Many beurre blanc recipes call for adding between 1/2 and 1 tsp of lemon juice at the end. I was wondering if this plays any chemical role to the sauce or if it is added to enhance flavor? Thank you.
Vinegar and shallots reduced by 2/3s. Remove from heat and whip in whole butter with the tines of a fork. It won't hold together any longer than it takes to eat whatever it's on so a little extra acid shouldn't hurt. Feel free to add whatever your muse dictates.
The acid helps to keep the butter emulsified.
I suspected it has something to do with emulsification, but since vinegar is a major ingredient as well, I was unsure about the lemon juice. Do the two acids behave differently here?
Oh no, that would be for flavor. I've seen recipes with just lemon and just vinegar.
Agree with Greenstuff. The acid helps set the emulsion by rapidly coagulating proteins, and also adds a layer of flavor.