The Power of Flour, Part Three: Génoise
As a result of the experimentation we performed, featured in previous postings of "The Power of Flour," we found that we preferred potato starch to cornstarch when converting both bleached and all-purpose flour to simulate cake flour. Woody and I were then curious to see what would happen if we substituted equal weight potato starch for the cornstarch component in a classic génoise.
The baking time and height of the cakes were identical. The cornstarch version had a slightly tighter and more velvety crumb. The potato starch version had a slight potato flavor which was masked by the syrup. (Note if making génoise with more clarified butter and less syrup the potato flavor might not be masked as effectively.) Conclusion: For a classic yellow génoise we prefer the 50 grams cornstarch but equal weight potato starch is an acceptable close substitute. By volume, instead of 1/2 cup minus 1 tablespoon cornstarch use 1/4 cup plus 2-1/2 teaspoons potato starch. (However, for flavor and texture we prefer 100% Wondra flour to either combination, except when using decorative fluted tube pans as the finished height is slightly lower when using the Wondra.)
COMPARISON SLICES OF CORNSTARCH VS. POTATOSTARCH
CORNSTARCH AND CAKE FLOUR
POTATO STARCH AND CAKE FLOUR