The first time I heard of putting mayonnaise in a cake, I was shocked. A condiment? In a baked good? But the first time I actually tasted a cake with mayonnaise, in the recipe for Easy Chocolate Snack Cake from The Complete Baking Book for Young Chefs, I was even more shocked. The results don’t lie: Mayonnaise makes this chocolate snack cake perfectly moist. It turns out that there’s a good explanation for that.
Mayonnaise is primarily an emulsion of egg yolks and oil, both of which are common ingredients in cake, plus a bit of acid such as vinegar or lemon juice. It also contains an emulsifier called lecithin, which helps the oil coat the flour’s protein particles. All this means that adding mayonnaise to the cake batter boosts the moisture of the final product—and leaves none of its characteristic taste. Testing showed that using oil or butter instead of mayo made for a drier cake, but keeping the eggs in addition to the mayonnaise improved richness and springiness. After trying this recipe you may never think of mayo as just a mere condiment again!
