Poaching appears throughout classical French technique as the cooking method for delicate proteins that cannot withstand direct heat: eggs, quenelles, fish, and whole poultry. The French white-cut chicken (poulet poché) and the English boiled chicken represent the same technique — poaching — applied to the same protein with entirely different cultural aesthetics in presentation.
Poaching is cooking a protein in liquid at a temperature below the boil — typically 75–85°C for most proteins, with variations specific to each. At this temperature, protein fibres coagulate gently rather than seizing and expelling moisture, producing a result that retains maximum juiciness. The liquid is not merely a cooking medium; it is a flavour exchange — the protein seasons the liquid and the liquid seasons the protein.
- **Temperature by protein type:** - Fish: 65–70°C — the lowest practical poaching temperature; fish protein denatures rapidly and overcooks easily above 70°C - Chicken (whole): 80–85°C — the lower temperature maintains juicy, silky breast flesh - Eggs: 82–88°C — below this the white sets incompletely; above this the white toughens before the yolk is warm - Quenelles: 80–85°C — gentle heat allows the protein network to set gradually and the preparation to expand - **Cold start for whole birds:** Placing a whole bird in cold court-bouillon or stock and raising the temperature slowly produces more evenly cooked flesh than plunging into hot liquid. - **Aromatics:** The poaching liquid should be flavoured before the protein enters — a court-bouillon of wine, vegetable, and herbs for fish; a seasoned chicken stock for poultry. An unseasoned poaching liquid produces an unseasoned result. - **The ice bath:** Immediately after removing from the liquid, some proteins (particularly chicken for cold service) benefit from an ice bath, which stops the cooking precisely and tightens the skin. Decisive moment: For fish: the moment of opacity. A fish fillet transitions from translucent to opaque as the proteins denature — watch the transition happening from the outside in. The fish is done when the opaque zone has reached the centre. At 65°C, this is a gentle transition; at 85°C it happens in seconds. The window between correct and overcooked at 70°C is approximately 90 seconds. Sensory tests: **Sight — fish:** The flesh changes from translucent grey-green to opaque white as it poaches. The transition zone is visible and progresses from the outside in. When the centre of the thickest part shows no translucency, the fish is done. **Feel — chicken:** Press the thigh joint where it meets the body. No pink in the joint. The juices that run out of the pierced thigh are clear.
Jacques Pépin's Complete Techniques