. Simmer until the carrots are tender. Drain and reserve the liquid. In a blender or food processor, blend the carrots with a small amount of cooking liquid. Strain out the pulp. Simmer again to reduce the liquid.
Green: Um, I tried to mix spinach powder with a little bit of water, but the end-product turned out grainy and weird. Next time, I would steam and puree some fresh basil or spinach and make a pesto frosting of sorts...
Blue: Here's the deal - I bought some spirulina powder (which is actually made of blue-green algae!!), but it smelled far too fishy for my taste. So alas, no blue icing for this watercolor cake!
Now, make the cake. Preheat the oven to 350 degrees F. Butter and flour two 9-inch round cake pans. In a large bowl, combine the oil, sugar, salt, eggs, cinnamon, and ginger. In a small bowl, combine the flour and baking soda. Add the flour mixture to the oil mixture and mix together. Add the carrots and stir until just combined. Pour the batter into the cake pans. Bake for 35-40 minutes. Remove from the oven and cool for a few minutes. Remove the cakes from the pans and cool completely before frosting.
Next, make the icing. In a large bowl, combine the butter, cream cheese, salt, and vanilla. Add 3 cups of confectioners' sugar and mix until smooth and fluffy. If the consistency is too thin, add more sugar. To assemble, put one of the cooled cakes on a cake stand or a plate. Frost the top of the first cake layer. Carefully set the second cake on top of the first. Spread the frosting on the top and sides of the cake.
Finally, watercolor your cake! Swirl the natural food colors as desired on the frosted cake. (Or if you have leftover frosting, stir in dyes to make more muted, pastel frosting colors.)
Results and Discussion: The natural dyes seemed like they would be a labor of love. But in hindsight, they really weren't that hard. However, some colors were easier to achieve than others. Beets, raspberries, and blueberries all worked wonderfully. Spinach powder and spirulina powder, not so much. But it actually didn't matter because the carrot cake was delicious.
