Cocoa contains starch, which tends to absorb moisture in a batter. Consequently, when cocoa is added to a mix—for example, to change a yellow cake to a chocolate cake—the quantity of flour is reduced to compensate for this added starch. Exact adjustments will vary depending on the product. However, the following may be used as a rule of thumb:
- Reduce the flour by ⅜ (37.5%) of the weight of cocoa added.
- Thus, if 1 pound cocoa is added, the flour is reduced by 6 ounces. Or, if 400 g cocoa is added, reduce the flour by 150 g.