At what stage should lemon juice be added to Hollandaise sauce?

Adding lemon juice to Hollandaise sauce after thickening is crucial for several reasons.

First, the process of making Hollandaise involves emulsifying egg yolks with melted butter over gentle heat. This process requires careful temperature control; adding lemon juice too early can interfere with the emulsion and prevent the sauce from thickening properly, as the acidity of the lemon can denature the proteins in the egg yolks prematurely.

By waiting until the sauce has reached the desired thickness, you can then incorporate the lemon juice effectively. This timing allows the citrus to blend smoothly into the sauce without compromising its stability. Moreover, adding the lemon juice after thickening ensures that the sauce maintains a light and airy texture while imparting the desired acidity, enhancing the overall flavor profile without overwhelming it.

In summary, timing the addition of lemon juice until after the sauce has thickened ensures the successful emulsification of the ingredients, resulting in a stable and flavorful Hollandaise sauce.