Caramelisation and the Maillard reaction both produce brown colours and complex flavours through heat, but they are chemically distinct processes with different requirements, different products, and different optimal conditions. Conflating them produces recipes with imprecise instructions and results that vary unpredictably.
**Caramelisation:** - Involves sugars only — no protein or amino acid required - Temperature: 160–180°C for sucrose (the most common); varies by sugar type - Fructose: 110°C (lowest) - Glucose: 160°C - Sucrose: 160–180°C - Lactose: 203°C (the highest — why milk caramelises slower than other sugars) - Products: furanones (caramel flavour), diacetyl (butterscotch), hydroxymethylfurfural (HMF) - Application: caramel sauce, tarte tatin, crème brûlée crust, caramelised onions - Does not require protein — a sugar solution without protein will caramelise **The Maillard reaction:** - Requires both amino acid and reducing sugar - Temperature: begins above 120°C, optimal 140–165°C - Products: hundreds of compounds specific to the amino acid and sugar combination - Application: meat searing, bread baking, coffee roasting, chocolate roasting - Cannot occur without protein **The practical distinction:** - Onions "caramelised" by long, slow cooking: actually a combination of both. The sugars in onions caramelise; the amino acids in the onion protein undergo Maillard reactions. The deep flavour of correctly cooked onions comes from both processes. - Crème brûlée crust: pure caramelisation — no protein at the surface (egg protein is below the surface). - Seared steak crust: primarily Maillard — the protein-sugar combination produces the characteristic meat-specific flavour compounds. - Bread crust: primarily Maillard — the gluten proteins and the sugars of the dough react together.
Modernist Cuisine Vol. 2