Mousseline sauce, use the white or the yolk of the egg? I always used the yolk of the egg for preparing mousseline sauce, but sometimes I see recipes on the web where they use the white of the egg. 

Like in the definition on this site epicurious


  mousseline
  [moos-LEEN]
  1. Any sauce to which whipped cream or beaten egg whites have been added just prior to serving to give it a light, airy consistency.


So what's the 'orthodox' way of making mousseline sauce?

And what difference would it make to use the whites instead of the yolks?

I guess, I will have to try it one of these days, but was wondering about.
It should* be made (classically) with egg whites.  It is supposed to be a light hollandaise based sauce.  Obviously the white is lighter. All the fat from in the mousseline should come from the butter, not yolk.