Blanch / Blanchir

Blanching is a controlled short-exposure cooking technique in which food — most often vegetables, but also nuts, offal, or fruit — is plunged into a large volume of vigorously boiling water, held for a timed interval measured in seconds to a few minutes, then removed. The purpose varies by application. For green vegetables (haricots verts, asparagus, peas, broccolini), blanching activates and then denatures the chlorophyll-degrading enzyme chlorophyllase before it can destroy the vivid green color; a rapid follow-up ice bath arrests enzyme activity and cooking simultaneously, locking in vibrant color and crisp-tender texture. For almonds, tomatoes, stone fruits, and chestnuts, 30–60 seconds in boiling water loosens the skin so it peels cleanly by hand. For offal and strongly flavored meats (sweetbreads, trotters, salt-cured pork belly, bones for a consommé), blanching — called blanchir in classical French — removes blood, impurities, excess salt, and off-odors before the main cooking begins. For leafy greens such as spinach or chard, 30 seconds extracts bitter oxalic acid and wilts the leaf for compression or stuffing. Water quantity matters critically: a large pot (at least 6 L of water per 500 g of vegetables) ensures the boiling temperature recovers in seconds after food is added, which keeps the window of enzyme activity predictable. Salt — 10 g per liter, approximating seawater — seasons, raises the boiling point marginally, and helps preserve pigment.

“Blanch the haricots verts for 90 seconds in heavily salted boiling water, then transfer immediately to an ice bath to set their color before dressing.”

• TechniqueBlanch-and-Shock
• ConceptEnzyme Activity
• TechniqueParboil

1. 1.Harold McGee — On Food and Cooking (2004)
2. 2.The Culinary Institute of America — The Professional Chef, 9th ed. (2011)
3. 3.Auguste Escoffier — Le Guide Culinaire (1903)
4. 4.Heston Blumenthal — The Fat Duck Cookbook (2008)

Confidence: high