Week 7: Stage 3 Overview: Transport, Kinetics and Transformation

Why cooking is best modelled as three coupled processes — heat and mass transport, reaction kinetics, and phase transition — not one vague "heat."

5 April 2027

Outline#

• Recap: Stage 2 explained what gives a food material its structure at rest. Stage 3 asks how cooking changes that structure — the processes a cook actually controls with a stove, a timer and a lid.
• Three distinct processes, each with its own governing model, that together make up “cooking”: heat conducting or convecting into the material (Module 7), a chemical reaction proceeding at a temperature- dependent rate (Module 8), and a material crossing a phase or state boundary — melting, gelatinising, vitrifying (Module 9).
• Why these are modelled separately even though they happen simultaneously in a real pot: each has a distinct governing equation and a distinct timescale, and conflating them (treating “doneness” as one number) is exactly the kind of unexamined claim this course asks you to unpack.
• Setting up Module 9’s glass-transition framing, which Stage 4 depends on directly: a food crossing from a rubbery to a glassy state on cooling or drying is the same physical event as a food losing crispness on re-humidifying, examined from opposite directions.
• What this sets up for Stage 4: Modules 10–12 fit models to data and invert them, and every model they use is drawn from this stage.