According to Michel Roux's book Desserts, a Lifelong Passion,"Unbeaten egg whites can be kept frozen in an airtight container for several weeks.

Egg yolks: To freeze, whisk lightly with 5-10% sugar, then freeze at -25C/-13F for no more than four weeks.

Egg yolks 'burn' on contact with sugar or salt, so they must be beaten immediately with a whisk or spatula until completely homogeneous, otherwise they will form into hard little granules, which are impossible to break up."

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