I was planning to make a Pumpkin Mousse for Thanksgiving.  My recipe says to fold the whipped cream into the pumpkin mixture.  What does it mean to 'fold' something, and when do you use this technique?

--Laurel

In cooking, folding is a mixing technique that is used to gently combine ingredients where a more aggressive method would cause one of the ingredients to lose volume.  Commonly, the ingredient that is of concern is either whipped cream or beaten egg whites. The lighter ingredient, in this case the whipped cream, is put into a bowl already containing the heavier one, the pumpkin mixture.

To fold them together, cut down through the center of the ingredients with the edge of a spatula until it touches the bottom of the bowl, near to you.  Then turn your wrist until the spatula is parallel to the bottom of the bowl.  Lift, continuing to turn the spatula so that the ingredients on the bottom are brought gently up and folded over top of the mixture.  In total, the blade of the spatula will make three quarters of a rotation.  If you are right handed, usually you will rotate the spatula clockwise while sweeping it in a right to left, again clockwise, direction.  After each fold, use the other hand to turn the bowl one quarter turn and repeat until the ingredients are evenly mixed, using as few folds as possible.

The gentle motion of folding will blend the ingredients without beating air out of the mixture, as would happen with, for instance, a whisk.

Some instructions will say to make a figure eight pattern while moving the spatula into the bowl before each fold.  This isn't really necessary.  With a little practice, folding ingredients will become quite easy.