Folding is quite simply the process of combining two or more ingredients by lifting rather than stirring. It is a technique most often used when attempting to mix ingredients where one or more is of a very delicate nature. A good example is when attempting to fold a thicker substance through whisked egg whites.
Egg whites that have been whisked contain little bubbles of air in them and stirring them with another ingredient would simply knock all the air out of these bubbles. By folding the ingredients together these air bubbles are retained.
- Place the puree in a large mixing bowl.
- Add the whisked egg whites.
- Using a rubber spatula, carefully mix the two ingredients by getting the spatula under the puree and lifting up and through the egg whites.
- Turn the bowl and scrape the edges clean.
- Repeat the process a few times until the two ingredients are suitably combined.
In some cases you may choose to first fold only half of the delicate substance (egg whites) with the thicker substance (puree) in order to soften the thicker ingredient, and then fold in the remaining delicate substance (egg whites) at the end.