When folding, a lighter product is folded into a heavier one, creating a homogeneous light mixture. This technique is especially important when making sponge cakes as the entire texture and leavening power of the cake is dependent on how well the whipped egg whites are folded into the other ingredients. There are a couple of tricks to folding:
1: Don’t under whip the whites or cream, as some of the air will be lost during folding no matter how quickly or gently you do it.
2: Mix approx 1/3 of the lighter mixture into the heavier one. This will enable the remaining mixture to be incorporated with more ease.
3: Next Fold in the remaining thirds one at a time, waiting till the first of the two is almost homogeneous.
4: Fold with either a whisk or a rubber spatula. Don’t over mix, because this will lose volume. Starting at the bottom of the bowl, work in a spiral motion, slowly and gently, bit by bit moving the heavier mixture onto and into the lighter one. Since you already mixed some of the light mix into the heavier one, it’s now light enough to sit on the light one without flattening it.
5: Bake immediately.
