Julia Child's documentation of mayonnaise — both the hand method and the recovery of broken mayonnaise — remains the clearest explanation of emulsion mechanics in popular food writing. Her specific instruction on how to rescue a broken sauce transformed home cooking by removing the fear of the irreversible failure.
A stable emulsion of egg yolk, acid, and oil produced by adding oil drop by drop to beaten yolk until the emulsion establishes, then adding oil more quickly as the emulsion stabilises. The science: lecithin in the egg yolk positions itself at the oil-water interface, preventing the fat droplets from coalescing.
- Room temperature ingredients — cold egg yolks and cold oil resist emulsification. All ingredients must be at the same temperature [VERIFY: approximately 20°C] - The first addition is critical — the first drops of oil must be added one at a time, whisking constantly, until a thick, stable emulsion has formed in the base of the bowl. Once established, oil can be added in a thin stream - Acid timing: Child adds acid (lemon juice or vinegar) at the beginning AND at the end. Beginning acid: provides some emulsification assistance and flavour base. Ending acid: adjusts flavour after the oil has diluted the initial seasoning - The recovery technique: if the mayonnaise breaks (oil separates), start fresh with a new yolk in a clean bowl and slowly whisk the broken mayonnaise into it as if it were the oil. The new yolk has enough lecithin to re-emulsify the broken batch [VERIFY] - 240ml oil maximum per yolk — beyond this the emulsion is destabilised by excess oil and breaks spontaneously [VERIFY] Decisive moment: The establishment — when the yolk and first drops of oil thicken into a pale, dense, slow-moving mass that clings to the whisk. This is the emulsion forming. From this moment oil can be added more quickly without risk of breaking.
ZUNI CAFÉ COOKBOOK + JULIA CHILD