Lipids

Appears in

Published 2003

About

Lipids (fats, oils, and emulsifiers) interfere with aeration. Depending on the type and the amount, lipids either slow down aeration or prevent it from happening at all. This is especially true of egg yolk lipids—lecithin in particular—more so than of shortening or vegetable oil. Even a small amount of yolk can prevent whites from whipping.

Lipids interfere with aeration by coating proteins, preventing them from unfolding and aggregating. But they do more. Lipids compete with proteins for a spot at the foam’s bubble surface. Since lipids themselves cannot form a strong, cohesive network the way egg proteins can, lipid-coated bubbles expand rapidly, only to collapse.

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