Assisting in Leavening

As with eggs, fats help incorporate air into baked goods and, in doing so, contribute to leavening and additional tenderizing. Fats are not leaveners themselves—air, steam, and carbon dioxide are the leaveners—but fats play an important role in the leavening process. The four main ways that fats assist in leavening have been discussed elsewhere in this chapter but are recapped here.

The leavening that occurs in flaky pastries was just discussed, when layers of solid fat create gaps upon melting, gaps that expand from steam pressure. Additionally, all plastic fats contain some entrapped air. The air is distributed throughout the fat as very tiny bubbles. Some fats—butter and margarine—contain water droplets as well. Both air bubbles and water droplets contribute to leavening in baked goods, and this is the second way that fats assist with leavening.